The Natural History of Arachnoid Cysts: Endoscopic and Cine-Mode MRI Evidence of a Slit-Valve Mechanism

Abstract

Arachnoid cysts are space-occupying lesions filled with CSF-like content and surrounded by a membrane resembling arachnoid matter. They are regarded as a developmental abnormality of the arachnoid, originating from a splitting or duplication of this membrane. However, precise etiology and natural history remain controversial. Different hypo-theses have been developed including agenesis of brain structures, arachnoiditis, active fluid secretion, and pulsatile pump. We present a review of the literature concerning these items and report one case of a suprasellar arachnoid cyst in which a slit-valve mechanism was observed by means of cine-mode MRI preoperatively and confirmed during the endoscopic Intervention.

Key words

Arachnoid cyst - Endoscopy - Magnetic resonance imaging - Physiopathology