Post Traumatic Rupture of Arachnoid Cyst-CT

Arachnoid cysts are a well-recognized benign intracranial lesion occuring most commonly in the middle cranial fossa. Spontaneous and post-traumatic intracystic and subdural haemorrhage has also been reported. This is case of young girl with minor trauma resulting in subdural rupture of the arachnoid cyst.  Arachnoid cysts derive from the meninx primitive, embryologically, which is the primitive membrane ensheathing the developing central nervous system (CNS). As subarachnoid CSF accumulates, this meninx cavitates and resorbs under normal circumstances leaving only the subarachnoid space and the arachnoid membrane. During this process, the arachnoid membrane may split with secretion of fluid by the arachnoid cells into the resulting cleft ultimately yielding a cyst – the so called arachnoid cyst – which is truly intra-arachnoid anatomically.