Spinal cord involvement by C4–C5 Vertebral subluxation in rheumatoid arthritis: A description of 2 cases examined at necropsy

In 2 cases of severe, longstanding rheumatoid arthritis involving the cervical spine, a progressive spinal cord syndrome developed in which spastic paraparesis was combined with a lower motoneuron paresis affecting the upper limbs. In both cases necropsy showed the cause to be subluxation between the C4 and C5 vertebral bodies and backward encroachment into the spinal canal of the upper and posterior part of the C5 vertebral body. A feature of the spinal cord abnormality was central infarction, apparently caused by an effect on a patent anterior spinal artery and manifested not only at the site of spinal cord compression but for several spinal cord segments caudal to this level.