Rheumatology 2001; 40: 811-815
© 2001 British Society for Rheumatology
Original Papers |
Factors predictive of subsequent deterioration in rheumatoid cervical myelopathy
Centre for Rheumatic Diseases, Glasgow Royal Infirmary and
1 Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK
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Abstract |
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 Top Abstract IntroductionPatients and methodsResultsDiscussionReferences |
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Objective. To identify the features of rheumatoid cervical spine disease associated with deterioration resulting in the need for surgical intervention or death.
Patients and methods. Patients with rheumatoid cervical myelopathy who underwent cervical spine magnetic resonance imaging (MRI) between 1991 and 1996 were identified. Patients requiring immediate surgical intervention were excluded. The remainder were divided into two groups. Deterioration group: patients requiring surgical intervention during the follow-up period and deaths resulting from cervical myelopathy. Conservative group: all other patients. Relevant clinical features and radiology reports were extracted retrospectively from the casesheet.
Results. The deterioration group comprised 11 patients (12%), median time to deterioration 15 months (range 4–84 months). The conservative group included 82 patients. Initial clinical features did not differ significantly between the two groups. Sixty per cent of those patients with compression or impingement at the atlanto-axial level on first MRI deteriorated over a median of 12 months (range 4–36 months).
Conclusion. Deterioration is likely if there is evidence of cord compromise at the atlanto-axial level on MRI regardless of initial clinical and plain X-ray features.
KEY WORDS: Rheumatoid arthritis, Cervical myelopathy, Magnetic resonance imaging.
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Introduction |
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TopAbstractIntroductionPatients and methodsResultsDiscussionReferences |
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Plain X-ray studies have shown that up to 80% of patients with rheumatoid arthritis (RA) have involvement of the cervical spine after 10 yr, and of these 40% may be expected to deteriorate neurologically [1]. The optimal timing of surgery remains controversial, especially where there are no neurological findings [2].
As part of an audit examining outcome after surgical intervention, we have attempted to identify the features of rheumatoid cervical spine disease associated with deterioration resulting in the need for surgical intervention or death. The initial results have been published [3].
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Patients and methods |
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TopAbstractIntroductionPatients and methodsResultsDiscussionReferences |
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Study cohort
RA patients attended two urban rheumatology clinics (comprising five consultant rheumatologists) and had been referred for magnetic resonance imaging (MRI) of the cervical spine between 1991 and 1996. Patients were identified retrospectively from radiology departmental records. Patients with RA undergoing cervical spine surgery were identified from the West of Scotland Surgical Mortality Database. The majority of decisions regarding surgical intervention were made by a single consultant neurosurgeon with a special interest in cervical spine disease.
Inclusion criteria
The patients fulfilled 1987 American College of Rheumatology criteria for the diagnosis of RA [4] and underwent MRI and/or cervical spine surgery between 1991 and 1996.
Indications for MRI
All MRI scans were authorized by a consultant rheumatologist using one or more of the following criteria:
- (a) cervical spine pain not controlled with conservative management;
- (b) neurological symptoms or signs suggestive of cervical myelopathy;
- (c) atlanto-axial subluxation on plain X-ray.
- (b) neurological symptoms or signs suggestive of cervical myelopathy;
Indications for surgery
If cervical spine surgery was required on the basis of the initial scan the patient was excluded from further analysis. Thereafter the indications for surgery were:
- (a) uncontrolled cervical spine pain;
- (b) progressive neurological impairment attributable to cervical spine instability;
- (c) progressive radiological deterioration.
- (b) progressive neurological impairment attributable to cervical spine instability;
Groups for analysis
Deterioration group: included deaths as a direct consequence of cervical spine disease and those who required surgical intervention during the follow-up period.
Conservative group: all other patients including those who died from causes unrelated to cervical myelopathy.
