Chiari type I malformation presenting as hemifacial spasm: Case report

OBJECTIVE AND IMPORTANCE: We report on a patient with a Chiari I malformation presenting with right hemifacial spasm. Clinicians should consider the downward displacement of the hindbrain as a rare cause of hemifacial spasm in Chiari I malformation. CLINICAL PRESENTATION: An 18-year-old man was admitted with right hemifacial spasm. The results of the neurological examination were normal except for the facial spasm. Magnetic resonance imaging demonstrated a Chiari I malformation without syringomyelia. After surgery, the hemifacial spasm completely resolved. INTERVENTION: Posterior fossa decompression, C1 laminectomy, and duraplasty were performed. CONCLUSION: The hemifacial spasm could be attributed to compression and/or traction of the facial nerve because of downward displacement of the hindbrain in Chiari I malformation. Compression and/or traction might create irritation of the facial nerve that causes hemifacial spasm. Resolution of the hemifacial spasm after posterior fossa-decompression could explain the facial nerve irritation in Chiari I malformation. Clinicians should consider Chiari I malformation as a cause of hemifacial spasm and posterior fossa decompression as a potential treatment.