Two cases of symptomatic interhemispheric arachnoid cyst in the elderly.

We recently experienced two cases of symptomatic interhemispheric arachnoid cyst (IHAC) in the elderly, both extending into the frontoparietal region. Both patients presented with more than an 8-year history of progressive hemiparesis and underwent capsule resection in combination with internal drainage to the pericallosal cistern via the interhemispheric approach. Postoperatively, the cyst cavities were greatly reduced in size, and neurologic signs and symptoms were markedly improved. A discussion of the diagnosis, mechanism of symptom onset, and management of symptomatic IHAC in the elderly is presented.