Ankylosing spondylitis manifested by spontaneous anterior atlantoaxial subluxation

The onset of ankylosing spondylitis is usually characterized by lower back pain and stiffness in young adults; early diagnosis is not easy, but the disease is generally identified within a few years of onset. Anterior atlantoaxial subluxation may occur in the late stage of ankylosing spondylitis, but early spontaneous subluxation is rarely seen. We present a case of ankylosing spondylitis with an initial symptom of neck pain, rather than lower back pain, due to spontaneous anterior atlantoaxial subluxation. After medical and surgical intervention, except for limited range of motion, the patient experienced neither neck pain nor weakness of his left limbs during the next 8 mo of follow-up.