U.S. patent application number 14/120294 was filed with the patent office on 2014-12-25 for unitary multilumen cranial bolt.
This patent application is currently assigned to Thermal Technologies, Inc.. The applicant listed for this patent is H. Frederick Bowman, Dean Honkonen, Sammy M. Khalifa. Invention is credited to H. Frederick Bowman, Dean Honkonen, Sammy M. Khalifa.
Application Number | 20140378775 14/120294 |
Document ID | / |
Family ID | 52111455 |
Filed Date | 2014-12-25 |
United States Patent
Application |
20140378775 |
Kind Code |
A1 |
Bowman; H. Frederick ; et
al. |
December 25, 2014 |
Unitary multilumen cranial bolt
Abstract
A unitary multilumen cranial bolt for use in multimodal
monitoring of a plurality of physiological parameters in brain
tissue incorporates a plurality of lumens, each lumen directing a
catheter borne sensor through a bore hole in the cranium and into
brain tissue of a patient. The lumens are configured to cause the
catheters to splay outward as they enter the cranial cavity and
reach their intended depth of penetration. Each lumen is associated
with a guide. The guides are adapted for use with introducers that
enable fragile and/or flexible sensors to be introduced into brain
tissue. Each catheter borne sensor can be positioned and
repositioned within brain tissue independently of all other
sensors.
Inventors: |
Bowman; H. Frederick;
(Needham, MA) ; Khalifa; Sammy M.; (Mountain View,
CA) ; Honkonen; Dean; (Groton, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bowman; H. Frederick
Khalifa; Sammy M.
Honkonen; Dean |
Needham
Mountain View
Groton |
MA
CA
MA |
US
US
US |
|
|
Assignee: |
Thermal Technologies, Inc.
Cambridge
MA
|
Family ID: |
52111455 |
Appl. No.: |
14/120294 |
Filed: |
May 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61956959 |
Jun 20, 2013 |
|
|
|
Current U.S.
Class: |
600/235 |
Current CPC
Class: |
A61B 5/6865 20130101;
A61B 5/6868 20130101; A61B 5/4064 20130101; A61B 2562/046 20130101;
A61B 5/6852 20130101 |
Class at
Publication: |
600/235 |
International
Class: |
A61B 5/00 20060101
A61B005/00 |
Claims
1. A device for providing access to the cranial cavity of a patient
comprising: a unitary body having a proximal end and a distal end
and forming a plurality of lumens therethrough extending between
said proximal and distal ends, said distal end of said unitary body
forming a threaded shank for engaging the wall of a burr hole
through the cranium of a patient; wherein the locations of said
lumens at said distal end are angularly displaced about the axis of
rotation of said shank with respect to the locations of said lumens
at said proximal end so that said lumens are skewed relative to the
axis of rotation of said shank, said lumens converging from a
relatively disparate locations in the proximal end of said unitary
body to relatively close proximity in said shank without
intersecting, each lumen having a proximal end situated outside the
cranial wall when the device is in use and a distal end accessing
the interior of the cranial wall when the device is in use.
2. The device according to claim 1 wherein the angular
displacements are such that each lumen intersects in said unitary
body the path that an adjacent lumen would take if the distal end
of the adjacent lumen were not angularly displaced with respect to
its proximal end.
3. The device according to claim 1 wherein the angular displacement
of the distal ends of said lumens relative to the proximal ends of
said lumens about the axis of rotation of said shank is
approximately 75.degree..
4. The device according to claim 1 further comprising one or more
tubular guides connected to one or more of said lumens at their
proximal ends for conducting a catheter to said lumen.
5. The device according to claim 4 wherein each said tubular guide
is flexible further comprising a connector for mounting each said
flexible guide to one of said lumens, each said connector having an
expanded zone for engaging and holding in place a flexible
guide.
6. The device according to claim 4 further comprising a tubular
introducer adapted to be inserted through a tubular guide and its
associated lumen for introducing a delicate catheter borne sensor
through said guide and lumen into the interior of the cranial
wall.
7. The device according to claim 6 further comprising a stylet
within said introducer for stiffening said introducer during
installation of said introducer through a tubular guide and its
associated lumen.
8. The device according to claim 7 wherein the distal end of said
stylet includes means for opening the Dura to provide access to
brain tissue.
9. The device according to claim 6 wherein the distal end of said
introducer includes means for opening the dura to provide access to
brain tissue.
10. The device according to claim 1 wherein the close proximity of
said lumens within said threaded shank defines a nadir of
convergence of said lumens in said shank, the separation of each
one of said lumens from adjacent lumens in the nadir of convergence
being not more than the diameter of the larger of said one and said
adjacent lumens and not substantially less than 0.009 inch.
11. The device according to claim 1 wherein the close proximity of
said lumens within said threaded shank defines a nadir of
convergence of said lumens in said shank, the separation of each
one of said lumens from adjacent lumens in the nadir of convergence
being approximately 0.01 inch.
12. A bolt for providing access to the cranial cavity of a patient
comprising a solid, unitary body having a proximal end and a distal
end, a threaded shank at the distal end and at least three but not
more than five lumens traversing the length of said body between
the proximal end and the distal end, the distal ends of said lumens
being angularly displaced with respect to the proximal ends of said
lumens, said lumens at their proximal ends being located radially
outward from the axis of rotation of said threaded shank and
converging from the outward locations toward each other and toward
the axis of rotation of said threaded shank for causing said lumens
to be nested compactly together about the axis of rotation without
intersecting.
13. A device according to claim 12 wherein said lumens define
divergent paths from their distal ends.
