Neural networks are like well-maintained highways throughout the brain.
What is MS?
Multiple sclerosis (MS) is an autoimmune disease that can affect your life in many ways.
Approximately 2.8 million people worldwide have MS. While there is no known cure, treatment options have expanded over the last decades, and ongoing research continues to address MS, its symptoms, and its causes.
MS affects your central nervous system
MS is an autoimmune disease where your own immune cells attack your central nervous system (CNS). The CNS includes your brain, spinal cord, and optic nerves.
Normally, immune cells patrol for signs of infection (such as viruses and bacteria). When they find one, they attack it. Generally, B cells make antibodies that help the immune system recognize the infectious substance, and T cells attack the infectious substance and help control the immune response.
The CNS operates by sending signals through the nerve cells, also called neurons. These neurons help you process and respond to the world around you.
MS impacts the communication between neurons
Myelin is a substance that forms a protective layer over parts of individual neurons in the CNS. This helps neurons send signals rapidly.
In MS, for unknown reasons, immune cells attack myelin, damaging or destroying it and causing inflammation.
When myelin is damaged or destroyed, it becomes harder for neurons to communicate with each other quickly and effectively. The neurons themselves can also be damaged in MS.
Areas where inflammation has damaged or destroyed myelin are called lesions. Your doctor can often see these lesions using magnetic resonance imaging (MRI).
Everyone experiences brain atrophy (also known as brain shrinking) with age. However, the occurrence of lesions in patients with MS speeds up brain atrophy. Brain atrophy appears early in the course of the disease and accelerates with MS progression.
Consider the below for an example of how MS can impact communication in the CNS
With MS, these highways become damaged and, over time, may become disconnected. This can cause signals to move slower and less efficiently within neural networks.
The brain can build new connections to try and repair damage. However, its ability to build these new connections decreases over time.
As the brain tries to build so many new connections, it can become less efficient. Think of it like taking a detour or a dirt road—you can still get to your destination, but it usually takes longer. This means your brain may process information slower than those who do not have MS, and it may take you longer to think through simple daily tasks.
MS can take time to diagnose
There’s no single test that can diagnose MS, so healthcare professionals must use a variety of methods to evaluate people for MS. They’ll take a detailed medical history, perform a neurologic exam, and may order different kinds of tests. These tests include MRIs, spinal fluid tests, and blood tests.
If the results of these tests and exams meet certain criteria, an MS diagnosis is given.
Before being diagnosed with MS, a person can experience radiologically
isolated syndrome (RIS) or clinically isolated syndrome (CIS)
RIS: Experienced in people who had an MRI that showed an abnormality in their brain or spinal cord that looked similar to an MS lesion. These individuals have no past or current neurologic symptoms at the time the abnormality is found.
CIS: Experienced in people who have a first episode of neurologic symptoms caused by inflammation in the CNS and damage to myelin. The signs and symptoms of CIS are similar to those of MS but don’t yet meet the full criteria for an MS diagnosis.
Diagnosed MS can take a few forms. These include relapsing-remitting MS (RRMS), secondary progressive MS (SPMS) with or without relapses, and primary progressive MS (PPMS).
RRMS affects most people with MS (85%) and is characterized by recurring relapses followed by a period of recovery or remission. Relapses are episodes of new symptoms or worsening of old symptoms that may occur at the same time as MS lesions in the CNS.
You'll notice on this page that the different forms of MS are shown graphically. Relapses are represented by the heightened bars in the graph. While each relapse is followed by a period of remission or recovery, the level of remission or recovery decreases over time and the disease continues to get worse.
Relapses can vary in intensity from mild to severe, and the symptoms they cause can vary from person to person. Some symptoms include changes in vision, difficulties with walking or balance, or extreme fatigue, and can last from a few days to a few months. After a relapse, the symptoms can disappear completely but sometimes they don’t. If symptoms continue after a relapse, they can lead to further disability.
50% of people diagnosed with RRMS who go untreated will eventually progress to SPMS within 10 years, and 90% will progress within 25 years. In SPMS, illustrated in the graph, neurologic function steadily gets worse over time with or without relapses.
PPMS is a type of MS where neurologic function gradually gets worse once symptoms begin, without relapses or remission. This type of MS affects approximately 15% of newly diagnosed individuals.