Chiari malformation type 1 presenting as isolated unilateral foot drop with rapid recovery following posterior fossa decompression

Background: Chiari malformation (CM) type 1 is characterized by descent of the cerebellar tonsils resulting from crowding of the posterior fossa. In 30% of cases, it is associated with syringomyelia. When symptomatic, it may result in a classic constellation of symptoms. Case Presentation: Here we describe a case of a 16-year-old male who presented with isolated, unilateral foot drop due to CM type 1 and holosyrinx. This unique presentation is extremely rare, and we additionally present a review of all other reported cases in the literature. After undergoing posterior fossa decompression with C1 laminectomy and duraplasty, our patient made a complete neurological recovery within 2 weeks postoperatively and his MRI entire spine at 3 months postoperatively demonstrated a nearly complete resolution of the holosyrinx with significant decompression of the foramen magnum. Conclusion: This rare presentation highlights the importance of maintaining a broad differential, particularly in pediatric patients, and expediting the workup in order to offer a surgical decompression within 1–2 months of foot weakness to maximize the probability of a full neurological recovery.