The authors describe the case of a 29-year-old man presenting with left retrooccipital and cervical pain associated with left ear fullness and rhythmic tinnitus. Head rotation movements on the right side and the Valsalva maneuver increased symptoms. A CT scan identified hyperpneumatization of the left temporal bone extending to the occipital bone as well as pneumarthrosis of the atlantoaxial joint. Surgical treatment involving obliteration of the fistula with bone and fat grafts via a computer-aided transmastoid approach was proposed. The surgery resolved all of the patient's symptoms except for the ear fullness. In this case the authors described an original treatment for spontaneous atlantoaxial pneumarthrosis. Long-term follow-up is needed to evaluate the risk of the recurrence of abnormal occipital bone pneumatization and to assess joint function.