Chronic progressive myelopathies occurring in the absence of lesion dissemination continue to present a difficult diagnostic challenge. In the present study 19 patients with progressive myelopathy were evaluated retrospectively. Patients were divided into groups based on the presence or absence of sensory involvement. Thirteen patients had both motor and sensory involvement and only 6 had a pure motor syndrome. Of the 13 patients with sensory involvement seven (54%) had evidence of lesion dissemination and probable MS. Only 1/6 (16%) of those with pure motor syndromes had evidence of lesion dissemination. Those patients were more likely to suffer from hereditary spastic paraparesis or primary lateral sclerosis. It is suggested that patients with chronic progressive myelopathies involving both sensory and motor systems without evidence of lesion dissemination may have a variant of MS in which there is isolated involvement of the spinal cord.