Endovascular treatment of partially thrombosed intracranial aneurysms: case series and systematic review

Partially thrombosed intracranial aneurysms (PTIAs) are rare, complex, and have a distinct natural history compared with non-thrombosed aneurysms. PTIAs show increased rates of recurrence despite angiographic intraluminal occlusion following endovascular treatment (EVT). Our single-center experience, along with a systematic review, identifies presenting features, rates of angiographic occlusion, complications, recurrence, and retreatment.

A single-center retrospective review of consecutive patients with PTIA using imaging-based inclusion criteria was performed. Rates of angiographic occlusion, complications, recurrence, and retreatment were evaluated. In conjunction, a systematic review was conducted in accordance with PRISMA-P (Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols) guidelines through PubMed, Scopus, and Google Scholar searches for studies on EVT of PTIA. After pooling patients undergoing EVT, presenting features and rates of occlusion and retreatment were assessed.

Between 2018 and 2023, 22 PTIAs met imaging-based inclusion criteria. Eighteen underwent EVT: four coiling, two stent-assisted coiling, 11 flow diversion (FD), and one FD-assisted coiling. Mass effect was the most common symptom to herald diagnosis (8/18, 44.4%). Of 12 patients with adequate follow-up, 58% had near-complete or complete occlusion, 22% recurred, and 22% were retreated. For the systematic review, a total of 12 retrospective studies were included. In pooled analysis (n=259), including the present series, complete occlusion was achieved in 62%, 80%, 78%, and 100% for coiling±stent, Woven EndoBridge (WEB), FD, and parent vessel occlusion (PVO), respectively. Retreatment occurred in 51%, 54%, 15%, and 3% with coiling±stent, WEB, FD, and PVO, respectively.

PTIAs have a complex pathogenesis, poor natural history, and often undergo retreatment. The results suggest FD to be an increasingly utilized treatment option. Coil±stent and the WEB device appear to have poorer outcomes and higher retreatment rates. If able to tolerate, PVO remains a viable option with high occlusion and low retreatment rates.