MS is a chronic disease of the central nervous system, disrupting functions of the brain, spinal cord, and optic nerves. MS produces injury in the central nervous system when the immune system mistakenly attacks myelin and the axons they cover. Areas of myelin damage are known as lesions, and these eventually fill in with scar tissue referred to as plaques.

The damage from lesions disrupts the transmission of nerve impulses from the central nervous system to the rest of the body causing a variety of symptoms. Although likely, at least in part, to be autoimmune in nature, with both genetic and environmental risk factors, the cause of MS is unknown. With no known cure, there are numerous treatments that can slow disease progression and positively impact a variety of symptoms.

Background

Symptoms of MS depend on which areas of the brain, optic nerves, and spinal cord develop MS lesions. The criteria for an MS diagnosis are based upon the principle of lesions “disseminated in space and time.” Symptoms may occur in various timeframes. Typical age onset is 25-45, but 5% have onset under age 18, and 8% have symptom onset at age 50 or older.

Acutely, patients may have new symptoms that that evolve over hours to days, plateau in severity, and then are followed by remission that may be complete (especially in younger patients) or incomplete. This is Relapsing-Remitting MS (RRMS) which is the most common presentation in young adults and children.

By definition, a relapse is when these symptoms occur for the first time, are not associated with fever or infection, and last for more than 24 hours. A relapse can be confirmed by the onset of new symptoms, signs on neurological examination, and the appearance of a lesion by a Gadolinium-enhanced (Gd+) MRI scan. Over the lifetime of the MS patient, relapses may occur randomly and without warning, and diminish with age.  The time course over which MS lesions develop and the number and location of lesions is different for everyone, and thus symptoms and timing of symptom arrival will be different for everyone.

As people age, in a minority of patients, the slow progression of new symptoms — especially gait and cognitive dysfunction — may essentially replace the relapses. This is typically not associated with obvious new MRI lesions. This is referred to as Secondary Progressive MS (SPMS), and mean onset of the slow progression is about 40-45.

Finally, about 15% of patients don’t have relapses when young, but simply have slow progression from the outset, also with a mean age of onset of about 40-45.  This is called Primary Progressive MS (PPMS). Notably, slow progression of disability independent of relapses may occur throughout the lifetime of the patient, but is more easily seen in older patients, when relapses are much less conspicuous.

Early Signs and Symptoms

  • The most common early signs of MS include vision problems, numbness and tingling, walking and mobility difficulties, dizziness, and muscle pain or spasticity.