Neuro-myopathic flexion deformities of the cervical spine.

A study is presented of six patients who suffered flexion (chin-on-chest) deformity of the cervical spine on a neuropathic or myopathic basis. An awareness of this possibility is recommended, differentiating these patients from those with similar deformities due to ankylosing spondylitis, trauma, or primary degenerative change. Recognition is based on a detailed history, weakness of neck extension, electrodiagnostic studies, and muscle biopsy. A mildly elevated creatine phosphokinase (CPK) was the only consistent laboratory finding. Appropriate surgical correction of severe deformity involves anterior surgical release of contracted sternomastoid muscles, halo-dependent traction, posterior vertebral inferior facet resection, and spinal fusion over an adequate length, supplemented with internal fixation. Where extension correction involves extensive vertebral body separation anteriorly, additional anterior keystone strut grafting is indicated.