Cervical ankylosis following Grisel's syndrome in a 14-year-old boy with infectious mononucleosis.

Non-traumatic atlanto-axial subluxation (Grisel's syndrome) is an uncommon complication of neck space infection or otolaryngologic procedures. It most frequently affects children, although it may occur in adults. We present a 14-year-old boy with Grisel's syndrome as a complication of infectious mononucleosis proceeding to cervical ankylosis.