Posterior fossa subdural hygroma with supratentorial chronic subdural haematoma.

Posterior fossa subdural hygromas are very rare. They tend to occur following direct occipital trauma. We present an unusual case of complex subdural hygroma of the posterior fossa, which was associated with a supratentorial chronic subdural haematoma. This developed after an apparently minor injury to the head. The unusual features of our case are discussed. We also review the literature and discuss the natural history and pathogenesis of subdural hygroma.