Hemifacial spasm as a manifestation of pilocytic astrocytoma in a pediatric patient.

Hemifacial spasm is a disorder of the seventh cranial nerve, which is characterized by irregular, involuntary and recurrent tonic and clonic contractions of the ipsilateral facial expression muscles. This disorder affects mainly adults, and there are few cases reported in childhood. The main etiologies are vascular problems, although tumors are an important cause of hemifacial spasm via a direct or an indirect mass effect. We report a 6-year-old girl who presented with right hemifacial spasm. Magnetic resonance imaging showed a lesion in the cerebellopontine angle, extending from the midbrain to the pons with a slight mass effect on the fourth ventricle. The histological examination revealed a pilocytic astrocytoma.