Cochleovestibular Nerve Compression Syndrome Caused by Intrameatal Anterior Inferior Cerebellar Artery Loop: Synthesis of Best Evidence for Clinical Decisions

Introduction Intrameatal cochleovestibular neurovascular conflict is a rare condition with specific clinical and therapeutic implications. Although surgery is commonly indicated in other neurovascular conflicts, for this subset of patients there is little evidence to guide treatment decisions. Moving from a case description, we performed a review of the literature on this topic to systematically present the best available evidence to guide clinical decisions. Methods We performed a literature review on reported cases of surgically treated intrameatal anterior inferior cerebellar artery (AICA)–cochleovestibular nerve neurovascular conflict, analyzing preoperative clinical data, surgical techniques, and outcomes. We analyzed the levels of evidence using the King's College guidelines. Discussion We found 35 studies of neurovascular compression of the cochleovestibular nerve by AICA for 536 patients operated on to resolve their neurovascular conflict. Only 4 of these studies describe intrameatal AICA neurovascular conflicts, for 9 cases, including our own. Tinnitus was the most frequent symptom (9/9), followed by vertigo (2/9). Our case was the only one showing unilateral hearing loss. Surgery consisted of microsurgical mobilization of the AICA loop performed through a retrosigmoid craniotomy. Tinnitus and vertigo resolved after surgery in all cases, whereas hearing loss did not improve after surgery. Conclusions Surgical treatment offers the best results for tinnitus and vertigo, but it seems to have no effect on hearing loss, not even at long-term follow-up. Microvascular decompression should be proposed to intrameatal symptomatic patients before the onset of hearing loss.