Arnold-Chiari malformation is a congenital malformation of the skull near the foramen magnum in which the cerebellum and the medulla are caudally displaced. This herniation of the brainstem causes down-beat nystagmus and oscillopsia, the most commonly presenting sign and symptom, respectively. Differential diagnoses for the Arnold-Chiari malformation include, but are not limited to, demyelinating disease, tumor, and vascular disorders. Symptoms will generally worsen with time and may even be brought on during exercise or valsalva maneuvers. A correct diagnosis can lead to timely surgical intervention which can improve the quality of eye movements. Treatment generally involves the surgical decompression of the surrounding spinal tissue.