Bilateral hypoplasia of the internal carotid artery, presenting as a subarachnoid hemorrhage secondary to intracranial aneurysmal formation: a case report

INTRODUCTION: Hypoplasia of the internal carotid artery is a rare congenital anomaly, with only 24 cases of bilateral internal carotid artery hypoplasia reported to date. Here, we present the case of a 48-year-old woman with bilateral internal carotid artery hypoplasia. She had a collateral circulation through the vertebrobasilar system; however given the high pressure flow she developed aneurysmal formations in the posterior communicating artery. To the best of our knowledge, only seven reported cases of internal carotid artery hypoplasia have been associated with intracranial aneurysmal formations. CASE PRESENTATION: A 48-year-old Sindhi woman from Karachi, Pakistan, presented to our emergency room with a sudden onset headache and was diagnosed as having a subarachnoid hemorrhage. Digital subtraction angiography revealed hypoplasia of her internal carotid artery bilaterally with an associated fusiform aneurysm of the posterior communicating artery. Our patient declined any operative intervention in view of the associated risks. She died of a rebleed six weeks after her initial presentation. CONCLUSION: Bilateral internal carotid artery occlusions can present with subarachnoid hemorrhages due to associated intracranial aneurysm formation. Prior knowledge about the possible existence of such angioarchitectural arrangement is mandatory for an early diagnosis. However, even with prompt diagnosis, management options with acceptable risk-benefit equations are still unavailable.