Introduction: Subdural hematoma without subarachnoid hemorrhage secondary to intracranial aneurysm rupture is rare and may complicate patient management due to delay in diagnosis and subsequent treatment. Herein, we describe a case presenting with pure SDH secondary to the rupture of a posterior communicating artery infundibular dilatation (PcoA-ID). To the best of our knowledge, this is the first case of rupture of a PcoA-ID with SDH in the convexity and tentorium, which also tracked into the upper cervical spine along the subdural space. Additionally, we briefly discuss the previously published cases of pure SDH secondary to intracranial aneurysm rupture. Case Report: A 44-year-old female presented with headache, dizziness, nausea and left-sided diplopia to an outside institution. Initial diagnostic work-up showed no intracranial hemorrhage, however, magnetic resonance angiography and subsequent digital subtraction angiography revealed left posterior communicating artery infundibular dilatation. Two days later, the patient presented with a loss of consciousness. Computed tomography was positive for bilateral hemispheric subdural hematoma with no evidence of subarachnoid hemorrhage. Digital subtraction angiography showed left posterior communicating artery infundibular dilatation and pseudoaneurysm originating from the inferior area of the infundibular dilatation, concerning recent rupture. Balloon assisted coil embolization was performed and the patient had a good outcome without any neurological deficit. Conclusion: Subdural hematoma in a young adult without a history of trauma or coagulopathy warrants additional vascular imaging to search for underlying vascular lesions. It should also be kept in mind that infundibular dilatation may rupture and cause a pure subdural hematoma.

A Case of Subdural Hematoma without Subarachnoid Hemorrhage Secondary to Rupture of Posterior Communicating Artery-infundibular Dilatation