Brain Tissue Sodium Concentration in Clinically Isolated Syndrome (S41.007)

Background: Increased total sodium concentration, which may reflect neurodegeneration, has been demonstrated in the brain of patients with relapsing remitting, secondary progressive and primary progressive multiple sclerosis (MS). However, it is still unknown if increased sodium is seen in subjects presenting with a clinically isolated syndrome (CIS). Objective: The aim of this study is to estimate the total sodium concentration in the normal appearing white matter, cortical grey matter, deep grey matter and T2 lesions in patients presenting with a CIS. Methods: We recruited 16 CIS subjects (8F:8M), mean age 33.5(±7.3) years within 3 months from symptom onset and 10 healthy controls (6F:4M), mean age 34.20 years (±7.1). Patients had a median EDSS of 1.0 (range 1.0 - 2.0). Five of the CIS subjects had an abnormal MRI at baseline. Quantitative total sodium MRI was performed in all subjects using a 3T scanner. Linear regression models were used to compare differences between groups adjusting for age and gender. Results: Increased sodium concentration was seen in T2 lesions compared to normal appearing white matter in CIS subjects (45.2mM ± 8.322mM versus 35.1mM ± 6.2mM, p=0.019). A trend towards increased sodium concentration was seen in the normal appearing white matter (35.1mM ± 6.2mM versus 32.5mM ± 2.5mM, p=0.058), cortical grey matter (45.4mM ± 4.0mM versus 42.4mM ± 2.7mM, p=0.189) and deep grey matter (36.8mM ± 2.9mM versus 35.5mM ± 3.2mM, p=0.108) in CIS patients when compared to controls. Conclusion: Despite a small cohort (recruitment is ongoing), this study extends the findings of increased sodium concentration in MS to people with CIS. Increased total sodium levels could potentially be used as a biomarker of neuroaxonal dysfunction and loss at the onset of a first demyelinating event, and may be useful in predicting conversion to MS and future disability in patients with a CIS. Disclosure: Dr. Cawley has nothing to disclose. Dr. Solanky has nothing to disclose. Dr. Prados has nothing to disclose. Dr. Collorone has nothing to disclose. Dr. Ourselin has nothing to disclose. Dr. Gandini Wheeler – Kingshott has nothing to disclose. Dr. Toosy has received personal compensation for activities with Biogen Idec. Dr. Miller has nothing to disclose. Dr. Thompson has nothing to disclose. Dr. Ciccarelli has received personal compensation for activities with Novartis, Biogen and GE as a consultant.