Cervical subluxation in rheumatoid arthritis

Cervical subluxation in rheumatoid arthritis

Authors
Peter H Schur, MD
Bradford L Currier, MD

Section Editor
Ravinder N Maini, BA, MB BChir, FRCP, FMedSci, FRS

Deputy Editor
Paul L Romain, MD

All topics are updated as new evidence becomes available and our peer review process is complete.

Literature review current through: May 2016. &#124 This topic last updated: Feb 25, 2016.

INTRODUCTION — The discovertebral joints in the cervical spine may be affected in patients with rheumatoid arthritis (RA) with resulting osteochondral destruction [1,2]. A review of the clinical manifestations and treatment of atlantoaxial (C1 to C2) and subaxial subluxation in RA is presented here. The clinical features and general medical management of RA, as well as the differential diagnosis and general evaluation of the patient with neck pain and of cervical spine disorders, are discussed separately. (See "Clinical manifestations of rheumatoid arthritis" and "General principles of management of rheumatoid arthritis in adults" and "Evaluation of the patient with neck pain and cervical spine disorders".)
CERVICAL INVOLVEMENT — Cervical joint destruction in patients with rheumatoid arthritis (RA) may lead to vertebral malalignment (eg, subluxation), causing pain, neurological deficit, and deformity. Risk factors for development of cervical subluxation include older age at onset of RA, more active synovitis, higher levels of C-reactive protein, rapidly progressive erosive peripheral joint disease, and early peripheral joint subluxations [3,4]. Both atlantoaxial and subaxial (below C2) joints may be involved.
Atlantoaxial disease — Among the joints of the cervical spine, the atlantoaxial joint is prone to subluxation in multiple directions, potentially leading to cervical myelopathy [5]. The atlas (C1) can move anteriorly, posteriorly, vertically, laterally, or rotationally relative to the axis (odontoid and body of C2):
●Abnormal anterior movement on the axis is the most common type of subluxation. It often results from laxity of the transverse ligament induced by proliferative C1 to C2 synovial tissue, but may also occur as a result of erosion or fracture of the odontoid process [6].
●Posterior movement on the axis can occur only if the odontoid peg has been fractured from the axis or has been destroyed.
●Vertical movement in relation to the axis is least common; it results from destruction of the lateral atlantoaxial joints or of bone around the foramen magnum [7].
●Vertical atlantoaxial subluxation may occur in those with initial anterior-posterior subluxation. Vertical subluxations are believed to have a worse prognosis than the other varieties [8].
Pathogenesis — There are two possible mechanisms for involvement of the intervertebral joints in the cervical spine in RA:
●Extension of the inflammatory process from adjacent neurocentral joints (the joints of Luschka, which are lined by synovium) into the discovertebral area.
●Chronic cervical instability initiated by apophyseal joint destruction, subsequently leading to vertebral malalignment or subluxation [9]. This may produce microfractures of the vertebral endplates, disc herniation, and degeneration of disc cartilage.
Bursal spaces exist between the cervical interspinous processes. In some rheumatoid patients, bursal proliferation has led to radiographically demonstrated destruction of the spinous processes [10].
The involvement and severity of cervical spine disease in RA parallels the progression of peripheral joint erosions. As a result, cervical subluxation is more likely in those with erosions of the hands, feet, hips, and/or knees [11,12].
Neurological findings may occur when the space available for the brain stem, spinal cord, or nerve roots is compromised by vertebral subluxation.
Asymmetric apophyseal joint erosion may cause scoliosis manifested as head tilt. Joint destruction and/or spontaneous fusion often lead to reduced range of motion. Anterior atlantoaxial or subaxial subluxations may cause the head to protrude forward, leading to positive sagittal balance.
Prevalence — Although decreases in rates of hospitalizations for certain manifestations of severe RA (eg, rheumatoid vasculitis, splenectomy for Felty’s syndrome) were recorded in California, no significant decrease in rates of hospitalization for cervical spine surgery was noted from 1983 to 2001 [13]. However, the clinical experience of experts in spinal surgery is that the rate of occipital-cervical fusion has decreased with the advent of more effective disease-modifying antirheumatic drugs (DMARDs). The prevalence of cervical involvement among those with RA varies with the patient subset studied.
