Cervical dystonia in Bechterev disease resulting in atlantoaxial rotatory subluxation and cranio-cervical osseous fusion

Study Design. We report on a 46-year-old man with atlantoaxial rotatory subluxation and cranio-cervical osseous fusion secondary to cervical dystonia (CD) and concomitant ankylosing spondylitis (AS). Objective. To describe treatment of CD under these unusual circumstances. Summary of Background Data. CD may cause several complications due to enhanced spinal degeneration. Primary and secondary nonresponders to conservative treatment may benefit from neurosurgical procedures including denervation procedures or functional stereotactic neurosurgery. However, if spinal fixation has occurred, usually, treatment of dystonia is considered to be not appropriate. Nevertheless, in the rare case, neurosurgical intervention may still be useful to improve dystonic pain. Methods. After a 4-year history of severe CD, the head was rotated to the left in a rigidly fixed position. Three-dimensionally rendered computed tomography imaging studies revealed fixed rotation of the occiput and the C1 vertebra at an angle of 45 degrees to the C2 vertebra. There was abnormal ossification of the facet joints and the ligaments of the odontoid. Results. The patient experienced marked relief of his neck pain after deactivation of the dystonic right sternocleidomastoid muscle by partial myectomy and the left posterior neck muscles by selective posterior ramisectomy. Conclusion. Although rare, the concomitant occurrence of AS and CD should alert treating physicians and result in timely treatment of dystonia.