Microsurgical Trapping and Dual Revascularization for a Giant Fusiform Posterior Cerebral Artery Aneurysm

Giant fusiform distal posterior cerebral artery (PCA) aneurysms are rare and complex lesions that require distal perfusion preservation when treated. Standard treatment modalities for complex aneurysms (e.g. coiling, flow-diversion or clipping) may compromise blood flow to eloquent territory or result in incomplete occlusion, particularly when a branch arises from the aneurysm.^1-3 When fusiform PCA aneurysms are treated with proximal occlusion or trapping, distal revascularization is essential to achieve complete exclusion while avoiding ischemic complications.^1,4-6 We present a giant PCA aneurysm treated with trapping and revascularization of the affected efferent arteries using both an extracranial to intracranial revascularization of the calcarine artery (CalcA), and reimplantation of the posterior inferior temporal artery (PITA). A 52-year-old male without neurological deficits was referred to our institute after documented growth of a giant fusiform PCA aneurysm diagnosed on chronic headache workup. Imaging revealed a partially thrombosed aneurysm involving the ambient (P2P) and quadrigeminal (P3) segments of PCA, causing midbrain compression and vasogenic edema.^7-9 A posterior interhemispheric approach was used to expose the aneurysm obtaining proximal and distal control. After exposure of the CalcA, a protective Occipital artery-CalcA end-to-side bypass was performed, allowing aneurysm trapping and thrombectomy without ischemia time. Finally, a P2P-PITA end-to-end bypass was made to maintain PCA anterograde flow and avoid the stump thrombosis phenomenon.^4,5,10 The patient was discharged home without deficits and postoperative imaging showed bypass patency and no major ischemic lesions. The patient consented to procedure and publication of his image. Institutional review board approval was deemed unnecessary.