Postinfectious neurologic syndromes: A prospective cohort study

OBJETIVES: 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 minimun 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 facotrs 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 shoud 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.