Aneurysm in the internal auditory meatus

Abstract

The successful surgical treatment of an intrameatal aneurysm is reported, and the signs, symptoms, and neurootological findings discussed. Anatomical consideration of the course of the anterior inferior cerebellar artery and origin of internal auditory artery are emphasized. KEY WORDSintraeranial aneurysm anterior inferior eerebellar artery internal auditory meatus MONG aneurysms of the vertebrobasilar system, an aneurysm of the anterior inferior cerebeUar artery located in the internal auditory canal is very rare. In reviewing the literature, we could find only two surgical cases. 2,4,5 We are reporting a third case. Case ReportA 35-year-old woman was in good health until September 26, 1969, when she suddenly had a severe headache with subsequent nausea and repeated vomiting: after 1 week, the headache gradually improved. On October 22, she experienced a peculiar sensation as if stored water abruptly poured out of her left ear; shortly thereafter the severe headache and repeated vomiting returned. The next morning, she was admitted to a local hospital, where lumbar puncture was performed. The cerebrospinal fluid was bloody and the pressure 270 mm H20. On November 2, facial palsy appeared on the left side, and 2 days later she noticed a left hearing loss and tinnitus. The headache and tinnitus increased in severity, and on No-vember 21 she was transferred to the Tokyo Metropolitan Police Hospital.Examination. Vital signs and general physical examination were normal. The patient was fully alert and oriented, complaining of a continuous headache at the midportion of the left occipital region, which increased on body movement. She complained of a stiff neck but the neck moved normally on testing. Motor and sensory examination was normal; there was no dysdiadochokinesis or hypotonia or signs of pyramidal disease. Handwriting was normal. Although she felt unsteady on standing and walking, the Romberg was absent and gait was normal. Eye movements were normal but there was horizontal nystagmus on right lateral gaze. Pupillary reaction and fundi were normal. The left corneal reflex was diminished, but facial sensation was normal. There was a droop of the left corner of the mouth, and the left eye did not close fully. There was some hearing impairment on the left, and taste was impaired on the anterior two thirds of the left side of the tongue. Other cranial nerves were normal.

Occipital Artery-Anterior Inferior Cerebellar Artery Bypass With Microsurgical Trapping for Exclusively Intra-meatal Anterior Inferior Cerebellar Artery Aneurysm Manifesting as Subarachnoid Hemorrhage

“…Intra-meatal AICA aneurysms are extremely rare, with only 16 previous cases. [2][3][4][5][7][8][9][10]12,16,17,[19][20][21] Ten of these 16 patients were treated by microsurgical neck clipping 4,[8][9][10]17,[19][20][21] by opening the meatus with extensive nerve dissection, 5 patients underwent meatal loop trapping without bypass, 2,3,7,12,16) and one patient with unruptured aneurysm was managed by microsurgical packing of the internal auditory canal. 5) None of the 5 patients treated by simple meatal loop trapping developed cerebellar infarction, probably due to the favorable collateral blood supplies from dominant PICA and superior cerebellar artery.…”

“…None of the 5 previous patients undergoing meatal loop trapping developed brain stem infarction. 2,3,7,12,16) The subarcuate artery rarely originates from the meatal segment of the AICA (4%), but occlusion could result in VII/VIII cranial nerve palsy. 14) Taken together, meatal loop trapping is considered to carry acceptable risks despite the substantial risk of hearing disturbance caused by ischemia.…”

“…[2][3][4][5][7][8][9][10]12,16,17,[19][20][21] Female prevalence (female/male＝15/1) is remarkable, with mean patient age of 53 years. Most patients (15/16) developed subarachnoid hemorrhage (SAH) at the onset, [2][3][4][7][8][9][10]12,16,17,[19][20][21] and only one presented with hearing disturbance due to the mass effect of the aneurysm. 5) The pathological nature of intra-meatal aneurysm is unclear.…”

Aneurysm of the internal auditory artery: Our experience and review of the literature

“…Most of the distal aneurysms of AICA, excluding aneurysms of BA-AICA junction, caused subarachnoid haemorrhage [2, 4, 7, 8, 10, 12, 13-17, 19-21, 23, 25, 26-30, 32-34, 36, 38, Present study], sometimes followed by cerebellar [8], medullary [8] and lower cranial nerve signs [16,20], with [2,4,7,12,13,15,17,20,21,23,25,28,29,[32][33][34]36 syndromes of cerebello-pontine angle lesions, caused 8th [2,4,7,12,15,17,20,21,23,25,28,29,[32][33][34], 7th [2,4,7,12,13,15,17,20,21,25,29,32,…”

“…The distribution of aneurysms in the posterior circulation in percentage is as follows: posterior cerebellar artery (PCA) 14 (7.4-34), basilar artery bifurcation (BAB) 53 (50-66), basilar artery (BA)-superior cerebellar artery (SCA) junction and SCA 8 (5)(6)(7)(8)(9)(10)(11)(12), BA trunk 5, vertebral artery (VA), VA-BA junction, posterior inferior cerebellar artery (PICA), PICA-VA junction 20 [5,36]. The occurrence of aneurysms of anterior inferior cerebellar artery (AICA) is less than 1% [13,27].…”