US 3298372 A
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Jan. 17, 1967' M. FEINBERG 3,298,372v
SURGICAL HYDROCEPHALUS SHUNTSLEEVE FOR PLACEMENT IN A VERTEBRA Filed Dec. 17, 1963 F I G. 3
INVENTOR Fl G. 5 MAURICE V FEINBERG BY 6% 6M.
ATTORNEYS United States Patent 3,298,372 SURGICAL HYDROCEPHALUS SHUNT SLEEVE FOR PLACEMENT IN A VERTEBRA Maurice Feinberg, 536 Clinton Road, Broolrline, Mass. 02146 Filed Dec. 17, 1963, Ser. No. 331,278 3 Claims. (Cl. 128-350) This invention relates to apparatus for treating hydrocephalus. It relates more particularly to a surgical device for treating progressive hydrocephalus of the communicating type by draining cerebral spinal fluid (CSF) from the subarachnoid space surrounding the brain and spinal cord into the body of a lumbar vertebra.
Cerebral spinal fluid functions as a shock absorber for the brain and spinal cord and is thought also to carry nutrients to, and metabolites from the central nervous system. A normal person produces between 300 and 500 cc. of CSF in a twenty-four hour period. This fluid is normally absorbed at various CSF-blood interfaces in and around the subarachnoid space. The rate of fluid absorption depends on the pressure diflerential between the CSF and the venous system. Physiologically, minor increases or decreases in the production or absorption of the CSF can be handled properly by the organism.
Progressive hydrocephalus occurs when there is an excessive pressure buildup of CSF within the cavities or ventricles located within the brain. The fluid pressure buildup produces dilation and distention of the ventricles, causing the delicate brain tissue to be compressed against the inside of the skull. Hydrocepthalic babies heads will enlarge with a rate that is determined by the degree of the malady, and can possibly result in death. Adults will generally go into a coma or some degree of paralysis.
The increased fluid pressure within the brain compartments is due either to an increase in the production of or a decrease in the absorption of CSF, or to an obstruction to the CSF pathways. If the pressure buildup is due to an excessive production of or insuflicient absorption of the CSF, but with no obstruction to the CSF pathways in the ventricular system and spinal canal, the condition is called communicating hydrocephalus. If on the other hand, it is due to an obstruction preventing free communication of CSF between the ventricles and spinal subarachnoid space, the condition is called obstructive hydrocephalus. This invention deals with the former or communicating type of hydrocephalus in which the CSF is able to flow freely into the spinal subarachnoid space.
Prior attempts to reduce or alleviate abnormally high CSF pressure within the ventricles have involved the use of ventricular shunts to controlledly carry the fluid from the ventricles to one of the various venous cavities within the body able to accommodate the fluid. For example, ventriculo-caval shunts have been used to carry excess CSF from a ventricle to the internal jugular vein and atrium of the heart. Other shunt devices have been employed to carry CSF to the ureter or various other body cavities. These procedures have, however, not been entirely satisfactory because they involve the introduction of'long catheters, tubes or other similar foreign bodies directly into the vascular system, very often resulting in infection such as bacteremia, or obstruction. Also they must employ some sort of valve to prevent back-flow of blood into the shunt. The valve often changes its operating characteristics or becomes wholly inoperative thus requiring additional surgery to effect its repair or replacement. The ventriculo-caval shunts are particularly troublesome because they must be continually changed or modified, since the vascular end of the shunt tends to pull out of position as the patient grows.
3,298,372 Patented Jan. 17, 1967 ice It is known that the spongy bone marrow is receptive to and absorbs CSF. Therefore, a potentially far simpler and safer procedure for reducing abnormally high CSF pressure in cases of communicating hydrocephalus would be to drain the fluid from the spinal subarachnoid space directly into the cancellous or reticular structure of a vertebra. In fact, the infusion rate of CSF into the marrow of a lumbar vertebra with a pressure factor of 60 centimeters is in the order of 500 cc. per hour, equal to the amount of CSF produced mainly by the choroid plexus in about 24 hours.
