Sodium buildup in the brain appears to be associated with disability in patients with multiple sclerosis (MS), according to a French study.

The accumulation of sodium, which can be detected by magnetic resonance imaging (MRI), may be a biomarker for the degeneration of nerve cells that occurs in MS patients.

The study, published online in the journal Radiology, found that individuals with early-stage MS showed sodium buildup in specific regions of the brain, while those with more advanced MS showed buildup throughout the entire brain.

According to the researchers, the accumulation of sodium in motor regions of the brain were directly associated to the severity of disability observed in patients with advanced MS.

Patrick Cozzone, Ph.D., director emeritus of the Center for Magnetic Resonance in Biology and Medicine, a joint unit of National Center for Scientific Research (CNRS) and Aix-Marseille University in Marseille, France, explained: “A major challenge with multiple sclerosis is providing patients with a prognosis of disease progression. It’s very hard to predict the course of the disease.”

Multiple Sclerosis is an autoimmune disease that affects the brain and spinal cord. The type and severity of MS symptoms, as well as the progression of the disease, vary from one patient to another.

In the study, the team used a specific type of imaging technology that provides information on the sodium content of cells in the body, known as 3 Tesla (3T) sodium MRI in order to study relapsing-remitting MS (RRMS).

Dr. Wafaa Zaaraoui, Ph.D., research office at CNRS, explained:

“We collaborated for two years with chemists and physicists to develop techniques to perform 3T sodium MRI on patients. To better understand this disease, we need to probe new molecules. The time has come for probing brain sodium concentrations.”

The 3T sodium MRI was performed on 26 patients with RRMS, the most common form of MS, in which flare-ups of symptoms are followed by periods of recovery.

Of the study participants, 14 had early-stage RRMS and 12 had advanced-stage disease. In addition, the team examined 15 age- and sex-matched healthy participants without MS.

For patients with early-stage RRMS, the MRI results showed abnormally high concentrations of sodium in the brainstem, cerebellum, and temporal pole regions of the brain. Abnormally high sodium accumulation was found throughout the entire brains of patients with advanced-stage RRMS – even in brain tissue that appeared to be normal.

Dr. Zaaraoui said: “In RRMS patients, the amount of sodium accumulation in gray matter associated with the motor system was directly correlated to the degree of patient disability.”

At present, there are only treatments to slow down the progression of MS. According to the researchers using sodium buildup as an indicator of neuron degeneration may help in the development of potential new treatments.

Jean-Philippe Ranjeva, Ph.D., professor in neuroscience at Aix-Marseille University, explained: “Brain sodium MR imaging can help us to better understand the disease and to monitor the occurrence of neuronal injury in MS patients and possibly in patients with other brain disorders.”

Written by Grace Rattue