Long term MRI follow-up of patients with post infectious encephalomyelitis: evidence for a monophasic disease

Post infectious encephalomyelitis and multiple sclerosis are both inflammat ory demyelinating disorders of the central nervous system. Whereas multiple sclerosis is a multi phasic disease with recurrent episodes disseminated i n time and place, post infectious encephalomyelitis is usually considered t o be a monophasic illness. This study used serial brain MRI to clarify whet her the latter hypothesis holds for the long term. Post infectious encephal omyelitis was defined as the development of a central nervous system white matter disorder occurring in close temporal relationship with a viral, bact erial or other infection. There were eleven patients, mean age at presentat ion 21 years (4-48), and mean period of follow-up of 8 years (3.5-11). T2-w eighted brain MRI was abnormal in all II cases during the acute stages of t he illness. On follow-up 6 patients had made a complete clinical recovery, 3 patients had mild residual deficits and one severe neurological deficits necessitating ventilatory support. No patient experienced an exacerbation d uring the follow-up period. MRI revealed complete resolution of abnormaliti es in 3 and partial resolution in 7; new white matter lesions were seen in only one patient. This long term follow-up study suggests that there is a d efinable group with post infectious encephalomyelitis who exhibit a monopha sic clinical and MRI pattern in the long term. (C) 1999 Elsevier Science B. V. All rights reserved.