J.Sales-Llopis

Neurosurgery Department, University General Hospital of Alicante, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Alicante, Spain

Retro-odontoid cervical synovial cysts are rare diseases located posteriorly to a dense axis.

Attributable to degenerative changes in the atlantoaxial joints and atlantoaxial instability ¹⁾.

Because the atlanto-dens joint is a synovial joint, its degeneration can lead to subchondral cyst formation and synovitis and predispose affected individuals to fracture ²⁾.

Association with Forestier's disease has been reported in only one previous study. Cyst probably develop as a result of enhanced mechanical stress on the only remaining mobile joint. In the literature treatment of retro-odontoid mass associated with Forestier has usually involved occipito-cervical fusion with transoral decompression ³⁾.

Although retro-odontoid synovial cysts remain rare, an increasing number have been reported in the literature. Affecting adults in the sixth decade of life.

Retro-odontoid synovial cysts produce slowly progressive upper spinal cord symptoms.

Can be achieved by means of magnetic resonance imaging (MRI).

An anterolateral approach facilitates access to lesions located anterior to the craniocervical junction without harming the atlantoaxial joints, and can also treat small lesions in the ventral mid-portion of the craniocervical junction without compression of spinal cord ⁴⁾.

Most reports have focused on surgical treatment, only a few have examined nonsurgical treatment. However, several months are required after nonsurgical treatment until cyst regression.

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 the knowledge of Velán et al. this is the first reported case of an atlantoaxial synovial cyst successfully treated with a minimally invasive procedure ⁵⁾.

Ikegami et al. report on a case with a retro-odontoid synovial cyst, and the immediate reduction of the cyst was confirmed following lateral atlantoaxial joint puncture and arthrography.

A 52-year-old woman presented with atlantoaxial instability. She complained of neck pain and numbness in her hands. Magnetic resonance imaging (MRI) revealed a retro-odontoid synovial cyst. Lateral atlantoaxial joint puncture and arthrography were performed.

Two days after treatment, the patient showed significant improvement in the numbness of her hands, and a follow-up MRI revealed an immediate reduction in the cyst. Over a 4.5-year follow-up period, no recurrence of the clinical symptoms occurred.

Lateral atlantoaxial joint puncture may immediately reduce retro-odontoid synovial cysts, and the lateral atlantoaxial joint has a communication channel with the retro-odontoid synovial cyst via the atlantodental joint. Once disappearance of the cyst is confirmed, an acceptable long-term outcome can be achieved with nonsurgical treatment even in cases with atlantoaxial instability ⁶⁾.