U.S. patent application number 12/617658 was filed with the patent office on 2010-04-15 for system and method for providing phototherapy to the brain.
Invention is credited to Luis De Taboada, Jackson Streeter.
Application Number | 20100094384 12/617658 |
Document ID | / |
Family ID | 34865136 |
Filed Date | 2010-04-15 |
United States Patent
Application |
20100094384 |
Kind Code |
A1 |
De Taboada; Luis ; et
al. |
April 15, 2010 |
SYSTEM AND METHOD FOR PROVIDING PHOTOTHERAPY TO THE BRAIN
Abstract
A therapeutic treatment system and method are provided. The
therapeutic system includes a light source adapted to irradiate at
least a portion of the brain with light and a non-light energy
source adapted to apply non-light energy to the at least a portion
of the brain. The therapeutic treatment method includes irradiating
at least a portion of a patient's brain with light and applying a
non-light energy to the at least a portion of the patient's brain.
The therapeutic treatment method provides therapeutic treatment
without damaging the scalp tissue of the patient.
Inventors: |
De Taboada; Luis; (Carlsbad,
CA) ; Streeter; Jackson; (Reno, NV) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET, FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
34865136 |
Appl. No.: |
12/617658 |
Filed: |
November 12, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11482220 |
Jul 7, 2006 |
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12617658 |
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10682379 |
Oct 9, 2003 |
7303578 |
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11482220 |
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10287432 |
Nov 1, 2002 |
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10682379 |
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60442693 |
Jan 24, 2003 |
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60487979 |
Jul 17, 2003 |
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60502147 |
Sep 11, 2003 |
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60336436 |
Nov 1, 2001 |
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60369260 |
Apr 2, 2002 |
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Current U.S.
Class: |
607/88 ; 600/9;
601/2 |
Current CPC
Class: |
A61N 5/0617 20130101;
A61N 5/0613 20130101; A61N 2005/067 20130101; A61N 2005/0647
20130101; A61N 1/40 20130101; A61N 2005/0652 20130101; A61N 5/0622
20130101; A61N 2005/0659 20130101; A61N 7/00 20130101; A61N
2005/007 20130101 |
Class at
Publication: |
607/88 ; 601/2;
600/9 |
International
Class: |
A61N 5/06 20060101
A61N005/06; A61N 7/00 20060101 A61N007/00; A61N 2/00 20060101
A61N002/00 |
Claims
1. A method of controlling a combined therapeutic treatment to a
patient's brain to treat at least one of stroke and Alzheimer's
disease, the method comprising: transmitting at least one first
control signal to a light source, wherein the light source is
responsive to the at least one first control signal by generating
light configured for transmission through the scalp of the patient
to a target area of the brain; and transmitting at least one second
control signal to an ultrasound transducer, wherein the ultrasound
transducer is responsive to the at least one second control signal
by generating ultrasonic energy configured for transmission through
intervening tissue to the target area of the brain, and wherein
said light and ultrasonic energy are configured for providing
combined treatment to the brain to treat at least one of stroke and
Alzheimer's disease.
2. The method of claim 1, wherein said light and said ultrasonic
energy are configured for providing combined treatment to the brain
without ablating the intervening tissue.
3. The method of claim 1, wherein the ultrasound transducer is
responsive to the at least one second control signal by
transmitting ultrasonic energy concurrently with transmitting of
light from the light source in response to the at least one first
control signal.
4. The method of claim 1, wherein the light has an irradiance
between about 0.01 mW/cm.sup.2 and about 100 mW/cm.sup.2 at a depth
of 3 centimeters below the surface of the patient's scalp.
5. The method of claim 1, wherein the light has a wavelength
between about 780 nm and about 840 nm.
6. A method of treating stroke in a patient's brain, the method
comprising: identifying a patient suffering from an ischemic event;
irradiating at least a portion of the patient's brain through the
skull of said patient with light having a wavelength between about
780 nm and about 840 nm, wherein said light has an irradiance
sufficient to penetrate through the skull and cause neuroprotective
effects following the ischemic event; applying a non-light energy
to at least the portion of the patient's brain, wherein said light
and non-light energy are configured to provide treatment to at
least the portion of the patient's brain without damaging the scalp
tissue of the patient.
7. The method of claim 6, wherein the non-light energy comprises
ultrasonic energy.
8. The method of claim 6, wherein the non-light energy comprises
radio frequency energy.
9. The method of claim 6, wherein the non-light energy comprises
magnetic energy.
10. The method of claim 6, wherein the light has an irradiance
between about 100 mW/cm.sup.2 and about 10 W/cm.sup.2 at the
patient's scalp.
11. The method of claim 6, wherein applying the non-light energy
occurs concurrently with irradiating the at least a portion of the
patient's brain.
12. A method of treating Alzheimer's disease in a patient's brain,
the method comprising: identifying a patient suffering from
Alzheimer's disease; irradiating at least a portion of the
patient's brain through the skull of said patient with light,
wherein said light has an irradiance sufficient to penetrate
through the skull and cause neuroprotective effects; applying a
non-light energy to at least the portion of the patient's brain,
wherein said light and non-light energy are configured to provide
therapeutic treatment to at least the portion of the patient's
brain without damaging the scalp tissue of the patient.
13. The method of claim 12, wherein applying the non-light energy
occurs concurrently with irradiating the at least a portion of the
patient's brain.
14. The method of claim 12, wherein the light has a wavelength
between about 780 nm and about 840 nm.
15. The method of claim 12, wherein the non-light energy comprises
ultrasonic energy.
16. The method of claim 12, wherein the non-light energy comprises
radio frequency energy.
17. The method of claim 12, wherein the non-light energy comprises
magnetic energy.
18. The method of claim 12, wherein the light has an irradiance
between about 100 mW/cm.sup.2 and about 10 W/cm.sup.2 at the
patient's scalp.
19. A therapeutic system for providing therapy to a patient's
brain, the therapeutic system comprising: a light source adapted to
irradiate at least a portion of the brain with light; an element
adapted to inhibit temperature increases at the scalp, wherein the
element is adapted to apply pressure to at least a portion of the
scalp to blanch the portion of the scalp, wherein at least a
portion of the element is in an optical path of the light from the
light source to the scalp; and a non-light energy source adapted to
apply non-light energy to at least the portion of the brain.
20. The therapeutic system of claim 19, wherein the light has a
wavelength between about 780 nm and about 840 nm.
21. The therapeutic system of claim 19, wherein the non-light
energy source comprises an ultrasonic energy source.
22. The therapeutic system of claim 19, wherein the non-light
energy source comprises a radio frequency field source.
23. The therapeutic system of claim 19, wherein the non-light
energy source comprises a magnetic field source.
24. The therapeutic system of claim 19, wherein the light source is
adapted to irradiate at least a portion of the brain with light
having an irradiance between about 0.01 mW/cm.sup.2 at a depth of
approximately 2 centimeters below the patient's dura.
25. A therapeutic system for providing therapy to a patient's
brain, the therapeutic system comprising: a light source adapted to
irradiate at least a portion of the brain with light; and a
non-light energy source adapted to apply non-light energy to at
least the portion of the brain, wherein the light source and the
non-light source are adapted to irradiate at least the portion of
the brain and to apply the non-light energy to at least the portion
of the brain concurrently.
26. The therapeutic system of claim 25, wherein the light has a
wavelength between about 780 nm and about 840 nm.
27. The therapeutic system of claim 25, wherein the non-light
energy source comprises an ultrasonic energy source.
28. The therapeutic system of claim 25, wherein the non-light
energy source comprises a radio frequency field source.
29. The therapeutic system of claim 25, wherein the non-light
energy source comprises a magnetic field source.
30. The therapeutic system of claim 25, wherein the light source is
adapted to irradiate at least a portion of the brain with light
having an irradiance between about 0.01 mW/cm.sup.2 at a depth of
approximately 2 centimeters below the patient's dura.
31.-50. (canceled)
Description
CLAIM OF PRIORITY
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/482,220, filed Jul. 7, 2006, which is a
continuation of U.S. patent application Ser. No. 10/682,379, filed
Oct. 9, 2003, and which claims benefit to U.S. Provisional
Application No. 60/442,693, filed Jan. 24, 2003, U.S. Provisional
Application No. 60/487,979, filed Jul. 17, 2003, and U.S.
Provisional Application No. 60/502,147, filed Sep. 11, 2003, and
which is a continuation-in-part of U.S. patent application Ser. No.
10/287,432, filed Nov. 1, 2002, which claims benefit to U.S.
Provisional Application No. 60/336,436, filed Nov. 1, 2001 and U.S.
Provisional Application No. 60/369,260, filed Apr. 2, 2002. U.S.
patent application Ser. Nos. 11/482,220, 10/682,379 and 10/287,432
and U.S. Provisional Application Nos. 60/442,693, 60/487,979,
60/502,147, 60/336,436, and 60/369,260 are incorporated in their
entireties by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates in general to phototherapy,
and more particularly, to novel apparatuses and methods for
phototherapy of brain tissue affected by stroke.