Data collection
Data were collected for patients who satisfied the inclusion criteria, using the base hospital, and if necessary, the neurosurgical case records. These included basic demographic details, relevant symptoms and signs, and reports of radiological appearances on plain cervical spine X-ray and MRI. For those undergoing surgery, details of the operative procedure and post-operative complications were obtained and Ranawat grade [5] (Table 1
), symptomatology and functional change were recorded at the first post-operative visit and annually thereafter. In those managed conservatively after MRI (conservative group), details of symptomatology and Ranawat grade were recorded annually.
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Statistical analysis
All information was entered into a Microsoft Access database and analysed with SPSS and Excel software using 
2, Fisher's exact test and Mann–Whitney tests as appropriate.
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Results |
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TopAbstractIntroductionPatients and methodsResultsDiscussionReferences |
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One hundred and eighty-seven patients who underwent MRI or cervical spine surgery between 1991 and 1996 were identified. Ninety-four patients were excluded from analysis: 55 had diagnoses other than RA and 21 records were absent.
Eighteen patients underwent cervical spine surgery immediately following MRI. Of the remaining 93 patients, 82 were managed conservatively and 11 deteriorated, of whom nine required surgical intervention, one patient died at a later date from an unrelated cause and two patients died as a direct consequence of cervical spine disease.
Relevant clinical and demographic details of the two groups at the time of the initial MRI are outlined in Table 2. The median age at symptom onset was 59 yr (range 44–70 yr) in the deterioration group and 58 yr (range 16–87 yr) in the conservative group. The median disease duration was 16 yr in both groups, range 11–48 yr in the deterioration group and 1–59 yr in the conservative group. There were no significant differences when the two groups were compared with a Mann–Whitney test, apart from a higher median number of joint replacements in the deterioration group [2 (range 0–6) vs 0 (range 0–5) in the conservative group, P<0.05, Mann–Whitney] suggesting more aggressive disease.
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Comparison was made of the neurological signs and symptoms at the time of initial presentation in each group. The percentage of patients with each clinical feature who subsequently deteriorated was also analysed. No statistically significant differences were found (
2 or Fisher’s exact test where appropriate; Fig. 1, Table 3).
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Radiology
MRI scans were available for 91 of the 93 patients at presentation (two MRI reports could not be traced). Eighty-seven per cent of the initial MRI scans were performed in neutral. Six patients whose only complaint was of cervical spine pain had evidence of cervical cord compression on MRI. Surgery has been required subsequently in one of these patients and two patients with subaxial cord compression have died from unrelated causes. Three patients remain stable with follow-up at 5, 12 and 36 months.
When the level of compromise was examined (Table 4, Fig. 1
), 60% of the patients with compression or impingement at the atlanto axial level deteriorated over a median of 12 months (range 4–36 months) compared with only two (18%) of those with subaxial disease.
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Surgical outcome
The median follow-up for the nine patients requiring surgery was 38 months (range 15–69 months). The median time to deterioration was 23 months (range 4–51 months). All patients had evidence of impingement or compression on initial MRI scan.
Six of nine patients underwent surgery as a result of progressive neurological impairment with pain, two of nine patients had intractable pain only and one of nine had progressive neurological involvement with no pain.
Three months following surgery, 56% of patients had no pain, 11% experienced no change and 11% had noted an improvement in symptoms of pain. Seventy-eight per cent felt there was a subjective improvement in function. Ranawat grade at initial MRI, immediately prior to surgery and at first follow-up were available for five patients (Table 4). Three patients were returned to their pre-MRI Ranawat category at presentation. Patient 1 developed a cerebellar abscess in the post-operative period resulting in persistent neurological deficit. Patient 4 sustained a dramatic and rapid deterioration and surgery did not result in a return to her original neurological status.
Mortality
In the deterioration group, two patients who were under regular neurosurgical review died 16 and 24 months after presentation as a direct result of cervical myelopathy. Surgical intervention was not performed as a result of comorbidity in both cases. A third patient died 30 months after surgery from an unrelated cause. Five deaths occurred in the conservative group (renal failure, perforated bowel and gastrointestinal bleed; cause was unknown in the other two cases).