●In one series of 113 patients with RA referred for hip or knee arthroplasty, 61 percent had roentgenographic evidence of cervical spine instability [12].
●An inception cohort study of 103 patients with RA (of whom 69 survived at least 20 years to have lateral radiographs of the cervical spine) documented anterior atlantoaxial subluxation and vertical subluxation in 23 and 26 percent, respectively [14]. None of these patients required surgical procedures on the cervical spine.
●In a group of 476 hospitalized patients with RA, vertical subluxation was noted in 4 percent [15].
●In a group of 165 Greek patients in an outpatient setting, with mean age of 60 years and duration of disease of 12 years, the prevalence of atlantoaxial subluxation of ≥2.5 mm on lateral radiograph was 21 percent, but neurologic impairment was only present in one patient [16]. Subaxial subluxation ≥1 mm at one or more levels was present in 44 percent.
An increased risk of radiographic cervical spine involvement has been associated with the presence in serum of rheumatoid factor and with an elevated C-reactive protein level, but has not been associated with the presence of human leukocyte antigen (HLA)-DR4 [4,17].
Symptoms — Involvement of cervical joints may result in significant pain. However, passive range of motion may be normal in the absence of muscle spasm. The earliest and most common symptom of cervical subluxation is pain radiating superiorly towards the occiput [18]. Additional symptoms of subluxation include:
●Spastic quadriparesis is slowly progressive.
●Sensory findings are also common, including painless sensory loss in the hands or feet.
●In patients with C1 to C2 subluxation, transient episodes of medullary dysfunction (such as respiratory irregularity) were associated with vertical penetration of the odontoid process of C2 and with probable vertebral artery compression [19]. Sudden death may occur. The rate, reported as 10 to 20 percent in the older literature, is uncertain.
Neurologic findings in patients with atlantoaxial subluxation may also include myelopathy, sensory loss, paresthesias in the C2 area (greater occipital neuralgia), decreased sensation in the distribution of the fifth cranial nerve, and nystagmus. Subaxial subluxations, which narrow the intervertebral foramina, may cause radiculopathy.
Neurologic signs and symptoms often have little relationship to the size of the abnormally widened space between the arch of the atlas and the anterior aspect of the dens (anterior atlantodental interval [AADI]) or to the amount of subluxation between subaxial vertebrae. The magnitude of the space available for the cord (SAC) in the subaxial spine or at C1 to C2, where it is known as the posterior atlantodental interval (PADI), does correlate with the incidence of neurological compromise [20]. The symptoms of spinal cord compression that demand immediate attention and intervention include [21]:
●A sensation of the head falling forward upon flexion of the cervical spine
●Changes in levels of consciousness
●“Drop” attacks
●Loss of sphincter control
●Respiratory dysfunction
●Dysphagia, vertigo, convulsions, hemiplegia, dysarthria, or nystagmus
●Peripheral paresthesias without evidence of peripheral nerve disease or compression
●Lhermitte’s phenomenon, an electric shock-like sensation in the neck radiating down the spine or into the arms, produced by forward flexion of the neck
However, instead of compression of the spinal cord, some of these symptoms may be due to compression of the vertebral arteries, which must wind through foramina within the lateral aspects of C1 and C2. Findings on magnetic resonance imaging (MRI) may help distinguish between these two possibilities.