[0004] 2. Description of the Related Art
[0005] Stroke, also called cerebrovascular accident (CVA), is a
sudden disruption of blood flow to a discrete area of the brain
that is brought on by a clot lodging in an artery supplying that
area of that brain, or by a cerebral hemorrhage due to a ruptured
aneurysm or a burst artery. The consequence of stroke is a loss of
function in the affected brain region and concomitant loss of
bodily function in areas of the body controlled by the affected
brain region. Depending upon the extent and location of the primary
insult in the brain, loss of function varies greatly from mild or
severe, and may be temporary or permanent. Lifestyle factors such
as smoking, diet, level of physical activity and high cholesterol
increase the risk of stroke, and thus stroke is a major cause of
human suffering in developed nations. Stroke is the third leading
cause of death in most developed nations, including the United
States.
[0006] Until recently, stroke treatment was restricted to providing
basic life support at the time of the stroke, followed by
rehabilitation. Recently, new drug therapies have taken the
approach of breaking up blood clots or protecting surviving at-risk
neurons from further damage.
[0007] Thrombolytic therapy includes aspirin or intravenous heparin
to prevent further clot formation and to maintain blood flow after
an ischemic stroke. Thrombolytic drugs include tissue plasminogen
activator (TPA) and genetically engineered versions thereof, and
streptokinase. However, streptokinase does not appear to improve
the patient's outlook unless administered early (within three hours
of stroke). TPA when administered early appears to substantially
improve prognosis, but slightly increases the risk of death from
hemorrhage. In addition, over half of stroke patients arrive at the
hospital more than three hours after a stroke, and even if they
arrive quickly, a CT scan must first confirm that the stroke is not
hemorrhagic, which delays administration of the drug. Also,
patients taking aspirin or other blood thinners and patients with
clotting abnormalities should not be given TPA.
[0008] Neuroprotective drugs target surviving but endangered
neurons in a zone of risk surrounding the area of primary infarct.
Such drugs are aimed at slowing down or preventing the death of
such neurons, to reduce the extent of brain damage. Certain
neuroprotective drugs are anti-excitotoxic, i.e., work to block the
excitotoxic effects of excitatory amino acids such as glutamate
that cause cell membrane damage under certain conditions. Other
drugs such as citicoline work by repairing damaged cell membranes.
Lazaroids such as Tirilazed (Freedox) counteract oxidative stress
produced by oxygen-free radicals produced during stroke. Other
drugs for stroke treatment include agents that block the enzyme
known as PARP, and calcium-channel blockers such as nimodipine
(Nimotop) that relax the blood vessels to prevent vascular spasms
that further limit blood supply. However, the effect of nimodipine
is reduced if administered beyond six hours after a stroke and it
is not useful for ischemic stroke. In addition, drug therapy
includes the risk of adverse side effects and immune responses.
[0009] Surgical treatment for stroke includes carotid
endarterectomy, which appears to be especially effective for
reducing the risk of stroke recurrence for patients exhibiting
arterial narrowing of more than 70%. However, endarterectomy is
highly invasive, and risk of stroke recurrence increases
temporarily after surgery. Experimental stroke therapies include an
angiography-type or angioplasty-type procedure using a thin
catheter to remove or reduce the blockage from a clot. However,
such procedures have extremely limited availability and increase
the risk of embolic stroke. Other surgical interventions, such as
those to repair an aneurysm before rupture remain controversial
because of disagreement over the relative risks of surgery versus
leaving the aneurysm untreated.
[0010] Against this background, a high level of interest remains in
finding new and improved therapeutic apparatuses and methods for
the treatment of stroke. In particular, a need remains for
relatively inexpensive and non-invasive approaches to treating
stroke that also avoid the limitations of drug therapy.
SUMMARY OF THE INVENTION
[0011] One aspect of the present invention provides a therapy
apparatus for treating a patient's brain. The therapy apparatus
comprises a light source having an output emission area positioned
to irradiate a portion of the brain with an efficacious power
density and wavelength of light. The therapy apparatus further
comprises an element interposed between the light source and the
patient's scalp. The element is adapted to inhibit temperature
increases at the scalp caused by the light.
[0012] Another aspect of the present invention provides a therapy
apparatus for treating brain tissue. The therapy apparatus
comprises a light source positioned to irradiate at least a portion
of a patient's head with light. The light has a wavelength and
power density which penetrates the cranium to deliver an
efficacious amount of light to brain tissue. The therapy apparatus
further comprises a material which inhibits temperature increases
of the head.
[0013] Another aspect of the present invention provides a therapy
apparatus for treating a patient's brain. The therapy apparatus
comprises a light source adapted to irradiate at least a portion of
the brain with an efficacious power density and wavelength of
light. The therapy apparatus further comprises an element adapted
to inhibit temperature increases at the scalp. At least a portion
of the element is in an optical path of the light from the light
source to the scalp.
[0014] Another aspect of the present invention provides a therapy
apparatus for treating a patient's brain. The therapy apparatus
comprises a light source adapted to irradiate at least a portion of
the brain with an efficacious power density and wavelength of
light. The therapy apparatus further comprises a controller for
energizing said light source so as to selectively produce a
plurality of different irradiation patterns on the patient's scalp.
Each of said irradiation patterns is comprised of at least one
illumination area that is small compared to the patient's scalp,
and at least one non-illuminated area.
[0015] Another aspect of the present invention provides a method
comprising interposing a head element between a light source and
the patient's scalp. The element is comprised of a material which,
for an efficacious power density at the brain, inhibits temperature
increases at the scalp.
[0016] Another aspect of the present invention provides a therapy
apparatus for treating a patient's brain. The therapy apparatus
comprises a light source adapted to irradiate at least a portion of
the brain with an efficacious power density and wavelength of
light. The therapy apparatus further comprises a biomedical sensor
configured to provide real-time feedback information. The therapy
apparatus further comprises a controller coupled to the light
source and the biomedical sensor. The controller is configured to
adjust said light source in response to the real-time feedback
information.
[0017] Another aspect of the present invention provides a method of
treating brain tissue. The method comprises introducing light of an
efficacious power density onto brain tissue by directing light
through the scalp of a patient. Directing the light comprises
providing a sufficiently large spot size on said scalp to reduce
the power density at the scalp below the damage threshold of scalp
tissue, while producing sufficient optical power at said scalp to
achieve said efficacious power density at said brain tissue.
[0018] Another aspect of the present invention provides a method of
treating a patient's brain. The method comprises covering at least
a significant portion of the patient's scalp with a light-emitting
blanket.
[0019] Another aspect of the present invention provides a method of
treating a patient's brain following a stroke. The method comprises
applying low-level light therapy to the brain no earlier than
several hours following said stroke.
[0020] Another aspect of the present invention provides a method
for treating a patient's brain. The method comprises introducing
light of an efficacious power density onto a target area of the
brain by directing light through the scalp of the patient. The
light has a plurality of wavelengths and the efficacious power
density is at least 0.01 mW/cm.sup.2 at the target area.
[0021] Another aspect of the present invention provides a method
for treating a patient's brain. The method comprises directing
light through the scalp of the patient to a target area of the
brain concurrently with applying an electromagnetic field to the
brain. The light has an efficacious power density at the target
area and the electromagnetic field has an efficacious field
strength.
[0022] Another aspect of the present invention provides a method
for treating a patient's brain. The method comprises directing an
efficacious power density of light through the scalp of the patient
to a target area of the brain concurrently with applying an
efficacious amount of ultrasonic energy to the brain.
[0023] Another aspect of the present invention provides a method of
providing a neuroprotective effect in a patient that had an
ischemic event in the brain. The method comprises identifying a
patient who has experienced an ischemic event in the brain. The
method further comprises estimating the time of the ischemic event.
The method further comprises commencing administration of a
neuroprotective effective amount of light energy to the brain no
less than about two hours following the time of the ischemic
event.
[0024] For purposes of summarizing the present invention, certain
aspects, advantages, and novel features of the present invention
have been described herein above. It is to be understood, however,
that not necessarily all such advantages may be achieved in
accordance with any particular embodiment of the present invention.
Thus, the present invention may be embodied or carried out in a
manner that achieves or optimizes one advantage or group of
advantages as taught herein without necessarily achieving other
advantages as may be taught or suggested herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 schematically illustrates a therapy apparatus
comprising a cap which fits securely over the patient's head.
[0026] FIG. 2 schematically illustrates a fragmentary
cross-sectional view taken along the lines 2-2 of FIG. 1, showing
one embodiment of a portion of a therapy apparatus comprising an
element and its relationship to the scalp and brain.
[0027] FIG. 3 schematically illustrates an embodiment with an
element comprising a container coupled to an inlet conduit and an
outlet conduit for the transport of a flowing material through the
element.
[0028] FIG. 4A schematically illustrates a fragmentary
cross-sectional view taken along the lines 2-2 of FIG. 1, showing
another embodiment of a portion of a therapy apparatus comprising
an element with a portion contacting the scalp and a portion spaced
away from the scalp.
[0029] FIG. 4B schematically illustrates a fragmentary
cross-sectional view taken along the lines 2-2 of FIG. 1, showing
an embodiment of a portion of a therapy apparatus comprising a
plurality of light sources and an element with portions contacting
the scalp and portions spaced away from the scalp.
[0030] FIGS. 5A and 5B schematically illustrate cross-sectional
views of two embodiments of the element in accordance with FIG. 4B
taken along the line 4-4.
[0031] FIGS. 6A-6C schematically illustrate an embodiment in which
the light sources are spaced away from the scalp.
