Recurrent subarachnoid bleeding in association with dural substitute. Report of three cases.

Three cases of recurrent subarachnoid bleeding are reported. The hemorrhages occurred at intervals of up to 10 years after posterior fossa craniotomy with closure using grafts of Silastic dural substitute. In one case, reexploration showed that the hemorrhage had arisen from a neomembrane formed at the site of the dural substitute; in the others, circumstantial evidence suggested a similar pathology.