US20070010725A1 - Localizing device for ventriculostomy - Google Patents

Abstract

A localizing apparatus includes a frame, a linear reference marker, and a target marker. The frame includes a first portion fixable to a first anatomical reference point. The linear reference marker is rotatable about the first anatomical reference point to align a second anatomical reference point with the first anatomical reference point. The target marker is rotatable about the first anatomical reference point to establish an angle from the linear reference marker such that the target marker is located in a desired plane.

Description

FIELD OF THE INVENTION
• The invention generally relates to locating devices. The invention finds particular application in medical devices referencing skull locations with respect to ventricles.
BACKGROUND OF THE DISCLOSURE
• Most surgical neurological procedures require accurate placement of medical instruments within the patient's brain. A common neurological surgical procedure is a ventriculostomy in which a cerebral ventricle drain, shunt or catheter is implanted. The purpose of the drain or shunt (with or without a transducer or fiberoptic device) is to relieve high pressure cerebrospinal fluid (CSF) in a patient's cerebral ventricles resulting from congenital brain malformations, acute or chronic infections, tumors, intraventricular hemorrhage, normal pressure hydrocephalus or other intracranial space-occupying lesions, as well as to provide a reliable means to measure intracranial pressure or to deliver medication into the cerebrospinal fluid space.
• Procedures for the placement of ventricular drains, shunts and catheters rely on the skill of the neurosurgeon. These procedures are often expensive and time consuming. After imaging the brain, the neurosurgeon forms a burr hole in the skull and guides a catheter through the burr hole toward landmarks on the ipsilateral or contralateral of the patient's head. The neurosurgeon must accurately conceptualize the internal topography of the brain during the procedure, and rely on this conceptualization to effectively place the catheter within the cerebral ventricle. In some procedures, the neurosurgeon checks the location of the catheter by imaging another CT scan of the brain following the operation. By verifying the position of the catheter within the brain, the neurosurgeon can effect longer shunt patency and decrease morbidity rates due to shunt malpositioning, as well as assure the accurate delivery of medication within the ventricle and the accurate measurement of intracranial pressure.
BRIEF SUMMARY OF THE INVENTION
• A localizing apparatus includes a frame, a linear reference marker, and a target marker. The frame includes a first portion fixable to a first anatomical reference point. The linear reference marker is rotatable about the first anatomical reference point to align a second anatomical reference point with the first anatomical reference point. The target marker is rotatable about the first anatomical reference point to establish an angle from the linear reference marker such that the target marker is located in a desired plane.
• Another aspect of the invention provides an apparatus to position instruments within a target. The apparatus includes a probe, a reference marker, and a target marker. The probe is configured to attach to a first reference point. The reference marker is configured to rotate about a center axis of the probe including an end configured to align a second reference point with the first reference point. The target marker is configured to rotate about the axis and to be positioned at an angle such that the target marker is located in a plane that transversely passes through the target.
• Another aspect provides a localizing apparatus including a frame having a first and second end, an annular guide, a linear reference marker, and a linear target marker. The frame is configured to extend in an arc around a head and has an outer diameter surface and an inner diameter surface. The annular guide extends from the outer diameter surface to the inner diameter surface and is configured to direct the instrument toward the surface of the head. The first end of the frame is configured to fix the frame to a first anatomical reference point. The second end of the frame is configured to fix the frame to a second anatomical reference point. The linear reference marker is configured to rotate about the first end and to align a third anatomical reference point with the first anatomical reference point. The linear target marker is configured to rotate about the first end. The linear target marker is positioned at an angle from the linear reference marker such that the linear target marker is located in a plane that passes through the desired portion of the head.
• Yet another aspect of the invention provides a method for localizing a portion of the brain. The method includes locating a first anatomical reference point, extending a first line from the first anatomical reference point to a second anatomical reference point such that the reference points are located in a sagittal plane, positioning a second line in the sagittal plane to pass through the first anatomical reference point at a determined angle from the first line such that the second line is oriented in a transverse plane that passes through the portion of the brain.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a schematic diagram of a first embodiment of a localizing device for ventriculostomy;
• FIG. 2 is a lateral view of the first embodiment ofFIG. 1 donned by a patient;
• FIG. 3 is a schematic diagram of a sagittal scan of a brain;
• FIG. 4 is a schematic diagram of an axial scan of a hydrocephalic brain;
• FIG. 5 is a schematic diagram of a second embodiment of a localizing device for ventriculostomy; and
• FIG. 6 is a front view of the second embodiment ofFIG. 4 donned by a patient.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
• Referring now to the drawings, which are not intended to limit the invention but instead illustrate several exemplary embodiments,FIG. 1 illustrates a schematic of a localizingdevice10 for ventriculostomy made in accordance with the teachings of the present invention. The localizingdevice10 includes aU-shaped frame12,probes14,markers16,17 and18, and aprotractor20. Theprobes14 are threadedly received in theframe12 and lie on anaxis19. Themarkers16,17 and18, and theprotractor20 are rotatably attached to theframe12 so that themarkers16,17,18 andprotractor20 may rotate about theaxis19. Theframe12 may also rotate about theaxis19. When thedevice10 is donned by a patient, theprobes14 are fixed to the skull in the external auditory meati and theframe12,anatomical reference marker16,perpendicular reference marker17,target marker18, andprotractor20 may rotate about theaxis19.
• Theframe12 is generally in the shape of an arc. Theframe12 includes afirst end22 and asecond end24. Anouter surface26 and aninner surface28 of theframe12 define the inner and outer arc lengths of theframe12. In the embodiment shown inFIG. 1, theframe12 is made of a member having a circular cross section. Theframe12, however, may have various cross sections without limiting functionality. Theframe12 is configured with an array of annular or othershaped guides30 that extend from theouter surface26 to theinner surface28 of theframe12. Theguides30 may extend perpendicular to the inner andouter surfaces28 and26 or may be angled to direct an instrument toward a specific region under theframe12. By adjusting the angle and the lateral placement of theguides30 on theframe12, a neurosurgeon may choose alternative paths to the target.
