SPINA BIFIDA.
BY JOHN ASHHURST, JR., M.D.
DEFINITION.—By the term spina bifida is meant a congenital malformation of the vertebral column, consisting in the absence of a part—commonly the spinous processes and laminæ—of one or more of the vertebræ, and thus permitting a protrusion of the spinal meninges, which, with their contents, form a tumor of variable size and shape, usually in the lumbo-sacral region.
SYNONYMS, ETC.—Of the various names which have been proposed for this affection, most are objectionable, as not expressing with sufficient definiteness what is meant. Thus, hydrorachis (the term generally employed by French writers), hydrorachitis, spinal hydrocele, etc., convey merely the notion of an accumulation of fluid within the spinal canal, and are as applicable to simple serous effusions in that part, whether occurring as a complication of hydrocephalus or as the result of injury, as to the special affection under consideration. Again, myelochysis—pouring out or protrusion of the spinal marrow—would imply that the cord itself was necessarily involved in the tumor, which is certainly not always the case. The terms schistorachis (cleft spine) and atelorachidia (defective spine—a name suggested by Béclard) would be preferable, and are really more accurate than the name spina bifida, since, as a matter of fact, the spinous processes are, as a rule, not bifid, but totally deficient. The latter term, however, has the advantage of being more familiar, and may be retained simply as a matter of convenience. It is said by Itard to have been first employed by the Arabian physicians.
HISTORY.—Spina bifida does not appear to have been known to the ancients, the earliest recorded observations of the affection being found in the writings of Bauhinus (1560-1624), of Tulpius (1593-1674), of Bonetus (1620-89), and of Ruysch (1638-1731). Good accounts of the affection may be found in the Dictionnaire des Sciences médicales (tome xxii., Paris, 1818), and particularly in Holmes's Surgical Treatment of the Diseases of Infancy and Childhood (2d ed., London, 1869), in Follin and Duplay's Traité de Pathologie externe (tome iii.), and in Treves's article on “Malformations and Injuries of the Spine” in the International Encyclopædia of Surgery (vol. iv., New York, 1884).
ETIOLOGY.—There are two conditions essential to the formation of a spina bifida: (1) an arrest of development, or at least a defective closure, of the vertebral arches; and (2) a dropsical condition either of the central canal of the spinal cord or of the subarachnoid spaces; but which of these is the antecedent condition it is, as justly remarked by Erb, impossible to decide. Spina bifida often occurs as a complication of hydrocephalus, and is itself often complicated with an atrophic and deformed condition of the lower extremities—a circumstance which led Tulpius to suggest that the malformation was caused by a malposition of the fœtus in utero, an explanation which it seems hardly necessary to waste time in considering. Salzmann observed spina bifida in two children born of the same mother, and Camper noticed it in twins.
SYMPTOMATOLOGY.—Spina bifida forms a tumor—or, more rarely, several tumors—in the region of the vertebral column, usually discovered at birth, but occasionally not noticed until a later period. Thus, Lancisi mentions a case in which the tumor first made its appearance in a hydrocephalic child at the age of five years, and J. L. Apin one in which the patient reached the age of twenty before any swelling was manifested. If these records are accepted as authentic, the only satisfactory explanation is that of Itard—viz. that the bony deficiency existed from the time of birth, and that the dropsical protrusion did not occur until afterward: this seems to me more reasonable than the suggestion of the younger Andral, that the vertebræ underwent a process of secondary softening and absorption. The part most frequently affected is the lumbar region, but cases are not wanting of the occurrence of spina bifida in the cervical, dorsal, and sacral regions, and even, in at least one case (Genga's), in the coccyx. The tumor almost invariably occupies the median line, and projects directly backward: in at least four cases, however, recorded by Bryant, Emmet, and Thomas, the tumor protruded anteriorly from deficiency of the vertebral bodies.