14. A system for providing access into the cranial cavity of a
patient for a catheter borne sensor comprising: a unitary body
having a proximal end and a distal end; a threaded shank at the
distal end of said unitary body for engaging the wall of a burr
hole through the cranium of a patient; a plurality of lumens formed
through the unitary body at skewed angles with respect to the axis
of rotation of said shank and converging from disparate locations
in the proximal end of said unitary body toward each other to
define a nadir of convergence in said shank, each lumen having a
proximal end situated outside the cranial wall when the device is
in use and a distal end accessing the interior of the cranial wall
when the device is in use; and one or more tubular guides
attachable to said unitary body at the proximal end of one or more
of said lumens for guiding a catheter from the exterior of the
cranial cavity to the interior thereof.
15. The system according to claim 14 wherein four lumens formed
within said unitary body further comprising four of said tubular
guides, one attached to the proximal end of each lumen.
16. The system according to claim 14 further comprising at least
one tubular introducer adapted to pass through a guide and its
associated lumen for introducing to the cranial cavity a flexible
or delicate catheter borne sensor.
17. The system according to claim 16 further comprising means at
the distal end of said introducer for opening the dura when inside
the cranial cavity to allow access to brain tissue for a catheter
mounted sensor.
18. The system according to claim 14 wherein said skewed angles are
such that each lumen intersects the path that an adjacent lumen
would take if such adjacent lumen were not skewed with respect to
said axis of rotation.
19. The system according to claim 14 wherein the proximity at said
nadir of convergence of each one of said lumens to an adjacent
lumen is not more than the diameter of the smaller of said one
lumen and said adjacent lumen and not substantially less than 0.009
inch.
20. The system according to claim 14 wherein the proximity of each
one of said lumens to an adjacent lumen at said nadir of
convergence is approximately 0.01 inch.
21. The system according to claim 14 wherein said lumens define a
nadir of convergence at the distal end of said shank.
22. A system for providing access into the cranial cavity of a
patient for a catheter borne sensor comprising: a unitary body
having a proximal end and a distal end; a threaded shank at the
distal end of said unitary body for engaging the wall of a burr
hole through the cranium of a patient; a plurality of lumens
extending through the unitary body without intersecting, each lumen
having a proximal end situated outside the cranial wall when the
device is in use and a distal end accessing the interior of the
cranial wall when the device is in use; a tubular guide attached to
said unitary body at the proximal end of each of said lumens for
guiding a catheter borne sensor from the exterior of the cranial
cavity to the proximal end of each said lumen; and at least one
tubular introducer adapted to pass through a tubular guide and its
associated lumen for introducing into the cranial cavity a flexible
or delicate catheter borne sensor.
23. The system according to claim 22 wherein four lumens extend
through said unitary body further comprising four of said tubular
guides, one attached to the proximal end of each lumen.
24. The system according to claim 22 further comprising means on
one or more of said tubular guides for releasably fixing in place a
catheter borne sensor introduced into the cranial cavity through
said tubular guide, each one of said fixing means being operable
independently of other fixing means to fix in place and release the
catheter borne sensor introduced through the tubular guide
associated with said one fixing means for positioning and
repositioning one of the catheter borne sensors independently of
other catheter borne sensors.
Description
BACKGROUND OF THE INVENTION
[0001] Brain injury accounts for millions of injuries and thousands
of deaths annually. Traumatic brain injury accounts for more than a
million injuries each year in the United States alone. Brain injury
also occurs in cases of subarachnoid hemorrhage which typically
result from cerebral aneurysm but also may occur in connection with
accidents and traumatic brain injury.
[0002] Treatment for brain injured patients must address the
initial injury and the likely eventual onset of secondary ischemic
brain injury. Secondary neurological injury may occur hours or even
days after the initial injury. Commonly it is associated with post
injury swelling of brain tissue within the confined space of the
cranial cavity. It is therefore necessary to monitor various
physiological parameters within brain tissue if secondary injury is
to be predicted and possibly avoided or, when it occurs, most
effectively treated.
[0003] The onset of secondary damage to brain tissue is difficult
to predict. To address this difficulty simultaneous neuromonitoring
of a number of predictive physiological parameters, termed
multimodal monitoring, is used. Multimodal monitoring assesses and
presents to the medical practitioner insight into the condition of
the brain injured patient as indicated by the concurrent monitoring
of several parameters. This facilitates the forecasting of
secondary neurological injury and the treatment of brain
injuries
SUMMARY OF THE INVENTION
[0004] This invention facilitates the forecasting of secondary
neurological injury during treatment of brain injuries. Certain
parameters when detected and monitored are instrumental in this
forecasting. Examples of such parameters include intracranial
pressure, cerebral blood flow (i.e.: perfusion), temperature,
oxygen, and neurological parameters assessed through microdialysis
and electroencephalography. Probes sensitive to parameters to be
monitored are inserted into the brain tissue and provide data to
appropriate monitors. Each probe comprises an elongated catheter
with a sensor at or near its distal end. The sensor is adapted to
sense one or more of the physiological parameters to be monitored
and is introduced to the site in the brain where the parameter is
to be assessed. Desired locations for a sensor vary in depth and
lateral separation. Separation of the sensors in some cases is
mandated to prevent crosstalk. For example, to avoid thermal
contamination between sensors a temperature sensor or an oxygen
sensor is located outside the thermal influence region of a heated
cerebral blood flow (i.e.: perfusion) sensor.
[0005] To monitor various physiological parameters within the brain
tissue of a patient, catheter borne sensors are introduced into the
brain tissue through a burr hole drilled through the cranium of the
patient. To direct the sensors to the intended locations a
multilumen cranial bolt is installed in the burr hole. Each lumen
or channel in the cranial bolt accepts an individual probe that is
adapted to monitor one or several particular parameters.
[0006] It is an object of this invention to provide a cranial bolt
with one or more lumens that may be associated with a guide to
facilitate the introduction of a catheter borne sensor through the
lumen and into brain tissue.
