Rheumatoid Arthritis of the Cervical Spine

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Chapter Synopsis	Rheumatoid arthritis is a chronic autoimmune inflammatory polyarthritis that often involves the joints of the upper and subaxial cervical spine. The common spinal manifestations include atlantoaxial subluxation, rheumatoid basilar invagination, and subaxial subluxation.
Important Points	Selection of the appropriate approach, technique, and construct depends on the severity of symptoms and preoperative reducibility of the subluxation or basilar invagination, or both.
Clinical and Surgical Pearls	Because this disease preferentially affects the upper cervical spine, knowledge of the neurovascular anatomy at the craniocervical region that often is disrupted is key to successful surgical management, feasibility, and selection of the appropriate surgical construct.
Clinical and Surgical Pitfalls	Assessment of bone quality should not be overlooked in patients with rheumatoid arthritis, and efforts should be made to optimize bone health by using a multidisciplinary strategy.

Rheumatoid arthritis is a chronic autoimmune inflammatory polyarthritis of the peripheral joints. It often involves the joints of the upper and subaxial cervical spine and has a variety of pathologic entities and a spectrum of clinical presentations. The introduction of disease-modifying antirheumatic drugs (DMARDs) and of agents that block tumor necrosis factor-α (TNF-α) altered the natural history of the disease by preserving the integrity and function of the joints. Thus, the incidence and severity of rheumatic spinal disorders encountered by most spine surgeons have decreased since the 1990s.

In-depth knowledge of the pathophysiology, natural history, and management of the spinal disorders that result from this chronic disease is important and facilitates decision making when treating these disorders, which can be challenging and complex. Involvement of the cervical spine in patients with rheumatoid arthritis is also associated with higher morbidity and mortality than is similar cervical spine involvement in patients who do not have rheumatoid arthritis. The goal of this chapter is to describe the pathophysiology and clinical presentation of patients with rheumatoid arthritis–related involvement of the cervical spine, more specifically atlantoaxial subluxation, occipitoatlantoaxial impaction, and subaxial subluxation.

Pathophysiology

Approximately one fourth of patients with rheumatoid arthritis will have at least radiographic involvement of the cervical spine, mainly the upper cervical spine. The synovial joints between the transverse atlantal ligament and the odontoid process, the alar ligament, and the joints between the anterior arch of the atlas and the odontoid are frequently affected. With chronic inflammation, the transverse ligament weakens and eventually ruptures. Decalcification also takes place and erodes the odontoid. This process results in various degrees of atlantoaxial subluxation.

The atlanto-occipital and atlantoaxial joints can also be affected. With destruction and collapse of these joints and lateral atlantal masses, the odontoid process telescopes rostrally, with resulting occipitoatlantoaxial impaction or basilar invagination. Subaxially, the facet joints can be involved, leading to variable degrees of subaxial subluxations and deformity. However, because of the presence of intervertebral disks, which are spared in this inflammatory process, subaxial subluxation is usually a late manifestation of the disease.

Presentation

Although the occurrence of radiographic evidence of disease as atlantoaxial subluxation in asymptomatic patients is common, the most frequent presenting symptom is pain. It is usually a combination of occipital and neck pain that either is caused by mechanical instability or is radicular, as a result of compression of C1 and C2 nerves. A positive Sharp-Purser test is a clicking sensation in extension that results with spontaneous reduction of atlantoaxial subluxation.

Neurologic manifestations are less common and are caused by mechanical neurovascular compression on the cervical spine and cervicomedullary junction. Patients may present with cervical myelopathy manifesting as gait dystaxia, hand clumsiness, and difficulty with dexterity. Objective findings of myelopathy include weakness, hyperreflexia, and positive Hoffmann, Babinski, and Lhermitte signs. Cruciate paralysis and even sudden death from respiratory arrest have also been reported. The deep tendon reflex may not be elicited because of appendicular joint destruction.

Clinical Entities

Atlantoaxial subluxation, occipitoatlantoaxial impaction, and subaxial subluxation can occur separately or in combination in patients with rheumatoid arthritis.

Atlantoaxial Subluxation

Anterior subluxation of the atlas on the axis results from weakening and disruption of the transverse ligament following joint inflammation around it. The subluxation can be anterior, posterior, lateral, or rotatory. This disorder is diagnosed with plain radiography as an increased anterior atlantodens interval, as well as a decreased posterior atlantodens interval in flexion ( Fig. 27-1 ). An anterior atlantodens interval greater than 5 mm is diagnostic. A posterior atlantodens interval of less than 14 mm is more predictive of neurologic deficit. Patients can be symptomatic or can present with neck pain and later with neurologic deficits, depending on the degree of spinal cord compression.

Patients with symptomatic instability are generally managed with operative stabilization. If the subluxation is reducible, a posterior approach and fixation are used ( Figs. 27-2 and 27-3 ). This fixation is achieved with semirigid constructs, such as Brooks and Gallie wiring, or rigid constructs with the use of transarticular C1-C2 screws ( Fig. 27-4 ) or C1 lateral mass screws and either C2 pars interarticularis/pedicle screws ( Fig. 27-5 ) or C2 translaminar screws. Occipitocervical fusion may be considered in this patient population ( Fig. 27-6 ), given the increased risk of craniocervical settling. When the subluxation is not reducible or when it is associated with anterior pannus compressing the upper cervical spine, anterior release of odontoid is generally required before posterior fusion.