• Themarkers16,17,18 are relatively positioned with respect to one of theprobes14 so that a neurosurgeon may reference certain anatomical points or planes as the portion of the brain is isolated for the ventriculostomy. Theprotractor20 can be aligned with one of themarkers16,17, or18 such that angles can be measured between themarkers16,17, or18. When themarkers16,17,18 are properly positioned by the surgeon, then theframe12 may be rotated to align theframe12 with one of themarkers16,17,18.
• Theprobes14 are threadedly received in theframe12 as is conventional in the art. Theprobes14 may be advanced along theaxis19 toward one another and also retracted along theaxis19 by rotation relative to theframe12. Contactsurfaces36 of theprobes14 are configured to contact an anatomical reference point, such as the external auditory meati, of the patient's head so that theframe12,markers16,17,18 and theprotractor20 may be fixed but for pivotal movement about theaxis19. Theprobes14 may also fix the pivotal motion of theframe12 so that the frame may not rotate about theaxis19. For example, a small hole may be positioned on thearc12 to accommodate a locking screw. The locking screw is tightened down when the correct desired angulation of thearc12 has been obtained, locking the arc in place with respect to thefixed probes14. In an additional embodiment theEAM probes14 may have prefixed accommodations, e.g. depressions, to provide easier locking down of the screw. Such a configuration allows a surgeon to use the fixedframe12 to guide surgical tools during surgery.
• FIG. 2 is a lateral view of the localizing device ofFIG. 1 donned by a patient. Theprobes14 are advanced on opposite sides of a patient'shead50 until the contact surfaces36 (FIG. 1) of the probes contact a desired reference such as the external auditory meati. When theprobes14 are so positioned, themarkers16,17,18 and theprotractor20 are all centered for rotation about an axis normal to the external auditory meati. In this example, the external auditory meati serve as an anatomical reference point for localizing the portion of the brain. Themarkers16,17,18 can be rotated about the anatomical reference point to align with other anatomical reference points and to define desired angles between the markers.
• For example, theanatomical reference marker16 may align the external auditory meati (centered on probe14) with the most posterior point on the mandibular angle21 (angulus mandibulae). Themandibular angle21, the ipsilateral angle of the mandible when the jaw is closed, is a palpable anatomical reference point on the head (e.g. seeFIG. 162: Eduard Pernkopf, Atlas of Topographical and Applied Human Anatomy, Volume I: Head and Neck. 2^ndRevised Edition. Urban & Schwarzenberg, Baltimore-Munich, 1980). After theanatomical reference marker16 is aligned along this mandibulomeatal line (MML), theprotractor20 can reference angles with respect to the MML. Optionally, aperpendicular reference marker17 may be aligned at 90° to the MML to create a perpendicular reference (angle θ). Thetarget marker18 may then be rotated to measure an angle from the perpendicular reference marker17 (angle β) or the anatomical reference marker16 (angle α) to mark a desired plane in which the target ventricle of the brain lies. Alternatively, themarkers16,17,18 may be set in a fixed relative relationship so that a predetermined target portion of the ventricle is localized without theprotractor20. In this embodiment, when theanatomical reference marker16 is aligned with the MML, thetarget marker18 aligns with the plane that transversely intersects the target portion of the brain.
• If thetarget marker18 is projected transversely into a brain50 (FIG. 3), thetarget marker18 intersects acerebral ventricle54 of thebrain50. For a frontal horn ventriculostomy, the angle measured between theperpendicular reference marker17 and the target marker18 (angle β,FIG. 2) is approximately 35°to 55°, or approximately 125° to 145° between theanatomical reference marker16 and the target marker18 (angle α). Once the target has been isolated in the sagittal plane, then the target is isolated in the transverse plane. As shown inFIG. 4, the lateral ventricles extend from near the midline sagittal plane laterally toward the sides of the brain. Theventricles54 may be located by projecting a line that intersects the midline sagittal plane about 5to 6cm below the inner table of the skull.
• The guides30 (FIG. 2) are oriented to direct an instrument into the brain such that the instrument would intersect the midline sagittal plane at a depth of approximately 5 to 6 cm from the inner table of the skull. This direction in the transverse plane intersects the frontal horn of the lateral ventricle (cornu anterius) of the brain. Theframe12 is then locked in place, and the annular guides are used to direct a catheter or probe toward a target, such as the frontal horn of the lateral ventricle of the brain. While this example has explained a frontal horn ventriculostomy, it should be particularly understood that a similar procedure may be used to perform lateral ventricle body, posterior (occipital) and inferior horn, and third and fourth ventriculostomies, and further understood that this method may be used to identify other targets of the brain for other procedures For example, enlargement of angle β to approximately 85° to 95° would result in preferential targeting of the atrium of the lateral ventricle (enlarged region at the junction of the body, temporal and occipital horns of the lateral ventricle).
• Referring now toFIG. 5, a lateral view of another embodiment of a localizingdevice70 for ventriculostomy is shown. The localizingdevice70 includesmarkers72,74,76, a rotational frame or probe78, and aprotractor80. Theprobe78 is disposed relative to an anatomical reference point by adhesive, elastic band, surgical tape and the like. Themarkers72,74,76, and theprotractor80 are angularly positionable about theprobe78. Themarkers72,74, and76 rotate about an axis19'. Themarkers72,74,76 are relatively positionable with respect to theprobe78 so that a neurosurgeon or user may reference certain points or targets such as a portion of the brain being isolated for a procedure. Theprotractor80 is oriented relative to themarkers72,74,76 to enable measurement of angles between the markers. When themarkers72,74,76 are positioned by the surgeon, the frame thetarget marker76 localizes the target portion of the brain in the sagittal plane.
• As best illustrated by the embodiment inFIG. 6, thetarget marker76 may be made of a bendable material or otherwise angularly deformable material. Thetarget marker76 may also include a number ofguides84 extending through thetarget marker76. Theguides84 are positioned along thetarget marker76 such that a mark made on the surface of the head intersects a ventricle when a perpendicular path from the surface of the head is followed from the mark. Once the cerebral ventricle of the brain is isolated in the sagittal plane, then thetarget marker76 may be bent across the surface of the head to locate the targeted portion of the brain in the transverse plane (the ideal point on the surface of the head for canulation of the ventricle).
• There have been described and illustrated herein embodiments of the apparatus and method of the present invention. While in accordance with the patent statutes, a preferred embodiment has been presented, it is not intended that the scope of the invention be limited thereto. It is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. For example, those skilled in the art will appreciate that certain features of one embodiment may be combined with features of another embodiment to provide yet additional embodiments. It will therefore be appreciated by those skilled in the art that other modifications could be made to the provided invention without deviating from its spirit and scope as so claimed and described.