[0007] It is also an object of this invention to facilitate the
introduction of delicate sensors into brain tissue. Delicate
sensors are those that are fragile and subject to damage when being
introduced or which are so flexible that they tend to kink in the
lumens through which they are to be introduced. Also, such sensors
may not readily penetrate the Dura. Examples of delicate sensors
are those whose function depends in part on the use of fragile
membranes, such as those used to measure oxygen and those used in
connection with microdialysis. A related object is to provide one
or more introducers for optional use with delicate catheters and
sensors. An introducer is fed through a guide, the associated lumen
in the bolt and the cranial bore in order to conduct the delicate
catheter borne sensor through the guide, the lumen and the skull
bore and into brain tissue without causing the catheter to kink or
the delicate sensor to be damaged.
[0008] It is an object of this invention to provide a unitary
multilumen cranial bolt in which are formed lumens that exit the
distal end of the bolt along divergent paths so that catheters
introduced through the lumens diverge within the brain tissue and
position catheter mounted sensors at disparate locations within the
brain.
[0009] It is another object of this invention to minimize the size
and number of burr holes. To this end, in multimodality monitoring,
a plurality of probes are introduced through a single cranial bolt
installed in a burr hole. Multiple channels or lumens extend
through the bolt with each channel having a proximal end situated
to be outside the skull cavity when the bolt is installed and a
distal end open to the cranial cavity.
[0010] A further object of this invention is to provide users the
ability to adjust and readjust the depth of one or more catheter
insertions independently of the fixation-in-place of other
catheters.
[0011] The cranial bolt has a solid, unitary body defining a
relatively broad proximal portion that narrows to a smaller distal
portion defining a shank shaped to enter and engage the burr hole.
Multiple lumens are formed through the solid, unitary body between
the proximal end and the distal end of the unitary body. Having
multiple lumens extending through a unitary, solid body simplifies
construction and use, reduces cost and optimizes sensor orientation
and separation. Particularly, the unitary structure facilitates
introduction of the bolt into the skull opening with the rotary
axis of the bolt normal to the surface of the skull. This properly
aligns the lumens for receiving the insertion of catheter borne
sensors.
[0012] To minimize the size of the burr hole to be drilled in the
skull of a patient it is necessary to minimize the width of the
shank of the cranial bolt. Yet, in a multilumen bolt, all the
lumens must pass through the shank. Minimization of the width of
the shank is accomplished by having a plurality of lumens (three,
four or five for example) converge within the body of the bolt from
disparate locations in the relatively broad proximal end of the
bolt to pass through the narrow shank of the bolt in close
proximity to each other. Each lumen has a proximal end situated
outside the cranial wall when the device is in use and a distal end
at the distal end of the shank to access the interior of the
cranial wall when the device is in use. The lumens converge from
the disparate locations in the proximal end of the bolt to close
proximity in the small distal end of the bolt or shank without
intersecting. The zone or locus at which the lumens reach their
closest proximity, each lumen having minimal separation from
adjacent lumens, is termed the nadir of convergence. This is in the
shank and typically would be at or near the distal end of the
shank.
[0013] Convergence of the lumens toward a nadir in the shank,
without more, does not produce the desired separation in the brain
tissue of catheter borne sensors introduced through the lumens.
Catheters introduced into brain tissue are to be oriented along
divergent paths to separate the sensors from each other. To achieve
this the lumens are skewed with respect to the central axis of the
bolt. This establishes divergent paths for catheters introduced
through the lumens so the catheters splay outward, away from each
other, as they penetrate brain tissue. The separation of the
proximal ends of the lumens at the proximal end of the bolt and the
skewed orientation of the lumens in the bolt result in a
configuration that affords comfortable working separation for the
medical practitioner when introducing catheters into the lumens and
separation in the brain tissue of sensors introduced through the
lumens.
[0014] To orient the lumens so as to provide divergent paths for
catheters, the cranial bolt is constructed with the distal ends of
the lumens angularly displaced with respect to the proximal ends of
the lumens about the central (i.e.: rotary) axis of a threaded
shank. This produces for the lumens a skewed path through the bolt
relative to the central axis. The skew and the convergence of the
lumens can provide the largest separation available for a given
diameter of the threaded shank.
[0015] The angle of rotation existing between the proximal and
distal ends of any particular lumen is such that the particular
lumen would intersect in the bolt the path an adjacent lumen would
take if the distal end of the adjacent lumen were not also rotated
with respect to its proximal end. Restated, the skew of the lumens
relative to the central axis of the bolt is such that each lumen
intersects in the unitary body the path that an adjacent lumen
would take as the lumens converge if the distal end of the adjacent
lumen were not also angularly displaced with respect to its
proximal end.
[0016] In a preferred embodiment, the separation of each one of the
lumens from adjacent lumens in the nadir of convergence is not more
than the diameter of the larger of the one lumen and the adjacent
lumens and not substantially less than 0.01 inch. An acceptable
minimal separation in a bolt formed of a unitary mass of titanium
is 0.009 inch, slightly less than 0.01 inch. The minimum separation
determined when the bolt is formed can be one to minimize the
diameter of the shank of the bolt while preserving the structural
integrity of the bolt during installation and use.
[0017] In a preferred embodiment the cranial bolt is of titanium
with a plastic wing mounted on the proximal portion of the bolt,
the wing being used to manually screw the bolt into a burr hole
drilled in the skull of a patient. This provides MRI compatibility
along with favorable manufacturing and thermal characteristics.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a perspective view of a cranial bolt of a
preferred embodiment of this invention with the lumens through the
bolt shown in dotted lines.
[0019] FIG. 1a is a perspective view of the cranial bolt of FIG. 1
showing the lumens with the body of the bolt shown in phantom.
[0020] FIG. 2 is a plan view of the proximal end of the cranial
bolt of FIG. 1.
[0021] FIG. 3 is a cross-sectional view taken along line 3-3 of
FIG. 2.
[0022] FIG. 4 is a view of the cranial bolt of FIG. 1 with certain
accessory elements mounted thereon.
