Anterior Inferior Cerebellar Artery Aneurysm Mimicking a Vestibular Schwannoma

Abstract

Anterior inferior cerebellar artery (AICA) aneurysms are rare pathologies that may present with hearing loss, facial paralysis, vertigo, and tinnitus. Otologic symptoms at the time of presentation may prompt physicians to order an MRI, which can lead to the misdiagnosis of AICA aneurysms as vestibular schwannomas. We discuss the case of a 27-year-old female who presented with sudden-onset vertigo and right-sided hearing loss. She was found to have a right homogeneously enhancing internal auditory canal (IAC) mass abutting the vestibular nerve on post-gadolinium T1 MRI two hours after the presentation, which was initially diagnosed as a vestibular schwannoma. Serial T1 MRI highlighted the evolution of blood products within this mass by presenting as bright at two days and dark at two months after presentation. Profound ipsilateral sensorineural hearing loss and absent vestibulocochlear function were confirmed on audiometry and vestibular testing, respectively. The diagnostic cerebral angiogram was complicated by an iatrogenic right mid-cervical vertebral artery dissection, and the patient ultimately underwent successful embolization two months after presentation with the resolution of all presenting symptoms except right-sided hearing loss. Early recognition and treatment of an AICA aneurysm may help prevent associated vascular complications, and they should be considered as part of the differential diagnosis for IAC lesions despite their rarity.

Anatomic Variants in the Anterior Inferior Cerebellar Artery Encountered During Resection of Vestibular Schwannomas

“…Thoughtful preoperative review for close juxtaposition of AICA with petrous dura could be considered when planning TL approach to be cautious when opening the presigmoid dura to avoid vascular injury. In addition, it is possible that AICA variants may also mimic VS lesions-2 articles describe an AICA aneurysm centered distal in the IAC mimicked a small intracanalicular VS. [20][21][22] Another report identified a radiation-induced AICA pseudoaneurysm that required surgical treatment but was clearly identified preoperatively. 23 In addition, 1 study proposed that hearing outcomes may have some relationship with AICA loops into the IAC, with generally better hearing outcomes with AICA loops outside IAC.…”

Internal iliac artery aneurysm masquerading as a sciatic nerve schwannoma: illustrative case

“…All but one of the previously reported cases have involved the intracranial vestibular nerve. [7][8][9][10][11] There has been only one reported case involving the lower extremity, in which an aneurysm of the posterior tibial artery had a preoperative diagnosis of a tibial/saphenous nerve schwannoma. 12 To the best of our knowledge, no case in the literature has reported an internal iliac artery (IIA) branch aneurysm being misdiagnosed as a sciatic nerve schwannoma.…”