The size of a spina bifida varies from that of a walnut to that of a child's head, or even larger: in some rare instances, such as those recorded by Lezelius and Richard, the whole spinal column has been cleft, and the tumor has extended from nucha to sacrum; but cases of this kind seldom come under the surgeon's observation, as children with such extensive deformity usually perish shortly after birth. The shape of the swelling is rounded, or more often oval; it is commonly sessile, but occasionally pedunculated; and it is sometimes lobulated, the lobules being separated by more or less distinct sulci. The skin covering the tumor is in some cases normal, with more or less fat in the subcutaneous connective tissue, but more often thin, tightly stretched, red, shining, and occasionally ulcerated; more rarely it is thickened and leathery, as in a case referred to by Sir Prescott Hewett. Sometimes a navel-like depression is found at some part of the surface, corresponding, as pointed out by Follin and Duplay, and by Erb, to the place of attachment, on the interior of the sac, of the terminal extremity of the spinal cord. The cutaneous investment is sometimes altogether wanting, the spinal dura mater itself forming the external covering of the tumor. It is in these cases especially that ulceration and rupture are apt to occur.
Spinæ bifidæ are usually soft and fluctuating, and occasionally partially reducible; their tension and elasticity are increased when the child is in the upright position or during the acts of expiration and crying, and are diminished during inspiration or when the child is laid upon its face. When the part is relaxed a bony prominence can be felt on either side, and the aperture in the vertebral column can be more or less distinctly outlined. The swelling is apt to be painful on pressure. If the tumor is of moderate size and covered with healthy skin, there are usually no constitutional symptoms, and, even where ulceration and rupture occur, the opening may heal and a spontaneous cure may possibly ensue. More often, as the tumor increases in bulk—or at any time if pressure be made upon it—various nervous symptoms are observed: drowsiness, muscular twitchings, convulsions, and often paraplegia and paralysis of the sphincters. Rupture is usually followed by the development of spinal meningitis, or may prove directly the cause of death by the loss of cerebro-spinal fluid which it causes; in other instances, however, if the rupture be a small one, healing may occur (as already mentioned) or a fistulous opening may persist; in rare cases the fluid may escape by a process of transudation without rupture, as in an example recorded by Laborie.
As may be inferred from what has already been said, the course of spina bifida is usually rapid and toward a fatal termination. In some instances, however, as in cases observed by Holmes, and more recently by Lithgow, spontaneous recovery has followed the obliteration of the channel which unites the sac with the cavity of the spinal membranes; and in other instances, without a cure having been effected, life has been prolonged for very many years. Thus, Behrend reports a case in which a patient with spina bifida lived to the age of fifty, and Holmes refers to another in which death resulted from an independent disease at the age of forty-three. But a still more remarkable case was recorded by Callender, the patient in this instance having reached the age of seventy-four.
PATHOLOGY AND MORBID ANATOMY.—The most important points for consideration in respect to the anatomy of spina bifida are the relations which the spinal cord and spinal nerves bear to the sac, and the nature of the contained fluid. It is ordinarily said that the spinal cord itself commonly enters the sac of a spina bifida—the report of the London Clinical Society's committee gives the proportion of cases in which it does so at 63 per cent.—and Holmes figures a specimen from the museum of St. George's Hospital, London, in which this condition is obviously present; on the other hand, Mayo-Robson in eight operations only once found the cord implicated; and the late John B. S. Jackson of Boston—whose name will be recognized as one of high authority in regard to all questions of morbid anatomy—once assured me that he had made very many dissections of spinæ bifidæ, and that he had invariably found that the cord stopped short of the sac, and that only the nerves entered the latter: this, as negative evidence, cannot of course contravene such positive evidence as that of the specimen referred to by Holmes, but it would seem to show that the condition was a less common one than is generally supposed, and that in at least a fair proportion of cases the cord itself did not form part of the sac contents. This remark applies especially to those cases in which the fluid is accumulated in the subarachnoid space, and in which, as pointed out by Sir P. Hewett, the cauda equina or spinal nerves are pushed by the vis a tergo into the sac; but when the dropsical effusion occupies the central canal of the cord, this is apt to be flattened and spread out like a thin lining to the sac, just as the brain is spread over the inner wall of the skull in cases of internal hydrocephalus; and, on the other hand, when the accumulated fluid fills the cavity of the arachnoid the cord is apt to be pushed forward, and the sac may be entirely devoid of all nerve-structures. Such, too, according to Giraldès, is the case in spina bifida of the cervico-dorsal region.