[0023] FIGS. 4(a), 4(b), 4(c) and 4(d) are cross-sectional views of
FIG. 4 taken along lines a-a, b-b, c-c and d-d, respectively.
[0024] FIG. 5(a) is a distal view of a cranial bolt according to
this invention showing angular displacement of proximal and distal
ends of lumens extending through the cranial bolt.
[0025] FIG. 5(b) is a proximal view of a cranial bolt of FIG. 5(a)
illustrating spatial relationships of lumens extending through the
cranial bolt.
[0026] FIG. 6 is a view of the cranial bolt of FIGS. 1 and 4 with
accessory elements attached.
[0027] FIG. 7 shows the cranial bolt of FIG. 6 with catheters
introduced into the brain of a patient.
[0028] FIG. 8 is a view of the cranial bolt of FIG. 6 with one
catheter introduced through a lumen into the brain of a patient
using an introducer device and in another lumen an introducer is in
place.
[0029] FIG. 9 is a cross-sectional view showing an introducer with
a catheter introduced therethrough.
[0030] FIG. 9(a) is a cross-sectional view along line a-a of FIG.
9.
[0031] FIG. 10 shows an alternate embodiment of the cranial
bolt.
[0032] FIG. 11 shows the contents of a kit associated with the use
of the cranial bolt of this invention.
[0033] FIG. 12 is a flow chart identifying steps associated with
installation and use of the cranial bolt of this invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0034] Reference is made to FIGS. 1 and 1a. Cranial bolt 10 is
formed as a unitary body with a proximal end 14 and a distal end
16. The unitary body has a proximal section 15 polygonal in cross
section (in FIG. 1a square) and a cylindrical distal section
forming a shank 18 with threads 12. Between the section 15 and the
shank 18 is a tapered midsection 17 (in FIG. 1a truncated cone).
Passageways or lumens 20 are formed through the unitary bolt 10
from the proximal end 14 to the distal end 16, passing through the
unitary body of the bolt including the shank 18. The lumens are
designated 20(a), 20(b), 20(c) and 20(d) to distinguish individual
lumens in various views. (The numeral 20 without a letter
designates all or multiple lumens collectively or an
undifferentiated single lumen.) The lumens 20 may be alike or
different. In FIG. 1, lumen 20(a) has a larger bore than the other
lumens. The threaded shank 18 is adapted to engage the wall of a
burr hole in a patient's skull to mount the bolt 10. The treaded
shank is screwed about axis 22 into the burr hole in the skull with
the threads 12 of the shank engaging the inner wall of the skull
bore. Typically, when the distal end 16 of the shank 18 aligns with
the inner wall of the skull the bolt is correctly positioned.
[0035] The distal ends of the lumens 20 are in communication with
the cranial cavity; the proximal ends of the lumens 20 are spaced
apart outside the cranial cavity and facilitate access by the
medical practitioner. The lumens 20 (i.e.: the central axes of the
lumens) are skewed with respect to the rotational axis 22 (See
FIGS. 4(a)-4(d)) of the threaded shank 18 to define for catheters
inserted through the lumens 20 divergent paths into the cranial
cavity. This is achieved by forming the lumens 20 with their distal
ends displaced angularly with respect to their proximal ends about
the axis of rotation 22 of the threaded shank 18. The axis of
rotation of the shank, also termed the central axis of the bolt 10,
is the axis about which the bolt is turned as the threaded shank 18
is screwed into a burr hole in the cranium of a patient. The
unitary bolt 10 may be formed of a medical grade material such as
titanium.
[0036] In FIG. 2 the proximal end 14 of the bolt is illustrated
showing the proximal ends of four lumens 20. The lumens may be of
the same size or of different sizes depending on the anticipated
usage. In FIG. 2 lumen 20(a) is of a larger diameter than the other
three. Enlargements 24 countersunk into the proximal ends of the
lumens 20 will be described in connection with FIG. 6.
[0037] FIG. 3 is a cross-sectional view taken along line 3-3 of
FIG. 2. The lumens all pass through the bolt 10 at skewed angles
with respect to the axis of rotation 22 of the bolt 10. (In some
embodiments the angles of skew may vary somewhat according to
various factors including the diameters of the lumens and the
dimensions of the bolt.) Lumen 20(a) is shown in dotted lines
extending from the opening at the proximal end to opening at the
distal end, a small portion at the distal end being cut-away in
this cross-sectional view. Lumen 20(d) is shown in dotted lines
extending from its opening at the proximal end to a midsection of
the bolt, the remainder of the lumen including the distal end being
cut-away in this cross-sectional view. A distal portion of lumen
20(b) is shown in cut-away, the remainder of the lumen including
the proximal end not being shown in this cross-section. Lumen 20(c)
is not seen in this view.
[0038] As seen in FIG. 1 and FIG. 3, the lumens 20 converge from
their disparate proximal locations in the relatively large proximal
end 14 of the bolt 10 toward each other to establish a close
proximity or nadir of convergence in the relatively small
cylindrical shank 18 and, in one embodiment, at the distal end 16
of the shank 18. It will be observed from FIGS. 1 and 2 that the
proximal ends of the lumens (20a, 20b, 20c, and 20d) are at
disparate locations in the proximal end 14 of the bolt 10,
displaced radially outward from the central axis of rotation 22.
From their proximal locations the lumens 20 converge inward toward
each other and toward the axis 22 as they traverse the length of
bolt 10 to converge in the distally located shank 18. Further, the
distal ends of the lumens 20 are angularly displaced about the axis
of rotation 22 with respect to the proximal ends of the lumens. The
convergence of the lumens 20 toward the axis 22 and angular
rotation of the lumens about the axis are such that the distal ends
of the lumens 20 are nested to fit compactly together about the
axis 22 in the shank 18.
