Multiple sclerosis, MS, is a neurodegenerative disorder affecting the brain,
spinal cord, and optic nerve, causing a number of neurological symptoms.
The nervous system provides rapid communication between body organs, as well as with the outside
environment. Nerve cells communicate with each other via their long axons, which act like
high-speed cables, or conducting wires. Most axons are wrapped in a protective sheath called myelin,
which functions as an insulator around a wire - it helps speed up the signals that travel within.
In MS, this myelin sheath is damaged; signal transmission becomes slow or even blocked.
Depending on the part of the nervous system that is affected, symptoms can vary greatly from
patient to patient, as well as over the disease course in the same patient, but a common feature
is a SUDDEN onset of one or more of the following: - limb weakness or numbness,
typically on one side of the body; - unsteady gait or lack of coordination;
- bladder, bowel, or sexual dysfunction; - electric-shock sensation upon neck bending;
- double vision, blurry vision, or vision loss, typically in one eye,
– and dizziness, slurred speech, or cognitive impairments.
Most MS patients present with a characteristic relapsing-remitting disease course, in which
periods of symptoms, known as relapses, alternate with periods of NO symptoms, or remissions.
Symptoms of a relapse typically arise over hours to days, worsen and then gradually
subside over several weeks. Some patients may retain residual symptoms during remission.
After about 10-20 years, the majority of these patients progress to secondary-progressive MS,
where symptoms constantly worsen without remission.
A small number of patients experience a steady progression of the disease from the onset,
without discernible relapse or remission. This form is known as primary-progressive MS.
MS can occur at any time in life but is typically diagnosed between 20
and 40 years of age. Women are 2 to 3 times more likely to develop MS than men. Other
risk factors include family history, being of white race, living in a temperate climate,
having vitamin D deficiency, autoimmune diseases, or previous infection with Epstein-Barr virus.
Demyelinating lesions can be seen on MRI scans of the brain and spinal cord of
MS patients. MS is considered an autoimmune disease in which the body's immune system
attacks its own tissues. Recurrent inflammation is believed to damage the myelin sheath,
as well as the axons underneath. Bouts of inflammation correspond to relapsing periods.
Remission results when inflammation subsides and the body is able to repair the damage.
Over time, however, the damage may become too severe to be repaired.
This is when the disease progresses to the secondary-progressive form.
Most people with relapsing-remitting MS can be diagnosed based on the characteristic
pattern of the symptoms. Diagnosis is then confirmed with MRI scans.
People with progressive disease or unusual symptoms are more challenging to diagnose. In
these cases, diagnosis is typically done by ruling out other conditions with a number of tests.
For acute relapses, corticosteroids are typically prescribed to reduce inflammation.
Plasma exchange, in which the liquid portion of the blood is removed and replaced with
a new solution, may be used for people who do not respond to medications. This process
“cleans” the blood, removing the offending immune factors that cause damage to the nervous tissue.
A number of drugs have been approved for disease-modifying therapies, with the goal
of reducing the relapse rate. They differ in effectiveness and safety profile
and must be selected carefully for each patient based on their individual health status.