Dissecting aneurysm of the anterior inferior cerebellar artery in the internal auditory canal presenting with deafness without hemorrhage: A case report and literature review

Abstract

Background: Anterior inferior cerebellar artery (AICA) aneurysms in the internal auditory canal (IAC) are rare. We have reported a case of dissecting AICA aneurysm in the IAC presenting initially with the eighth nerve palsy followed by the seventh nerve palsy without hemorrhage. Case Description: A 68-year-old woman presented with a sudden onset of vertigo accompanied by deafness and tinnitus on the right side that was preceded by intermittent right retroauricular pain 2 weeks before. Audiogram showed severe sensorineural hearing loss. Computed tomography and magnetic resonance imaging (MRI) indicated absence of prior subarachnoid hemorrhage. Magnetic resonance angiogram (MRA) suggested a tiny aneurysm at the fundus of the IAC accompanied with thinning of the lateral pontine segment of the AICA. Conservative treatment led to moderate improvement of the symptoms. However, the patient developed the right retroauricular pain again, followed by the right facial paralysis 5 months later but still without signs of hemorrhage on MRI. Digital subtraction angiogram showed dissecting aneurysm in the IAC. The patient was managed with oral steroids and direct intervention was avoided due to a risk of ischemia supposed by large area irrigated by the AICA. Follow-up MRA 18 months after the first presentation showed improvement in the narrowing of the AICA proximal to the aneurysm. The patient was functionally independent despite right-sided hearing loss and slight facial paresis. Conclusion: This report warns physicians that a dissecting AICA aneurysm without subarachnoid hemorrhage may cause eighth and seventh nerve palsy.

Spontaneous AICA Dissection Presenting With Isolated Audiovestibular Loss

“…Images in Neurology ated with subarachnoid hemorrhage. 2 Given that the AICA is a small intracranial artery, it is helpful to keep in mind that conventional computed tomography angiography or magnetic resonance angiography may be insufficient to identify isolated stenoocclusive lesions due to AICA dissection without aneurysmal changes. 3 Immediate cerebral catheter angiography can be a useful neuroimaging modality for accurate early diagnosis of AICA dissection.…”

“…To our knowledge, primary isolated audiovestibular loss and subsequent AICA infarction caused by AICA dissection have rarely been reportedinpreviousliterature.Moreover,mostexistingreportsonAICA dissection involve dissecting aneurysms associated with subarachnoid hemorrhage. 2 Given that the AICA is a small intracranial artery, it Multimedia CME at jamacmelookup.com is helpful to keep in mind that conventional computed tomography angiography or magnetic resonance angiography may be insufficient to identify isolated steno-occlusive lesions due to AICA dissection without aneurysmal changes. 3 Immediate cerebral catheter angiography can be a useful neuroimaging modality for accurate early diagnosis of AICA dissection.…”