[0039] FIG. 4 shows cranial bolt 10 with connectors 26 and wing-nut
element 32 (described in connection with FIG. 6) mounted thereon.
Four cross-sectional views are taken along lines (a)-(a), (b)-(b),
(c)-(c) and (d)-(d) of FIG. 4. These views show locations of lumens
20 as they appear at the proximal end 14 of the bolt 10 (FIG. 4a),
in the proximal section 15 of the bolt (FIG. 4b), in the midsection
17 of the bolt at its junction with the shoulder of the threaded
shank 18 (FIG. 4c) and at the distal end 16 of the shank (FIG. 4d).
Beginning with FIG. 4(a) and continuing through the views of FIGS.
4(b), 4(c) and 4(d) the location of each lumen is advanced
counterclockwise relative to the previous view. The angular
displacement between FIGS. 4a and 4d of a lumen 20 is referred to
as the angle of rotation of the lumen. This is described further in
connection with FIGS. 5(a) and 5(b).
[0040] FIG. 5(a) illustrates the skew introduced by the angular
displacement about the central axis 22 of the distal ends of the
lumens 20 relative to their proximal ends. FIG. 5(a) is a view of
the bolt 10 from its distal end 16 with the distal and proximal
ends of the lumens 20 shown. The distal ends of lumens 20a, 20b,
20c and 20d are shown in solid lines and the respective proximal
ends are shown in dotted lines. The angle of rotation between the
proximal and distal ends of lumen 20a is designated .alpha., the
angle of rotation between the proximal and distal ends of lumen 20b
is designated .beta., the angle of rotation between the proximal
and distal ends of lumen 20c is designated .gamma., the angle of
rotation between the proximal and distal ends of lumen 20d is
designated .delta.. To accommodate differences in the lumens the
degrees of angular rotation of the distal ends of the various
lumens 20 may not be exactly equal in all configurations. When the
degree of angular rotation is relatively small it is not necessary
for the degrees of angular rotation of the various lumens 20 to be
different. However, for example, when the degree of angular
rotation approaches the maximum that can be had without causing the
lumens to intersect, it may be desirable to have unequal angles of
displacement among the various lumens. In a bolt having lumens of
different diameters an asymmetrical geometry may optimize the
closeness of the lumens at the distal end of the bolt and thus
enable minimization of the diameter of the shank to be achieved.
That is, in a bolt with lumens of differing diameters, an
individual lumen may have a different degree of angular rotation
than another lumen. By way of example, viewing FIGS. 2 and 3, in
the configuration shown the overall length of the bolt 10 is
approximately 1.00 inch, the proximal end is 0.3185 inch square and
the distal shank end is 0.228 inch in diameter; the diameter of
lumen 20a is 0.132 inch and lumens 20b, 20c and 20d are each 0.059
inch diameter. In this configuration angle of rotation .alpha. is
75.degree.. Angles of rotation .beta., .gamma. and .delta. have
angular values that may be the same or more or less than
75.degree.. Angles of rotation are chosen to provide a desired
divergence of the paths established by the lumens 20 and that
minimize the diameter distal shank. All of these dimensions and
proportions are by way of example. The proximal end may be of any
convenient polygonal configuration, oval or circular for example.
The length of the midsection 17 can conveniently be determined for
various applications to provide a desired overall bolt length.
[0041] FIG. 5(b) is a view of the bolt 10 of FIG. 5(a) from its
proximal end 14 showing the paths formed through the bolt 10 by the
lumens 20. As seen in FIG. 5(b) the path of each lumen 20 overlaps
the path of an adjacent lumen and the lumens appear in this planar
view to intersect. However, the lumens do not intersect. The area
of apparent intersection of the lumens is shown in cross-hatch. In
the planar view of FIG. 5(b) the apparent intersection of lumen 20a
and 20d is shown as a-d; the apparent intersection of lumen 20d and
20c is shown as d-c; the apparent intersection of lumen 20c and 20b
is shown as c-b; and the apparent intersection of lumen 20b and 20a
is shown as b-a. The lumens 20 do not actually intersect because
all of their distal ends are angularly displaced relative to their
proximal ends. Hypothetically, if the distal end of one of the
several lumens 20 were not angularly displaced relative to its
proximal end, that lumen would intersect an adjacent lumen as it
and the other lumens converge toward each other. The magnitude of
the angular displacement of the distal ends of the lumens relative
to their proximal ends is determined to provide a desired degree of
divergence of the paths established by the lumens and
correspondingly the desired splay for catheters introduced through
the lumens, without causing the lumens to intersect.
[0042] FIG. 6 shows the cranial bolt 10 with elements to facilitate
its use. Tubular guides 30 mounted on the bolt 10 extend the reach
of the lumens without increasing the overall profile of the bolt 10
and serve to guide catheter borne sensors to the proximal ends of
the lumens. Guides 30 are connected to the bolt 10 using connectors
26. Each lumens 20 at its proximal end has an enlarged bore 24 to
form a seat for a connector 26. The connectors 26 are set within
the enlarged bores 24 to mount the tubular guides 30 and have
expanded zones or barbs 28 to firmly engage and hold the tubular
guides 30 in place. Guides 30 may be flexible to facilitate ease of
use by the medical practitioner and can be formed from polyvinyl
chloride tubing. Desirably, the bore within a particular lumen 20,
the bore within the mating connector 26 and the bore within the
mounted tubular guide 30 are the same. The proximal ends of guides
30 are fitted with devices for fixing in place catheters that have
been introduced through the guides 30. These devices may include a
Luer Lock fitting 36.
[0043] The wing-nut element 32 mounted on the body of the bolt 10
is shaped to fit tightly around and be affixed to the polygonal
proximal section 15 of the bolt 10. The element 32 is used to
manually screw the threaded shank 18 of the bolt 10 into a burr
hole in the skull of a patient. The element 32 affixed to the body
of the bolt 10 obviates the requirement for installation tools.
