Pure tentorial subdural hematoma from rupture of aneurysm along the transmastoid branches of the occipital artery

BACKGROUND: Pure subdural hematoma (without subarachnoid, intraventricular, or intraparenchymal hemorrhage) due to a ruptured intracranial aneurysm is rare. Most reported cases involve an aneurysm along the internal carotid artery, posterior communicating artery, or middle cerebral artery. No reports have described an aneurysm along the transmastoid branches of the occipital artery. CASE DESCRIPTION: A 70-year-old female presented with sudden-onset, excruciating headaches, associated with dizziness, nausea, and emesis. There was no history of trauma. Computed tomography (CT) head demonstrated a pure tentorial subdural hematoma. Vascular imaging revealed bilateral aneurysms along the transmastoid branches of the intracranial portion of both the occipital arteries. Consequently, these branches were embolized, with no residual filling of the aneurysms. After the procedure, the patient remained neurologically well. The patient was monitored appropriately for vasospasm, and was discharged home 10 days after presentation. CONCLUSION: Rupture of aneurysms along intracranial branches of the occipital artery can lead to pure subdural hematoma along the tentorium.