Pure Acute Subdural Hematoma of Cortical Non-mycotic Microaneurysmatic Etiology: A Report of Two Cases and a Literature Review.

Pure acute subdural hematoma (ASDH) is an uncommon clinical presentation of ruptured intracranial aneurysms, and only rarely, the culprit is a cortical microaneurysm.Mortality can be high; thus, appropriate diagnosis and treatment are crucial. Due to its extreme rarity, there are no available guidelines.We aimed to describe two clinical cases of pure ASDH due to cortical microaneurysm rupture, and a literature review was performed. A 33-year-old man, with no history of head trauma, was admitted with headache and left hemiparesis. Computed tomography (CT) showed right convexity ASDH, and CT angiography excluded intracranial vascular malformations. An emergent craniotomy was performed, and a microaneurysm was identified; the lesion was electrocoagulated and wrapped in muslin. The patient was discharged three weeks after with a modified Rankin Scale (mRS) of 1. A 58-year-old woman was admitted to the emergency room (ER) with a presumed history of head trauma. The Glasgow Coma Scale (GCS) was 4, and the left pupil was mydriatic. A CT scan showed a left convexity ASDH. Emergent decompressive craniotomy was performed, and the cortical surface beneath the hematoma revealed a microaneurysm that was clipped. The neurological status improved, but she perished 14 days after the procedure for nosocomial pneumoniae. To date, few cases of pure ASDH due to cortical non-mycotic microaneurysm rupture were reported, including the two described in this article. Digital subtraction angiography (DSA) continues to be the gold standard for diagnosis. Nevertheless, the possibility of angiographically unvisualized lesions should be considered. The risk of rebleeding is high, and it foresees a worse outcome. Prompt diagnosis and treatment are imperative to achieve better outcomes, and the craniotomy must be extensive to expose a large area of the brain surface beneath the hematoma to assess a possible bleeding source. After treatment, the outcome is good in most published cases. In patients presenting with nontraumatic ASDH, after the imageological exclusion of vascular intracranial malformations, the craniotomy for hematoma evacuation should be large to visualize all the brain surface beneath the hematoma to identify possible microaneurysm as the source of bleeding. To improve the outcome, the microaneurysm should be treated to prevent rebleeding.