Threads 12 on the shank 18 are of the self-threading type and
engage the wall of the bore drilled through the cranium. Cranial
bolt threads are chosen for torque and sealing characteristics. A
cranial opening no larger than 5.3 mm in diameter is desirable in
some applications. This accordingly determines the diameter of the
threaded shank 18. In operation a catheter with a sensor at or near
its distal end is inserted through fittings 36, tubular guide 30,
connector 26 and lumen 20 and into the brain tissue. When the
desired depth of penetration into brain tissue is achieved the Luer
Lock 36 is engaged to fix the catheter in the desired position. The
system of FIG. 6 will accommodate up to four catheters, one through
each lumen 20. When less than four catheters are inserted the
unused lumens are sealed.
[0044] FIG. 7 illustrates a device of the type shown in FIG. 6
installed in the skull 42 of a patient. (Elements designated by
numerals 20, 30, 38, 46, 48 etc. and not followed by a letter
designate all or multiple similar elements collectively or any one
single element of several similar elements. Elements designated by
numerals followed by a letter identify a specific one of several
similar elements. For example, catheters 38a, 38b, 38c and 38d are
labeled individually and in a manner to identify the proximal ends
of the catheters with the corresponding distal ends.) Four
catheters 38(a), 38(b), 38(c) and 38(d) extend through four
respective guides 30(a), 30(b), 30(c) and 30(d), the associated
lumens 20 (lumens not shown in FIG. 7) of the bolt 10 and into
brain tissue 40. Each guide 30 has at its proximal end fixation
elements 34 and 36 for securing in place catheters 38 that are
introduced.
[0045] The fixation elements are each independent of the others so
each catheter 38 is independently secured in place.
Correspondingly, once catheters 38 are secured in place, any
catheter can be repositioned without disrupting the placement of
any other catheter. This can be significant. For example, if a
catheter 38 bearing a perfusion sensor is positioned deep and near
a pulsatile vessel or shallow and near the distal end of the bolt
10 it may not give an accurate result. In such a case the fixation
element securing the catheter is disengaged, the depth of the
catheter is adjusted until results deemed to be true are obtained
and the fixation element is reengaged.
[0046] FIG. 8 shows the device of this invention with one catheter
38b installed through introducer 46b, the introducer being
installed through guide 30b and the bolt 10 to access brain tissue
40. The catheter 38b is installed through the introducer 46b to
enter the brain tissue 40. Sensor 39b near the distal end of the
catheter 38b is in place to monitor a physiological parameter of
the brain tissue 40. Either a Touhy-Borst fixation device 37b or a
Luer Lock 34b is engaged to fix the catheter 38b and its sensor 39b
in place. A second introducer 46d is in place to receive a second
catheter through guide 30d. The introducer 46d includes a flexible,
hollow tube 48d and a stylet 50. The stylet is a solid thin wire or
rod that is inserted through the tube 48d when the introducer 46d
is being installed. The stylet 50 extends slightly beyond the tip
of the hollow tube 48d. The stylet may have a sharpened surface or
other cutter 52 at its distal end to open the Dura 44 that covers
the brain tissue 40 as the hollow tube 48d is inserted through the
guide 30d and bolt 10 to the brain tissue 40. The stylet 50
stiffens the tube 48d to facilitate installation and fills the bore
of the tube 48d to prevent brain tissue from entering the tube when
it accesses brain tissue 40. When the introducer tube 48d is in
place the stylet 50 is withdrawn from the tube 48d, leaving the
tube 48d open to receive a catheter 38 (catheter not shown in FIG.
8). An introducer 46 is used when the catheter 38, or more likely a
sensor 39 at the distal end of the catheter, is very delicate. This
can occur is when a fragile or flexible sensor will not readily
penetrate the Dura 44 or when an elongated flexible sensor tends to
kink in the guide 30 or lumen 20. Examples of delicate (i.e.:
fragile or flexible) sensors are those used to measure oxygen and
those used in connection with microdialysis. In a typical installed
position the distal end of the introducer tube 48 is extends into
brain tissue. The extent to which an introducer tube 48 and an
introduced catheter extend into brain tissue varies but frequently
the depth approximates one centimeter. In FIG. 8 one tube 48b
extends through guide 30b, a connector 26 and a lumen 20 (hidden)
within the bolt 10. A catheter 38b is installed through the tube
48b. A second catheter 38 (not shown) is to be introduced through a
tube 48d installed through the guide 30d and the associated
connector 26 and lumen 20 (hidden) within the bolt 10. The stylet
50, shown in place, will be removed to admit insertion of the
second catheter through the tube 48d. As an alternate to the cutter
52 being located on the stylet 50, the cutter may be formed at the
distal end of the tube 48. Once a lumen is traversed and the Dura
is pierced delicate sensors can be advanced into brain tissue.
[0047] If one or more introducers 46 are used it or they are placed
individually after installation of the bolt 10. Referring to the
example of FIG. 8, up to four catheters 38 may be installed, one
through each of the guides 30. When a catheter 38 is in the
intended position the Touhy-Borst fixation device 37 associated
with the guide 30 through which the catheter 38 is introduced is
tightened to fix the catheter 38 in the intended position. Any one
catheter so positioned can be repositioned without disturbing any
other catheter. If, for example, the catheter 38b is to be
repositioned from an initially installed position where fixation
device 37b had been employed to fix it in place, the fixation
device 37b is released. The introducer tube 48b and the catheter
38b are then moved within guide 30b to increase or decrease the
depth of penetration of the catheter 38b and the sensor 39b at its
distal end. The outward splay of the catheter 38b changes in
proportion to the change in its depth of penetration. When the
sensor 39b is repositioned the fixation device 37b is reengaged to
fix the introducer tube 48b and catheter 38b in the new position
and to fix the sensor 39b at the new depth of penetration within
the brain tissue 40. This does not disturb catheters introduced
through guides 30a, 30c or 30d. The depth of penetration of each
introducer tube 48 is adjusted and readjusted independently of any
installed introducer or catheter. This allows users to adjust the
depth of one or more catheters 38 without unlocking the
fixation-in-place of other catheters. Operation to reposition a
sensor when an introducer is not used is essentially the same. For
example, referring again to FIG. 8, if a catheter 38 (not shown)
were installed within the guide 30c without an introducer, the
fixation device 37c would be released to reposition the catheter.
