Postinfectious neurologic syndromes: a prospective cohort study.

OBJECTIVES

Postinfectious neurologic syndromes (PINSs) of the CNS include heterogeneous disorders, sometimes relapsing. In this study, we aimed to a) describe the spectrum of PINSs; b) define predictors of outcome in PINSs; and c) assess the clinical/paraclinical features that help differentiate PINSs from multiple sclerosis (MS).

METHODS

In this prospective cohort study, adult inpatients with PINSs underwent extensive diagnostic assessment and therapeutic protocols at inclusion and during a minimum 2-year follow-up. We compared them with newly diagnosed, treatment-naive patients with MS, also prospectively recruited.

RESULTS

The study sample comprised 176 patients with PINSs aged 59.9 ± 17.25 years (range: 18-80 years) divided into 2 groups: group 1 (CNS syndromes, 64%)-encephalitis, encephalomyelitis, or myelitis; and group 2 (CNS + peripheral nervous system [PNS] syndromes, 36%)-encephalomyeloradiculoneuritis or myeloradiculoneuritis. We observed the patients for 24 to 170 months (median 69 months). Relapses, almost invariably involving the spinal cord, occurred in 30.5%. PNS involvement was an independent risk factor for relapses (hazard ratio 2.8). The outcome was poor in 43% of patients; risk factors included older age, greater neurologic disability at onset, higher serum-CSF albumin percentage transfer, myelitis, and PNS involvement. Steroid resistance occurred in 30% of the patients, half of whom responded favorably to IV immunoglobulins. Compared with MS, PINSs were characterized by older age, lower tendency to relapse, and distinct CSF findings.

CONCLUSIONS

The category of PINSs should be revised: most of the clinical variants have a poor prognosis and are not readily classifiable on the basis of current knowledge. PNS involvement has a critical role in relapses, which seem to affect the spine only.