U.S. patent application number 11/869131 was filed with the patent office on 2008-02-21 for stereoguide for clamping neurosurgical instruments.
Invention is credited to Steven Streatfield Gill.
Application Number | 20080045973 11/869131 |
Document ID | / |
Family ID | 9932789 |
Filed Date | 2008-02-21 |
United States Patent
Application |
20080045973 |
Kind Code |
A1 |
Gill; Steven Streatfield |
February 21, 2008 |
STEREOGUIDE FOR CLAMPING NEUROSURGICAL INSTRUMENTS
Abstract
A stereoguide including first and second guide elements spaced
relative to each other through which instruments are passed along
an axis of insertion towards a target; characterised by a first
clamp having a clamping position on the axis between the guide
elements and the target and a second clamp having a clamping
position on the axis of insertion and on the opposite side of the
guide elements to the first clamp for clamping instruments passing
through the guide elements.
Inventors: |
Gill; Steven Streatfield;
(Bristol, GB) |
Correspondence
Address: |
KOHN & ASSOCIATES, PLLC
30500 NORTHWESTERN HWY
STE 410
FARMINGTON HILLS
MI
48334
US
|
Family ID: |
9932789 |
Appl. No.: |
11/869131 |
Filed: |
October 9, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10507360 |
Jan 28, 2005 |
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PCT/GB03/01027 |
Mar 11, 2003 |
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11869131 |
Oct 9, 2007 |
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Current U.S.
Class: |
606/130 |
Current CPC
Class: |
A61B 90/11 20160201 |
Class at
Publication: |
606/130 |
International
Class: |
A61B 17/00 20060101
A61B017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 12, 2002 |
GB |
0205773.5 |
Claims
1. A stereoguide comprising first and second guide elements spaced
relative to each other through which instruments are passed along
an axis of insertion towards a target; characterised by a first
clamp having a clamping position on the axis between the guide
elements and the target and a second clamp having a clamping
position on the axis of insertion and on the opposite side of the
guide elements to the first clamp for clamping instruments passing
through the guide elements.
2. A stereoguide according to claim 1, wherein each clamp is
moveable away from its clamping position.
3. A stereoguide according to claim 3, wherein each clamp is
swivelable away from its clamping position.
4. A stereoguide according to claim 1, wherein the second clamp is
disposed between the guide elements and the target.
5. A stereoguide according to claim 4, further comprising a post
extending from the first guide element and carrying the first
clamp, and a leg extending from the second guide element and
carrying the second clamp.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation Application of U.S.
patent application Ser. No. 10/507,360 filed Jan. 28, 2005, which
is a United States National Phase Patent Application of
International Application PCT/GB03/01027 filed Mar. 11, 2003, which
claims priority to Great Britain Patent Application Serial No.
0205773.5 filed Mar. 12, 2002, all of which are incorporated herein
by reference.
BACKGROUND OF THE INVENTION
[0002] (1) Field of the Invention
[0003] The present invention relates to apparatus for use in
neurosurgery, and to a method of positioning neurosurgical
apparatus. The apparatus and method are particularly useful in
stereotactically targeting treatment of abnormalities of brain
function, and for the infusion of therapeutic agents directly into
the brain parenchyma.
[0004] (2) Description of Related Art
[0005] Where therapeutic agents will cause unwanted side effects if
delivered to healthy parts of the brain, delivery of the agent to
exactly the right place is important. Examples of treating
abnormalities of brain function include the acute infusion of
Gamma-amino-buturic-acid agonists into an epileptic focus or
pathway to block transmission, and the chronic delivery of opiates
or other analgesics can be infused directly to the peri-aqueductal
grey matter or to thalamic targets for the treatment of intractable
pain. Also, cytotoxic agents can be delivered directly into a brain
tumour. Intraparenchymal infusion can also be used to deliver
therapeutic agents to brain targets that can not be delivered
systemically because they will not cross the blood-brain barrier.
