Sacral agenesis. Neurologic and neuropathologic features.

The neurologic deficits in sacral agenesis involve motor function much more than sensory function, in a lumbosacral distribution; autonomic involvement, with neurogenic bladder, is variable. Relative sensory sparing may be due to the derivation of sensory nerves from neural cre, t tissue, which is uninvolved. An occult sacral meningomyelocele with ectopic neural tissue was found at necropsy in one of our patients. Primary amyoplasia may account for small but histologically normal muscles derived from the same somites as the aplastic vertebrae.