Predictive factors for post-poliomyelitis syndrome.

Post-poliomyelitis syndrome (PPS) is generally defined as a clinical syndrome of new weakness, fatigue, and pain in individuals who have previously recovered from acute paralytic poliomyelitis. The purpose of this study was to identify, through a case-control study design, factors that predict subsequent PPS in patients with prior paralytic poliomyelitis. Among patients attending a university-affiliated hospital post-polio clinic, "cases" were patients with new weakness and fatigue, and "controls" were patients without these complaints. A chart review of 353 patients identified 127 cases and 39 controls. Logistic regression modeling was used to calculate adjusted and unadjusted odds ratios. In univariate analyses, significant risk factors for PPS were a greater age at time of presentation to clinic (p = 0.01), a longer time since acute polio (p = 0.01), and more weakness at acute polio (p = 0.02). Other significant associated, but not necessarily causal factors were a recent weight gain (p = 0.005), muscle pain (p = 0.01) particularly that associated with exercise (p = 0.005), and joint pain (p = 0.04). Multivariate analyses revealed that a model containing age at presentation to clinic, severity of weakness at acute polio, muscle pain with exercise, recent weight gain, and joint pain best distinguished cases from controls. Age at acute polio, degree of recovery after polio, weakness at best point after polio, physical activity, and sex were not contributing factors. These findings suggest that the degree of initial motor unit involvement as measured by weakness at acute polio, and possibly the aging process and overuse are important in predicting PPS.

The accuracy of magnetic resonance imaging in patients with suspected multiple sclerosis. The Rochester-Toronto Magnetic Resonance Imaging Study Group.

OBJECTIVE: To design and implement a methodologically rigorous study to examine the accuracy of magnetic resonance imaging (MRI) in a patient population clinically suspected of having multiple sclerosis (MS). DESIGN AND SETTING: Three hundred three patients, who were referred to two university medical centers because of the suspicion of MS, underwent MRI of the head and double-dose, contrast-enhanced computed tomography (CT) of the head. The images were read by two observers individually and without knowledge of the clinical course or final diagnosis. Patients were followed up for at least 6 months and reevaluated clinically with subsequent neurological examination. Final diagnosis (MS or not MS) was made by a panel of neurologists on the basis of the clinical findings at presentation, those that developed during follow-up, and other diagnostic tests. The results of the imaging procedures were excluded to avoid incorporation bias. Diagnostic accuracy was assessed using receiver-operating characteristic analysis and likelihood ratios. RESULTS: Magnetic resonance imaging of the head was considerably more accurate than CT in diagnosing MS. The area under the receiver-operating characteristic curve for MS was 0.82 (compared with 0.52 for CT) indicating that MRI was a good but not definitively accurate test for MS. A "definite MS" reading on an MRI of the head was specific for MS (likelihood ratio, 24.9) and essentially established the diagnosis, especially in patients clinically designated as "probable MS" before testing. However, MRI of the head was negative for MS in 25% and equivocal in 40% of the patients considered to have MS by the diagnostic review committee (sensitivity, 58%). CONCLUSIONS: Magnetic resonance imaging of the head provided assistance in the diagnosis of MS when lesions were visualized. Its ability far exceeded imaging with double-contrast CT. The sensitivity and, therefore, the predictive value of a negative MRI result for MS were, however, not sufficiently high for a normal MRI to be used to conclusively exclude the diagnosis of MS.