They can occur in 1 of 3 regions of the AICA:
1) craniocaudal (high or low riding)
2) mediolateral-premeatal (proximal)
3) meatal-postmeatal (distal).
SAH is the most common presentation. The relationship between the aneurysms and the meatus is an important factor for neurological dysfunction 1).
3D-CTA and MRA may be considered as diagnostic adjuncts 2).
Six cases of anterior inferior cerebellar artery (AICA) aneurysms treated at one center are presented. The six cases of AICA aneurysms were surgically treated. The clinical features, surgical process, complications, and follow-up are demonstrated. Six patients with six AICA aneurysms were presented including one AVM accompanied aneurysm and one giant aneurysm. Five aneurysms had ruptured, one was unruptured. Five patients presented with subarachnoid hemorrhage (SAH) including two with intraventricular hemorrhaging and one with an intraparenchymal hematoma. One aneurysm was proximal, two were distal, and three were meatal. All cases were treated surgically. Retrosigmoid and far-lateral craniectomy were included. Navigation was accomplished through intraoperative ultrasound and fluorescent angiography. Resection of the aneurysm after clipping was significant. The most common postoperative deficit involved the cranial nerves in four patients. Follow-up was available for all patients for a mean of 68 months. SAH is the most common presentation. The relationship between the aneurysms and the meatus is an important factor for neurological dysfunction. 3D-CTA and MRA may be considered as diagnostic adjuncts. Several special surgical techniques used in our cases are worth noting. Endovascular therapy for AICA aneurysms is in the process of development and should be reserved for special cases 3).
Between 1997 and 2009, EVT was attempted for 9 AICA aneurysms. Six patients presented with SAH, and 3 aneurysms were found incidentally. The location of the aneurysms was the proximal AICA in 7 and the distal AICA in 2. Five aneurysms originated from an AICA-PICA variant. Clinical outcomes and procedural complications were evaluated, and angiography was performed 6, 12, and 24 months after embolization to confirm recanalization of the coiled aneurysm.
EVT was technically successful in 7 patients (78%). Surgical trapping was performed in 1 patient after failure of EVT, and another aneurysm occluded spontaneously, along with the parent artery during EVT. In 7 patients, the AICAs had good patency on postoperative angiography. Stent-assisted coiling was performed in 3 patients. Follow-up angiographies were performed in 7 patients and showed no evidence of recanalization or progressive occlusion with further thrombosis except in 1 patient. There was no evidence of aneurysm rupture during the follow-up period, and 8 patients were able to perform all usual activities (mRS score, 0-1).
EVT may provide a feasible and safe option as an alternative, though a microsurgical option is initially considered for the management of AICA aneurysms. Further follow-up and more experience are also necessary 4).
Sato S, Adachi H, Imamura H, Sakai N, Tani S, Narumi O, Sakai C, Arimura K, Morimoto T, Shibata T, Agawa Y, Shimizu K, Kikuchi H. [A Case of Stent-Assisted Coil Embolization for Ruptured Anterior Inferior Cerebellar Aneurysm after Iatrogenic Vertebral Arteriovenous Fistula]. No Shinkei Geka. 2017 Nov;45(11):997-1002. doi: 10.11477/mf.1436203635. Japanese. PubMed PMID: 29172206 5).