Atlantoaxial joint synovial cyst: diagnosis and percutaneous treatment.

Synovial cysts at the atlantoaxial level are found uncommonly. Lumbar symptomatic cases are treated by percutaneous cyst aspiration with or without corticoid injection or by surgical resection, but synovial cysts at the C1-C2 level are usually treated by surgery. We report here a 92-year-old woman with a retro-odontoid synovial cyst producing spinal cord compression that was treated by percutaneous aspiration of the cyst under CT guidance. To our knowledge, this is the first reported case of an atlantoaxial synovial cyst successfully treated with a minimally invasive procedure.