For example, the treatment of patients with Parkinson's disease,
Alzheimer's disease, head injury, stroke and multiple sclerosis may
be carried out by the infusion of neurotrophic factors to protect
and repair failing or damaged nerve cells. Neurotrophins may also
be infused to support neural grafts transplanted into damaged or
malfunctioning areas of the brain in order restore function.
[0006] Intraparenchymal drug delivery has been demonstrated in non
human primates and in rats. For intraparenchymal drug delivery to a
human or non-human brain, it is proposed that a catheter be
implanted, and the drug be pumped intermittently or continuously to
the desired brain target. For long term drug delivery, a pump
containing a reservoir would be implanted subcutaneously and the
reservoir refilled as necessary percutaneously through a palpable
port.
[0007] In particular, U.S. Pat. No. 6,042,579 discloses techniques
for treating neurodegenerative disorders by the infusion of nerve
growth factors into the brain.
[0008] It is not just catheters which can be inserted into the
brain parenchyma, but also other instruments such as electrodes.
Stimulating and lesioning electrodes are used in a variety of
surgical procedures, including deep brain stimulation (DBS)
electrodes. A surgeon wishing to stimulate or lesion a particular
area of nervous tissue can target the end of an electrode to the
target site so that a desired electrical current can be delivered.
Numerous methods are known for targeting the electrode to the
desired site including stereotactic methods.
[0009] An example of a currently used DBS electrode is supplied by
Medtronic Inc. of Indianapolis, Minn. Such electrodes typically
have a diameter of about 1.27 mm with four ring electrodes of the
same diameter positioned at their distal end.
[0010] In order to perform neurosurgery, the surgeon needs, in the
first instance, to identify the position of the desired target.
This is normally achieved by fixing a stereotactic reference frame
to the patient's head which can be seen on diagnostic images, and
from which measurements can be made. The stereotactic frame then
acts as a platform from which an instrument is guided to a desired
target using a stereoguide that is set to the appropriate
co-ordinates. Once an instrument is guided to the desired target,
treatment can begin.
[0011] A number of difficulties are encountered in such
neurosurgical procedures. Sub-optimal placement of the instrument
being inserted may lead to significant morbidity or treatment
failure. Brain targets for treating functional disorders are
usually deeply situated and have small volumes. For example, a
desired target for treating Parkinson's disease is situated in the
sub-thalamic nucleus and is 3-4 mm in diameter, or an ovoid of 34
mm in diameter and 5-6 mm in length. Other targets such as the
globus palladus or targets in the thalamus are usually no more than
1-2 mm larger. For such a small target sub-optimal placement of as
little as 1 mm will not only reduce the effectiveness of the
treatment, but may also induce unwanted side affects such as
weakness, altered sensation, worsened speech and double vision.
However, functional neurosurgical targets are often difficult or
impossible to visualise on diagnostic images, and so that the
actual position may need to be inferred with the reference to
visible landmarks in the brain and using a standard atlas of the
brain to assist the process. Anatomical variations between an
individual and the atlas, and even between different sides of the
same brain of an individual means that placement may be
sub-optimal. Other reasons for sub-optimal placement may result
from patient movement during image acquisition, or geometric
distortion of imaging which can be intrinsic to the images method.
Also, during surgery, brain shift can occur which might result from
the change in the head position from that during image acquisition
to the position on the operating table, from leakage of
cerebrospinal fluid when a burr hole is made with a subsequent
sinking of the brain, and also from the passage of the instrument
through the brain. Surgeons attempt to correct these errors by
performing electrophysiological studies on the patient undergoing
functional neurosurgery, kept awake during the procedures.
