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July 1980

Cisterna Magna Cyst

Arch Neurol. 1980;37(7):469. doi:10.1001/archneur.1980.00500560099027

To the Editor.—  Alker et al's report "Radiology of a Large Cisterna Magna Cyst" (Archives 36:376-379, 1979) describes an 18-year-old woman admitted for seizures and headaches. A pneumoencephalogram showed a huge cystic structure in the posterior fossa that was thought to be a dilated cisterna magna. They believed that the cyst was acting as a mass lesion exerting pressure on posterior fossa structures without causing hydrocephalus.At the time of operation, some evidence of "long-standing pressure" was noted. After surgery, the seizures and headaches disappeared. They mentioned that such marked enlargement of the cisterna magna is rare. We reported1 the incidence of "mega cisterna magna" in 3,000 computerized tomography (CT) scans and found 11 such cases. One of our cases also had a thin skull in the area of the cyst. In two cases, surgical intervention gave no symptomatic relief. We believed it was most likely that the mega