MR Reveals Atrophy in Key Region of Brain of Multiple Sclerosis Patients

These atrophy measurements offer an improvement over existing technology for evaluating patients at risk for MS.

MS develops as the body’s immune system attacks and damages myelin, the protective layer of fatty tissue that surrounds nerve cells within the brain and spinal cord. Symptoms include visual disturbances, muscle weakness, and trouble with coordination and balance. People with severe cases can lose the ability to speak or walk.

Approximately 85% of individuals with MS suffer a first, short-term neurologic event known as clinically isolated syndrome (CIS). A conclusive MS diagnosis is based on a combination of factors, including medical history, neurologic exams, development of a second clinical attack, and detection of new and enlarging lesions with contrast-enhanced or T2-weighted MRI.

“For some time we’ve been trying to understand MRI biomarkers that predict MS development from the first onset of the disease,” said Robert Zivadinov, MD, PhD, FAAN, from the Buffalo Neuroimaging Analysis Center of the University at Buffalo (Buffalo, NY, USA). “In the last couple of years, research has become much more focused on the thalamus.”

Recent studies demonstrated atrophy of the thalamus in all different MS disease types and detected thalamic volume loss in pediatric MS patients. “Thalamic atrophy may become a hallmark of how we look at the disease and how we develop drugs to treat it,” Dr. Zivadinov said.

For this study, published online April 2013, in the journal Radiology, Dr. Zivadinov and colleagues examined the link between the development of thalamic atrophy and conversion to clinically definite MS. “One of the most important reasons for the study was to understand which regions of the brain are most predictive of a second clinical attack,” Dr. Zivadinov said. “No one has really looked at this over the long term in a clinical trial.”

The investigators utilized contrast-enhanced MRI for initial evaluation of 216 CIS patients. They performed follow-up scans at six months, one year, and two years. Over two years, 92 of 216 patients (42.6%), converted to clinically definite MS. Decreases in thalamic volume and increase in lateral ventricle volumes were the only MRI measures independently associated with the development of clinically definite MS. “First, these results show that atrophy of the thalamus is associated with MS,” Dr. Zivadinov said. “Second, they show that thalamic atrophy is a better predictor of clinically definite MS than accumulation of T2-weighted and contrast-enhanced lesions.”

The findings suggest that measurement of thalamic atrophy and increase in ventricular size may help identify patients at high risk for conversion to clinically definite MS in future clinical trials involving CIS patients. “Thalamic atrophy is an ideal MRI biomarker because it’s detectable at very early stage,” Dr. Zivadinov said. “It has very good predictive value, and you will see it used more and more in the future.”

The researchers are continuing to follow the study group, with plans to publish more findings from the four-year follow-up. They are also trying to determine more about the physiology of the thalamic involvement in MS. “The next step is to look at where the lesions develop over two years with respect to the location of the atrophy,” Dr. Zivadinov said. “Thalamic atrophy cannot be explained entirely by accumulation of lesions; there must be an independent component that leads to loss of thalamus.”

There is no known cure for MS, but early detection and treatment can slow development of the disorder. MS affects more than two million people worldwide, according to the Multiple Sclerosis International Foundation.

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