The catheter then would be repositioned within the guide 30c to
increase or decrease its depth of penetration. The fixation device
37c would be reengaged to fix the catheter in its new position.
[0048] FIG. 9 is a cross-sectional view along one installed
catheter 38 in which an introducer 46 is used. The catheter 38
extends through the passageway or bore within the introducer tube
48; the tube 48 extends through the guide 30. FIG. 9(a) is a cross
section taken along line a-a of FIG. 9 which shows the catheter 38
within the tube 48 and the tube 48 within the guide 30. The
catheter 38 does not entirely fill the tube 48 (or the guide 30
when no introducer is used) but has surrounding space. When the
catheter 38 is in place with the sensor 39 at the desired location
in the brain tissue 40, Luer fittings 34 are adjusted to fix the
catheter and sensor in place.
[0049] FIG. 10 shows an alternate configuration of a unitary
multilumen bolt 200. The unitary bolt body 215 forms a shank 218 at
its distal end. Four lumens 220(a), 220(b), 20(c) and 220(d) are
bored through the unitary body of the bolt 200 along paths that
converge toward each other but do not intersect. The locations of
the distal ends of the lumens 220 are angularly displaced with
respect to their proximal ends. The lumens provide simultaneous
access through the bolt 200 for four catheters. Angular
displacement of the distal ends of the lumens 220 relative to their
proximal ends provides divergent paths for catheters introduced
through the lumens into brain tissue. The lumens 220 through the
device 200 of FIG. 10 are alike, having the same diameter, and the
angular displacements between the proximal and distal ends of the
several lumens 220 are equal. Enlarged bores 224 at the proximal
ends of lumens 220 provide secure seats for connectors 26 (not
shown in FIG. 10).
[0050] FIG. 11 shows the elements of a Quad Lumen Bolt Kit. It
includes instruments used to place catheter borne sensors in brain
tissue during surgery or in an intensive care unit. The kit
includes a unitary multi-lumen bolt 110 having a body tapered from
a relatively broad, square proximal end to a relatively narrow
threaded cylindrical shank 118 at a distal end. The bolt 110 is
fitted with a wing-nut element 132. A guide 130 is attached to the
proximal end of each lumen (hidden) in the cranial bolt 110 by
means of a connector element 126. The guide 130 has a Luer fitting
136 at its proximal end. In this embodiment the guides 130 are
shown of various lengths, the lengths being adapted to the
anticipated need of the installing surgeon. Relatively speaking,
guide 130(a) is short, guides 130(b) and 130(d) are of intermediate
length and guide 130(c) is long. Two sensor introducers 146 are
shown, one of length appropriate for guide 130c and one of length
appropriate for guides 130(b) and 130(d). Introducers 146 can be
supplied in lengths appropriate for any or all guides. Each
introducer incorporates a hollow tube 148, a stylet 147 and a Luer
fitting 136(a). The stylet 147 extends through the bore of the
hollow tube 148 to stiffen the tube and facilitate its insertion
through the guide 130 and into brain tissue. The stylet 147
substantially fills the hollow tube 148 so that, upon insertion of
the tube 148 into brain, brain tissue will not advance up the bore
of the hollow tube 148. The tube 148 has a sharpened end 149
capable of cutting the Dura covering brain tissue 40. The Luer
fitting 136(a) is adapted to mate with a Luer fitting 136 at the
distal end of a guide 130. The Luer fitting 136 on a guide 130 may
also mate directly with a Luer element installed on a catheter or
other device to be introduced through a guide 130. Touhy Borst
compression fittings 137 provided with the kit are for optional use
at the proximal ends of guides 130. A compression fitting 137 may
be used to fix an installed catheter in place. A compression
fitting 137, when installed on a guide 130, can also be used to
seal the proximal end of the guide when, in a particular instance,
it is not used. Sealing caps 170 are provided for sealing the
proximal end of any unused guide 130 that is not associated with a
compression fitting 137. A guide extension 160 may optionally be
used when needed. The guide extension 160 has a Luer fitting 136 at
its proximal end and at the opposite end a fitting 162 to mate with
the Luer fitting 136 at the proximal end of a selected guide
130.
[0051] For the convenience of the surgeon the kit includes a
scalpel 172 and a drill bit 164 with adjustable depth collar 166 to
mark the correct drilling depth. A hex nut 167 on the depth collar
and hex wrench 168 are used to adjust the position of the depth
collar 166 on the drill bit 164 prior to use. The size of the drill
bit 164 ensures the burr hole in the skull of a patient is
correctly sized for the threaded shank 118 of the bolt 110.
[0052] The entire system has a universal aspect. Individual lumens
through the bolt 110, guides 130, optional introducers 146, Luer
fittings 136 and compression fittings 137 are not dedicated to a
particular sensor or catheter but are broadly and very nearly
universally applicable. This facilitates use in a wide range of
multimodality monitoring events and provides the medical
practitioner with a broad range of choices during use.
[0053] The flow chart of FIG. 12 illustrates a protocol for
installing the cranial bolt 10. The bolt introduction site is
prepared and an appropriate scalp incision is made. The scalp is
retracted so the skull is exposed. (Step 310) The hex wrench 168
and hex nut 167 are used to secure the depth collar 166 at the
appropriate position on the drill bit 164 to mark the intended
drill depth. (Step 312) The drill bit 164 is mounted in an
appropriate drill (not shown) to drill at the insertion site a burr
hole perpendicular (i.e.: normal) to the surface of the skull.
