Spontaneous Intracystic Hemorrhage in an Arachnoid Cyst with Ipsilateral Subdural Hematoma: A Case Report and Review of Literature

Arachnoid cysts (ACs) are benign, congenital, fluid-filled compartments between two layers of the arachnoid membrane. In the majority of cases, ACs are asymptomatic and detected as an incidental finding on imaging. A case of spontaneous intracystic hemorrhage into an arachnoid cyst and ipsilateral subdural hematoma with no history of trauma is reported. A 23-year-old male presented with history of headache for 2 months at a referring hospital. He was treated conservatively and brought to our hospital after an episode of seizure and vomiting with worsening of the headache. Non-contrast head CT and MRI demonstrated arachnoid cyst with hemorrhage within it in the left temporal fossa and early subacute subdural hemorrhage along the left fronto-temporo-parietal cerebral convexities. Frontotemporoparietal craniotomy with subdural haematoma evacuation and marsupialisation of the arachnoid cyst was performed. Until a postoperative year, the patient had no headache and no neurological deficits. Arachnoid cysts are incidentally detected on neuroimaging. Hemorrhage into the cyst is a rare complication following head trauma. Subdural hygromas and hematomas are also rare associations and less than 30 cases of arachnoid cysts with spontaneous hemorrhage are reported in literature. Although very rare, spontaneous intracystic hemorrhage into an arachnoid cyst may occur and possibility of such a complication should be considered in the evaluation of patients with raised intracranial pressure and associated intracranial hemorrhage elsewhere.