Brown-Sequard syndrome caused by hyperextension in a patient with atlantoaxial subluxation due to an os odontoideum.

Brown-Sequard syndrome is an uncommon complication of atlantoaxial arthrodesis. A 50-year-old female visited our emergency department after falling from a ladder. Radiologic evaluations revealed chronic C1-2 instability with acute spinal cord injury. The day after atlantoaxial fusion was performed, she developed left-sided motor weakness and the loss of right-sided pain and temperature sensation. Based on physical examination and radiologic findings, we diagnosed her as having Brown-Sequard syndrome. Spine surgeons performing this procedure should therefore consider Brown-Sequard syndrome if a patient displays signs of postoperative hemiplegia.