The major difficulty with this type of procedure thus far, however, has been the inability to obtain and maintain a passage for the flow of fluid from the subarachnoid space into the body of the vertebra and to maintain a suflic-iently large CSF-bone marrow-blood interface to absorb enough CSF in order to maintain normal pressure in the CSF system. For example, a wedge-shaped or frusto-conical screw, resembling a common wood screw having a rounded head, was tried. The screw had a small longitudinal bore running from end to end and a communicating transverse bore of like size located near its narrow end. However, the screw did not obtain a large enough CSF-blood interface. Further, invariably during its insertion, the wedge-shaped body of the screw displaced and compressed the reticular substance of the vertebra in its path, thus forming around the screw a shell or wall of nonreticular marrow which was unable to adequately absorb the CSF and which actually inhibited withdrawal of the CSF from the subarachnoid space. The screw suffered from temporary blockage atits orifice, and even became permanently blocked by scar tissue, completely clogging the screw bore. Consequently, CSF could not establish contact with the bone marrow and therefore could not be absorbed, subsequently requiring surgical removal or replacement of the screw.
Most importantly, however, prior screw devices were not satisfactory because just as the aforementioned shunts, they took the regulation and control of the absorption of CSF away from the body. CSF pressure no longer changed with changes in the hydrodynamic characteristics of the blood and CSF, but was made essentially constant by the shunt or screw.
Accordingly, it is a general object of this invention to obtain and maintain continuous flow of cerebral spinal fluid from the spinal subarachnoid space into the body of a vertebra.
Another object of this invention is to provide apparatus for treating hydrocephalus which obtains a large CSF- bone marrow-blood interface within the body of a vertebra and by which the regulation of absorption and control of CSF pressure are retained by the body.
Still another object of this invention is to provide ap paratus for treating hydrocephalus which has multiple passages for preventing permanent and even most temporary blockages of CSF flow.
It is a still further object of this invention to provide apparatus for treating hydrocephalus which need not be changed or modified as the patient grows.
It is among the more specific objects of this invention to provide apparatus for treating hydrocephalus which has no moving parts, is relatively easily inserted into the body, is compatible with the body and which may remain permanently in the body even after the hydrocephaletic condition disappears.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and the apparatus embodying features of construction, combinations of elements and arrangements of parts which are adapted to effect such steps, all as exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.
For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in connection with the accon panying drawing, in which:
FIG. 1 is a diagram showing the application of my apparatus to a patient lying in a prone position;
FIG. 2 is a perspective view of a drainage insert embodying the invention;
FIG. 3 is a side view, with parts cut away, showing the insert positioned within the body of the fourth lumbar vertebra;
FIG. 4- is a section along the line 44 of FIG. 3, and
FIG. 5 is a perspective view of a modified form of the invention.
Referring to FIG. 1, a surgical insert indicated generally at is inserted into the body 12 through an incision 14 in the lower back, held open by retractors 15.
Access is obtained to the spinal subarachnoid space 16 adjacent a lumbar vertebra, say the fourth, L (FIG. 4) through an incision 17 in the posterior portion of the dura 16a and held open by sutures 19. A hole is then drilled through the anterior dura wall 16b into the body of the vertebra, forming a deep well 18 in the cancellous substance therein. The well 18 is then flushed and the insert 10 seated snugly therewithin, after which the body incisions 14, 17 are closed. Properly seated, the device forms a permanent connection between the spinal subarachnoid space 16 and the interior of the vertebra L Referring now to FIG. 2 of the drawing, the surgical apparatus 10 is constructed of stainless steel or other material which is readily sterilizable, is acceptable to the body, and produces no electrolytic action therewith. In its preferred embodiment it comprises a thin-walled cylindrical shell 20 open at both ends and having an axial passage 22. The size of shell 20 is determined by the size of the vertebra into which it is to be inserted, which in turn depends somewhat on the age of the patient. In general, the vertebral volume occupied by shell 20 should be as large as possible without unduly weakening the vertebra. For example, infants can accommodate a shell 20 approximately 7 inch long and inch wide, whereas in adults, a shell approximately 1 inch long and inch wide has been used successfully.
