Subarachnoid Hemorrhage as Result of Retrocorporeal Artery Aneurysm Rupture: Rare Sequel of Subclavian Steal Syndrome.

Background: Subclavian steal phenomenon can cause retrograde flow in the vertebral artery as a result of ipsilateral occlusion of the subclavian artery. This phenomenon has various clinical presentations, such as claudication of the affected extremity or intermittent vertebrobasilar ischemia. Aneurysm formation in the spinal cord circulation is exceptionally rare but may occur secondary to collateral formation in subclavian steal syndrome.

Case Description: The case presented herein is a 53-year-old male who presented with headache and severe neck pain. Imaging studies revealed that the patient had subarachnoid hemorrhage in the perimedullary and cervicomedullary cisterns and extending to C3-C7 ventrally. Computed tomography angiography reconstruction demonstrated an aneurysmally dilated vessel dorsal to the C6 vertebral body within the spinal canal. Catheter-based angiography of the right subclavian artery demonstrated retrograde flow within the left vertebral artery and confirmed proximal left subclavian artery occlusion, findings diagnostic of subclavian steal. Further, a branch of the right thyrocervical trunk supplied a retrocorporeal artery collateral to the left vertebral artery, which also contributed to the anterior spinal artery.

Conclusions: After endovascular coiling of the aneurysm, the patient had no neurologic deficits or postoperative complications. Postoperative angiography revealed complete obliteration with no residual aneurysm. Imaging further demonstrated patency of the radiculomedullary (anterior spinal) artery.