[0032] FIGS. 7A and 7B schematically illustrate the diffusive
effect on the light by the element.
[0033] FIGS. 8A and 8B schematically illustrate two light beams
having different cross-sections impinging a patient's scalp and
propagating through the patients head to irradiate a portion of the
patient's brain tissue.
[0034] FIG. 9A schematically illustrates a therapy apparatus
comprising a cap and a light source comprising a light blanket.
[0035] FIGS. 9B and 9C schematically illustrate two embodiments of
the light blanket.
[0036] FIG. 10 schematically illustrates a therapy apparatus
comprising a flexible strap and a housing.
[0037] FIG. 11 schematically illustrates a therapy apparatus
comprising a handheld probe.
[0038] FIG. 12 is a block diagram of a control circuit comprising a
programmable controller.
[0039] FIG. 13 schematically illustrates a therapy apparatus
comprising a light source and a controller.
[0040] FIG. 14 schematically illustrates a light source comprising
a laser diode and a galvometer with a mirror and a plurality of
motors.
[0041] FIGS. 15A and 15B schematically illustrate two irradiation
patterns that are spatially shifted relative to each other.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0042] Low level light therapy ("LLLT") or phototherapy involves
therapeutic administration of light energy to a patient at lower
power outputs than those used for cutting, cauterizing, or ablating
biological tissue, resulting in desirable biostimulatory effects
while leaving tissue undamaged. In non-invasive phototherapy, it is
desirable to apply an efficacious amount of light energy to the
internal tissue to be treated using light sources positioned
outside the body. (See, e.g., U.S. Pat. No. 6,537,304 to Oron and
U.S. patent application Ser. No. 10/353,130, both of which are
incorporated in their entireties by reference herein.) However,
absorption of the light energy by intervening tissue can limit the
amount of light energy delivered to the target tissue site, while
heating the intervening tissue. In addition, scattering of the
light energy by intervening tissue can limit the power density or
energy density delivered to the target tissue site. Brute force
attempts to circumvent these effects by increasing the power and/or
power density applied to the outside surface of the body can result
in damage (e.g., burning) of the intervening tissue.
[0043] Non-invasive phototherapy methods are circumscribed by
setting selected treatment parameters within specified limits so as
to preferably avoid damaging the intervening tissue. A review of
the existing scientific literature in this field would cast doubt
on whether a set of undamaging, yet efficacious, parameters could
be found. However, certain embodiments, as described herein,
provide devices and methods which can achieve this goal.
[0044] Such embodiments may include selecting a wavelength of light
at which the absorption by intervening tissue is below a damaging
level. Such embodiments may also include setting the power output
of the light source at very low, yet efficacious, power densities
(e.g., between approximately 100 .mu.W/cm.sup.2 to approximately 10
W/cm.sup.2) at the target tissue site, and time periods of
application of the light energy at a few seconds to minutes to
achieve an efficacious energy density at the target tissue site
being treated. Other parameters can also be varied in the use of
phototherapy. These other parameters contribute to the light energy
that is actually delivered to the treated tissue and may play key
roles in the efficacy of phototherapy. In certain embodiments, the
irradiated portion of the brain can comprise the entire brain.
Element to Inhibit Temperature Increases at the Scalp
[0045] FIGS. 1 and 2 schematically illustrate an embodiment of a
therapy apparatus 10 for treating a patient's brain 20. The therapy
apparatus 10 comprises a light source 40 having an output emission
area 41 positioned to irradiate a portion of the brain 20 with an
efficacious power density and wavelength of light. The therapy
apparatus 10 further comprises an element 50 interposed between the
light source 40 and the patient's scalp 30. The element 50 is
adapted to inhibit temperature increases at the scalp 30 caused by
the light.
[0046] As used herein, the term "element" is used in its broadest
sense, including, but not limited to, as a reference to a
constituent or distinct part of a composite device. In certain
embodiments, the element 50 is adapted to contact at least a
portion of the patient's scalp 30, as schematically illustrated in
FIGS. 1-4. In certain such embodiments, the element 50 is in
thermal communication with and covers at least a portion of the
scalp 30. In other embodiments, the element 50 is spaced away from
the scalp 30 and does not contact the scalp 30.
[0047] In certain embodiments, the light passes through the element
50 prior to reaching the scalp 30 such that the element 50 is in
the optical path of light propagating from the light source 40,
through the scalp 30, through the bones, tissues, and fluids of the
head (schematically illustrated in FIG. 1 by the region 22), to the
brain 20. In certain embodiments, the light passes through a
transmissive medium of the element 50, while in other embodiments,
the light passes through an aperture of the element 50. As
described more fully below, the element 50 may be utilized with
various embodiments of the therapy apparatus 10.
[0048] In certain embodiments, the light source 40 is disposed on
the interior surface of a cap 60 which fits securely over the
patient's head. The cap 60 provides structural integrity for the
therapy apparatus 10 and holds the light source 40 and element 50
in place. Exemplary materials for the cap 60 include, but are not
limited to, metal, plastic, or other materials with appropriate
structural integrity. The cap 60 may include an inner lining 62
comprising a stretchable fabric or mesh material, such as Lycra or
nylon. In certain embodiments, the light source 40 is adapted to be
removably attached to the cap 60 in a plurality of positions so
that the output emission area 41 of the light source 40 can be
advantageously placed in a selected position for treatment of a
stroke or CVA in any portion of the brain 20. In other embodiments,
the light source 40 can be an integral portion of the cap 60.
[0049] The light source 40 illustrated by FIGS. 1 and 2 comprises
at least one power conduit 64 coupled to a power source (not
shown). In some embodiments, the power conduit 64 comprises an
electrical conduit which is adapted to transmit electrical signals
and power to an emitter (e.g., laser diode or light-emitting
diode). In certain embodiments, the power conduit 64 comprises an
optical conduit (e.g., optical waveguide) which transmits optical
signals and power to the output emission area 41 of the light
source 40. In certain such embodiments, the light source 40
comprises optical elements (e.g., lenses, diffusers, and/or
waveguides) which transmit at least a portion of the optical power
received via the optical conduit 64. In still other embodiments,
the therapy apparatus 10 contains a power source (e.g., a battery)
and the power conduit 64 is substantially internal to the therapy
apparatus 10.
[0050] In certain embodiments, the patient's scalp 30 comprises
hair and skin which cover the patient's skull. In other
embodiments, at least a portion of the hair is removed prior to the
phototherapy treatment, so that the therapy apparatus 10
substantially contacts the skin of the scalp 30.
[0051] In certain embodiments, the element 50 is adapted to contact
the patient's scalp 30, thereby providing an interface between the
therapy apparatus 10 and the patient's scalp 30. In certain such
embodiments, the element 50 is coupled to the light source 40 and
in other such embodiments, the element is also adapted to conform
to the scalp 30, as schematically illustrated in FIG. 1. In this
way, the element 50 positions the output emission area 41 of the
light source 40 relative to the scalp 30. In certain such
embodiments, the element 50 is mechanically adjustable so as to
adjust the position of the light source 40 relative to the scalp
30. By fitting to the scalp 30 and holding the light source 40 in
place, the element 50 inhibits temperature increases at the scalp
30 that would otherwise result from misplacement of the light
source 40 relative to the scalp 30. In addition, in certain
embodiments, the element 50 is mechanically adjustable so as to fit
the therapy apparatus 10 to the patient's scalp 30.
[0052] In certain embodiments, the element 50 provides a reusable
interface between the therapy apparatus 10 and the patient's scalp
30. In such embodiments, the element 50 can be cleaned or
sterilized between uses of the therapy apparatus, particularly
between uses by different patients. In other embodiments, the
element 50 provides a disposable and replaceable interface between
the therapy apparatus 10 and the patient's scalp 30. By using
pre-sterilized and pre-packaged replaceable interfaces, certain
embodiments can advantageously provide sterilized interfaces
without undergoing cleaning or sterilization processing immediately
before use.
[0053] In certain embodiments, the element 50 comprises a container
(e.g., a cavity or bag) containing a material (e.g., gel). The
container can be flexible and adapted to conform to the contours of
the scalp 30. Other exemplary materials contained in the container
of the element 50 include, but are not limited to, thermal exchange
materials such as glycerol and water. The element 50 of certain
embodiments substantially covers the entire scalp 30 of the
patient, as schematically illustrated in FIG. 2. In other
embodiments, the element 50 only covers a localized portion of the
scalp 30 in proximity to the irradiated portion of the scalp
30.
[0054] In certain embodiments, at least a portion of the element 50
is within an optical path of the light from the light source 40 to
the scalp 30. In such embodiments, the element 50 is substantially
optically transmissive at a wavelength of the light emitted by the
output emission area 41 of the light source 40 and is adapted to
reduce back reflections of the light. By reducing back reflections,
the element 50 increases the amount of light transmitted to the
brain 20 and reduces the need to use a higher power light source 40
which may otherwise create temperature increases at the scalp 30.
In certain such embodiments, the element 50 comprises one or more
optical coatings, films, layers, membranes, etc. in the optical
path of the transmitted light which are adapted to reduce back
reflections.
[0055] In certain such embodiments, the element 50 reduces back
reflections by fitting to the scalp 30 so as to substantially
reduce air gaps between the scalp 30 and the element 50 in the
optical path of the light. The refractive-index mismatches between
such an air gap and the element 50 and/or the scalp 30 would
otherwise result in at least a portion of the light propagating
from the light source 40 to the brain 20 to be reflected back
towards the light source 40.
