Bilateral Internal Carotid Artery Agenesis with Basilar Tip Aneurysm

Introduction Major congenital abnormalities involving the internal carotid arteries (ICA) are rare. Bilateral ICA agenesis is extremely rare and only a handful of cases have been reported so far.

Material and Methods A 40-year-old Malay woman presented with syncopal attack postdefecation. She was diagnosed with a bilobed aneurysm at the basilar tip with bilateral internal carotid arteries agenesis. Ideally, a cerebral angiogram should have been performed, as it remains the gold standard for diagnosis and basilar tip aneurysms are usually amenable to endovascular coiling. However, in a rural neurosurgical center like ours, this option was not readily available.

Results Subsequently, we performed a pterional craniectomy and surgically ligated the basilar tip aneurysm. Patient recovered with minimal residual neurological deficit. Postoperative cerebral angiogram confirmed the successful placement of aneurysmal clip. This was our first experience in microsurgical clipping of aneurysm with complete absence of anterior circulation. Preoperative imaging enabled us to identify the collateral supply and care was taken intraoperatively to avoid compromising it. In conclusion, in a setting where endovascular approach is not available, surgical clipping of cerebral aneurysm is still possible even in the presence of major anomaly of cerebral vasculature.

Keywords internal; carotid; artery; agenesis