Patient with Chiari malformation Type I presenting with inducible hemifacial weakness

In this report, the authors describe the first known case of inducible hemifacial weakness in a patient with Chiari malformation Type I (CM-I). The patient was a 14-year-old girl with a 1-year history of right facial paresis induced by sustained leftward head rotation. These episodes were characterized by weak activation of her right facial muscles with preserved eye opening and closure. Additionally, she had hypernasal speech, persistent headaches, and intermittent left arm twitching. Magnetic resonance imaging demonstrated a CM-I. A suboccipital craniectomy and C-1 laminectomy were performed for decompression of the CM-I, with duraplasty and coagulation of the pial surface of the cerebellar tonsils. At the 9-month follow-up, the patient's inducible hemifacial weakness had completely resolved. Her symptoms were thought to have resulted from the CM-I, perhaps due to traction on the right facial nerve by the ectopic tonsils with head rotation.