title: Rapid Visual Deterioration Caused by Posterior Fossa Arachnoid Cyst.
abstract: Posterior fossa is a site next to the middle fossa where arachnoid cyst frequently occurs. Generally, most arachnoid cysts are asymptomatic and are found incidentally in most cases. Although arachnoid cysts are benign and asymptomatic lesions, patients with posterior fossa arachnoid cysts often complain of headaches, gait disturbance, and ataxia due to the local mass effects on the cerebellum. We observed a patient with a posterior fossa arachnoid cyst who had visual symptoms and a headache, but did not have gait disturbance and ataxia. We recommended an emergency operation for decompression, but the patient refused for personal reasons. After 7 days, the patient revisited our hospital in a state of near-blindness. We suspected that the arachnoid cyst induced the hydrocephalus and thereby the enlarged third ventricle directly compressed optic nerves. Compressed optic nerves were rapidly aggravated during the critical seven days; consequently, the patient's vision was damaged despite the operation. Considering the results of our case, it is important to keep in mind that the aggravation of symptoms cannot be predicted; therefore, symptomatic arachnoid cysts should be treated without undue delay.
authors.affiliation: Department of Neurosurgery, Sungkyunkwan University, School of Medicine, Kangbuk Samsung Hospital, Seoul, Korea.
authors.forename: Chang Jin
authors.initials: CJ
authors.lastname: Shin
authors.affiliation: Department of Radiology, Sungkyunkwan University, School of Medicine, Kangbuk Samsung Hospital, Seoul, Korea.
authors.forename: Myeongho
authors.initials: M
authors.lastname: Rho
authors.affiliation: Department of Neurosurgery, Sungkyunkwan University, School of Medicine, Kangbuk Samsung Hospital, Seoul, Korea.
authors.forename: Yu Sam
authors.initials: YS
authors.lastname: Won
authors.affiliation: Department of Neurosurgery, Sungkyunkwan University, School of Medicine, Kangbuk Samsung Hospital, Seoul, Korea.; Graduate School of Medicine, Yonsei University, Seoul, Korea.
authors.forename: Si On
authors.initials: SO
authors.lastname: Kim
keywords: Arachnoid cysts; Papilledema; Posterior fossa; Visual field defect