The committee of the London Clinical Society classify cases of spina bifida in three divisions: (1) Those in which the membranes only protrude (spinal meningocele); (2) those in which the protrusion involves both the cord and membranes (meningo-myelocele); and (3) those in which the central canal of the cord itself forms the cavity of the sac (syringo-myelocele). The last variety is the rarest, as the second is the most common. In meningo-myeloceles the spinal cord with its central canal is continued within the median, vertical portion of the sac, and at this part there is no covering of true skin; the nerve-roots which traverse the sac arise from this intramural portion of the central nervous system.
Humphry of Cambridge, England, makes a somewhat similar classification of spinæ bifidæ, recognizing as the most common variety the hydrorachis externa anterior, in which the fluid occupies the subarachnoid space in front of the spinal cord, and in which “the cord and the nerves are stretched backwards and outwards upon the sac, and are there confluent, together with the arachnoid, pia mater, and dura mater, or their representatives, in the thin membrane which forms the hindmost part of the wall of the sac;” rarer forms are the hydro-meningocele, or hydrorachis externa posterior, in which the fluid accumulates behind the cord, which does not enter the sac, and the hydro-myelocele or hydrorachis interna, in which the fluid occupies the central spinal canal.
The theory which, according to the Clinical Society's committee, best explains the pathological anatomy of spina bifida is that which assumes a primary defect of development of the mesoblast from which the structures closing in the vertebral furrow are developed.
The fluid of spina bifida appears to be identical in character with the cerebro-spinal fluid. Bostock found that it was very slightly clouded by the application of heat, and that it contained, in 100 parts, 97.8 of water, 1.0 of chloride of sodium, 0.5 of albumen, 0.5 of mucus, 0.2 of gelatin, and some traces of lime. Five specimens more recently analyzed by Hoppe-Seyler gave an average of 98.8 parts water, 0.15 parts proteids, and 1.06 extractives and salts. Turner found a reaction somewhat similar to that of grape-sugar, as had been previously found by Bussy and Deschamps in cerebro-spinal fluid itself, but in two specimens analyzed by Noad for Holmes it was at least very doubtful whether sugar was actually present. “The first specimen was found to be completely neutral; its specific gravity was 1.0077; it contained phosphates, but no reaction could be obtained resembling that of sugar. The second specimen ... did give a reaction with copper like that of sugar, but no trace of fermentation could be obtained.” Three analyses, however, made by Halliburton for the London Clinical Society's committee showed uniformly a decided trace of sugar, with a diminution in the quantity of proteids, which appeared to consist entirely of globulin.
In some cases the sac of a spina bifida contains, besides nerve-structures and cerebro-spinal fluid, both fibrous and fatty tissues.
DIAGNOSIS.—Ordinary fatty tumors have been mistaken for spinæ bifidæ, but such an error could only be committed through carelessness: more difficult is the diagnosis from certain forms of congenital cyst, occupying the median line of the back, and still more difficult the diagnosis from the several affections known as false spina bifida. In the former case the distinction might be made by noting the irreducibility, constant shape, and unchanging tenseness of the cyst, and perhaps, as suggested by T. Smith, by tracing the line of spinous processes beneath it; some information, too, might perhaps be gained by chemical examination of the fluid obtained by puncture. Under the name of false spina bifida Holmes includes three distinct conditions: these are—(1) a true spina bifida, in which the connection with the spinal membranes has in some way been obliterated, the sac then communicating with the vertebral canal, but not with the theca; (2) a congenital, cystic, or fatty tumor, taking its origin within the vertebral canal, and projecting through an opening caused by a gap in the laminæ; and (3) a tumor containing fœtal remains, and properly regarded as an example of included fœtation. In any of these cases a positive diagnosis might be impossible, and the probable nature of the tumor could only be inferred by noting the absence of one or more of the characteristic symptoms of true spina bifida.
PROGNOSIS.—The prognosis of spina bifida is without question unfavorable; at the same time the affection is by no means to be considered, as it was formerly, one of an invariably fatal character, for, apart from the fact already mentioned that several cases are on record in which patients with untreated spina bifida have reached adult life, and even old age, the modern method of treatment has proved so much more successful than those formerly employed that in favorable cases surgical interference affords at least a reasonable prospect of recovery. The circumstances which especially furnish grounds for an unfavorable prognosis are the rapid growth of the tumor, the thinning or ulceration of its coverings, and the occurrence of nervous symptoms, and particularly of paralysis or convulsions.
