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.