Neurological Recovery After Endovascular Occlusion of Ruptured A2 AICA Aneurysm

Overview

This case study reports successful neurological recovery following endovascular parent artery occlusion (ePAO) of a ruptured A2 segment aneurysm of the anterior inferior cerebellar artery (AICA). Despite initial audiovestibular loss and facial palsy due to internal auditory artery (IAA) occlusion, the patient demonstrated significant improvement in hearing, vertigo, and facial nerve function over 50 days and maintained functional independence at 24 months.

Background

AICA aneurysms, particularly those located on the A2 segment near the meatal loop, are rare and challenging to treat due to their nonsaccular morphology and proximity to critical neurovascular structures. Surgical clipping or stand-alone coiling is often difficult, and parent artery occlusion (PAO) is frequently required. The internal auditory artery (IAA), which supplies cranial nerves VII and VIII and inner ear structures, originates from the AICA meatal loop, making its occlusion during treatment a risk factor for facial palsy and audiovestibular deficits. Collateral circulation from the superior and posterior inferior cerebellar arteries may compensate for AICA territory ischemia, but IAA occlusion typically results in irreversible inner ear infarction.

Data Highlights

Key Findings

• Endovascular parent artery occlusion (ePAO) of a ruptured A2 segment AICA aneurysm was successfully performed despite anatomical challenges.
• Postoperative complications included left-sided facial palsy (H-B grade III), sensorineural hearing loss, vertigo, and loss of tongue taste due to IAA occlusion.
• Brain diffusion-weighted imaging showed no ischemic lesions in the brainstem or cerebellum postoperatively.
• Facial palsy improved from H-B grade III to complete recovery by postoperative day 50 with corticosteroid therapy.
• Hearing threshold and vertigo symptoms improved significantly by day 50, with symmetric audiometry results.
• At 24 months, the patient maintained mild hearing loss but full functional independence and no residual aneurysm on angiography.

Clinical Implications

Endovascular parent artery occlusion can be a viable treatment option for ruptured A2 segment AICA aneurysms when direct clipping or coiling is not feasible. Despite the risk of IAA occlusion and resultant audiovestibular deficits, neurological recovery including hearing and facial nerve function is possible, likely aided by collateral circulation and appropriate postoperative management. Clinicians should monitor for facial palsy and hearing loss post-procedure and consider corticosteroid therapy to support nerve recovery.

Conclusion

This case demonstrates that ePAO of ruptured A2 segment AICA aneurysms, although associated with initial cranial nerve deficits due to IAA occlusion, can result in substantial neurological recovery and favorable long-term outcomes. Careful patient selection and postoperative management are essential to optimize recovery.

References

1. Author/Source/Year -- Neurological Recovery After Endovascular Occlusion of a Ruptured A2 Segment Aneurysm of the Anterior Inferior Cerebellar Artery: A Case Study