TREATMENT.—This may be either palliative or radical. If the tumor be not increasing materially in size, the surgeon may properly content himself with palliative measures—applying equable support and perhaps slight pressure by the use of a well-padded cap of gutta-percha or leather, an air-pad, or, as advised by Treves, a simple pad of cotton smeared with vaseline, and a bandage; if the tumor be small and covered with healthy integument, painting its surface with collodion may be of service through the contractile property of that substance. Radical measures are only indicated when the child, otherwise healthy, seems to have his life threatened by the rapid growth of the tumor, causing risk of ulceration and rupture, or giving rise to convulsions or paralysis. The principal modes of treatment to be considered under this heading are—(1) simple tapping or paracentesis; (2) injection of iodine; (3) ligation of the neck of the sac; and (4) excision.
(1) Paracentesis, a simple evacuation of the fluid contents of the sac, is the only operation ordinarily justifiable in cases attended by paralysis or other grave nervous manifestations. The puncture should be made in the lower part of the sac and at a distance from the median line (in the course of which the nerve-structures are particularly distributed), and only a small quantity of fluid—a few drachms or at most one or two ounces—should be removed at a time, the instrument being at once withdrawn if convulsions follow, and the wound being instantly closed with lint dipped in compound tincture of benzoin. Either an aspirator-tube or a small trocar may be used, and the operation may be repeated if necessary, pressure being maintained during the intervals. Paracentesis has occasionally though not often proved curative.
(2) Injection of Iodine.—This mode of treatment was introduced about the same time by Velpeau and by Brainard of Chicago. The latter surgeon's method consists in injecting, after only partially emptying the tumor, a solution of iodine with iodide of potassium (iodine, 5 grs.; iodide of potassium, 15 grs.; water, 1 fl. oz.), allowing it to flow out again, washing out the sac with water, and finally reinjecting a portion of the cerebro-spinal fluid originally evacuated; and the former's, in completely evacuating the tumor, and then injecting a mixture of iodine and iodide of potassium, each one part to ten parts of water. Each of these plans has met with a fair measure of success;1 but the modification introduced by James Morton of Glasgow is a great improvement, and affords what is actually the most successful mode yet devised for dealing with spina bifida. Morton employs a solution of iodine in glycerin (iodine, 10 grs.; iodide of potassium, 30 grs.; glycerin, 1 fl. oz.), which has the advantage of being less diffusible than the aqueous solution, and therefore less liable to enter the spinal canal. The tumor is about half emptied, and a small quantity—from fluid drachm ss to fluid drachm iij of the solution—is then slowly injected, and allowed to remain. The operation is repeated after a few days if necessary. Of 50 cases known to Morton as having been treated in this way up to May, 1885, 41 were regarded as successful; but of 71 cases collected by the London Clinical Society's committee, only 39 had been benefited by the operation.
1 In a case recently recorded by Woltering, however, iodine injection was followed by death within half an hour.
The introduction of iodine into the sac of a spina bifida is, according to Morton, only justifiable in cases unattended by paralysis; under opposite circumstances I should be disposed to try a plan recently employed with success by Noble Smith in a case of meningocele—viz. injecting the iodo-glycerin solution into the coverings of the sac, and as close to it as possible without perforating it.
(3) and (4). Ligation and excision have each occasionally effected a cure, but more often have but helped to precipitate a fatal issue. A successful case of ligation followed by excision has been recently recorded by Löbker. The elastic ligature, applied around the neck of the sac (if this be pedunculated), has been employed by Laroyenne, Ball, Colognese, Baldossare, Mouchet, and other surgeons, and of 6 cases collected by Mouchet, 3 ended in recovery. Another success has been recently recorded by Turretta. The écraseur has been used, but its employment cannot be recommended. Compression by clamps is advised by Schatz of Rostock. Ligation is best adapted to cases occurring in the cervical and dorsal regions, in which, as pointed out by Giraldès, nerve-elements are less likely to be involved. Excision, supplemented by transplantation of a strip of periosteum from a rabbit, has been successfully resorted to by Mayo-Robson and by R. T. Hayes of Rochester, N. Y.; and simple excision, with suture in separate lines of the sac and integuments, by Mayo-Robson, Atkinson, and Jessop. The Clinical Society's committee in all refers to 23 cases treated by excision, 16 of which are said to have been successful.