(Step 314) When drilled to the intended depth the drill is removed
(Step 316) and Dura surrounding the brain tissue may be pierced in
cruciate fashion with the included scalpel 172 or the Dura may be
pierced later in the procedure. (Step 318) The cranial blot 110 is
manually threaded into the burr hole in the skull until the threads
of the shank 118 are fully seated or until a depth is reached which
in the surgeon's judgment corresponds to the thickness of the
skull. The cranial bolt 110 is manually screwed clockwise into the
burr hole using the wing nut element 132 mounted on the bolt. When
the bolt is installed the proximal end of the threaded shank 118
should approximately align with the inner surface of the skull.
(Step 320) After implantation the scalp incision is closed and
sutured around the bolt and the wound site is dressed. (Step 322) A
probe with associated sensor is selected. The chosen sensor
corresponds to a physiological parameter to be monitored and a
determination is made as to whether an introducer 146 is needed for
the chosen probe. (Step 324) Some probes, for example a perfusion
probe (i.e.: cerebral blood flow probe), are sufficiently robust
that they can be inserted without using an introducer 146. Such a
perfusion probe is the Q Flow 500.TM. Perfusion Probe from Hemedex,
Inc., Cambridge, Mass., USA.
[0054] In the case of a robust probe introduced without an
introducer 146, the probe is introduced directly through a guide
130 and a lumen of bolt 110. (Step 330) For example, the probe may
be introduced through the short guide 130(a) and through the
associated lumen within the bolt 110 into contact with brain
tissue. (See FIGS. 1-4 for views of lumens 20 through the cranial
bolt 10. The lumens through bolts 10 and 110 are the same or
similar.) A perfusion probe frequently penetrates about 2.0-3.0 cm.
from the distal end of shank 118 into the brain tissue although
other depths may be selected by the surgeon. The perfusion probe
consists mainly of a catheter with a perfusion sensor at the distal
end. Insertion depth for the sensor can be gauged by cm. markings
on the catheter. The Touhy Borst compression fitting 137 at the
proximal end of the guide 130(a) is tightened by turning its cap
clockwise to secure the perfusion probe in place. (Step 332) The
perfusion probe is sufficiently robust that it may pierce the Dura
if that was not a part of the bolt installation protocol.
Additional perfusion probes and/or other probes may be inserted
through other guides 130 and the associated lumens in the bolt 110.
A sealing cap 170 is used to seal any unused guide 130. Monitoring
of selected parameters by the installed sensors begins. (Step
334)
[0055] In the case of a probe with a delicate sensor or a catheter
that tends to flex, kink or jam inside a guide 130 or inside a
lumen through the bolt 110, an introducer 146 is used. For example,
oxygen sensors and sensors used for neurological parameters may
involve a delicate membrane lacking sufficient rigidity to pierce
the Dura. When an introducer 146 is used, the hollow tube 148 of
the introducer, with a stylet 147 inside the tube bore, is passed
through a selected guide 130 and its associated lumen. The stylet
147 fills the bore of the hollow tube 148 and extends slightly
beyond the tip of the tube. The stylet may have a sharpened end 149
which can be used to penetrate the Dura 44 if that is not a part of
the procedure for installing of the bolt 110. The Luer fitting
136(a) of the introducer 146 is engaged with the fitting 136 of the
guide 130. The stylet 147 is then withdrawn from the hollow tube
148; (Step 326) this hollow tube 148 then constitutes a receptor a
delicate catheter borne sensor. A catheter securing device 137, if
needed, is mounted on the fitting 136 of the selected guide 130
(Step 328). The delicate sensor is then extended through the tube
148 and placed in the desired location within the brain tissue.
(Step 330) The compression fitting 137 is tightened to secure the
sensor in place. (Step 332) A sealing cap 170 is used to seal any
unused guide 130. Monitoring of selected parameters by the
installed sensors begins. (Step 334)
[0056] The sensors chosen must be of the appropriate size for the
guide selected. In one example, referring to FIG. 11: guide 130(a)
has an inner diameter of 0.054 inch and extends 2.6 inches from the
distal end of the bolt; guide 130(b) has an inner diameter of 0.043
inch and extends 4.2 inches from the distal end of the bolt; guide
130(c) has an inner diameter of 0.080 inch and extends 4.7 inches
from the distal end of the bolt; and guide 130(d) has an inner
diameter of 0.054 inch and extends 4.2 inches from the distal end
of the bolt. If a longer guide is needed the extender 160 can be
used. Luer fitting 162 of the extender engages a fitting 136 on a
guide 130; the Luer element 136 on the extender 160 replacing the
element 136 on the guide 130.
[0057] Catheter mounted probes that monitor various physiological
parameters are introduced by means of the cranial bolts here
described, one catheter per lumen. In addition to perfusion
sensors, examples of catheter borne sensors that may be introduced
include those for temperature, oxygen, intracranial pressure and
neurological parameters assessed through microdialysis and
electroencephalography. A probe sensitive to one or more of each of
the parameters to be monitored is inserted into the brain tissue
for providing data to an appropriate monitor. In each case a sensor
is located at the site in the brain where the parameter is to be
assessed.
[0058] The paths of the lumens 20 through the cranial bolt 10
described above in connection with FIGS. 1-6 or paths with similar
characteristics are present in all the cranial bolts herein
described and cause the probes (i.e.: the catheters and associated
sensors) to splay outward and diverge as they penetrate the brain
tissue. The sensors thus have lateral separations in the brain
tissue that increase with depth. That is, lateral separation
between various sensors will vary depending on the depths selected
for the several probes introduced.
[0059] The invention is not to be deemed as limited to the herein
described embodiments except as defined by the following
claims.
* * * * *