Researchers Discover New Subtype of Multiple Sclerosis

A team of researchers has discovered a new subtype of multiple sclerosis (MS), providing a better understanding of the individualized nature of the disease.

Demyelination of cerebral white matter is believed to be responsible for the neuronal degeneration and associated permanent neurologic disability in persons with MS. But findings from magnetic resonance imaging (MRI) of the brain suggest that demyelination and neuronal degeneration can occur independently.1

In the new findings, researchers at the Cleveland Clinic in Cleveland, Ohio, identified for the first time a subtype MS that features neuronal loss but no demyelination of the brain’s white matter.2 The new subtype is indistinguishable from traditional MS on MRI and was only able to be detected during autopsy.

The researchers performed postmortem examinations of the brains of 100 patients who had died with MS to determine whether they showed pathologic evidence of cortical neuronal loss independent from demyelination of cerebral white matter. They examined and compared centimeter-thick slices of the brains to look for areas of cerebral white matter with the discoloration that indicates demyelination (referred to as typical MS) and areas without the discoloration (referred to as myelocortical MS). Demyelinated lesions were detected in the spinal cord and cerebral cortex but not in the cerebral white matter of people with myelocortical MS. Compared with control brains, neuronal loss was greater in myelocortical MS cortexes than in typical MS cortexes.

The researchers concluded that myelocortical MS is an MS subtype characterized by demyelination of spinal cord and cerebral cortex but not of cerebral white matter. “Cortical neuronal loss is not accompanied by cerebral white-matter demyelination and can be an independent pathological event in myelocortical multiple sclerosis,” they wrote. They also called for further study of the “molecular mechanisms of primary neuronal degeneration and axonal pathology” in myelocortical MS.

­­—Michael Gerchufsky

References:

  1. Trapp BD, Vignos M, Dudman J, et al. Cortical neuronal densities and cerebral white matter demyelination in multiple sclerosis: a retrospective study [published online August 21, 2018]. Lancet Neurol. doi: https://doi.org/10.1016/S1474-4422(18)30245-X.
  2. Cleveland Clinic researchers discover novel subtype of multiple sclerosis [press release]. Cleveland, OH: Cleveland Clinic; August 21, 2018. https://newsroom.clevelandclinic.org/2018/08/21/cleveland-clinic-researchers-discover-novel-subtype-of-multiple-sclerosis/.