Physical findings — Physical findings relating to the spine which are suggestive of atlantoaxial subluxation include:
●Loss of cervical lordosis
●Scoliosis
●Resistance to passive spine motion
●Abnormal protrusion of the anterior arch of the atlas felt by the examining finger on the posterior pharyngeal wall
In addition, neurologic findings appropriate to the symptoms described above may be seen, including:
●Increased deep tendon reflexes (seen in myelopathy)
●Extensor plantar responses
●Hoffman’s sign
●Muscle weakness, spasticity, or muscle atrophy
●Gait disorders
●Decreased deep tendon reflexes (seen in radiculopathy)
IMAGING FINDINGS — Patients with mild, nonspecific neck or occipital pain can be evaluated initially by conventional radiography, but patients with evidence of subluxation or of C1 to C2 synovitis require careful observation and magnetic resonance imaging (MRI) examination if symptoms or signs progress. The use of conventional radiographs, computerized tomography (CT), and MRI are discussed below. (See 'Symptoms' above and 'Physical findings' above and 'Conventional radiography' below and 'CT scan' below and 'Magnetic resonance imaging' below.)
Conventional radiography — Among patients with atlantoaxial subluxation, plain radiographic views of the cervical spine (anteroposterior, lateral, open-mouth, flexion, and extension) may reveal more than 3 mm of separation between the odontoid peg and the C1 arch (image 1) [19,22]. Separation between C1 and C2 (anterior subluxation) of 9 mm or more or a posterior atlantodental distance of less than 14 mm is associated with an increased incidence of cord compression [20,23,24]. In addition, if the space available for the spinal cord is less than 13 mm anywhere in the cervical region, there is an increased risk for neurologic impairment. In symptomatic patients, the films in flexion should be taken only after radiographs (including an open-mouth view) have excluded an odontoid fracture or severe atlantoaxial subluxation.
These structures may be difficult to visualize effectively using conventional radiographic techniques because of osteopenia, the small size of the multiple joints in the cervical spine, the large mass of soft tissue surrounding the spine, and the lower borders of the occipital bones. In addition, the usual landmarks may be obliterated in advanced disease [25].
Since neck positioning required for intubation prior to surgery may be fatal among patients with rheumatoid arthritis (RA) and unrecognized C1 to C2 disease, and since subluxation is not always symptomatic, radiographic evaluation of the cervical spine is advised for all patients with RA scheduled to undergo surgery requiring manipulation of the neck for either anesthesia or surgery [26].
CT scan — CT can demonstrate spinal cord compression by revealing the loss of subarachnoid space, attenuation of the transverse ligament, and bony and soft tissue changes in patients with C1 to C2 subluxation (image 2) [27,28]. However, not all studies have found that CT is helpful in this setting. In one study of 12 patients, for example, CT provided additional useful information in only one patient [28]. CT and CT angiography are useful for preoperative planning. The reformatted sagittal CT scan can precisely document the position of the odontoid with respect to the foramen magnum, the degree of atlantoaxial dislocation, and the relationships among the upper cervical spine joints [29].
CT is also helpful in planning the best surgical technique to be used in each case and in assessing the size of the implants to be used. It is used to determine the type of fixation that can be used, such as C-1 posterior arch versus lateral mass screws or C-2 pars, pedicle, or laminar screws [30]. A contrast-enhanced CT scan can be useful to diagnose inflammatory soft tissue proliferation in patients unable to undergo MRI (eg, those with aneurysm clips, body implants, wires or plates, some heart valves, some implanted electrodes) [31].
Magnetic resonance imaging — MRI is particularly valuable in the assessment of cervical spine disease in RA, because it permits visualization of the pannus producing cord compression, the spinal cord, and bone (image 3) [32-35]. MRI is the modality of choice for early diagnosis of cervical involvement, because it has high sensitivity in detecting inflammatory changes in the joints even before instability develops [36]. MRI can provide information about neural tissue (spinal cord and nerve roots) and the contents of the epidural space and is the radiological modality of choice in evaluating for possible spinal cord compression [37].
The development of neurological dysfunction is strongly associated with MRI evidence of spinal canal stenosis, particularly in patients with evidence of upper cervical cord or brainstem compression or of subaxial myelopathy [38]. Bone marrow edema (BME) can be observed by MRI in patients with early cervical spine involvement; the edema may be seen in the odontoid process, in the vertebral endplates, and in the subaxial interapophyseal joints [39]. Higher erythrocyte sedimentation rates were associated with more severe atlantoaxial joint synovitis.
