Treatment pitfalls in recurrent dolichoectatic basilar trunk aneurysm with flow diversion: illustrative case.

backgroundIntracranial arterial dolichoectasia (IADE), also known as dilative arteriopathy, is a vascular disorder characterized by arterial elongation, dilation, and tortuosity, predominantly affecting the vertebrobasilar system. Fusiform and dolichoectatic aneurysms of the basilar trunk and vertebrobasilar system are a rare but challenging subset of aneurysms associated with IADE, exhibiting a high recurrence rate and limited treatment options. Flow diversion has emerged as an endovascular treatment approach for managing these aneurysms, although it does come with significant risks. OBSERVATIONS: A 54-year-old patient presented with a large fusiform basilar trunk aneurysm (BTA) secondary to IADE and underwent flow diversion with Pipeline embolization devices. Despite initial stabilization, the aneurysm recurred multiple times over several years, requiring additional flow diversion procedures. The patient later developed hydrocephalus, necessitating placement of a ventriculoperitoneal shunt, which was complicated by a basilar artery thrombus and ischemic stroke requiring thrombectomy. Long-term follow-up revealed ongoing aneurysm remodeling and persistent symptoms. LESSONS: This case highlights the challenges of managing recurrent dolichoectatic BTAs with flow diversion, the importance of long-term surveillance, and the risk of complications, including hydrocephalus and ischemic events, following intervention. Individualized treatment strategies are essential to mitigate complications and optimize outcomes. https://thejns.org/doi/10.3171/CASE25131.