[0056] In addition, certain embodiments of the element 50 comprise
a material having, at a wavelength of light emitted by the light
source 40, a refractive index which substantially matches the
refractive index of the scalp 30 (e.g., about 1.3), thereby
reducing any index-mismatch-generated back reflections between the
element 50 and the scalp 30. Examples of materials with refractive
indices compatible with embodiments described herein include, but
are not limited to, glycerol, water, and silica gels. Exemplary
index-matching gels include, but are not limited to, those
available from Nye Lubricants, Inc. of Fairhaven. Mass.
[0057] In certain embodiments, the element 50 is adapted to cool
the scalp 30 by removing heat from the scalp 30 so as to inhibit
temperature increases at the scalp 30. In certain such embodiments,
the element 50 comprises a reservoir (e.g., a chamber or a conduit)
adapted to contain a coolant. The coolant flows through the
reservoir near the scalp 30. The scalp 30 heats the coolant, which
flows away from the scalp 30, thereby removing heat from the scalp
30 by active cooling. The coolant in certain embodiments circulates
between the element 50 and a heat transfer device, such as a
chiller, whereby the coolant is heated by the scalp 30 and is
cooled by the heat transfer device. Exemplary materials for the
coolant include, but are not limited to, water or air.
[0058] In certain embodiments, the element 50 comprises a container
51 (e.g., a flexible bag) coupled to an inlet conduit 52 and an
outlet conduit 53, as schematically illustrated in FIG. 3. A
flowing material (e.g., water, air, or glycerol) can flow into the
container 51 from the inlet conduit 52, absorb heat from the scalp
30, and flow out of the container 51 through the outlet conduit 53.
Certain such embodiments can provide a mechanical fit of the
container 51 to the scalp 30 and sufficient thermal coupling to
prevent excessive heating of the scalp 30 by the light. In certain
embodiments, the container 51 can be disposable and replacement
containers 51 can be used for subsequent patients.
[0059] In still other embodiments, the element 50 comprises a
container (e.g., a flexible bag) containing a material which does
not flow out of the container but is thermally coupled to the scalp
30 so as to remove heat from the scalp 30 by passive cooling.
Exemplary materials include, but are not limited to, water,
glycerol, and gel. In certain such embodiments, the non-flowing
material can be pre-cooled (e.g., by placement in a refrigerator)
prior to the phototherapy treatment to facilitate cooling of the
scalp 30.
[0060] In certain embodiments, the element 50 is adapted to apply
pressure to at least a portion of the scalp 30. By applying
sufficient pressure, the element 50 can blanch the portion of the
scalp 30 by forcing at least some blood out the optical path of the
light energy. The blood removal resulting from the pressure applied
by the element 50 to the scalp 30 decreases the corresponding
absorption of the light energy by blood in the scalp 30. As a
result, temperature increases due to absorption of the light energy
by blood at the scalp 30 are reduced. As a further result, the
fraction of the light energy transmitted to the subdermal target
tissue of the brain 20 is increased.
[0061] FIGS. 4A and 4B schematically illustrate embodiments of the
element 50 adapted to facilitate the blanching of the scalp 30. In
the cross-sectional view of a portion of the therapy apparatus 10
schematically illustrated in FIG. 4A, certain element portions 72
contact the patient's scalp 30 and other element portions 74 are
spaced away from the scalp 30. The element portions 72 contacting
the scalp 30 provide an optical path for light to propagate from
the light source 40 to the scalp 30. The element portions 72
contacting the scalp 30 also apply pressure to the scalp 30,
thereby forcing blood out from beneath the element portion 72. FIG.
4B schematically illustrates a similar view of an embodiment in
which the light source 40 comprises a plurality of light sources
40a, 40b, 40c.
[0062] FIG. 5A schematically illustrates one embodiment of the
cross-section along the line 4-4 of FIG. 4B. The element portions
72 contacting the scalp 30 comprise ridges extending along one
direction, and the element portions 74 spaced away from the scalp
30 comprise troughs extending along the same direction. In certain
embodiments, the ridges are substantially parallel to one another
and the troughs are substantially parallel to one another. FIG. 5B
schematically illustrates another embodiment of the cross-section
along the line 4-4 of FIG. 4B. The element portions 72 contacting
the scalp 30 comprise a plurality of projections in the form of a
grid or array. More specifically, the portions 72 are rectangular
and are separated by element portions 74 spaced away from the scalp
30, which form troughs extending in two substantially perpendicular
directions. The portions 72 of the element 50 contacting the scalp
30 can be a substantial fraction of the total area of the element
50 or of the scalp 30.
[0063] FIGS. 6A-6C schematically illustrate an embodiment in which
the light sources 40 are spaced away from the scalp 30. In certain
such embodiments, the light emitted by the light sources 40
propagates from the light sources 40 through the scalp 30 to the
brain 20 and disperses in a direction generally parallel to the
scalp 30, as shown in FIG. 6A. The light sources 40 are preferably
spaced sufficiently far apart from one another such that the light
emitted from each light source 40 overlaps with the light emitted
from the neighboring light sources 40 at the brain 20. FIG. 6B
schematically illustrates this overlap as the overlap of circular
spots 42 at a reference depth at or below the surface of the brain
20. FIG. 6C schematically illustrates this overlap as a graph of
the power density at the reference depth of the brain 20 along the
line L-L of FIGS. 6A and 6B. Summing the power densities from the
neighboring light sources 40 (shown as a dashed line in FIG. 6C)
serves to provide a more uniform light distribution at the tissue
to be treated. In such embodiments, the summed power density is
preferably less than a damage threshold of the brain 20 and above
an efficacy threshold.
[0064] In certain embodiments, the element 50 is adapted to diffuse
the light prior to reaching the scalp 30. FIGS. 7A and 7B
schematically illustrate the diffusive effect on the light by the
element 50. An exemplary energy density profile of the light
emitted by a light source 40, as illustrated by FIG. 7A, is peaked
at a particular emission angle. After being diffused by the element
50, as illustrated by FIG. 7B, the energy density profile of the
light does not have a substantial peak at any particular emission
angle, but is substantially evenly distributed among a range of
emission angles. By diffusing the light emitted by the light source
40, the element 50 distributes the light energy substantially
evenly over the area to be illuminated, thereby inhibiting "hot
spots" which would otherwise create temperature increases at the
scalp 30. In addition, by diffusing the light prior to its reaching
the scalp 30, the element 50 can effectively increase the spot size
of the light impinging the scalp 30, thereby advantageously
lowering the power density at the scalp 30, as described more fully
below. In addition, in embodiments with multiple light sources 40,
the element 50 can diffuse the light to alter the total light
output distribution to reduce inhomogeneities.
[0065] In certain embodiments, the element 50 provides sufficient
diffusion of the light such that the power density of the light is
less than a maximum tolerable level of the scalp 30 and brain 20.
In certain other embodiments, the element 50 provides sufficient
diffusion of the light such that the power density of the light
equals a therapeutic value at the target tissue. The element 50 can
comprise exemplary diffusers including, but are not limited to,
holographic diffusers such as those available from Physical Optics
Corp. of Torrance, Calif. and Display Optics P/N SN 1333 from
Reflexite Corp. of Avon, Conn.
Power Density
[0066] , Phototherapy for the treatment of stroke is based in part
on the discovery that power density (i.e., power per unit area or
number of photons per unit area per unit time) and energy density
(i.e., energy per unit area or number of photons per unit area) of
the light energy applied to tissue appear to be significant factors
in determining the relative efficacy of low level phototherapy.
This discovery is particularly applicable with respect to treating
and saving surviving but endangered neurons in a zone of danger
surrounding the primary infarct after a stroke or cerebrovascular
accident (CVA). Preferred methods described herein are based at
least in part on the finding that, given a selected wavelength of
light energy, it is the power density and/or the energy density of
the light delivered to tissue (as opposed to the total power or
total energy delivered to the tissue) that appears to be important
factors in determining the relative efficacy of phototherapy.
[0067] Without being bound by theory, it is believed that light
energy delivered within a certain range of power densities and
energy densities provides the desired biostimulative effect on the
intracellular environment, such that proper function is returned to
previously nonfunctioning or poorly functioning mitochondria in
at-risk neurons. The biostimulative effect may include interactions
with chromophores within the target tissue, which facilitate
production of ATP thereby feeding energy to injured cells which
have experienced decreased blood flow due to the stroke. Because
strokes correspond to blockages or other interruptions of blood
flow to portions of the brain, it is thought that any effects of
increasing blood flow by phototherapy are of less importance in the
efficacy of phototherapy for stroke victims. Further information
regarding the role of power density and exposure time is described
by Hans H. F. I. van Breugel and P. R. Dop Bar in "Power Density
and Exposure Time of He-Ne Laser Irradiation Are More Important
Than Total Energy Dose in Photo-Biomodulation of Human Fibroblasts
In Vitro," Lasers in Surgery and Medicine, Volume 12, pp. 528-537
(1992), which is incorporated in its entirety by reference
herein.
[0068] The significance of the power density used in phototherapy
has ramifications with regard to the devices and methods used in
phototherapy of brain tissue, as schematically illustrated by FIGS.
