[Arachnoidal cysts. A clinical, neuroradiologic and computed tomographic study].

The clinical features and neuroradiological and computertomographic findings in 125 patients with cystic intracranial processes, which were neither due to tumour nor of vascular origin, have been analysed. The intrathecal injection of iodinated contrast media is absolutely essential for the differential diagnosis of congenital cysts. CT demonstration using 2 mm. slices and coronal and sagittal reconstruction makes it possible to relate the lesions to surrounding brain structures. Additional anomalies of the brain can be diagnosed and considered when planning treatment. Air studies are no longer necessary, but plain films remain the first diagnostic step. In view of modern micro-surgical techniques, angiography remains of value in order to diagnose vascular anomalies at a pre-operative stage.