Hemifacial spasm caused by posterior fossa arachnoid cyst: Case Report

Abstract

Context: Hemifacial spasm (HFS) is characterized by continuous or intermittent spasmodic movements at the facial nerve motor territory.1,2,3 It mainly affects middle- aged adults and usually occurs by compression of the facial nerve by anomalous vascular loops of the anteroinferior and vertebral cerebellar artery.2,3,4,5 The arachnoid cyst at the cerebellopontine angle (CPA) is an rare cause of HFS, especially in children. Case report: A six-year-old female patient started presenting at 18 months HFS on the right side. She was initially treated with anticonvulsant without improvement. The patient came to our care at the age of six presenting 2-3 HFS per day and remissions lasting 3-4 weeks. Image exams reveled a CPA arachnoid cyst compressing the VII and VIII nerves complex. Surgical drainage of the cyst was performed as the treatment of choice. In postoperative period, the patient presented remission of HFS, and cranial tomography showed a decrease in cyst volume. In three months, there was remission of the signs without use of any medications. Conclusions: There was no report of arachnoid cyst in CPA as a cause of HFS in children. HFS occurs probably by chronic irritation, since birth, because of the contact of arachnoid cyst in the emergence of the VII and VIII nerves complex in the PCA. Therefore, treatment was chosen according to the cause of HFS. Movement disorder as a clinical manifestation of the cyst is rare, especially in pediatric population, and should be considered as one of the diagnostic hypotheses.