8A and 8B, which show the effects of scattering by intervening
tissue. Further information regarding the scattering of light by
tissue is provided by V. Tuchin in "Tissue Optics: Light Scattering
Methods and Instruments for Medical Diagnosis," SPIE Press (2000),
Bellingham, Wash., pp. 3-11, which is incorporated in its entirety
by reference herein.
[0069] FIG. 8A schematically illustrates a light beam 80 impinging
a portion 90 of a patient's scalp 30 and propagating through the
patient's head to irradiate a portion 100 of the patient's brain
tissue 20. In the exemplary embodiment of FIG. 8A, the light beam
80 impinging the scalp 30 is collimated and has a circular
cross-section with a radius of 2 cm and a cross-sectional area of
approximately 12.5 cm.sup.2. For comparison purposes, FIG. 8B
schematically illustrates a light beam 82 having a significantly
smaller cross-section impinging a smaller portion 92 of the scalp
30 to irradiate a portion 102 of the brain tissue 20. The light
beam 82 impinging the scalp 30 in FIG. 8B is collimated and has a
circular cross-section with a radius of 1 cm and a cross-sectional
area of approximately 3.1 cm.sup.2. The collimations,
cross-sections, and radii of the light beams 80, 82 illustrated in
FIGS. 8A and 8B are exemplary; other light beams with other
parameters are also compatible with embodiments described herein.
In particular, similar considerations apply to focussed beams or
diverging beams, as they are similarly scattered by the intervening
tissue.
[0070] As shown in FIGS. 8A and 8B, the cross-sections of the light
beams 80, 82 become larger while propagating through the head due
to scattering from interactions with tissue of the head. Assuming
that the angle of dispersion is 15 degrees and the irradiated brain
tissue 20 is 2.5 cm below the scalp 30, the resulting area of the
portion 100 of brain tissue 20 irradiated by the light beam 80 in
FIG. 8A is approximately 22.4 cm.sup.2. Similarly, the resulting
area of the portion 102 of brain tissue 20 irradiated by the light
beam 82 in FIG. 8B is approximately 8.8 cm.sup.2.
[0071] Irradiating the portion 100 of the brain tissue 20 with a
power density of 10 mW/cm.sup.2 corresponds to a total power within
the portion 100 of approximately 224 mW (10 mW/cm.sup.2.times.22.4
cm.sup.2). Assuming only approximately 5% of the light beam 80 is
transmitted between the scalp 30 and the brain tissue 20, the
incident light beam 80 at the scalp 30 will have a total power of
approximately 4480 mW (224 mW/0.05) and a power density of
approximately 358 mW/cm.sup.2 (4480 mW/12.5 cm.sup.2). Similarly,
irradiating the portion 102 of the brain tissue 20 with a power
density of 10 mW/cm.sup.2 corresponds to a total power within the
portion 102 of approximately 88 mW (10 mW/cm.sup.2.times.8.8
cm.sup.2), and with the same 5% transmittance, the incident light
beam 82 at the scalp 30 will have a total power of approximately
1760 mW (88 mW/0.05) and a power density of approximately 568
mW/cm.sup.2 (1760 mW/3.1 cm.sup.2). These calculations are
summarized in Table 1.
TABLE-US-00001 TABLE 1 2 cm Spot Size 1 cm Spot Size (FIG. 8A)
(FIG. 8B) Scalp: Area 12.5 cm.sup.2 3.1 cm.sup.2 Total power 4480
mW 1760 mW Power density 358 mW/cm.sup.2 568 mW/cm.sup.2 Brain:
Area 22.4 cm.sup.2 8.8 cm.sup.2 Total power 224 mW 88 mW Power
density 10 mW/cm.sup.2 10 mW/cm.sup.2
[0072] These exemplary calculations illustrate that to obtain a
desired power density at the brain 20, higher total power at the
scalp 30 can be used in conjunction with a larger spot size at the
scalp 30. Thus, by increasing the spot size at the scalp 30, a
desired power density at the brain 20 can be achieved with lower
power densities at the scalp 30 which can reduce the possibility of
overheating the scalp 30. In certain embodiments, the light can be
directed through an aperture to define the illumination of the
scalp 30 to a selected smaller area.
Light Source
[0073] The light source 40 preferably generates light in the
visible to near-infrared wavelength range. In certain embodiments,
the light source 40 comprises one or more laser diodes, which each
provide coherent light. In embodiments in which the light from the
light source 40 is coherent, the emitted light may produce
"speckling" due to coherent interference of the light. This
speckling comprises intensity spikes which are created by
constructive interference and can occur in proximity to the target
tissue being treated. For example, while the average power density
may be approximately 10 mW/cm.sup.2, the power density of one such
intensity spike in proximity to the brain tissue to be treated may
be approximately 300 mW/cm.sup.2. In certain embodiments, this
increased power density due to speckling can improve the efficacy
of treatments using coherent light over those using incoherent
light for illumination of deeper tissues.
[0074] In other embodiments, the light source 40 provides
incoherent light. Exemplary light sources 40 of incoherent light
include, but are not limited to, incandescent lamps or
light-emitting diodes. A heat sink can be used with the light
source 40 (for either coherent or incoherent sources) to remove
heat from the light source 40 and to inhibit temperature increases
at the scalp 30.
[0075] In certain embodiments, the light source 40 generates light
which is substantially monochromatic (i.e., light having one
wavelength, or light having a narrow band of wavelengths). So that
the amount of light transmitted to the brain is maximized, the
wavelength of the light is selected in certain embodiments to be at
or near a transmission peak (or at or near an absorption minimum)
for the intervening tissue. In certain such embodiments, the
wavelength corresponds to a peak in the transmission spectrum of
tissue at about 820 nanometers. In other embodiments, the
wavelength of the light is preferably between about 630 nanometers
and about 1064 nanometers, more preferably between about 780
nanometers and about 840 nanometers, and most preferably includes
wavelengths of about 790, 800, 810, 820, or 830 nanometers. It has
also been found that an intermediate wavelength of about 739
nanometers appears to be suitable for penetrating the skull,
although other wavelengths are also suitable and may be used.
[0076] In other embodiments, the light source 40 generates light
having a plurality of wavelengths. In certain such embodiments,
each wavelength is selected so as to work with one or more
chromophores within the target tissue. Without being bound by
theory, it is believed that irradiation of chromophores increases
the production of ATP in the target tissue, thereby producing
beneficial effects. In certain embodiments, the light source 40 is
adapted to generate light having a first wavelength concurrently
with light having a second wavelength. In certain other
embodiments, the light source 40 is adapted to generate light
having a first wavelength sequentially with light having a second
wavelength.
[0077] In certain embodiments, the light source 40 includes at
least one continuously emitting GaAlAs laser diode having a
wavelength of about 830 nanometers. In another embodiment, the
light source 40 comprises a laser source having a wavelength of
about 808 nanometers. In still other embodiments, the light source
40 includes at least one vertical cavity surface-emitting laser
(VCSEL) diode. Other light sources 40 compatible with embodiments
described herein include, but are not limited to, light-emitting
diodes (LEDs) and filtered lamps.
[0078] The light source 40 is capable of emitting light energy at a
power sufficient to achieve a predetermined power density at the
subdermal target tissue (e.g., at a depth of approximately 2
centimeters from the dura). It is presently believed that
phototherapy of tissue is most effective when irradiating the
target tissue with power densities of light of at least about 0.01
mW/cm.sup.2 and up to about 1 W/cm.sup.2. In various embodiments,
the subsurface power density is at least about 0.01, 0.05, 0.1,
0.5, 1, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, or 90 mW/cm.sup.2,
respectively, depending on the desired clinical performance. In
certain embodiments, the subsurface power density is preferably
about 0.01 mW/cm.sup.2 to about 100 mW/cm.sup.2, more preferably
about 0.01 mW/cm.sup.2 to about 50 mW/cm.sup.2, and most preferably
about 2 mW/cm.sup.2 to about 20 mW/cm.sup.2. It is believed that
these subsurface power densities are especially effective at
producing the desired biostimulative effects on the tissue being
treated.
[0079] Taking into account the attenuation of energy as it
propagates from the skin surface, through body tissue, bone, and
fluids, to the subdermal target tissue, surface power densities
preferably between about 10 mW/cm.sup.2 to about 10 W/cm.sup.2, or
more preferably between about 100 mW/cm.sup.2 to about 500
mW/cm.sup.2, will typically be used to attain the selected power
densities at the subdermal target tissue. To achieve such surface
power densities, the light source 40 is preferably capable of
emitting light energy having a total power output of at least about
25 mW to about 100 W. In various embodiments, the total power
output is limited to be no more than about 30, 50, 75, 100, 150,
200, 250, 300, 400, or 500 mW, respectively. In certain
embodiments, the light source 40 comprises a plurality of sources
used in combination to provide the total power output. The actual
power output of the light source 40 is preferably controllably
variable. In this way, the power of the light energy emitted can be
adjusted in accordance with a selected power density at the
subdermal tissue being treated.
[0080] Certain embodiments utilize a light source 40 that includes
only a single laser diode that is capable of providing about 25 mW
to about 100 W of total power output at the skin surface. In
certain such embodiments, the laser diode can be optically coupled
to the scalp 30 via an optical fiber or can be configured to
provide a sufficiently large spot size to avoid power densities
which would burn or otherwise damage the scalp 30. In other
embodiments, the light source 40 utilizes a plurality of sources
(e.g., laser diodes) arranged in a grid or array that together are
capable of providing at least about 25 mW to about 100 W of total
power output at the skin surface. The light source 40 of other
embodiments may also comprise sources having power capacities
outside of these limits.
