Symptomatic Unilateral Subdural Effusion as the First Presentation of Suprasellar Arachnoid Cyst

Background and Importance: Arachnoid cysts are benign nontumoral lesions that are usually found incidentally in brain imaging. Suprasellar Arachnoid Cysts (SSACs) are rare. They can cause hydrocephalus and increased intracranial pressure, lower cranial nerve impairment and endocrine disorder. Sometimes arachnoid cysts become complicated by subdural hematoma/hygroma.  Case Presentation: We describe a patient with a suprasellar arachnoid cyst that was complicated with symptomatic subdural effusion and increased intracranial pressure after minor trauma. Conclusion: Although these cysts are rarely complicated with subdural hematoma/hygroma, and intracystic hemorrhage, the probability of subsequent subdural hygroma and increased intracranial pressure should not be underestimated.