[0012] Intraparenchymal instruments may be guided to their targets
in the brain using stereotactic techniques. Typically, stereotactic
localisation of a brain target is accomplished by fixing the
stereotactic base ring to the skull and identifying the position of
the target using imaging techniques. The position of the target is
identified using three dimension co-ordinates by making
measurements from radio-opaque fiducials attached to the
stereotactic base ring. The stereotactic base ring may then be used
as a platform from which to guide instruments to the target using a
stereoguide on the stereotactic base ring that is set to the
measured co-ordinates. The instrument may then be guided towards
the target through the brain tissue. If the instrument is a
catheter, it is preferably rigidified by the insertion of a stiff
wire through its bore. Alternatively, a straight wire may be guided
to the target and the catheter introduced around the wire. The
instrument is inserted so that one end, the inserted end (also
referred to as the distal end), is located within the brain, and
the opposite end, which is the external end, (also referred to as
the proximal end) remains outside the brain. Once positioned, the
external end of the instrument can be fixed to the skull, and if it
is in a catheter, it can be connected to a pump whereby the
therapeutic agent may be administered.
[0013] Functional neurosurgical targets are deeply situated and
typically at a depth of 70-80 mm from the cortical surface. This
includes possible targets in the mesencephalon including the
subthalamic nucleus, the substantia nigra and the
pedunculor-pontine nucleus. The mesencephalon is a critical region
of the brain where is it is important to minimise trauma from the
passage of an electrode or catheter. It is typically at a depth of
about 70-80 mm from the skull surface and is contained within a
volume which has a height of approximately 20-25 mm.
[0014] The present invention seeks to optimise the placement of an
instrument, and to improve the manner in which multiple instruments
are inserted along the same axis.
SUMMARY OF THE INVENTION
[0015] According to a first aspect of the invention, there is
provided a stereoguide comprising first and second guide elements
through which instruments are passed along an axis of insertion
towards a target; characterised by a first clamp having a clamping
position on the axis between the guide elements and the target, or
on the opposite side of the guide elements for clamping instruments
passing through the guide elements.
[0016] The stereoguide guide is used to guide instruments along a
defined axis so that the instrument reaches the target. The
stereoguide in use is attached to a stereotactic frame.
[0017] The term "guide elements" as used herein means elements
which allow the movement of instruments along the axis of
insertion. The guide elements may comprise a split block having a
passage way allowing instruments to move along a defined axis.
Suitable guide elements are known to those skilled in the art and
include those Elekta Instruments AB.
[0018] Any instrument for use in neurosurgery may be used with the
stereoguide of the present invention, including catheters,
electrodes such as deep brain stimulating (DBS) electrodes, guide
wires and guide tubes such as those described in GB-A-2 357
700.
[0019] The axis of insertion is the axis along which instruments
are passed to reach the target. The axis of insertion is defined by
the position of the guide elements in accordance with standard
procedures of using the stereotactic frame.
[0020] The term "clamp" as used herein refers to a clamp which can
clamp the instrument passing through the guide elements and prevent
movement of the instrument along the axis of insertion (i.e.
preventing longitudinal movement of the instrument).
[0021] Preferably, the stereoguide further comprises a second clamp
having a clamping position on the axis of insertion and on the
opposite side of the guide elements to the first clamp for clamping
instruments passing through the guide elements. It is also
preferred that the or each clamp is movable away from its clamping
position and most preferred that the or each clamp is swivelable
away from its clamping position.
[0022] It is preferred that the second clamp is disposed between
the guide elements and the target. In such a case, it is further
preferred that the stereoguide include a post extending from the
first guide element and carrying the first clamp, and a leg
extending from the second guide element and carrying the second
clamp, wherein the second guide element is closer to the target
than the first guide element.
[0023] According to a second aspect of the invention, there is
provided a method of positioning an instrument at a target using a
stereoguide according to the first aspect of the invention, the
method comprising inserting a wire into a support tube; inserting
the wire and support tube together along an axis of insertion
towards the target via the guide elements of the stereoguide;
removing the support tube form the wire, leaving the wire in situ;
inserting a guide tube around the wire towards the target; securing
the guide tube in position; removing the wire; inserting the
instrument to the target via the guide tube.
[0024] Preferably the support tube has a stop at its proximal end
(i.e. the end that is not inserted) which abuts a guide element
preventing any further insertion of the support tube.