[0081] FIG. 9A schematically illustrates another embodiment of the
therapy apparatus 10 which comprises the cap 60 and a light source
comprising a light-emitting blanket 110. FIG. 9B schematically
illustrates an embodiment of the blanket 110 comprising a flexible
substrate 111 (e.g., flexible circuit board), a power conduit
interface 112, and a sheet formed by optical fibers 114 positioned
in a fan-like configuration. FIG. 9C schematically illustrates an
embodiment of the blanket 110 comprising a flexible substrate 111,
a power conduit interface 112, and a sheet formed by optical fibers
114 woven into a mesh. The blanket 110 is preferably positioned
within the cap 60 so as to cover an area of the scalp 30
corresponding to a portion of the brain 20 to be treated.
[0082] In certain such embodiments, the power conduit interface 112
is adapted to be coupled to an optical fiber conduit 64 which
provides optical power to the blanket 110. The optical power
interface 112 of certain embodiments comprises a beam splitter or
other optical device which distributes the incoming optical power
among the various optical fibers 114. In other embodiments, the
power conduit interface 112 is adapted to be coupled to an
electrical conduit which provides electrical power to the blanket
110. In certain such embodiments, the power conduit interface 112
comprises one or more laser diodes, the output of which is
distributed among the various optical fibers 114 of the blanket
110. In certain other embodiments, the blanket 110 comprises an
electroluminescent sheet which responds to electrical signals from
the power conduit interface 112 by emitting light. In such
embodiments, the power conduit interface 112 comprises circuitry
adapted to distribute the electrical signals to appropriate
portions of the electroluminescent sheet.
[0083] The side of the blanket 110 nearer the scalp 30 is
preferably provided with a light scattering surface, such as a
roughened surface to increase the amount of light scattered out of
the blanket 110 towards the scalp 30. The side of the blanket 110
further from the scalp 30 is preferably covered by a reflective
coating so that light emitted away from the scalp 30 is reflected
back towards the scalp 30. This configuration is similar to
configurations used for the "back illumination" of liquid-crystal
displays (LCDs). Other configurations of the blanket 110 are
compatible with embodiments described herein.
[0084] In certain embodiments, the light source 40 generates light
which cause eye damage if viewed by an individual. In such
embodiments, the apparatus 50 can be configured to provide eye
protection so as to avoid viewing of the light by individuals. For
example, opaque materials can be appropriately placed to block the
light from being viewed directly. In addition, interlocks can be
provided so that the light source 40 is not activated unless the
apparatus 50 is in place, or other appropriate safety measures are
taken.
Light Delivery Apparatuses
[0085] The phototherapy methods for the treatment of stroke
described herein may be practiced and described using, for example,
a low level laser therapy apparatus such as that shown and
described in U.S. Pat. No. 6,214,035, U.S. Pat. No. 6,267,780, U.S.
Pat. No. 6,273,905 and U.S. Pat. No. 6,290,714, which are all
incorporated in their entirety by reference herein, as are the
references incorporated by reference therein.
[0086] Another suitable phototherapy apparatus in accordance with
embodiments described here is illustrated in FIG. 10. The
illustrated therapy apparatus 10 includes a light source 40, an
element 50, and a flexible strap 120 adapted for securing the
therapy apparatus 10 over an area of the patient's head. The light
source 40 can be disposed on the strap 120 itself, or in a housing
122 coupled to the strap 120. The light source 40 preferably
comprises a plurality of diodes 40a, 40b, . . . capable of emitting
light energy having a wavelength in the visible to near-infrared
wavelength range. The element 50 is adapted to be positioned
between the light source 40 and the patient's scalp 30.
[0087] The therapy apparatus 10 further includes a power supply
(not shown) operatively coupled to the light source 40, and a
programmable controller 126 operatively coupled to the light source
40 and to the power supply. The programmable controller 126 is
configured to control the light source 40 so as to deliver a
predetermined power density to the brain tissue 20. In certain
embodiments, as schematically illustrated in FIG. 10, the light
source 40 comprises the programmable controller 126. In other
embodiments the programmable controller 126 is a separate component
of the therapy apparatus 10.
[0088] In certain embodiments, the strap 120 comprises a loop of
elastomeric material sized appropriately to fit snugly onto the
patient's scalp 30. In other embodiments, the strap 120 comprises
an elastomeric material to which is secured any suitable securing
means 130, such as mating Velcro strips, buckles, snaps, hooks,
buttons, ties, or the like. The precise configuration of the strap
120 is subject only to the limitation that the strap 120 is capable
of maintaining the light source 40 in a selected position so that
light energy emitted by the light source 40 is directed towards the
targeted brain tissue 20.
[0089] In the exemplary embodiment illustrated in FIG. 10, the
housing 122 comprises a layer of flexible plastic or fabric that is
secured to the strap 120. In other embodiments, the housing 122
comprises a plate or an enlarged portion of the strap 120. Various
strap configurations and spatial distributions of the light sources
40 are compatible with embodiments described herein so that the
therapy apparatus 10 can treat selected portions of brain
tissue.
[0090] In still other embodiments, the therapy apparatus 10 for
delivering the light energy includes a handheld probe 140, as
schematically illustrated in FIG. 11. The probe 140 includes a
light source 40 and an element 50 as described herein.
[0091] FIG. 12 is a block diagram of a control circuit 200
comprising a programmable controller 126 according to embodiments
described herein. The control circuit 200 is configured to adjust
the power of the light energy emitted by the light source 40 to
generate a predetermined surface power density at the scalp 30
corresponding to a predetermined energy delivery profile, such as a
predetermined subsurface power density, to the target area of the
brain 20.
[0092] In certain embodiments, the programmable controller 126
comprises a logic circuit 210, a clock 212 coupled to the logic
circuit 210, and an interface 214 coupled to the logic circuit 210.
The clock 212 of certain embodiments provides a timing signal to
the logic circuit 210 so that the logic circuit 210 can monitor and
control timing intervals of the applied light. Examples of timing
intervals include, but are not limited to, total treatment times,
pulsewidth times for pulses of applied light, and time intervals
between pulses of applied light. In certain embodiments, the light
sources 40 can be selectively turned on and off to reduce the
thermal load on the scalp 30 and to deliver a selected power
density to particular areas of the brain 20.
[0093] The interface 214 of certain embodiments provides signals to
the logic circuit 210 which the logic circuit 210 uses to control
the applied light. The interface 214 can comprise a user interface
or an interface to a sensor monitoring at least one parameter of
the treatment. In certain such embodiments, the programmable
controller 126 is responsive to signals from the sensor to
preferably adjust the treatment parameters to optimize the measured
response. The programmable controller 126 can thus provide
closed-loop monitoring and adjustment of various treatment
parameters to optimize the phototherapy. The signals provided by
the interface 214 from a user are indicative of parameters that may
include, but are not limited to, patient characteristics (e.g.,
skin type, fat percentage), selected applied power densities,
target time intervals, and power density/timing profiles for the
applied light.
[0094] In certain embodiments, the logic circuit 210 is coupled to
a light source driver 220. The light source driver 220 is coupled
to a power supply 230, which in certain embodiments comprises a
battery and in other embodiments comprises an alternating current
source. The light source driver 220 is also coupled to the light
source 40. The logic circuit 210 is responsive to the signal from
the clock 212 and to user input from the user interface 214 to
transmit a control signal to the light source driver 220. In
response to the control signal from the logic circuit 210, the
light source driver 220 adjust and controls the power applied to
the light sources 40. Other control circuits besides the control
circuit 200 of FIG. 12 are compatible with embodiments described
herein.
[0095] In certain embodiments, the logic circuit 110 is responsive
to signals from a sensor monitoring at least one parameter of the
treatment to control the applied light. For example, certain
embodiments comprise a temperature sensor thermally coupled to the
scalp 30 to provide information regarding the temperature of the
scalp 30 to the logic circuit 210. In such embodiments, the logic
circuit 210 is responsive to the information from the temperature
sensor to transmit a control signal to the light source driver 220
so as to adjust the parameters of the applied light to maintain the
scalp temperature below a predetermined level. Other embodiments
include exemplary biomedical sensors including, but not limited to,
a blood flow sensor, a blood gas (e.g., oxygenation) sensor, an ATP
production sensor, or a cellular activity sensor. Such biomedical
sensors can provide real-time feedback information to the logic
circuit 210. In certain such embodiments, the logic circuit 110 is
responsive to signals from the sensors to preferably adjust the
parameters of the applied light to optimize the measured response.
The logic circuit 110 can thus provide closed-loop monitoring and
adjustment of various parameters of the applied light to optimize
the phototherapy.
[0096] In certain embodiments, as schematically illustrated in FIG.
13, the therapy apparatus 310 comprises a light source 340 adapted
to irradiate a portion of the patient's brain 20 with an
efficacious power density and wavelength of light. The therapy
apparatus 310 further comprises a controller 360 for energizing
said light source 340, so as to selectively produce a plurality of
different irradiation patterns on the patient's scalp 30. Each of
the irradiation patterns is comprised of a least one illuminated
area that is small compared to the patient's scalp 30, and at least
one non-illuminated area.