A radial flange 24 having rounded top and bottom edges 24a, 24b respectively is formed integrally with one end of shell 20 and extends an appreciable radial distance out from the side of the shell. For reasons set forth below, flange 24 has a pair of slotted passages 25, 26, between the edges 24a and 24b and extending from the outer surface of the flange inwardly to passage 22. A pair of relatively deep, in-line slots 27, 28 are cut in the top of flange 24 at opposite sides thereof and between passages 25, 26.
Spaced from flange 24 is an array of large, elongated apertures 29, formed in shell 20 and disposed about the circumference of the shell. Apertures 29 extend almost to the opposite end of shell 20 and have opposite rounded ends 30. The number and width of apertures 29 are selected to provide maximum aperture area with minimum reduction in the rigidity of the shell 20. Although other aperture configurations are contemplated under this invention, the illustrated preferred embodiment of my invention has four identical apertures 29 separated by four identical shell portions .31 having approximately the same width as the apertures. The end of shell 20 opposite flange 24 is inwardly tapered at 32 to facilitate insertion of the shell 20 into well 18.
In order to permanently secure the insert within the body of a vertebra, a series of screw threads 33 extend out from the shell wall between flange 24 and apertures 29. The threads 33 engage the side of well 18 at the cortex of the vertebra L and cooperate therewith in the manner of .a nut and bolt. In some situations, however, particularly with small infants whose vertebrae have bone marrow surrounded by cartilage-bone in a 50%5'O% ratio, or 70%30% ratio, it may be desirable to extend the threads 33 down between the apertures 29 or to utilize a maze of protruding knurls in lieu of the threads 33.
Referring now to FIGS. 1 and 3, insert 10 is snugly seated within well 18 of the lumber vertebra L; by rotat ing it until the enlarged threaded portion 33 tightly grips the cortical substance found near the surface of the vertebra, and the flange 24 presses tightly against the anterior wall 16b of the dura. This screwing insertion may be facilitated by means of a simple T-shaped tool whose :arms fit into the slots 27, 28 in the top of flange 24. When the insert It) is properly seated CSF flows from the subarachnoid space 16 into vertebra L along the paths indicated by the solid arrows in FIG. 3. The apertures 29 open onto wide bands of uncompressed and absorptive cancellous substance 21, creating in the body of the vertebra a plurality of large area CSF-bone marrow-blood interfaces 34 across which the interchange of the CSF and blood constituents readily takes place. The effective area of the interfaces 34 increases even more after the device has been in place for only a relatively short time, because the cancellous substance 21 tends to expand somewhat through apertures 29 into shell 20', forming a plurality of rounded, very absorptive noses 35 (FIG. 4) having a greater surface area than the area of apertures 29. The noses 35, however, do not protrude so far as to block the passage 22 through shell 20.
It is important to note that my invention does not in any way control the rate of CSF absorption or flow. For even in an insert 10 suited for an infant, the passage 22 and apertures 29 are more than large enough to handle the CSF flow in an adult.
Furthermore, even when the shell 20 becomes, in effect, displaced toward the posterior face 6 of the vertebra L and takes up less of its overall volume as the patient grows, the apertures 29 still define a sufficient area of the absorptive cancellous substance 21 near the center of the vertebra to maintain large CSF-bone marrow-blood interfaces.
Thus, the rate of CSF absorption depends entirely on the hydrodynamic characteristics of the CSF and blood at the interfaces 34 with the result that control of CSF pressure and the amount of fluid with its electrolytes is always retained by the body.