Claims (19)

1.-20. (canceled)

21. A method for localizing a portion of a brain, comprising the steps of:

positioning a probe adjacent to a first anatomical reference point;

rotatably positioning a first indicator along a line intersecting the first anatomical reference point and a second anatomical reference point such that the indicator is located in a sagittal plane; and

rotatably positioning a second indicator parallel to the sagittal plane and defining a determined angle from the first indicator such that the second indicator is oriented in a transverse plane that passes through the portion of the brain.

22. The method ofclaim 21 wherein the first anatomical reference point comprises an external auditory meatus.

23. The method ofclaim 21 wherein the second anatomical reference point comprises a mandibular angulus mandibulae.

24. The method ofclaim 21 wherein the determined angle comprises an angle between 125° and 145°.

25. The method ofclaim 21 further comprising the step of positioning a third indicator perpendicular to the first indicator.

26. The method ofclaim 25 wherein the positioning a third indicator comprises positioning the third indicator at an angle between 35° and 55° from the second indicator.

27. The method ofclaim 21 further comprising the step of extending the second indicator into a transverse plane perpendicular to the sagittal plane.

28. The method ofclaim 27 further comprising the step of marking a position on a surface underlying the extended second indicator.

29. An apparatus comprising:

a probe configured for positioning adjacent to an external auditory meatus;

a first marker rotatably connected to the probe and configured for positioning along a mandibulomeatal line; and

a second marker rotatably connected to the probe and operable to establish a defined angle between the first and the second marker.

30. The apparatus ofclaim 29, further comprising a protractor configured for positioning the second marker at the angle.

31. The apparatus ofclaim 30, wherein the protractor is fixed to the first marker.

32. The apparatus ofclaim 29, wherein the defined angle at which the second marker is configured to be positioned relative to the first marker is between 125° and 145°.

33. The apparatus ofclaim 29, wherein the positioning of the probe adjacent to the external auditory meatus comprises attaching the probe to the external auditory meatus with an adhesive.

34. The apparatus ofclaim 29, wherein the second marker is configured to bend to a contour.

35. The apparatus ofclaim 29, wherein the second marker comprises guides configured to mark a position.

36. The apparatus ofclaim 29, comprising a third marker disposed in a perpendicular relationship to the first marker.

37. The apparatus ofclaim 29, further comprising a frame supporting the probe, the frame configured to extend around a head and terminate in an opposing probe positionable adjacent an opposite external auditory meatus.

38. The apparatus ofclaim 37, wherein the frame is configured with at least one guide that extends through the frame.

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