A dynamic (flexion-extension) MRI clearly delineates the relationship between the odontoid, foramen magnum, and cervical spinal cord, but prolonged flexion should be performed with caution because of the risk of cord compression [25]. In addition, gradient-echo MRI pulse sequences provide reliable visualization of the transverse atlantal ligament, permitting the clinician to distinguish rupture from stretching of the ligament and to visualize pannus compressing the cord [40].
The information gained from MRI is sufficiently additive to warrant the increased cost of this procedure, particularly if surgery is contemplated [33,41]. However, one drawback of MRI is that it often underestimates the degree of atlantoaxial subluxation when compared with flexion-extension plain film radiography. This was illustrated in a series of 23 patients with RA or juvenile idiopathic arthritis (JIA) who had both radiographs and MRI with flexion and extension views performed within a one-month time frame [42]. After accounting for magnification on the plain films, the measured atlantoaxial subluxation by MRI was less than that noted on radiographs in 19 of the 23 patients; in the worst case, the measured distance differed by 7 mm. Thus, unless flexion and extension MR images document excessive subluxation, plain film flexion-extension radiography is still needed to assess atlantoaxial stability, especially in patients with RA scheduled to undergo surgery requiring manipulation of the neck for either anesthesia or surgery. (See 'Conventional radiography' above.)
NATURAL HISTORY — As noted above, the onset of atlantoaxial subluxation alone is not inexorably associated with neurologic dysfunction or with an increased risk of death [43]. Although radiographic progression is common, it does not always correlate with neurologic deterioration [18,44-47]. Patients with plain film radiographic evidence of cervical subluxation, with or without neurologic symptoms, have a five-year mortality rate of 17 percent [7].
However, some patients with severe dislocation may be at risk of death. In one series of 104 consecutive autopsies of patients with rheumatoid arthritis (RA), 11 cases of severe dislocation were found [48]. In all 11, the odontoid protruded posterosuperiorly and impinged on the medulla within the foramen magnum. In five, spinal cord compression was determined to be the only cause of death.
Patients with subluxation and signs of spinal cord compression have a poor prognosis without surgery. In this setting, myelopathy progresses rapidly, and death may quickly ensue [49,50]. As an example, in a study of 21 patients with atlantoaxial subluxation and with signs of myelopathy who were managed medically, neurologic deterioration occurred in 16 of 21 (76 percent), and all were unable to walk within three years of follow-up [51]. None survived more than eight years. A systematic review of the literature revealed neurologic deterioration was almost inevitable in Ranawat II, IIIA, and IIIB patients (ie, those with findings to indicate a neurological deficit) treated nonoperatively. The 10-year overall survival rate was 40 percent [50].
Magnetic resonance imaging (MRI) findings may be more helpful than plain film radiography in determining prognosis. As an example, among 82 patients with MRI evidence of cord compression at the level of C1 to C2, 60 percent deteriorated with conservative management over a median of 12 months [52]. Those with subaxial cord compression fared better, with only 18 percent worsening with time. Among all patients, nine eventually required surgical intervention (six due to a combination of pain and progressive neurologic deficits, two due to pain only, and one due to painless neurologic deterioration).
An inability to walk preoperatively also confers a poor prognosis. In one study, only 20 percent of such patients improved after treatment [53].
PREVENTION — Limited evidence suggests that the administration of combination therapy consisting of disease modifying antirheumatic drugs (DMARDs) may help prevent the development of cervical spine subluxation. As an example, 195 patients with rheumatoid arthritis (RA) of recent onset (two years or less) were randomly assigned to a regimen of sulfasalazine, methotrexate, hydroxychloroquine, and prednisolone or to sulfasalazine alone [54]. Atlantoaxial impaction or anterior subluxation developed in 2 and 7 percent of the sulfasalazine alone group, respectively, but in none of those receiving combination therapy after two years of treatment. DMARD treatment was unrestricted after two years.
At five years of follow-up, the occurrence of anterior atlantoaxial subluxations was significantly associated with initial single DMARD therapy [55]. Atlantoaxial impaction or anterior subluxation developed more often in the initial single-therapy group compared with the initial combination therapy group (6 and 14 percent versus 1 and 3 percent, respectively).
