Summary Rheumatoid cervical spondylitis is seen in patients with rheumatoid arthritis (RA) and comprises 3 specific patterns of cervical spine instability, including atlantoaxial subluxation, basilar invagination, and subaxial subluxation Diagnosis is made radiographically with cervical spine flexion-extension radiographs and MRI studies to measure the degree of spinal cord compression Treatment may involve observation or decompression with instrumentation depending on patient neurologic status, degree of mechanical instability, and severity of spinal cord compression EPIDEMIOLOGY Present in 90% of patients with RA diagnosis often missed ETIOLOGY Cervical rheumatoid spondylitis presents with 3 main patterns of instability atlantoaxial subluxation most common form of instability basilar invagination subaxial subluxation Classification Ranawat Classification Class I Pain, no neurologic deficit Class II Subjective weakness, hyperreflexia, and dysesthesias Class IIIA Objective weakness, long tract UMN signs Patient is ambulatory Class IIIB Objective weakness, long tract UMN signs Patient is non-ambulatory Do NOT operate Presentation Symptoms symptoms and physical exam findings are similar to cervical myelopathy neck pain neck stiffness occipital headaches due to irritation of the lesser occipital nerve (a branch of the C2 nerve root) gradual onset of weakness and loss of sensation Physical exam hyperreflexia upper and lower extremity weakness ataxia (gait instability and loss of hand dexterity) Imaging Radiographs flexion-extension x-rays always obtain before elective surgery CT scan useful to delineate bony anatomy and for surgical planning MRI study of choice to evaluate the degree of spinal cord compression and identify myelomalacia General Treatment Nonoperative pharmacologic therapy pharmacologic treatment for RA has seen significant recent advances, which has led to a decrease in surgical intervention Operative spinal decompression and stabilization indications login to view 1 more bullet Atlantoaxial Subluxation Introduction present in 50-80% of patients with RA most commonly involves anterior subluxation of C1 on C2 (though lateral and posterior displacement may also occur) Mechanism caused by pannus formation between the dens and ring of C1, leading to the destruction of the transverse ligament and dens Radiographs controlled flexion-extension views to determine AADI and SAC / PADI AADI (anterior atlanto-dens interval) login to view 4 more bullets PADI / SAC (posterior atlanto-dens interval / space available for cord) login to view 2 more bullets Treatment nonoperative indicated in stable atlantoaxial subluxation operative posterior C1-2 fusion login to view 9 more bullets occiput-C2 fusion ± resection of posterior C1 arch login to view 5 more bullets odontoidectomy login to view 4 more bullets Basilar Invagination Introduction also known as superior migration of odontoid (SMO) tip of dens migrates above the foramen magnum present in 40% of RA patients often seen in combination with fixed atlantoaxial subluxation Mechanism cranial migration of the dens results from erosion and bone loss between the occiput, C1, and C2 Imaging radiographic lines Ranawat C1-C2 index login to view 4 more bullets McGregor's line login to view 3 more bullets Chamberlain's line login to view 4 more bullets McRae's line login to view 2 more bullets MRI cervicomedullary angle <135° suggests impending neurologic impairment Treatment operative occiput-C2 fusion login to view 4 more bullets transoral or anterior retropharyngeal odontoid resection login to view 2 more bullets Subaxial Subluxation Introduction present in 20% of patients with RA often occurs at multiple levels often combined with upper cervical spine instability lower spine involvement is more common with: steroid use males seropositive RA nodules present severe RA Pathophysiology pannus formation and soft-tissue instability of the facet and Luschka joints Radiographs subaxial subluxation (of vertebral body) of >4 mm or >20% indicates cord compression cervical height index (body height/width) <2.0 is almost 100% sensitive and specific for predicting neurologic compromise Treatment operative posterior fusion and wiring login to view 2 more bullets Operative Complications Failure to improve symptoms outcomes are less reliable in Ranawat grade IIIB (objectively weak with UMN signs and nonambulatory) Pseudarthrosis 10-20% rate decreases with extension of the construct to the occiput Adjacent level degeneration