Aneurysmal expansion presenting as facial weakness: case report and review of the literature.

OBJECTIVE AND IMPORTANCE: Facial paralysis and hemifacial spasm are rare presentations of aneurysms in the posterior fossa. We report an unusual case of rapidly progressive facial palsy caused by the acute expansion of an arteriovenous malformation-associated anteroinferior cerebellar artery aneurysm. The case is notable for the rapid progression of symptoms and their precise correlation with radiographic changes, emphasizing the potential dynamic nature of aneurysms associated with arteriovenous malformations.

CLINICAL PRESENTATION: A 56-year-old woman with severe headache and nausea was seen in a local emergency room, where she underwent a neurological examination with unremarkable results and a head computed tomographic scan demonstrating acute hemorrhage in the ambient cisterns. Conventional and computed tomographic angiograms demonstrated an arteriovenous malformation in the right cerebellopontine angle fed by the anteroinferior cerebellar and superior cerebellar arteries. A micro-aneurysm measuring 3 mm was noted within the internal carotid artery on the meatal loop of the anteroinferior cerebellar artery. Two weeks later, a rapidly progressive right facial weakness developed in the patient, progressing to complete facial plegia over 12 hours, and complete sensory neural hearing loss. Repeat angiography demonstrated expansion of the previously visualized aneurysm to 8 x 4 mm.

INTERVENTION: The patient was taken to surgery for clipping of the aneurysm, which required petrous drilling to unroof the canal. She has experienced substantial recovery of facial nerve function.

CONCLUSION: Although compression of the VIIth-VIIIth nerve complex is an unusual presentation for posterior fossa aneurysms, it represents an important potential complication of vascular pathological features. The rapid aneurysmal expansion, confirmed by imaging and correlating with the rapid onset of symptoms, gives an impressive demonstration of the anatomic changes that can occur in an aneurysm associated with an arteriovenous malformation.