Arachnoid cysts and head injury.

A number of hypotheses and much discussion surround the subject of intracranial arachnoid cysts (ICACs). Based on the observation of 7 cases of ICACs which were asymptomatic until aggravated by head injuries, the aetiopathological relationship between head injury and ICAC is discussed. Trauma is not the only origin of ICACs, but even a slight head injury is capable of provoking the rapid decompensation of a previously dormant ICAC.