Sodium Concentration in the Brain Linked to Greater Disability in Multiple Sclerosis

High sodium concentrations in the brains of patients with multiple sclerosis (MS) may be associated with higher levels of disability in patients with MS, particularly those with progressive disease.

High sodium concentrations in the brains of patients with multiple sclerosis (MS) may be associated with higher levels of disability in patients with MS, particularly those with progressive disease.

The authors of “Sodium Accumulation Is Associated with Disability and a Progressive Course in Multiple Sclerosis,” published in Brain, posited that “In multiple sclerosis there may be intracellular sodium accumulation due to neuroaxonal metabolic dysfunction, and increased extracellular sodium due to expansion of the extracellular space secondary to neuroaxonal loss.”

For the study, researchers used sodium magnetic resonance imaging to measure cortical sodium concentration in 27 healthy control subjects, 27 patients with relapsing-remitting MS, 23 with secondary-progressive MS, and 20 with primary-progressive MS.

They reported that sodium concentrations “were significantly higher in all subgroups of multiple sclerosis compared with controls, and deep gray and normal appearing white matter sodium concentrations were higher in primary and secondary-progressive multiple sclerosis.”

Patients with secondary-progressive MS had higher sodium concentrations in cortical grey matter, normal appearing white matter, and deep gray matter compared to patients with relapsing-remitting MS.

The researchers also found higher sodium concentrations in T1 lesions compared with normal appearing white matter. Patients with secondary-progressive MS and primary-progressive MS also had higher concentrations within lesions compared to patients with relapsing-remitting multiple sclerosis.

In their conclusion, the authors wrote “Sodium concentration is increased within lesions, normal appearing white matter and cortical and deep grey matter in multiple sclerosis, with higher concentrations seen in secondary-progressive multiple sclerosis and in patients with greater disability. Increased total sodium concentration is likely to reflect neuroaxonal pathophysiology leading to clinical progression and increased disability.”

Lead author David Paling, MB ChB, of the NMR Research Unit, Department of Neuroinflammation, Queen Square Multiple Sclerosis Centre, University College London Institute of Neurology, told the London Evening Standard that this study is important because it “it proves sodium accumulation in the nerves affects the progressive nature of the disease… We can now move forward to plan trials with medications that prevent sodium from getting into cells and causing damage… In addition, we now have an effective test to check if these treatments are working for MS patients, instead of waiting five to 10 years.”