In a study of 91 patients with RA treated with biologicals, the 44 patients without neck involvement at baseline were much less likely to develop neck radiographic progression than those 47 RA patients who had already developed neck involvement (7 versus 72 to 79 percent) [56].
An overview of the management of RA is presented elsewhere. (See "General principles of management of rheumatoid arthritis in adults".)
TREATMENT — Patients with cervical subluxation are treated medically and/or surgically based largely upon the presence or absence of signs of spinal cord compression.
Medical therapy — Patients with severe subluxation but without signs of cord compression are at risk for severe injury and perhaps death due to a variety of insults. These include minor falls, whiplash injuries, and intubation. Although the subject of some controversy, stiff cervical collars may be prescribed for stability; in one report, more than 50 percent of such patients benefited from this modality [57,58]. In some patients, halo traction may be of benefit, typically followed by surgery.
Collars that are not rigid (and, therefore, that are more comfortable for the patient) give reassurance to both the clinician and the patient but provide little structural support. Spinal manipulation is contraindicated.
The role of neck muscle strengthening exercises is uncertain. A decrease in anterior atlantoaxial subluxation was noted in a subgroup of seven patients with rheumatoid arthritis (RA) and unstable atlantoaxial joints during active isometric neck flexor muscle contraction [59]. While this suggests that isometric neck flexor exercise is probably safe, the efficacy of neck flexor muscle strengthening for symptoms related to subluxation, radiographic progression, and other important patient outcomes were not assessed in this study. In contrast with the neck flexors, isometric neck extensor muscle tightening worsened radiographically apparent atlantoaxial subluxation in those with unstable articulations. Thus, while further investigation of neck flexor strengthening may be warranted, isometric exercise of the neck extensors should be avoided.
Patients who have pain due to irritation of C2 nerve root but who do not have evidence of cord compression may benefit from agents used for chronic neuropathic pain (see "Overview of the treatment of chronic pain"). These patients may obtain some benefit from local nerve blocks, although the relief is generally temporary.
Surgery — Patients with subluxation and signs of spinal cord compression have a grave prognosis without surgical intervention to provide stability to the spine [1,19,50]. Although surgery for atlantoaxial subluxation has attendant risks, some data indicate that early operative treatment may delay the detrimental course of cervical myelopathy in RA [50,60]. (See 'Natural history' above.)
The benefits offered by surgical management of patients with atlantoaxial subluxation who have myelopathy include an improved survival rate, an improvement in myelopathy in some patients, and a decreased risk of neurologic progression. The beneficial effects of surgery were illustrated in an observational study that compared 19 patients with symptomatic atlantoaxial subluxation who underwent laminectomy and occipitocervical fusion with 21 others who were managed conservatively [51]. The 5- and 10-year survival rates for those who underwent surgery were 84 and 37 percent, respectively. In contrast, none of the 21 patients managed conservatively survived more than eight years. Neurologic improvement was noted in 68 percent following surgery, while, in the nonoperative group, 76 percent had neurologic deterioration.
Surgery is generally well-tolerated. In a prospective study of 532 patients with RA and with subluxations of the cervical spine seen between 1974 and 1999, 217 underwent surgery, of whom only 11 (5 percent) experienced residual neck pain or neurologic symptoms [61]. Such symptoms were associated with increased risk of death during the course of the study. There were reduced survival for patients with subaxial subluxations and an association of increased vertical settling with sudden death. There were few perioperative or postoperative complications.
Surgery should be considered carefully and on an individualized basis among patients with subluxation but without signs or symptoms of cord compression. In this setting, operative stabilization may be considered if symptoms develop, which is not uncommon. In one series of 84 patients with some form of subluxation but without cord or brainstem lesions, one-fourth worsened, and one-fourth improved without surgery over 5 to 14 years of follow-up [44].
