Formation of de Novo Symptomatic Premedullary Arachnoid Cyst in Adult.

Abstract

Intracranial de novo arachnoid cysts in adults are rare, suggesting the involvement of head trauma and inflammatory diseases. We report a symptomatic adult case of nontraumatic de novo arachnoid cyst on the ventral medulla oblongata. A 56-year-old man came to our hospital complaining of dysphagia and writing difficult since 3 months ago. There was no history of head injury or inflammatory disease. A 25-mm cystic lesion was found on the ventral side of the medulla oblongata on brain magnetic resonance imaging, and the lower cranial nerve and medulla oblongata were highly compressed. The lesion did not exist on magnetic resonance imaging performed 9 years ago. Capsular resection was performed, and the histologic diagnosis was a typical arachnoid cyst. After the operation, all neurologic symptoms disappeared and no recurrence has been observed after 6 months. The pathophysiology of nontraumatic de novo arachnoid cysts has many unknown features, and it appears necessary to accumulate further case reports.