Occult Lumbosacral Meningocele.

THE mildest form of the congenital anomalies classed under the generic term of spina bifida is the occult variety, in connexion with which nothing may be visible externally beyond a small median fold or dimple; a tuft of hair is sometimes present, sometimes a small lipoma. The palpating finger may discover evidence of ununited laminae and spinous processes. Through the gap no section of cord or membranes protrudes, but from the posterior aspect of the theca a fibrous band-the membrana reuniens-extends between the muscles to the under-surface of the skin at the dimple. Occasionally the back is entirely normal in appearance. Should spinal meninges project through the laminal opening at all they are generally considered to reach the skin invariably, bulging it outwards to form a rounded sac constituting a meningocele. This of course is immediately visible, of varying size, sessile or pedunculated, translucent, and in part perhaps replaceable. Its contents comprise cerebrospinal fluid within a lining of arachnoid dura, but no neural tissue except possibly the incidental herniation of a spinal root. The remarkable numerical preponderance of lower spine cases amid the total of all levels is apparent by a glance at the appended Table, derived from figures compiled by Stockmeyer'.