This is an elastic swelling consisting of the spinal meninges enclosing
a liquid, and in some cases the spinal cord as well, and protruding
between the unclosed laminæ of the vertebral rings, usually in the
region of the sacrum or loins. It is essentially an arrest of
development on the part of the vertebræ and enveloping muscles and skin,
and an extension of the cord and effusion of the meningeal and central
spinal liquids, in the absence of their bony and muscular support.
Hydrocephalus is no uncommon complication.
The _diagnosis_ may be based on the presence of an elastic, somewhat
transparent tumor, projecting from the vertebral spines, at birth. If it
contains a segment of the cord it is usually flattened, depressed on the
summit and often associated with paralysis.
As occurring in the lower animals this need not be treated. In man,
careful antisepsis and evacuation followed by injection of a solution of
iodine 10 grs., iodide of potassium 30 grs., and glycerine 1 oz., have,
in favorable cases, secured obliteration of the sac, but even then the
recovery has rarely been complete and permanent. Paralysis and death
have usually supervened.