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.