A Case of Facial Spasm Associated with Ipsilateral Cerebellopontine Angle Arachnoid Cyst

Abstract

The most common case of hemifacial spasm was reported to be vascular compression at the root exit zone (REZ) of the facial nerve. 1 Vascular compression was usually caused by the anterior inferior cerebellar artery (AICA), posterior inferior cerebellar artery, or vertebral artery. 2 Other causes of hemifacial spasms were known as posterior circulation aneurysms, 3 arteriovenous malformations, 4 and cerebellopontine angle (CPA) tumors, 5 but these cases are rarely observed. Among these cases, CPA arachnoid cyst is very rare, and we have never experienced a case. Herein, we report our experience on hemifacial spasm associated with CPA arachnoid cyst. Case ReportThis study was approved by the Ethics Committee of Asahikawa Medical University.A 66-year-old woman was admitted to our hospital with a chief complaint of twitching of the right facial muscle for 3 years. The spasm originated particularly in the inferior orbicularis oculi and did not extend to lower part of the face. The patient previously had Botox therapy at another hospital, but it was ineffective. Except for facial spasm, no neurologic abnormality, including hearing deficit, was observed. Preoperative T2-weighted magnetic resonance imaging demonstrated hyperintense area resembling an arachnoid cyst in the right CPA. The image also indicated that the REZ of the facial nerve was compressed by the AICA, which was displaced by the cyst (►Fig. 1).We performed cyst and microvascular decompression by a right suboccipital lateral approach. The cyst wall was clear and transparent. Upon excision of the cyst wall, we detected normal-looking cranial nerves VII and VIII. A branch of the AICA compressed the REZ of the facial nerve rostrally. The artery was separated from the REZ to completely decompress the facial nerve (►Fig. 2). To maintain the decompression, we attached the artery on tentorium cerebelli using Teflon felt and bioadhesion (blood-clotting factors). After surgery, the patient was immediately relieved of hemifacial spasm, and no neural complications such as facial paresis, hypoacusis, and dysphasia were observed. The surgical scar was also in good condition without any infections. On pathologic diagnosis, the cyst wall was revealed to be a typical arachnoid membrane.The patient was discharged 8 days after surgery in good condition. At follow-up 6 months after surgery, the patient was still symptom-free without any complications. DiscussionWe present the occurrence of hemifacial spasm and CPA arachnoid cyst in a patient who was fully treated by decompression of the cyst and microvascular structures. This case suggested that CPA arachnoid cysts can also play an important Keywords ► cerebellopontine angle arachnoid cyst ► hemifacial spasm ► microvascular decompression AbstractThe authors report a rare case of right cerebellopontine angle cyst related to hemifacial spasm. The patient was a 66-year-old woman with a 3-year history of right hemifacial spasm. The cyst was diagnosed preoperatively by T2-weighted magnetic resonance imaging, which demonstrated a ...