[0097] In certain embodiments, the light source 340 includes an
apparatus for adjusting the emitted light to irradiate different
portions of the scalp 30. In certain such embodiments, the
apparatus physically moves the light source 40 relative to the
scalp 30. In other embodiments, the apparatus does not move the
light source 40, but redirects the emitted light to different
portions of the scalp 30. In an exemplary embodiment, as
schematically illustrated in FIG. 14, the light source 340
comprises a laser diode 342 and a galvometer 344, both of which are
electrically coupled to the controller 360. The galvometer 344
comprises a mirror 346 mounted onto an assembly 348 which is
adjustable by a plurality of motors 350. Light emitted by the laser
diode 342 is directed toward the mirror 346 and is reflected to
selected portions of the patient's scalp 30 by selectively moving
the mirror 346 and selectively activating the laser diode 342. In
certain embodiments, the therapy apparatus 310 comprises an element
50 adapted to inhibit temperature increases at the scalp 30 as
described herein.
[0098] FIG. 15A schematically illustrates an irradiation pattern
370 in accordance with embodiments described herein. The
irradiation pattern 370 comprises at least one illuminated area 372
and at least one non-illuminated area 374. In certain embodiments,
the irradiation pattern 370 is generated by scanning the mirror 346
so that the light impinges the patient's scalp 30 in the
illuminated area 372 but not in the non-illuminated area 374.
Certain embodiments modify the illuminated area 372 and the
non-illuminated area 374 as a function of time.
[0099] This selective irradiation can be used to reduce the thermal
load on particular locations of the scalp 30 by moving the light
from one illuminated area 372 to another. For example, by
irradiating the scalp 30 with the irradiation pattern 370
schematically illustrated in FIG. 15A, the illuminated areas 372 of
the scalp 30 are heated by interaction with the light, and the
non-illuminated areas 374 are not heated. By subsequently
irradiating the scalp 30 with the complementary irradiation pattern
370'schematically illustrated in FIG. 15B, the previously
non-illuminated areas 374 are now illuminated areas 372', and the
previously illuminated areas 372 are now non-illuminated areas
374'. A comparison of the illuminated areas 372 of the irradiation
pattern 370 of FIG. 15A with the illuminated area 372' of the
irradiation pattern 370' of FIG. 15B shows that the illuminated
areas 372, 372' do not significantly overlap one another. In this
way, the thermal load at the scalp 30 due to the absorption of the
light can be distributed across the scalp 30, thereby avoiding
unduly heating one or more portions of the scalp 30.
Methods of Light Delivery
[0100] Preferred methods of phototherapy are based at least in part
on the finding described above that, for a selected wavelength, the
power density (light intensity or power per unit area, in
W/cm.sup.2) or the energy density (energy per unit area, in
J/cm.sup.2, or power density multiplied by the exposure time) of
the light energy delivered to tissue is an important factor in
determining the relative efficacy of the phototherapy, and efficacy
is not as directly related to the total power or the total energy
delivered to the tissue. In the methods described herein, power
density or energy density as delivered to a portion of the
patient's brain 20, which can include the area of infarct after a
stroke, appears to be important factors in using phototherapy to
treat and save surviving but endangered neurons in a zone of danger
surrounding the infracted area. Certain embodiments apply optimal
power densities or energy densities to the intended target tissue,
within acceptable margins of error.
[0101] As used herein, the term "neurodegeneration" refers to the
process of cell destruction resulting from primary destructive
events such as stroke or CVA, as well as from secondary, delayed
and progressive destructive mechanisms that are invoked by cells
due to the occurrence of the primary destructive event. Primary
destructive events include disease processes or physical injury or
insult, including stroke, but also include other diseases and
conditions such as multiple sclerosis, amylotrophic lateral
sclerosis, epilepsy, Alzheimer's disease, dementia resulting from
other causes such as AIDS, cerebral ischemia including focal
cerebral ischemia, and physical trauma such as crush or compression
injury in the CNS, including a crush or compression injury of the
brain, spinal cord, nerves or retina, or any acute injury or insult
producing neurodegeneration. Secondary destructive mechanisms
include any mechanism that leads to the generation and release of
neurotoxic molecules, including apoptosis, depletion of cellular
energy stores because of changes in mitochondrial membrane
permeability, release or failure in the reuptake of excessive
glutamate, reperfusion injury, and activity of cytokines and
inflammation. Both primary and secondary mechanisms contribute to
forming a "zone of danger" for neurons, wherein the neurons in the
zone have at least temporarily survived the primary destructive
event, but are at risk of dying due to processes having delayed
effect.
[0102] As used herein, the term "neuroprotection" refers to a
therapeutic strategy for slowing or preventing the otherwise
irreversible loss of neurons due to neurodegeneration after a
primary destructive event, whether the neurodegeneration loss is
due to disease mechanisms associated with the primary destructive
event or secondary destructive mechanisms.
[0103] As used herein, the term "neuroprotective-effective" as used
herein refers to a characteristic of an amount of light energy,
wherein the amount is a power density of the light energy measured
in mW/cm.sup.2. A neuroprotective-effective amount of light energy
achieves the goal of preventing, avoiding, reducing, or eliminating
neurodegeneration.
[0104] Thus, a method for the treatment of stroke in a patient in
need of such treatment involves delivering a
neuroprotective-effective amount of light energy having a
wavelength in the visible to near-infrared wavelength range to a
target area of the patient's brain 20. In certain embodiments, the
target area of the patient's brain 20 includes the area of infarct,
i.e. to neurons within the "zone of danger." In other embodiments,
the target area includes portions of the brain 20 not within the
zone of danger. Without being bound by theory, it is believed that
irradiation of healthy tissue in proximity to the zone of danger
increases the production of ATP and copper ions in the healthy
tissue and which then migrate to the injured cells within the
region surrounding the infarct, thereby producing beneficial
effects. Additional information regarding the biomedical mechanisms
or reactions involved in phototherapy is provided by Tiina I. Karu
in "Mechanisms of Low-Power Laser Light Action on Cellular Level",
Proceedings of SPIE Vol. 4159 (2000), Effects of Low-Power Light on
Biological Systems V, Ed. Rachel Lubart, pp. 1-17, which is
incorporated in its entirety by reference herein.
[0105] In certain embodiments, delivering the neuroprotective
amount of light energy includes selecting a surface power density
of the light energy at the scalp 30 corresponding to the
predetermined power density at the target area of the brain 20. As
described above, light propagating through tissue is scattered and
absorbed by the tissue. Calculations of the power density to be
applied to the scalp 30 so as to deliver a predetermined power
density to the selected target area of the brain 20 preferably take
into account the attenuation of the light energy as it propagates
through the skin and other tissues, such as bone and brain tissue.
Factors known to affect the attenuation of light propagating to the
brain 20 from the scalp 30 include, but are not limited to, skin
pigmentation, the presence and color of hair over the area to be
treated, amount of fat tissue, the presence of bruised tissue,
skull thickness, and the location of the target area of the brain
20, particularly the depth of the area relative to the surface of
the scalp 30. For example, to obtain a desired power density of 50
mW/cm.sup.2 in the brain 20 at a depth of 3 cm below the surface of
the scalp 30, phototherapy may utilize an applied power density of
500 mW/cm.sup.2. The higher the level of skin pigmentation, the
higher the power density applied to the scalp 30 to deliver a
predetermined power density of light energy to a subsurface site of
the brain 20.
[0106] In certain embodiments, treating a patient suffering from
the effects of stroke comprises placing the therapy apparatus 10 in
contact with the scalp 30 and adjacent the target area of the
patient's brain 20. The target area of the patient's brain 20 can
be previously identified such as by using standard medical imaging
techniques. In certain embodiments, treatment further includes
calculating a surface power density at the scalp 30 which
corresponds to a preselected power density at the target area of
the patient's brain 20. The calculation of certain embodiments
includes factors that affect the penetration of the light energy
and thus the power density at the target area. These factors
include, but are not limited to, the thickness of the patient's
skull, type of hair and hair coloration, skin coloration and
pigmentation, patient's age, patient's gender, and the distance to
the target area within the brain 20. The power density and other
parameters of the applied light are then adjusted according to the
results of the calculation.
[0107] The power density selected to be applied to the target area
of the patient's brain 20 depends on a number of factors,
including, but not limited to, the wavelength of the applied light,
the type of CVA (ischemic or hemorrhagic), and the patient's
clinical condition, including the extent of the affected brain
area. The power density of light energy to be delivered to the
target area of the patient's brain 20 may also be adjusted to be
combined with any other therapeutic agent or agents, especially
pharmaceutical neuroprotective agents, to achieve the desired
biological effect. In such embodiments, the selected power density
can also depend on the additional therapeutic agent or agents
chosen.
[0108] In preferred embodiments, the treatment proceeds
continuously for a period of about 10 seconds to about 2 hours,
more preferably for a period of about 1 to about 10 minutes, and
most preferably for a period of about 1 to 5 minutes. In other
embodiments, the light energy is preferably delivered for at least
one treatment period of at least about five minutes, and more
preferably for at least one treatment period of at least ten
minutes. The light energy can be pulsed during the treatment period
or the light energy can be continuously applied during the
treatment period.
