[Remarkable Recovery of Chronic Symptoms in an Adult with Middle Fossa Convexity Arachnoid Cyst after Cystoventriculostomy:A Case Report].

Intracranial arachnoid cysts(ACs)are thought to develop during infancy and remain clinically asymptomatic in most cases. AC is often diagnosed incidentally during imaging studies. The prognosis for the recovery of newly developed symptoms is usually favorable. However, the prognosis following surgery for chronic symptoms is still unclear. Herein, we report the case of an adult patient with right convexity AC whose chronic symptoms improved after surgery. The patient was a 63-year-old woman who had an AC in her right temporal convexity since the age of 59, without any symptoms, which was incidentally diagnosed on MRI. At 61 years of age, she visited a hospital complaining of slight weakness in her left upper limb. No changes were found on the MRI scan, but her visual field indicated the presence of a left homonymous hemianopia, and her cognitive function had decreased slightly. Two years later, she developed modest left hemiparesis;therefore, she underwent cystoventriculostomy to improve the symptoms of hemiparesis. After the surgery, the left hemiparesis recovered fully, and a remarkable improvement was noted in the left homonymous hemianopia and the degenerated cognitive functions. There are no clear guidelines regarding the surgical indications for AC in adults. Many reports suggest that new symptoms related to AC can be improved with surgery. However, amelioration of chronic symptoms has rarely been reported. The present case indicates that it is possible to improve the chronic symptoms of AC in adults with surgical procedures.