[0025] It is preferred that the inserting of the wire into the
support tube results in the wire projecting from the end of the
support tube. It is most preferred that the wire projects from the
support tube towards the target by about 25 mm.
[0026] Another preferred feature is that, once the wire is inserted
into the support tube they are fixed together by virtue of a finger
tightenable screw carried by the support tube. The finger
tightenable screw may form part of the stop referred to above.
After inserting the wire to the target, it is advantageous for the
first clamp to be clamped to the wire whereby the wire is held
securely.
[0027] It is preferred that removal of the support tube included
release of finger tightenable screw. According to a preferred
embodiment, removal of the support tube includes moving the support
tube along the wire until it is positioned between the first and
second clamps, clamping the wire with the second clamp when the
second clamp is between the target and the guide elements,
releasing the first clamp and withdrawing the support tube from the
wire. Preferably, the step of inserting the guide tube includes
passing the guide tube over the wire until the tube is positioned
between the first and second clamps, clamping the wire with the
first clamp, releasing the second clamp and moving the guide tube
towards the target. Finally, before removing the wire, both clamps
are released.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0028] Embodiments of the present invention will be described by
way of example only with reference to the drawings in which:
[0029] FIG. 1 is a view of a catheter for use with the stereoguide
according to the present invention;
[0030] FIG. 2 is a view showing part of the catheter of FIG. 1 with
internal features shown in dotted lines;
[0031] FIG. 3 is an end view of the catheter from the left hand end
of FIG. 2;
[0032] FIG. 4 shows a first phase of stereotactic insertion;
[0033] FIG. 5 shows a second phase of stereotactic insertion;
[0034] FIG. 6 shows a third phase of stereotactic insertion;
and
[0035] FIG. 7 shows a fourth phase of stereotactic insertion.
DETAILED DESCRIPTION OF THE INVENTION
[0036] As is explained above, the accuracy of insertion of an
instrument is crucially important.
[0037] FIGS. 1, 2 and 3 show a catheter 1 suitable for use with the
stereoguide of the present invention. The catheter 1 includes a
length of fine tubing 2, the outer diameter of which is no more
than 1 mm, and most preferably no greater than 0.7 mm. It is even
more preferred that the outer diameter be no more than 0.5 mm. In
this instance, the catheter tubing 2 is constructed from
polyurethane plastic and preferably from carbothane 55 DB20
(Thermedics Polymer Products, Woburn Mass., USA). The fine tubing 2
is linked to a length of connector tubing 3 via a hub 4. The
connector tubing 3 is, in this case, made from polyurethane
plastic, such as carbothane 85AB20, although other materials could
also be used.
[0038] The hub 4 in this case is also constructed using
polyurethane, such as carbothane 72 DB20. Again, other materials
may also be appropriate.
[0039] The fine tubing 2 is intended to be inserted into the brain
of a patient, whereas the connector tubing 3 is intended to lead to
a pump by which a therapeutic agent may be pumped intermittently or
continuously to a desired brain target. For long term drug
delivery, the pump would be implanted subcutaneously and the
reservoir refilled as necessary percutaneously through a palpable
port. In this case, the connector tubing 3 would also be inserted
subcutaneously.
[0040] The hub 4 includes a central body 5, which is generally
cylindrical and a pair of diametrical opposing wings 6 each
containing a countersunk hole whereby the hub may be screwed to the
outer surface of the skull of the patient.
[0041] The cylindrical body 5 of the hub 4 includes a passageway
passing through its complete length. The passageway includes a
first narrow passage 8 of uniform diameter into which the fine
tubing is inserted and securely held. The passageway also includes
a second wide passage 9 of uniform diameter into which the
connector tubing 3 is inserted and securely held. Between the first
and second passages 8, 9 is a third linking passage 10 which is
generally tapered in order to take account of the different
internal diameters of the fine tubing 2 and the connector tubing 3.
It will be noted that the ends of the third passage 10 are of the
same or very similar diameter to the internal diameters of the fine
tubing 2 and the connector tubing 3.
