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“Smouldering spots” in the brain may signal severe MS

US researchers have found that dark rimmed spots representing ongoing, "smouldering" inflammation in the brain, called chronic active lesions, may be a hallmark of more aggressive and disabling forms of multiple sclerosis (MS).

Researchers from the US National Institutes of Health (NIH) using a high-powered brain scanner and 3D printer, looked inside the brains of hundreds of MS patients and found it possible to use brain scans to detect which patients were highly susceptible to the more aggressive forms of the illness.

“The more chronic active lesions a patient has the greater the chances they will experience this type of MS," said Daniel S. Reich, MD., Ph.D, senior investigator at the NIH's National Institute of Neurological Disorders and Stroke and the senior author of the paper  published in JAMA Neurology.

As part of the latest research 192 MS patients who had entered a trial at the NIH's Clinical Centre were scanned. It was found that regardless of the treatment the patients were receiving, 56% of them had at least one rimmed lesion. Further analysis showed that 44% of patients had only rimless lesions; 34% had one to three rimmed lesions; and 22% had four or more rimmed lesions.

Researchers then compared the brain scans to the neurological examinations the patients received upon the trial enrolment. Patients who had four or more rimmed lesions were 1.6 times more likely to be diagnosed with progressive MS than those without rimmed lesions.

Moreover, these patients developed motor and cognitive disabilities at a younger age than the patients who had no rimmed lesions. When the researchers analysed key parts of the patients' brains, they found patients who had four or more rimmed lesions had less white matter than those who had no rimmed lesions.

The team then analysed a subset of patients whose brains had been scanned once every year for 10 years or longer. Their results suggested that, while the rimless lesions generally shrank, the rimmed lesions either grew or stayed the same size and were particularly damaged.

Finally, the team used a 3D printer to compare the spots they had seen on scans to the lesions they observed in brain tissue samples autopsied from a patient who had died during the trial. They found that all expanding rimmed spots seen on the scans had the tell-tale features of chronic active lesions when examined under a microscope.

"Our results support the idea that chronic active lesions are very damaging to the brain," said Dr Reich. "We need to attack these lesions as early as possible. The fact that these lesions are present in patients who are receiving anti-inflammatory drugs that quiet the body's immune system also suggests that the field of MS research may want to focus on new treatments that target the brain's unique immune system - especially a type of brain cell called microglia."

This study was published in the journal JAMA Neurology.

Source: MS-UK 14/08/2019

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