[0109] In certain embodiments, the treatment may be terminated
after one treatment period, while in other embodiments, the
treatment may be repeated for at least two treatment periods. The
time between subsequent treatment periods is preferably at least
about five minutes, more preferably at least about 1 to 2 days, and
most preferably at least about one week. In certain embodiments in
which treatment is performed over the course of multiple days, the
apparatus 10 is wearable over multiple concurrent days (e.g.,
embodiments of FIGS. 1, 3, 9A, 10, and 13). The length of treatment
time and frequency of treatment periods can depend on several
factors, including the functional recovery of the patient and the
results of imaging analysis of the infarct. In certain embodiments,
one or more treatment parameters can be adjusted in response to a
feedback signal from a device (e.g., magnetic resonance imaging)
monitoring the patient.
[0110] During the treatment, the light energy may be continuously
provided, or it may be pulsed. If the light is pulsed, the pulses
are preferably at least about 10 nanosecond long and occur at a
frequency of up to about 100 kHz. Continuous wave light may also be
used.
[0111] The thrombolytic therapies currently in use for treatment of
stroke are typically begun within a few hours of the stroke.
However, many hours often pass before a person who has suffered a
stroke receives medical treatment, so the short time limit for
initiating thrombolytic therapy excludes many patients from
treatment. In contrast, phototherapy treatment of stroke appears to
be more effective if treatment begins no earlier than several hours
after the ischemic event has occurred. Consequently, the present
methods of phototherapy may be used to treat a greater percentage
of stroke patients.
[0112] In certain embodiments, a method provides a neuroprotective
effect in a patient that had an ischemic event in the brain. The
method comprises identifying a patient who has experienced an
ischemic event in the brain. The method further comprises
estimating the time of the ischemic event. The method further
comprises commencing administration of a neuroprotective effective
amount of light energy to the brain. The administration of the
light energy is commenced no less than about two hours following
the time of the ischemic event. In certain embodiments,
phototherapy treatment can be efficaciously performed preferably
within 24 hours after the ischemic event occurs, and more
preferably no earlier than two hours following the ischemic event,
still more preferably no earlier than three hours following the
ischemic event, and most preferably no earlier than five hours
following the ischemic event. In certain embodiments, one or more
of the treatment parameters can be varied depending on the amount
of time that has elapsed since the ischemic event.
[0113] Without being bound by theory, it is believed that the
benefit in delaying treatment occurs because of the time needed for
induction of ATP production, and/or the possible induction of
angiogenesis in the region surrounding the infarct. Thus, in
accordance with one preferred embodiment, the phototherapy for the
treatment of stroke occurs preferably about 6 to 24 hours after the
onset of stroke symptoms, more preferably about 12 to 24 hours
after the onset of symptoms. It is believed, however, that if
treatment begins after about 2 days, its effectiveness will be
greatly reduced.
Example
[0114] An in vitro experiment was done to demonstrate one effect of
phototherapy on neurons, namely the effect on ATP production.
Normal Human Neural Progenitor (NHNP) cells were obtained
cryopreserved through Clonetics of Baltimore, Md., catalog
#CC-2599. The NHNP cells were thawed and cultured on
polyethyleneimine (PEI) with reagents provided with the cells,
following the manufacturers' instructions. The cells were plated
into 96 well plates (black plastic with clear bottoms, Becton
Dickinson of Franklin Lakes, N.J.) as spheroids and allowed to
differentiate into mature neurons over a period of two weeks.
[0115] A Photo Dosing Assembly (PDA) was used to provide precisely
metered doses of laser light to the NHNP cells in the 96 well
plates. The PDA included a Nikon Diaphot inverted microscope (Nikon
of Melville, N.Y.) with a LUDL motorized x,y,z stage (Ludl
Electronic Products of Hawthorne, N.Y.). An 808 nanometer laser was
routed into the rear epi-fluorescent port on the microscope using a
custom designed adapter and a fiber optic cable. Diffusing lenses
were mounted in the path of the beam to create a "speckled"
pattern, which was intended to mimic in vivo conditions after a
laser beam passed through human skin. The beam diverged to a 25
millimeter diameter circle when it reached the bottom of the 96
well plates. This dimension was chosen so that a cluster of four
adjacent wells could be lased at the same time. Cells were plated
in a pattern such that a total of 12 clusters could be lased per 96
well plate. Stage positioning was controlled by a Silicon Graphics
workstation and laser timing was performed by hand using a digital
timer. The measured power density passing through the plate for the
NHNP cells was 50 mW/cm.sup.2.
[0116] Two independent assays were used to measure the effects of
808 nanometer laser light on the NHNP cells. The first was the
CellTiter-Glo Luminescent Cell Viability Assay (Promega of Madison,
Wis.). This assay generates a "glow-type" luminescent signal
produced by a luciferase reaction with cellular ATP. The
CellTiter-Glo reagent is added in an amount equal to the volume of
media in the well and results in cell lysis followed by a sustained
luminescent reaction that was measured using a Reporter luminometer
(Turner Biosystems of Sunnyvale, Calif.). Amounts of ATP present in
the NHNP cells were quantified in Relative Luminescent Units (RLUs)
by the luminometer.
[0117] The second assay used was the alamarBlue assay (Biosource of
Camarillo, Calif.). The internal environment of a proliferating
cell is more reduced than that of a non-proliferating cell.
Specifically, the ratios of NADPH/NADP, FADH/FAD, FMNH/FMN and
NADH/NAD, increase during proliferation. Laser irradiation is also
thought to have an effect on these ratios. Compounds such as
alamarBlue are reduced by these metabolic intermediates and can be
used to monitor cellular states. The oxidization of alamarBlue is
accompanied by a measurable shift in color. In its unoxidized
state, alamarBlue appears blue; when oxidized, the color changes to
red. To quantify this shift, a 340PC microplate reading
spectrophotometer (Molecular Devices of Sunnyvale, Calif.) was used
to measure the absorbance of a well containing NHNP cells, media
and alamarBlue diluted 10% v/v. The absorbance of each well was
measured at 570 nanometers and 600 nanometers and the percent
reduction of alamarBlue was calculated using an equation provided
by the manufacturer.
[0118] The two metrics described above, (RLUs and % Reduction) were
then used to compare NHNP culture wells that had been lased with 50
mW/cm.sup.2 at a wavelength of 808 nanometers. For the
CellTiter-Glo assay, 20 wells were lased for 1 second and compared
to an unlased control group of 20 wells. The CellTiter-Glo reagent
was added 10 minutes after lasing completed and the plate was read
after the cells had lysed and the luciferase reaction had
stabilized. The average RLUs measured for the control wells was
3808 +/-3394 while the laser group showed a two-fold increase in
ATP content to 7513 +/-6109. The standard deviations were somewhat
high due to the relatively small number of NHNP cells in the wells
(approximately 100 per well from visual observation), but a
student's unpaired t-test was performed on the data with a
resulting p-value of 0.02 indicating that the two-fold change is
statistically significant.
[0119] The alamarBlue assay was performed with a higher cell
density and a lasing time of 5 seconds. The plating density
(calculated to be between 7,500-26,000 cells per well based on the
certificate of analysis provided by the manufacturer) was difficult
to determine since some of the cells had remained in the spheroids
and had not completely differentiated. Wells from the same plate
can still be compared though, since plating conditions were
identical. The alamarBlue was added immediately after lasing and
the absorbance was measured 9.5 hours later. The average measured
values for percent reduction were 22%+/-7.3% for the 8 lased wells
and 12.4%+/-5.9% for the 3 unlased control wells (p-value=0.076).
These alamarBlue results support the earlier findings in that they
show a similar positive effect of the laser treatment on the
cells.
[0120] Increases in cellular ATP concentration and a more reduced
state within the cell are both related to cellular metabolism and
are considered to be indications that the cell is viable and
healthy. These results are novel and significant in that they show
the positive effects of laser irradiation on cellular metabolism in
in-vitro neuronal cell cultures.
[0121] In certain embodiments, the phototherapy is combined with
other types of treatments for an improved therapeutic effect.
Treatment can comprise directing light through the scalp of the
patient to a target area of the brain concurrently with applying an
electromagnetic field to the brain. In such embodiments, the light
has an efficacious power density at the target area and the
electromagnetic field has an efficacious field strength. For
example, the apparatus 50 can also include systems for
electromagnetic treatment, e.g., as described in U.S. Pat. No.
6,042,531 issued to Holcomb, which is incorporated in its entirety
by reference herein. In certain embodiments, the electromagnetic
field comprises a magnetic field, while in other embodiments, the
electromagnetic field comprises a radio-frequency (RF) field. As
another example, treatment can comprise directing an efficacious
power density of light through the scalp of the patient to a target
area of the brain concurrently with applying an efficacious amount
of ultrasonic energy to the brain. Such a system can include
systems for ultrasonic treatment, e.g., as described in U.S. Pat.
No. 5,054,470 issued to Fry et al., which is incorporated in its
entirety by reference herein.
[0122] The explanations and illustrations presented herein are
intended to acquaint others skilled in the art with the invention,
its principles, and its practical application. Those skilled in the
art may adapt and apply the invention in its numerous forms, as may
be best suited to the requirements of a particular use.
Accordingly, the specific embodiments of the present invention as
set forth are not intended as being exhaustive or limiting of the
invention.
* * * * *