Rheumatoid cervical myelopathy.

The pain of rheumatoid synovitis in the neck seems often to be modest compared with that in the hands and feet, so that problems may not become apparent till later, when the ligaments and the bones have already been damaged. Ball' has described how rheumatoid cervical spondylitis looks to the pathologist. Synovitis in the apophysial joints, in the synovial tissue adjacent to the odontoid, and in clefts (the neurocentral or Luschka joints2) at the lateral margins of the intervertebral discs may spread and erode nearby ligaments, the annulus, and the disc spaces. The process may spread further and erode the bone. In the end the neck becomes unstable, with results readily recognisable in radiographs. Three patterns of abnormality occur either singly or together: the atlas shifts forward on the axis (atlantoaxial subluxation); one vertebral body shifts forward on the body of another at lower levels (subaxial subluxation); and, rarely, the axis telescopes into the atlas, driving the odontoid upwards (vertical subluxation). Atlantoaxial and subaxial subluxation, the most common types, may readily be measured.3 Methods for measuring vertical subluxation have been proposed,4 5 but the degree of penetration of the odontoid into the foramen magnum is easy to misjudge,6 and the damage caused depends on whether or not the peg is eroded and on its tilt.4 Each ofthese abnormalities could result in compression of the cord or, in the case of vertical subluxation, medullary compression. The relation between x-ray changes and neurological features, however, is inexact. One explanation is that disturbance of the blood supply to the cord contributes to the myelopathy7; even so, it is worth noting that x-ray appearances may deteriorate without progressive neural dysfunction.6 Radiographic changes are more likely to be found in patients with longstanding rheumatoid arthritis, especially when it is seropositive and peripherally destructive; an incidence of at least one in four seems a realistic figure.3 4 8 Nearly as many patients have symptoms or signs if looked for, but often with no disability3; considerably fewer patients have a serious problem. When problems do arise they are nearly always neurological, symptoms from the neck being variable and indeed often absent.7 Sudden death from medullary compression has been described9 and may be commoner than acknowledged because necropsy examinations are seldom done. Studies of the clinical course of this condition, however, suggest that patients with rheumatoid arthritis of the cervical spine do not have any shorter life expectancy than other patients with rheumatoid arthritis.3 Perhaps the infrequent severe vertical subluxation is a circumstance of special risk, though even then the outlook is not always bad.10 Other than that rare event of sudden death, a wide range of symptoms and signs (neck pain or clicks, sensory symptoms, weakness of limbs) has been listed,7 11 but a recentdescription of the clinical findings in 31 patients with rheumatoid cervical myelopathy makes thoughtful reading.12 Most patients had a sensory deficit, and about one-third had motor problems or disturbances of bladder function. The abnormal signs were usually sensory, though half the patients had a spastic tetraparesis. The sensory loss could easily have been attributed to a distal sensory neuropathy of the type delineated by Pallis and Scott.13 So-as the authors comment-the most common mode of presentation was the one least likely to be recognised; indeed, they found a mean delay of 31 weeks between the first symptoms and diagnosis, an experience which many clinicians would ruefully confess to sharing. Greater clinical vigilance is obviously needed. The biggest contribution that could be made to the management of rheumatoid spondylitis would be effective prevention; whether successful treatment with remission-inducing drugs such as gold could achieve this is not yet known. Adrenal corticosteroids have been suspected of aggravating the condition,3 but there is no firm evidence for this suspicion. When a patient has abnormal x-ray appearances but little clinical evidence of myelopathy the only advice that can be given is to avoid extreme movements of the head. Examples of risky circumstances worth specific mention are visits to the dentist or the hairdresser and having an anaesthetic. Wearing a collar has been said to help the neck to fuse in a favourable position,14 but the general view now is that a collar has no effect on the evolution of rheumatoid spondylitis.6 Patients with unstable subluxations who will tolerate a collar, however, may be best advised to wear one for its protective effect. Even when myelopathy is present patients may often be treated conservatively. The standard method is a moulded polyethylene collar supplemented by a period of bed rest, lying supine, for patients with more severe symptoms and mobile subluxations; reduction of atlantoaxial subluxation may be as good with bed rest as with traction, which has been thought to be dangerous.12 Such conservative treatment can occasionally produce surprisingly good results. The problem is that an effective collar is an uncomfortable collar, and any attempt to explain the reasons for wearing one, and the risks of removing it (to sleep or work, for instance), inevitably causes anxiety. For patients with rheumatoid arthritis this problem may be the proverbial last straw; many become bitter and resentful despite years of fortitude over their other disabilities. In such cases surgery may be the best answer. Comparison between conservative and surgical treatments is difficult because of the selection of cases and different surgical techniques. Ranawat et al5 had a large (27%) mortality rate in the two postoperative years, but many of these deaths were not obviously related to surgery, and, as Marks and Sharp'2 point out, this group of patients have a bad prognosis independent of the neurological state. Conaty and Mongan15 found that two-thirds of patients who had had atlantoaxial fusions improved, and Marks and Sharp'2 concluded that their surgically treated patients probably had a better prognosis. Though clinicians would probably disagree on the indications for surgery, recent results are sufficiently encouraging to justify a more aggressive attitude than hitherto. Certainly a surgical opinion should be sought for patients who have major atlantoaxial subluxations (a displacement greater than 30% of the sagittal diameter of the cervical canal), progressive subluxations, myelopathy (progressive or otherwise), or evidence of ischaemia of the brain stem. Since we cannot yet prevent rheumatoid damage to the neck should we not recognise it earlier and refer patients to the surgeons earlier ?