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May 1977

Supratentorial Arachnoid Cysts in Adults: A Discussion of Two Cases From a Pathophysiologic and Surgical Perspective

Author Affiliations

From the Department of Neurological Surgery (Dr Dyck), Los Angeles County and University of Southern California Medical Center, and the Department of Pathology (Dr Gruskin), St Vincent Medical Center, Los Angeles.

Arch Neurol. 1977;34(5):276-279. doi:10.1001/archneur.1977.00500170030004

• Large congenital arachnoid cysts are a rare cause of increased intracranial pressure and progressive neurologic deficits in adult life. We describe two patients, diagnosed by computerized axial tomography and surgically treated. The pertinent medical literature was reviewed. The outer cyst membranes were excised, and a communication between cyst and subarachnoid space was established.

When possible, the membranes and fluid content of these lesions should be studied. This fluid is best obtained by aspiration prior to dural incision. At present, three etiologic mechanisms of cyst enlargement appear tenable: (1) secretion of fluid by ependymal cells, (2) fluid ingress due to an osmotic gradient, and finally, (3) trapping of fluid by a ball-valve mechanism. Regardless of the reasons why these lesions enlarge, drainage of cyst content into the venous system warrants a clinical consideration.

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