Ruptured giant vertebrobasilar aneurysms: illustrative cases

BACKGROUND: Giant vertebrobasilar aneurysms are rare and have a poor natural history. Compared with smaller aneurysms, giant aneurysms have a significantly higher risk of rupture, and a posterior circulation location is itself an independent predictor of rupture regardless of size. Clinical presentation and symptomatology are highly variable, often with nonspecific symptoms progressing insidiously, resulting in delays of diagnosis. There are also significant treatment challenges. The authors describe their experience in 2 cases. OBSERVATIONS: Both patients presented with symptomatic brainstem compression. One patient presented with headache, gait difficulties, left face numbness, and facial droop. The other presented with left-sided trigeminal pain, sixth nerve palsy, blurry vision, and unsteady gait. Both patients developed catastrophic subarachnoid hemorrhage within days following presentation, before planned intervention, with rapid progression to death. LESSONS: Consistent with prior reports, both patients presented with symptomatic brainstem compression, which may have reflected aneurysm growth or instability. These data, along with prior reports, emphasize the poor clinical outcomes associated with symptomatic brainstem compression due to giant vertebrobasilar aneurysms, as well as the urgent and timely need to treat them despite no prior hemorrhage. Higher clinical suspicion is warranted, and further advances in endovascular technologies are necessary to provide reliable, improved clinical outcomes. https://thejns.org/doi/10.3171/CASE26399.