Clinical presentation and treatment of distal anterior inferior cerebellar artery aneurysms

Abstract

Aneurysms located at the distal portion of the anterior inferior cerebellar artery (AICA) are rare, and their clinical features are not fully understood. We report the clinical features and management of nine distal AICA aneurysms in nine patients treated during the past decade at Kagoshima University Hospital and affiliated hospitals. Our series includes seven women and two men. Of their nine aneurysms, eight were ruptured and one was unruptured; six were saccular and three were dissecting aneurysms. The most prevalent location was the meatal loop (n = 5) followed by the postmeatal (n = 3) and premeatal segment (n = 1) of the AICA, suggesting hemodynamic stress as an etiology of these distal AICA aneurysms. Of the nine patients, five presented with angiographic features suggestive of increased hemodynamic stress to the AICA and the common trunk of the posterior inferior cerebellar artery, with vertebral artery stenosis, marked laterality, and a primitive hypoglossal artery. We addressed eight aneurysms (eight patients) surgically; one aneurysm in one patient disappeared in the course of 3 months without surgical treatment. Of the eight surgically treated aneurysms, seven were ruptured and one was unruptured, five were clipped via lateral suboccipital craniotomy, two were trapped via lateral suboccipital craniotomy, and one was embolized. Good outcomes were obtained in six of the eight patients who underwent operation (75 %). We consider increased hemodynamic stress attributable to anatomic variations in the AICA and related posterior circulation to be the predominant contributor to the development of distal AICA aneurysms. Direct clipping and trapping yielded favorable outcomes in our series.

A Classification for the Anterior Inferior Cerebellar Artery—Subarcuate Artery Complex Based on the Embryological Development

“…ANOVA, analysis of variance; CI, confidence interval; SAA, subarcuate artery. circulation seem to contribute to the development of distal AICA aneurysms, 61,62 as well as high-flow situations, as vascularized tumors, 62,63 arteriovenous fistula, 64 and malformations. 65,66 Also, a case of ruptured aneurysm of a SAA feeding a dural arteriovenous fistula was reported.…”

Republished: Ruptured distal AICA pseudoaneurysm presenting years after vestibular schwannoma resection and radiation

“…The majority of AICA aneurysms originate at or very close to the AICA–basilar artery junction,1 34 leaving distal AICA aneurysms, such as the one reported here, as an extremely rare entity that has mostly been reported in case reports and series 3–32. The most common location for distal AICA aneurysms is the meatal segment 3. Occasionally, distal AICA aneurysms arise secondary to hemodynamic stress associated with cerebellar arteriovenous malformations or hemangioblastomas 9 21 30.…”

“…The most commonly used overall treatment is surgical clipping with AICA preservation 3–6 8–10 12 18 21 22 27. Other surgical approaches include surgical trapping3 9 13 18 and occipital to AICA bypass 29. The most commonly used endovascular treatment is PVO with coils 7 9 14 16 26 28.…”

Missed Anterior Inferior Cerebellar Artery Aneurysm Mimicking Vestibular Neuritis—Clues to Prevent Misdiagnosis

“…AICA-aneurysms represent a tiny fraction (1-2%), [7] with distal location being exceptional (0.03%-0.22%, ~30 cases annually). [7,8] While ~80% are diagnosed after rupture, [9] cerebello-pontine signs may be observed in unruptured AICA-aneurysms. [7,9] This includes sudden hearing-loss or vertigo followed by facial palsy, [10] isolated acute, [8] episodic or chronic vertigo, [11] misdiagnosed as vestibular schwannoma or other cerebellopontine-angle tumors.…”

“…[10,11] Warning signs in distal AICA-aneurysms may be observed in up to 50%. [8] With 250'000-500'000 AVS-cases annually, [2] distal AICA-aneurysms reflect <0.01%, making it a rare, but dangerous differential diagnosis. There should be a high-index of suspicion for vascular events, as current imaging techniques are limited for the inner ear and such changes are easily missed, sometimes requiring repeated imaging.…”