Still referring to FIG. 3, the slotted passages 25, 26 through the flange 24 and the slots 27, 28 in the top of flange prevent even temporary blockage of the subarachnoid end of the device 10 by providing auxiliary access to bore 22 from the side. If the proximal orifice 22a should be closed temporarily by a subarachn-oid membrane, CSF is still able to flow into the passage 22 through auxiliary passages 25-28 along the paths indicated by the dotted arrows.
FIG. 5 shows a modified insert particularly suited for infants. It is about one-half the size of the FIG. 2 device and it comprises an open-ended cylindrical shell 36 having an integral radial flange 37 at one end. A relatively deep circumferential groove 38 is cut in the side edge of flange 37, and an array of radial passages 39 extend from the groove 38 into the interior of the shell. A pair of large elongated elliptical apertures 40 are formed in the side of shell 36. Apertures 40 are spaced from flange 37 and extend almost to the opposite end of shell 36. The outside surface of shell 36 between the flange and the apertures is covered by a multiplicity of raised knurls 41 which engage the sides of and secure the device in the well 18 in the vertebra.
It is readily apparent from the foregoing that my invention affords a simple, safe procedure for maintaining continuous flow of CSF from the subbarachnoid space into the body of a vertebra without taking away from the body the ability to control or regulate the rate of absorption and the electrolytes of the CSF. The drainage insert prevents even temporary interruption of CSF absorption by providing auxiliary fluid passages which are not eifected by blockage. And once inserted into the body, it need not be removed as the patient grows. In fact, even if the patients hydrocephaletic condition regresses or disappears entirely it can still remain permanently in the body with no ill effects.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efliciently attained and, since certain changes may be made in the constructions set forth without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.
Having described my invention, what I claim as new and desire to secure by Letters Patent is:
1. Apparatus for treating hydrocephalus com-prising a thin-walled, cylindrical shell open at both ends for inserting into the marrow of a vertebra, said shell having relatively large inside and outside surface areas of comparable extent so as to define a relatively large chamber; a flange at one end of said shell; means on the exterior surface of said shell for frictionally engaging said vertebra when said shell is inserted thereinto, and a plurality of apertures in said shell, said apertures extending along a major portion of the length of said shell, and around a major portion of the circumference of said shell, so that fluid accumulating in said chamber can be rapidly released out through the other end of said shell and said apertures into several relatively large areas of marrow dispersed throughout the vertebra.
2. Apparatus for treating hydrocephalus comprising an elongated, cylindrical, open-ended shell; a radial flange integral with one end of said shell; a pair of slotted passages extending from opposite side edge portions of said flange toward each other and communicating with the interior of said shell; a pair of slots formed in the top of said flange at opposite sides of said shell, said slots being positi-oned between said pair of passages and extending parallel to the axis of said shell; a plurality of large elongated apertures disposed about the circumference of said shell, said apertures being spaced from said flange, and screw threads on the outside of said shell in the region between said apertures and said flange.
3. Apparatus for treating hydrocephalus comprising an elongated cylindrical open-ended shell for inserting into the body of a vertebra; one or more large apertures in said shell; a radial flange integral with one end of said shell; a relatively deep channel extending around the side edge of said flange; and array of fluid passages extending radially from the interior of said shell to the bottom of said channel, and means on the outside of said shell for frictionally engaging the body of said vertebra when said shell is inserted therewithin.
References Cited by the Examiner UNITED STATES PATENTS 2,431,587 11/1947 Schnee 128-348 2,488,232 11/1949 Peeler 468 2,819,719 1/1958 Utley et al. l28-350 OTHER REFERENCES Ziemnowitz: A New Trial of Operative Treatment of Hydnocephalous Communican Progressivus, Zentralblatt fuer Neurochurige, vol. 10, 1950, pp. 11-17.
RICHARD A. GAUDET, Primary Examiner.
DALTON L. TRULUCK, Examiner.