Some data support the hypothesis that early C1 to C2 fusion for atlantoaxial subluxation, before the development of superior migration of the odontoid, decreases the risk of further progression of cervical spine instability. A retrospective study of 110 patients with RA who underwent cervical spine fusion noted two major findings on follow-up [62]:
●Fifteen percent developed cervical instability; this occurred in 5.5 percent of those with atlantoaxial subluxation and in 36 percent of those with atlantoaxial subluxation and superior migration of the odontoid.
●No patient with C1 to C2 fusion for atlantoaxial subluxation subsequently developed superior migration of the odontoid.
A limiting factor is that the incidence of sustained neurologic deterioration related to surgery may be as high as 6 percent [63]. As a result, a skilled surgical team and a careful assessment of each patient are important elements of any therapeutic regimen.
Fortunately, the prognosis for patients with surgery appears to be improving due, in part, to earlier referral, enhanced technique, and better perioperative management. The outcomes of 27 patients with RA who had cervical fusions in the period of 1991 to 1996 (late cohort) were compared with those of 32 individuals whose surgery occurred in the period of 1974 to 1982 (early cohort) [64]. Only 7 percent of patients in the more recent group had severe cervical myelopathy prior to surgery, versus 34 percent in the earlier cohort. Compared with the early group, the late cohort had fewer early postoperative deaths (0 versus 9 percent), complications (22 versus 50 percent), failed surgeries (15 versus 28 percent), and reoperations (11 versus 20 percent). Among patients in the more recent cohort in whom there was sufficient information to judge a change in neurologic status with surgery (18 patients), improvement in and maintenance of the preoperative level of function were noted three months after surgery in one-third and two-thirds, respectively.
A systematic literature review identified 23 observational studies describing the neurologic outcome after surgery for 752 patients [50]. Patients with Ranawat I (asymptomatic patients with no neurologic deficit) and II (patients with subjective weakness with hyperreflexia and dysesthesia) neurologic status rarely deteriorated. Ranawat III patients (those with objective weakness and long tract signs) typically did not recover completely. The 10-year survival rates mirrored the Ranawat class and ranged from 77 percent to 30 percent for Ranawat I (no deficit) and IIIB (nonambulatory patients with objective weakness and long tract signs), respectively [50]. Outcomes were better with surgery than conservative treatment in all patients with neurologic involvement, but were similar for asymptomatic patients with no neurologic deficit (Ranawat I). The evidence is weak, however, and the ideal treatment for asymptomatic patients with radiographic instability awaits the results of a randomized control trial [65].
Even though Ranawat IIIB patients have a significantly worse outcome than all other groups [50], surgery may still offer the best quality of life and survival for these severely disabled patients [66]. Ideally, surgery should be offered before a significant neurologic deficit occurs.
The decompression and stabilization may need to extend into the subaxial spine. In one series, histopathologic studies of brain stems and spinal cords of nine patients with end-stage RA revealed significant subaxial myelopathy in the cervical spine related directly to compression, stretching, and movement of the spinal cord [67].
Transpedicle screw fixation using stereotactic guidance has also been used for stabilization [68]. Because the diameter of cervical pedicles is very small, this is considered a procedure with significant risk. However, use of full-scale, three-dimensional models in preoperative planning may lessen morbidity [69].
Occipitocervical fixation has also been employed to treat patients with unstable cervical spines. When this procedure was employed in 163 RA patients, 88 percent improved, 7 percent remained unchanged, and 5 percent progressed [70]. Complications included infection (10 percent) and progressive subluxation that required reoperation (4 percent).
SUMMARY AND RECOMMENDATIONS
●Cervical joint destruction in patients with rheumatoid arthritis (RA) may lead to vertebral malalignment (eg, subluxation), causing pain, neurological deficit, and deformity. Risk factors for cervical subluxation include older age at onset of RA, more active synovitis, higher levels of C-reactive protein, rapidly progressive erosive peripheral joint disease, and early peripheral joint subluxations. Both atlantoaxial and subaxial (below C2) joints may be involved. Estimates of the prevalence of cervical involvement among those with RA vary widely; fewer patients appear to require surgery since the 1990s. (See 'Cervical involvement' above and 'Prevalence' above.)
