Parainfectious myelitis: three distinct clinico-imagiological patterns with prognostic implications.

Seventeen parainfectious myelitis patients were studied for site, extent and severity of lesions. Three patterns were observed each having distinct clinical, electrophysiological and MRI features: 1) focal segmental myelitis--focal cord lesion with long tract signs and good prognosis; 2) ascending myelitis--continuous lesion from conus to mid-cord with upper and lower motor neuron signs (not necessarily spinal shock), dysautonomia and poor outcome; 3) disseminated myelitis--discrete lesions scattered throughout the cord with subtle signs in spinal segmental distribution, above and below the transverse level and moderate outcome. Severe autonomic dysfunction, denervation of paraspinal muscles, "dense" lesion on imaging and often (but not always) the absent somatosensory evoked potentials carried poor outcome. In conclusion "parainfectious myelitis" is a better term to describe transverse myelitis, as the lesion extends to a large vertical extent. Further classification into 3 subgroups may improve understanding of anatomical and physiological dysfunction and prediction of outcome.