This study will evaluate the influence of sleep apnea on clinical and radiological features of MS. Sleep apnea is associated with hypoxemia during sleep, which is likely detrimental to MS. Clinical data (MRI, lab results, medical history, labs, and sleep studies) of MS patients will be collected and analyzed. This will be done to study correlations between MRI, clinical data, lab studies and sleep studies. There is specific interest in the type of sleep apnea associated with MS, and whether MRI or clinical metrics of MS severity correlate with presence or absence of sleep apnea.