Isolated congenital cervical block vertebrae below the axis with neurological symptoms.

A reviews of 13 cases of symptomatic isolated congenital cervical fusion (block vertebrae) below the C2 level is presented. Ten cases were collected from a review of the English literature and three new cases were added. All 13 patients presented neurologic symptoms of radiculopathy and/or myelopathy with either no history of trauma or only minor trauma. Pathogenesis of symptoms is due to degenerative arthritis of the adjacent mobile segments, spinal stenosis, and subluxation of the adjacent mobile segments. The significance of coexisting spinal stenosis and segmental instability is emphasized and is related to the symptoms and treatment of the condition. Symptomatic patients can be treated satisfactorily with adequate decompressive laminectomy and fusion of the unstable segments.