Outcome conservative group
The conservative group was followed for a median of 12 months (range 4–84 months). Thirty-three per cent (27/82) have evidence of compression or impingement on MRI and have been followed for a median of 14 months (range 5–36 months). Four patients with axial compression or impingement, including one patient in whom surgery was felt to be contraindicated as a result of comorbidity, remain stable at 6, 12, 12 and 13 months. Eleven patients had compression or impingement at the subaxial level, of whom two have died of reasons unrelated to cervical spine disease, two patients were lost to follow-up, and the remainder are neurologically stable with follow-up ranging from 12 to 18 months. Impingement in the remaining 12 patients was thought to be related to degenerative disease as opposed to RA, and all remain stable.
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Discussion |
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TopAbstractIntroductionPatients and methodsResultsDiscussionReferences |
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This study aimed to determine which features of rheumatoid cervical myelopathy were associated with subsequent deterioration. During the study period, 11/93 (12%) deteriorated over a median of 15 months (range 4–84 months). Where axial compression or impingement was present on MRI, 60% (6/10) experienced a deterioration resulting in death or surgical intervention over a median of 12 months (range 4–36 months). Pathological series have suggested that cord atrophy in rheumatoid cervical myelopathy results from repeated traction injury as a result of compression, stretch and movement as opposed to an inflammatory process [6] and as the atlanto-axial joint is the most mobile segment of the cervical spine [7] this finding is not surprising.
Unfortunately, only 13% of the initial MRI scans in this series were performed in flexion and extension. Previous studies have shown that compression increases in flexion in 26% of patients with rheumatoid cervical myelopathy. Therefore, the extent of impingement/compression may have been underestimated [8].
In 1993, Boden et al. [9] investigated the predictive value of the posterior atlanto-dental interval (PADI). It was found that a PADI of less than 14 mm on plain X-ray had a 97% ability to detect patients with neurological deficit. Neurological recovery from surgery was unlikely if the PADI fell beneath 10 mm and complete motor recovery resulted if surgery was performed when the PADI was greater than 14 mm. In scans performed after 1993 this measurement was not routinely performed in our institution. We retrospectively examined the PADI in our 10 patients with axial impingement or compression. However, the relevant plain films were missing for five and in no patient was the PADI less than 14 mm at the time of initial MRI.
The results of this study must be treated with caution due to the retrospective nature and small numbers in the deterioration group. Study entry was determined by the clinical need for MRI. Therefore, patients were studied relatively late in the natural history of the disease. Unfortunately data collection is incomplete and it is impossible to determine if patients suffered permanent functional loss as a consequence of delaying surgery. It would appear from the available data that even with a PADI available, subsequent deterioration could not have been predicted. Outcome from cervical spine surgery is best when performed in patients falling into Ranawat categories I and II [2, 9, 10–13]. Neurological deterioration from rheumatoid cervical spine disease can occur precipitously, but it may be difficult to justify surgery to a patient with little or no neurological deficit. This study suggests that the risk of deterioration is high if compression or impingement of the cord at the atlanto-axial joint is present. This can be balanced against the risks of rheumatoid cervical spine surgery to an individual patient and may help facilitate the decision to intervene surgically.
In conclusion, we have found that deterioration is likely if there is evidence of compression or impingement at the atlanto-axial level on MRI regardless of the initial clinical and plain X-ray features. This information can be presented to patients and may help optimize the timing of surgical intervention.
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Acknowledgments |
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We would like to acknowledge the help of Dr Margaret-Mary Gordon with data collection, Mrs Margaret Brown, Mrs Joyce Shearer and Miss Helen Wilson in obtaining the appropriate case records, Mrs Helen Burton and the radiology departments at both the Southern General and Western Infirmary for providing the necessary information from the databases, Mr Bryon Jaques for computing expertise and Mrs Dorothy McKnight for her help with statistical analysis. Finally, we would like to thank the rheumatology consultants based at the Royal Infirmary and Gartnaval General Hospital for allowing us to access patient records.
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Notes |
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Correspondence to: J. D. Hamilton.
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