[Intraventricular arachnoid cyst].

INTRODUCTION. Intracranial arachnoids cysts are considered benign developmental anomalies that occur within the arachnoid membrane and generally contain clear and colourless fluid resembling cerebrospinal fluid. The prevalence of these cysts is higher in the first two decades of life, and the incidence is widely quoted as approximately 1% of all space-occupying intracranial lesions. Arachnoids cysts in the elderly person are a rare occurrence. We report the unusual presentation of a woman with an intraventricular arachnoid cyst treated with endoscopic technique. CASE REPORT. A 75-year-old woman presented with progressive hemiparesis of two years duration. Cranial MR imaging showed a right parieto-occipital intraventricular cyst with local mass effect and moderate dilatation of lateral ventricles. A right-sided burr hole was made and the arachnoids cyst was reached and cysto-ventricle shunting was realized. This was followed by a septum pellucidum fenestration. There were no complications during the surgery and the patient presented no symptoms at time of discharge. CONCLUSIONS. The neuroendoscopic approach to intraventricular arachnoid cysts was effective with few complications.