Objective: To present a case series of patients with progressive myelopathy in the setting of a solitary demyelinating lesion. Methods: We describe 7 patients evaluated over a 6-year period. All had progressive motor impairment attributable to an MRI lesion compatible with a demyelinating plaque in the brainstem or upper cervical spinal cord. At the time of evaluation, none met the International Panel imaging criteria for dissemination in space, and none described clinical symptoms consistent with relapses affecting other portions of the CNS. Results: Lesions identified were in the ventral cervicomedullary junction in 4 patients, the ventral spinal cord in 2 patients, and the pons in 1 patient. Median age at onset was 43 years (range 33-51 years). Median follow-up interval was 3 years (range 2-27 years). Six patients reached an Expanded Disability Status Scale (EDSS) score of 6.0 or worse. Median time to EDSS score of 6.0 was 7.5 years (range 1.5-26 years). Four had CSF findings characteristic of multiple sclerosis (MS). None had CSF, imaging, or serologic evidence of an alternative etiology of progressive myelopathy. In 3 patients, serial MRI scans of the brain and spinal cord demonstrated no accumulation of lesions. Postmortem examination of a fourth patient demonstrated an isolated pontine demyelinating lesion. Conclusions: Solitary demyelinating lesions may produce a progressive myelopathy similar to primary progressive MS. Demyelinating disease should be in the differential diagnosis of progressive myelopathy despite absence of dissemination in space.