Introduction Progressive neurological deficit from a solitary spatially isolated demyelinating lesion was first reported in 2012 (Schmalstieg et al). These patients did not fulfil International panel criteria for diagnosing Multiple Sclerosis or Neuromyelitis Optica spectrum disorder (which anyway typically lacks a progressive stage).

Method We describe a further 3 patients with a clinical picture of progressive myelopathy with a single demyelinating lesion, without evidence of dissemination in time or space. Alternative diagnoses were not applicable or ruled out.

Results Two of the patients had lesions in the cervical cord and one in the cranio–vertebral junction. One patient had some impingement of the cervical cord due to disc but the intrinsic cord lesion was not fully explained by the impingement and continued to have symptoms even after decompressive surgery. The lesions on the MRI resembled a typical demyelinating plaque in all the three cases. Serial images did not reveal any accumulation of new lesions in all the three patients. There was no clinical or radiological evidence of dissemination in space and time. One patient had positive oligoclonal bands and raised IgG index. Aquaporin antibodies were negative in all the three patients. Visual evoked potentials were normal in one patient while the others were not tested. Other extensive tests were normal. All of them had progressive symptoms despite immunosuppressive treatment (steroids, azathioprine, mitoxantrone) although one patient had some transient benefit from steroids.

Conclusion Solitary demyelinating lesions can produce progressive myelopathy like primary progressive Multiple Sclerosis. Though histology is as yet unavailable, it is more than likely to be demyelinating in nature. Thus solitary sclerosis should be in the differential diagnosis of progressive myelopathy and invasive diagnostic tests (like spinal cord biopsy) for suspected tumours/ granulomatous disorders must be carefully reconsidered in light of this additional possibility.