Cleveland Clinic Researchers Discover a New Subtype of Multiple Sclerosis

Researchers at the Cleveland Clinic have identified a subtype of multiple sclerosis, according to a study published in the Lancet Journal Tuesday. This new subtype of MS, myelocortical MS (MCMS), does not feature myelin sheath deterioration in a main part of the brain — a hallmark sign of “traditional” MS.

According to the National Multiple Sclerosis Society, MS occurs when your immune system attacks your central nervous system (CNS). This attack causes inflammation which damages your myelin sheath —  the fatty coating that protects nerve cells (neurons) in the brain and spinal cord. Because of this damage, your neurons aren’t able to send electrical impulses or “messages” to other parts of your brain. People with MS experience a large range of symptoms including fatigue, mobility issues and cognitive changes.

MCMS does not cause myelin sheath deterioration in the white brain matter of the cerebrum, the largest part of the brain consisting of the left and right hemispheres, researchers said. Nerve damage still occurs in this part of the brain as well as in other parts of the CNS typically damaged by MS. These areas include the cerebral cortex, which is the lining around the cerebrum, and the spinal cord. In patients with MCMS, myelin sheath deterioration still happens in the cerebral cortex and the spinal cord — just not the white matter of the cerebrum.

According to researchers, doctors likely won’t be able to differentiate MCMS from MS because the difference cannot be seen on an MRI. Lesions on MRIs are typically scars from myelin sheath loss. The lesions in MCMS patients looked like the scars seen in regular MS. The researchers were only able to identify MCMS postmortem.

The researchers studied the brains and spinal cords of 100 deceased MS patients who donated their bodies to science. Twelve of the brains displayed MCMS. Myelin sheath damage in the spine was greater in those with typical MS than those with the subtype.

“This study opens up a new arena in MS research,” Bruce Trapp, lead author of the study and chair of Cleveland Clinic’s Lerner Research Institute Department of Neurosciences, said. “It is the first to provide pathological evidence that neuronal degeneration can occur without white matter myelin loss in the brains of patients with the disease. This information highlights the need for combination therapies to stop disability progression in MS.”

Many of the medications used to manage MS are meant to prevent the disease from getting worse, limiting myelin sheath damage in the brain and spinal cord. The discovery of MCMS  could lead to better, more specific treatments.

“The importance of this research is two-fold,” Daniel Ontaneda, clinical director of the brain donation program at Cleveland Clinic’s Mellen Center for Treatment and Research in MS, said. “The identification of this new MS subtype highlights the need to develop more sensitive strategies for properly diagnosing and understanding the pathology of MCMS. We are hopeful these findings will lead to new tailored treatment strategies for patients living with different forms of MS.”