Painful torticollis following adenotonsillectomy: a cardinal sign of atlantoaxial subluxation.

An 11-year-old boy with a history of autism spectrum disorder attended the emergency department with his mother 8 days after an adenotonsillectomy reporting postoperative bleeding. Detailed physical examination revealed no active bleeding, but a rigid neck posture was noted. A head and neck CT scan demonstrated unilateral rotatory atlantoaxial subluxation and possible damage to the anterior spinal ligament.