[0042] From FIG. 2, it can be seen that the right hand end of the
hub 4 is frustoconical, and the end of the hub is planar and forms
a stop 11, the significance of which will be understood from the
description below.
[0043] The insertion of the catheter will now be described.
Firstly, a stereotactic frame is attached to the patient's skull
and the position of the intracranial target is identified by
imaging the patient wearing the stereotactic frame and defining the
position of the target as a three dimensional co-ordinate. This is
a standard technique within the field of neurosurgery and suitable
stereotactic frames are available from Elekta Instruments AB.
[0044] In this insertion technique, a number of phases or steps are
taken which are shown in FIGS. 4 to 7. As will be appreciated,
small diameter catheters have a tendency to drift off the planned
trajectory during insertion as a result of the flexibility inherent
in a small diameter instrument. Since neurosurgical targets are
often deeply situated, typically 70-80 mm from the surface of the
skull, and sometimes as much as 100 mm from the skull surface, the
catheter must normally be very rigid, and therefore of a larger
diameter.
[0045] Examples of possible targets include targets in the
mesencephalon including the subthalamic nucleus, the substantia
nigra and the pedunculor-pontine nucleus. The mesencephalon is a
critical region of the brain where is it is important to minimise
trauma from the passage of an electrode or catheter. It is
typically at a depth of about 70-80 mm from the skull surface and
is contained within a volume which has a height of approximately
20-25 mm.
[0046] In FIGS. 4 to 7, a stereoguide according to the present
invention is shown in use during the insertion of an instrument.
Stereoguides are carried by a stereotactic frame which is securely
attached to the skull of the patient. The stereoguide can be
adjusted on the stereotactic frame in order to be positioned very
accurately to direct a surgical instrument to the desired position.
Whereas stereoguides normally include two guide elements, the
stereoguide in FIGS. 4 to 7 also includes additional clamps.
Although the stereotactic frame is not shown in FIGS. 4 to 7, it
will be appreciated that the stereoguide is carried by the frame.
The stereoguide includes an upper guide element 16 and a lower
guide element 17 which are alignment in order to define the path of
any instrument being positioned in the brain of a patient. A post
18 extends upwardly from the upper guide element, the top of which
carries an upper clamp 24. A leg 19 extends downwardly from the
lower guide element and carries a lower clamp 25 at its lower end.
Both upper and lower clamps may be swivelled to and from positions
where they will meet the axis of the stereoguide. For example, is
will been seen in FIG. 4 that the upper clamp 24 is in alignment
with the axis of the stereoguide, whereas the lower clamp 25 is
not. The opposite position is shown in FIG. 5.
[0047] From the foregoing, it will be appreciated that the
stereoguide has as its purpose the longitudinal guidance of
instruments towards a target within the brain. It defines an axis
along which the instruments are inserted so that, provided there is
no deviation of the instrument caused by flexing during insertion,
the instrument will be very accurately directed towards the
target.
[0048] It will also be understood from the introduction to this
application that the target is the point within the brain which is
to be treated by the instrument, and to which the instrument is
directed by the stereoguide. The instruments that are intended to
be inserted include catheters for delivery of therapeutic agents,
electrodes for delivering electric pulses, guide tubes which are
inserted into the brain and through which other instruments may be
passed, and wires which may be used to rigidify tubular instruments
inserted into the brain or guide tubular instruments to a target in
the brain. The clamps have as their primary function the securing
of instruments during insertion or removal so as to prevent them
from moving longitudinally along the axis of insertion.
[0049] To facilitate insertion of fine instruments into
mesencephalic targets, insertion takes place as follows.
