Rheumatoid arthritis. Neuroanatomy, compression, and grading of deficits.

Study Design: The authors summarize published data regarding cervical spine involvement in rheumatoid arthritis, define the neurologic manifestations, and provide recommendations for management of these complex and difficult problems.

Objectives: The authors attempted to accurately define the neurologic lesions resulting from rheumatoid involvement of the cervical spine despite the complexity of the neuroanatomy of the cervicomedullary region and the diversity of pathology.

Summary Of Background Data: Despite the long-standing recognition of cervical spine involvement in rheumatoid arthritis, appreciation of the different neurologic manifestations of this disease has been lacking or misunderstood.

Methods: The authors reviewed the relevant neuroanatomy, neurovascular anatomy, and neuropathologic lesions that interact to create these complex and often confusing clinical situations.

Results: Rheumatoid arthritis produces encroachment on the brainstem and cervical spinal cord. The minimum space available at the craniocervical junction for the neural structures is 13 to 14 mm, which is fairly constant. Below C2, the available space is only 12 mm. When the amount of space reduced below this amount, there is, by definition, neural compression. The site of compression and/or repeated microcontusions will determine subsequent neurologic deficits. At the craniovertebral junction, neural compression and traumatic injury typically occur anteriorly at the pyramidal decussation producing cruciate paralysis with considerable weakness in both arms and minimal leg involvement. Cranial settling can result in lower medulla and cranial nerve dysfunction. Subaxial stenosis typically results in a more typical myelopathy.

Conclusions: Accurate diagnostic studies are mandated to determine the location of compression and to fully appreciate the resultant neurologic deficits. To improve more complete comprehension of the neurologic manifestations of rheumatoid arthritis, the relevant neuroanatomy, neurovascular anatomy, and neuropathologic lesions must be understood.