PREDICTORS OF OUTCOME IN THE QUADRIPARETIC NONAMBULATORY MYELOPATHIC PATIENT WITH RHEUMATOID-ARTHRITIS - A PROSPECTIVE-STUDY OF 55 SURGICALLY TREATED RANAWAT CLASS IIIB PATIENTS
Ath. Casey et al., PREDICTORS OF OUTCOME IN THE QUADRIPARETIC NONAMBULATORY MYELOPATHIC PATIENT WITH RHEUMATOID-ARTHRITIS - A PROSPECTIVE-STUDY OF 55 SURGICALLY TREATED RANAWAT CLASS IIIB PATIENTS, Journal of neurosurgery, 85(4), 1996, pp. 574-581
The functional results of surgery in patients with myelopathic nonambu
latory rheumatoid arthritis (Ranawat Class IIIb) are often disappointi
ng, with high rates of postoperative morbidity and mortality. The auth
ors therefore undertook a derailed investigation of a cohort of 55 Ran
awat Class IIIb patients (11 men and 44 women) with a mean age of 64.7
years who were recruited prospectively over a 10-year period (1983-19
93), to determine what factors may accurately predict a good surgical
outcome. Only 14 patients (25.5%) were judged to have had a favorable
outcome as determined by an improvement to Ranawat Class I or II or an
improvement of at least 0.5 points in the Stanford Health Assessment
Questionnaire disability index. The early postoperative mortality rate
was high (12.7%) in this group and almost one-quarter of the patients
were dead within 6 months. These poor results mirror those already pu
blished in the existing literature. Univariate analysis revealed that
age (p = 0.02), degree of vertical translocation (p = 0.05), and, more
importantly, spinal cord area (p = 0.006) were significant predictors
of outcome. Multiple logistic regression analysis showed that spinal
cord area (p = 0.026) was, in fact, the major determinant of outcome a
nd, indeed, of long-term survival (p = 0.001). The mean spinal cord ar
ea of those patients not achieving a good outcome was 44 mm(2). The at
lantodens interval (ADI) was nor shown to be a significant outcome det
erminant, which may be explained by the correlation between an increas
ing vertical translocation and a decreasing ADI (r = 0.4, p = 0.01). F
urthermore, as the degree of vertical translocation increased, the spa
ce available for the cord was observed to decrease (p = 0.003) commens
urate with a reduction in spinal cord area (p = 0.02). Together, these
findings strongly argue for earlier surgical intervention, before the
development of vertical translocation, permanent neurological damage,
and spinal cord atrophy can occur.