Dissecting anterior inferior cerebellar artery aneurysm treated by endovascular route: report of three cases and review

Anterior inferior cerebellar artery (AICA) aneurysms: a radiological study of 15 consecutive patients

Introduction

The aneurysms of the anterior inferior cerebellar artery (AICA) are rare lesions of the posterior circulation and to treat them is challenging. We aim to present anatomical and morphological characteristics of AICA aneurysms in a series of 15 patients.

Method

The DSA and CT angiography images of AICA aneurysms in 15 consecutive patients were analyzed retrospectively. Different anatomical characteristics were quantified, including morphology, location, width, neck width, length, bottleneck factor, and aspect ratio.

Results

Eighty percent of the patients were females. The age was 52.4 ± 9.6 (mean ± SD) years. 11 patients were smokers. Ten patients had a saccular aneurysm and five patients had a fusiform aneurysm. Aneurysm in 10 patients were located in the proximal segment, in three patients in the meatal segment, and in two patients in the distal segment. Ten out of 15 patients presented with a ruptured aneurysm. The size of AICA aneurysms was 14.8 ± 18.9 mm (mean ± SD). The aspect ratio was 0.92 ± 0.47 (mean ± SD) and bottleneck factor was 1.66 ± 1.65 (mean ± SD).

Conclusion

AICA aneurysms are rare lesions of posterior circulation predominantly found in females, present predominantly with subarachnoid hemorrhage, and are mostly large in size.

Treatment and Outcome of Anterior Inferior Cerebellar Artery (AICA) Aneurysms: Helsinki Series of 15 Consecutive Patients

Objective Anterior inferior cerebellar artery (AICA) aneurysms are rare posterior circulation lesions that are challenging to treat. This article presents the treatment and clinical outcome of AICA aneurysms in an unselected cohort of patients.

Methods A retrospective analysis of patient record files, digital subtraction angiography, and computed tomography angiography images of 15 consecutive patients harboring AICA aneurysms treated between 1968 and 2017.

Results Of the 15 AICA aneurysm patients reviewed, 12 (80%) were females. Twenty percent had intracerebral hemorrhage and 40% presented with intraventricular hemorrhage. Eleven out of 15 (73%) patients presented with subarachnoid hemorrhage (SAH); 82% of SAH patients had a good-grade SAH (Hunt and Hess grade 1–3). Eleven patients (73%) were treated surgically, three (20%) were treated conservatively, and one (7%) had coil embolization. In 27% of patients, a subtemporal approach with anterior petrosectomy was performed. A retrosigmoid approach was used in the remaining 73%. In 18% of the patients, a parent vessel occlusion was necessary to occlude the aneurysm. Five out of 11 (47%) of the patients developed postoperative cranial nerve deficits. Twenty-seven percent developed shunt-dependent hydrocephalus. All patients who presented with an unruptured AICA aneurysm had good clinical outcome (modified Rankin scale [mRS] 1–2). In patients with SAH, 82% achieved good clinical outcome and 18% had poor clinical outcome (mRS 3–6) after 1 year.

Conclusion Surgical treatment of AICA aneurysms has a high rate of cranial nerve deficits but most of patients have a good long-term clinical outcome.

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

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.

Parent Artery Occlusion against Dissecting Aneurysm Involving the Proximal Anterior Inferior Cerebellar Artery: Case Report and Literature Review

Dissecting aneurysms of the anterior inferior cerebellar artery (AICA) are rare. Few reports suggested that coil embolization and parent artery occlusion (PAO) would be valuable treatment options against dissecting AICA aneurysms. We report a case of PAO against dissecting aneurysm involving the proximal AICA and discuss the therapeutics and literature review of this pathology. A 69-year-old woman was referred to our hospital, and neurological examination revealed a semicoma (Hunt and Hess grade IV). Brain computed tomography (CT) established the diagnosis of Fisher group 3 subarachnoid hemorrhage (SAH), CT angiography revealed an extravasation near the clivus, while digital subtraction angiography showed no signs of dissection. Conservative treatment was administered, and repeated angiography on day 13 showed a pseudoaneurysm and false lumen in the left proximal AICA. The patient was in poor health condition, and endovascular therapy (EVT) of the left AICA was performed to minimize invasion. The PAO was successful with no severe ischemic damage to the brainstem and cerebellum. However, the general condition gradually deteriorated, and the patient expired on day 24. Since open surgery for dissecting AICA aneurysm is technically challenging and revascularization procedure is often required, the rapidly developing EVT is a viable alternative. Although preservation of the proximal AICA is usually necessary, PAO without revascularization procedure was performed to avoid the high risk of regrowth and re-rupture of the dissecting aneurysm with respect to the patient’s poor health condition. Hence, EVT is a viable option when microsurgery is contraindicated for treating dissecting AICA aneurysms.

Spontaneous resolution of ruptured dissecting anterior inferior cerebellar artery aneurysm: A rare case report

Dissecting anterior inferior cerebellar artery (AICA) aneurysms are extremely rare, and only nine cases are reported till date. We are reporting a case of ruptured dissecting distal AICA aneurysm with spontaneous resolution; first of its kind in the indexed literature.

Anterior inferior cerebellar artery aneurysms: Segments and results of surgical and endovascular managements

BACKGROUND

Anterior inferior cerebellar artery (AICA) aneurysms are rare and published clinical experience with these aneurysms is limited.

OBJECTIVE

The objective of this article is to report angiographic characteristics and results associated with premeatal, meatal and postmeatal segments, surgical and endovascular therapies.

METHODS

A literature review was performed through PubMed using "anterior inferior cerebellar artery aneurysm" through January 2016. Clinical data, angiograms, management techniques, and patient outcomes were reviewed for 47 collected cases in 30 previous reports.

RESULTS

Of these aneurysms, 21 (44.7%) were associated with meatal segment, 10 (21.3%) were postmeatal and 16 (34.0%) were premeatal. Patients with meatal aneurysms are more likely to present with subarachnoid hemorrhage and hearing loss and facial palsy (77.8%). Patient outcomes of meatal aneurysms presented with more neuropathies (51.7%) and cerebellar symptoms (14.3%) (p = 0.049). Four cases of meatal aneurysm with preoperative cranial nerve deficits (two VII and two VIII) showed improvement after surgery. Endovascular treatment achieved outcomes similar to surgical treatment (p = 0.327).

CONCLUSIONS

AICA aneurysms have a predilection for meatal segment. Patients with meatal aneurysms are more likely to present with subarachnoid hemorrhage and hearing loss and facial palsy. Patient outcomes of meatal aneurysms presented with more neuropathies and cerebellar symptoms. Endovascular treatment achieved outcomes similar to surgical treatment.

Dissecting Aneurysm of Anterior Inferior Cerebellar Artery Initially Presenting with Nonhemorrhagic Symptom

We report a patient with a probable dissecting aneurysm of the anterior inferior cerebellar artery (AICA) initially presenting with a nonhemorrhagic symptom, which resulted in subarachnoid hemorrhage. A 61-year-old woman suddenly experienced nausea. Computed tomography (CT) on admission showed a high-density mass with a double lumen in the right cerebellopontine angle without subarachnoid hemorrhage. Five days after the onset, she suddenly lost consciousness. CT demonstrated subarachnoid hemorrhage. Emergency angiography revealed a probable dissecting aneurysm at the lateral pontomedullary segment of the right AICA. Although the initial symptom is not hemorrhage, an unruptured dissecting aneurysm of the AICA may have a high risk of rupture. Immediate radical treatment to prevent subsequent rupture is necessary for even an unruptured dissecting aneurysm of the AICA.