[0050] Firstly, a small diameter tungsten guidewire 22 of 0.6 mm in
diameter is inserted in a tube 21 with an outer diameter of 1.7 mm
and fixed within the tube 21 with a finger-tightened grub screw 23
such that the wire 22 protrudes from the distal end of the tube 21
by 25 mm. The tube 21 and wire 22 can be seen in FIG. 4 showing the
first phase of insertion in which the tube 21 with the wire 22
projecting from its end can be seen. The finger tightened grub
screw 23 can be seen at the top (i.e. the proximal end) of tube 21,
in which the wire 22 is held. The proximal end of the tube 21 also
comprises a stop which abuts a guide element on insertion. The
distal end of the tube 21 is tapered over 20 mm, and the tube 21
has a stop at its proximal end.
[0051] Insertion takes place from a stereotactic frame in which the
target has been identified and defined in terms of three
dimensional co-ordinates. The stereotactic frame carries a
stereoguide according to the present invention. During the first
phase of insertion shown in FIG. 4, the tube and wire are together
lowered towards the target. In this case, the tube is 165 mm in
length from the stop to the distal end, and since the tube 21 and
the wire are inserted as a unit, the distance from the stop of the
tube to the tip of the guidewire 22 is 190 mm. The wire 22 extends
above the top of the tube by approximately 150 mm. The upper clamp
24 and the lower clamp 25, can be swivelled to positions of
engagement with the wire, tube or instrument which is being
inserted or removed.
[0052] Once the guidewire 22 has reached its target, the upper
clamp 24 is swivelled to clamp the proximal end of the guidewire
22. This prevents longitudinal movement of the wire. Once the grub
screw 23 has been loosened, the tube 21 can be withdrawn from the
brain leaving the wire 22 in situ. Once the tube 21 has been raised
up towards the upper clamp, the lower clamp can be swung across to
clamp the now exposed wire 22, and the upper clamp 24 can be
released, as shown in FIG. 5. This allows the tube 21 to be removed
altogether from the top of the wire 22.
[0053] A guide tube 31 is threaded onto the wire 22, and the upper
clamp 24 is then swung around and closed on the wire 22. The lower
clamp 25 can then be released to allow the guide tube 31 to be
inserted into the brain so that its distance is approximately 1 or
2 cm short of the target, also shown in FIG. 7. The guide tube 32
has at its upper end a head with a threaded outer surface which
permits the head to be screwed into the tapped burrhole in the
patient's skull, thereby securing the guide tube 31 securely in
position.
[0054] Once the guide tube 31 is installed, the guidewire 22 may be
removed and FIG. 7 shows that a 0.65 mm catheter 36 can then be
inserted down the guide tube 31 to the target. Alternatively other
instruments can be inserted at this point, such as an
electrode.
[0055] This method has the particular advantage that, on the first
pass, the guidewire being stiffened by the tube 21 will hit the
target, and then by inserting a guide tube short of the target, the
brain target will be fixed and the guide tube will facilitate the
insertion of a very fine instrument to the target. For the
treatment of certain conditions such as Alzheimer's disease it is
necessary to deliver nerve growth factors to targets in the nucleus
basalis through several in-dwelling catheters. If each catheter is
only 0.65 mm in diameter, multiple fine catheters can be inserted
without substantially disrupting the tissue it is intended to
regenerate.
[0056] To insert a DBS electrode, a similar technique can be used.
When the DBS electrode is not tubular (i.e. it has a closed end),
it is preferred that a 1.3 mm electrode or guide rod is used to
place a guide tube just short of the target. The DBS electrode is
then subsequently inserted down the guide tube, once the electrode
or guide rod has been removed. Alternatively, the DBS electrode is
tubular (i.e. has open ends), a straight wire can be guided to the
target and the electrode introduced around the wire.
[0057] Throughout this application, various publications, including
United States patents, are referenced by author and year and
patents by number. Full citations for the publications are listed
below. The disclosures of these publications and patents in their
entireties are hereby incorporated by reference into this
application in order to more fully describe the state of the art to
which this invention pertains.
[0058] The invention has been described in an illustrative manner,
and it is to be understood that the terminology which has been used
is intended to be in the nature of words of description rather than
of limitation.
[0059] Obviously, many modifications and variations of the present
invention are possible in light of the above teachings. It is,
therefore, to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described.
* * * * *