[Intracranial arachnoid cysts. A review].

The diagnosis of arachnoid cyst has become easier and more frequent with the general use of CTscanner and MRI. Their congenital origin is usually accepted. They correspond to liquid formations surrounded by an arachnoid sheet but their pathophysiologie remains unclear. When they are asymptomatic and incidentally discovered, they do not require any peculiar treatment. Variable neurological signs depending on location may be inaugural, although intracranial hypertension is the most frequent. The treatment of these symptomatic cysts remains surgical. Several options are possible: direct approach of the cyst, derivation of the cyst with different modalities, or endoscopic fenestration. This last technique, the most recent, seems to give interesting results especially for deep located cysts or those close to the ventricles.