What is Multiple Sclerosis?
Multiple sclerosis is a complex disease of the central nervous system (brain, spinal cord, and optic nerves) characterized by relapses (neurologic symptoms which appear rapidly but often improve over weeks or months), remissions and often progression of disability over time. MS is currently not a curable disease.
MS is thought to be an immune-mediated disease, meaning that errors in the function of the immune system cause damage in the central nervous system. The immune system functions to protect the body from various environmental hazards or pathogens such as viruses, bacteria and fungi. The immune system is very sophisticated and has regulatory mechanisms in place that prevent it from recognizing body tissues as a pathogen.
In an immune-mediated disease such as MS, these regulatory mechanisms are disrupted and the ability to ignore itself is lost. In MS, the immune system recognizes tissue within the central nervous system as a pathogen and therefore causes inflammation and damage.
How is Multiple Sclerosis diagnosed?Toggle accordion item
MS is diagnosed based on the patient’s history of symptoms (if they can be referred to the central nervous system) over time, the neurological examination, and imaging tests such as brain and/or spinal cord MRI. Sometimes other tests are used like evoked potentials, optical coherence tomography, and/or a spinal tap.
Blood tests are also used to make sure the symptoms are not caused by something other than MS. As there is no single test for MS, the diagnosis is made by summing together the history, neurological exam, MRI and other test findings and the exclusion of other illnesses.
What are the symptoms of MS?Toggle accordion item
Symptoms of MS vary among individuals but often include:
- Numbness or tingling in the limbs
- Impaired balance
- Change in vision such as blurred vision in one eye or double vision
- Change in bowel, bladder and sexual function
- Stiffness or tightness in the muscles
- Trouble walking
What is the course of MS over time?Toggle accordion item
Approximately 85% of patients begin the disease with relapsing-remitting MS. These patients experience episodic relapses (sometimes called flares, attacks or exacerbations) in which they experience the onset of symptoms over a few days or weeks, with gradual recovery over time, whether complete or incomplete.
Inflammatory changes on MRI are the hallmark of the relapsing phase of the disease. During the relapsing phase of the disease there is frequent gadolinium enhancement seen on MRI (areas on the MRI scan that show up as bright spots after injection of the contrast dye), which indicates areas of active inflammation. Gadolinium enhancement occurs about 5-10 times more frequently than clinical relapses.
Over time, some patients will experience less inflammatory changes and more of a slow, progressive worsening of multiple symptoms and disability, often termed “progression.” This is classified as secondary-progressive MS. Over time there can also be a decrease in brain volume. Approximately 15% of patients never have relapses; rather their disease is characterized by a progression of symptoms over time from the time of onset. This disease course is known as primary-progressive MS.