Disappearance of hemifacial spasm after ventriculoperitoneal shunting in a patient with achondroplasia--case report.

A 15-year-old boy with achondroplasia developed right hemifacial spasm associated with headache, vomiting, and hearing disturbance. Computed tomography showed hydrocephalus. A ventriculoperitoneal shunt was placed. His hydrocephalus subsequently resolved, the hemifacial spasm and headache disappeared, and his hearing disturbance improved. The episodes of hemifacial spasm were probably related to a small posterior cranial fossa volume, the so-called crowding of the posterior fossa. Increased intracranial pressure due to hydrocephalus apparently contributed to further reduction in the posterior cranial fossa volume and led to the hemifacial spasms. In addition, his hearing disturbance may have been the result of dysfunction of the cochlear nerve due to the increase in intracranial pressure caused by hydrocephalus.