OBJECTIVE At the conclusion of the report, the readers should be able to recognize the rare complication of adenotonsillectomy of Grisel syndrome, discuss its pathogenesis, and provide early, effective treatment. METHODS Analysis of the clinical presentation, plain radiographs, computed tomography scans, and magnetic resonance imaging scans of a child with Grisel syndrome after adenotonsillectomy. METHODS Retrospective study of the case record and a review of the literature regarding the pathogenesis, treatment modalities, outcome, and prognosis after early and delayed treatment of Grisel syndrome. RESULTS Pathophysiology of atlantoaxial subluxation revolves around the periodontoid vascular plexus that drains the posterosuperior pharyngeal region. Infectious and inflammatory emboli cause synovial engorgement, weakening paraspinal ligaments. Radiological studies play an important role in diagnosis. Treatment consists of cervical immobilization, muscle relaxants, analgesics, and antibiotics. Full resolution is expected with early conservative management. Failure to recognize the syndrome can lead to catastrophic results. CONCLUSIONS Recognition of Grisel syndrome in addition to other rare complications of adenotonsillectomy requires a high index of suspicion. Early intervention is the critical factor for a positive outcome. However, delayed diagnosis is common and can result in catastrophic consequences, including neurological deficits, cosmetic deformity and, in rare instances, paralysis and death in the short term.