Occipito-atlanto-axial subluxation is a type of high cervical injury. Misdiagnosis of this instability might cause several complications, including neurologic deficits. A radiologic evaluation must be performed and specific parameters that imply cervical instability must be confirmed. Full understanding of these parameters may prevent not only delayed diagnosis but also unexpected complication. We report a case of delayed detection of a cervical instability and emphasize the role of proper diagnosis.