Relapsing remitting multiple sclerosis (RRMS) patients have periodic relapses occurring at variable rates, but generally less than one per year. The factor complicating MS clinical trials is disease heterogeneity, which is one of the hallmarks of MS. The annualized relapse rate or the number of relapses is the most common primary outcome measure for RRMS clinical trials. Relapses are subjective. As symptoms fluctuate, and are influenced by many factors- fever, high ambient temperature, anxiety, intercurrent illness, and sleep deprivation, among others - it is often not clear whether an individual MS patient has experienced a relapse or not. Also, the required duration beyond which symptoms must persist has not been standardized. There are no demonstrably effective therapies for primary neuroprotection, though it appears possible to slow the neurodegerative process in early-stage MS with immunomodulatory or immunosuppressive drugs. Presumably, this form of neuroprotection is secondary to the anti-inflammatory effect.