●The atlantoaxial joint is prone to subluxation in multiple directions, potentially leading to cervical myelopathy. The atlas (C1) can move anteriorly, posteriorly, vertically, laterally, or rotationally relative to the axis (odontoid and body of C2). Abnormal anterior movement on the axis is the most common type of subluxation; it often results from laxity of the transverse ligament induced by proliferative C1 to C2 synovial tissue, but may also occur as a result of erosion or fracture of the odontoid process. (See 'Atlantoaxial disease' above.)
●The two possible mechanisms for involvement of the intervertebral joints in the cervical spine in RA are 1) extension of the inflammatory process from adjacent neurocentral joints (the joints of Luschka, which are lined by synovium) into the discovertebral area and 2) chronic cervical instability initiated by apophyseal joint destruction, subsequently leading to vertebral malalignment or subluxation. (See 'Pathogenesis' above.)
●Involvement of cervical joints may result in significant pain. However, passive range of motion may be normal in the absence of muscle spasm. The earliest and most common symptom of cervical subluxation is pain radiating superiorly toward the occiput. Additional symptoms of subluxation include slowly progressive spastic quadriparesis; sensory findings, including painless sensory loss in the hands or feet; transient episodes of medullary dysfunction (such as respiratory irregularity); and others. Sudden death may occur. Symptoms of spinal cord compression may also result from compression of the vertebral arteries. The symptoms of spinal cord compression that demand immediate attention and intervention include (see 'Symptoms' above):
•A sensation of the head falling forward upon flexion of the cervical spine
•Changes in levels of consciousness
•“Drop” attacks
•Loss of sphincter control
•Respiratory dysfunction
•Dysphagia, vertigo, convulsions, hemiplegia, dysarthria, or nystagmus
•Peripheral paresthesias without evidence of peripheral nerve disease or compression
•Lhermitte’s phenomenon, an electric shock-like sensation in the neck radiating down the spine or into the arms, produced by forward flexion of the neck
●Physical findings relating to the spine, which are suggestive of atlantoaxial subluxation, include loss of cervical lordosis, scoliosis, resistance to passive spine motion, and abnormal protrusion of the anterior arch of the atlas felt by the examining finger on the posterior pharyngeal wall. Neurologic findings appropriate to the symptoms described above may be seen, including increased deep tendon reflexes (seen in myelopathy); extensor plantar responses; Hoffman’s sign; muscle weakness, spasticity, or muscle atrophy; gait disorders; and decreased deep tendon reflexes (seen in radiculopathy). (See 'Physical findings' above.)
●Patients with mild, nonspecific neck or occipital pain can be evaluated initially by conventional radiography, but patients with evidence of subluxation or C1 to C2 synovitis require careful observation and magnetic resonance imaging (MRI) examination if symptoms or signs progress. Radiographic evaluation of the cervical spine is advised for all patients with RA scheduled to undergo surgery requiring manipulation of the neck for either anesthesia or surgery. (See 'Imaging findings' above.)
●Atlantoaxial subluxation alone is not inexorably associated with neurologic dysfunction or with an increased risk of death. Although radiographic progression is common, it does not always correlate with neurologic deterioration. However, some patients with severe dislocation may be at risk for death. Patients with plain film radiographic evidence of cervical subluxation, with or without neurologic symptoms, have a five-year mortality rate of 17 percent. Patients with subluxation and signs of spinal cord compression have a poor prognosis without surgery. (See 'Natural history' above.)
●Patients with severe subluxation but without signs of cord compression are at risk for severe injury and perhaps death due to a variety of insults. These include minor falls, whiplash injuries, and intubation. Such patients may benefit from rigid cervical collars. Surgery should be considered carefully and on an individualized basis among patients with subluxation but without signs or symptoms of cord compression. Patients with subluxation and signs of spinal cord compression have a grave prognosis without surgical intervention to provide stability to the spine. (See 'Treatment' above and 'Medical therapy' above and 'Surgery' above.)