Chiari malformation type I with extensive syringomyelia presenting as progressive bilateral foot drop: a case report

Chiari malformation type I (CMI) is a structural abnormality characterized by cerebellar tonsil herniation through the foramen magnum, often leading to disrupted cerebrospinal fluid dynamics and syringomyelia. While CMI commonly presents with occipital headaches and neck pain, atypical manifestations, such as bilateral foot drops, are exceedingly rare. We describe a 37-year-old female patient presenting with bilateral foot drop, which was later established to be caused by syringomyelia secondary to CMI. Magnetic resonance imaging revealed an 8 mm tonsillar descent and a syrinx extending to the conus medullaris. The patient refused surgical intervention and opted for conservative management; partial functional recovery was subsequently observed. This report emphasizes the importance of recognizing rare neurological presentations of CMI. To our knowledge, this is the first documented case of CMI with syringomyelia presenting as a bilateral foot drop.