Subarachnoid pouches of the posterior fossa with syringomyelia.

Three men are presented, all of whom were born with difficulty and later developed severe syringomyelia with collapsing cords on air myelography. Each had hydrocephalus and a sizable subarachnoid pouch in the posterior fossa. The clinical features and investigations are presented with a discussion of the aetiology and possible mechanisms concerned in pathogenesis and treatment. All three men had posterior fossa exploration over fifty years after birth, and the first two were also treated by valved ventriculo-atrial shunts. Each patient has improved a little since operation, but no certainty that this was due to surgery has been proved in any case; none has progressed since the last operation.