What Are The Four Different Forms Of Multiple Sclerosis?

Multiple sclerosis (MS) is a chronic disease that attacks the nervous system, potentially causing debilitating damage (via Mayo Clinic). According to a study by the National MS Society, nearly 1 million people in the U.S. live with MS. When a person has MS, the protective layers around the nerves (called myelin) are attacked by the immune system, causing the sheaths to break down and exposing the nerves to severe damage or deterioration. This leads to inflammation and lesions, which cause communication issues between your body and brain (via Healthline).

Symptoms of MS can vary widely. Some of the most common symptoms, according to Healthline, are fatigue, difficulty walking, vision problems, and speech difficulties. Other symptoms can include acute or chronic pain, tremors, cognitive troubles, difficulty chewing or swallowing, sleep issues, and problems with bladder control. The disease is diagnosed by a neurological exam, and can also include an MRI, lumbar puncture, and blood tests (via Healthline). While there is no cure for MS, treatment options are available and can help to manage symptoms and prevent disease progression. However, not all cases of MS look the same. In fact, MS is categorized into four different types.

According to the National MS Society, a person can have varying disease "courses" (or types). There's no way to know how the disease will progress for each person, but four different forms have been defined by the International Advisory Committee on Clinical Trials of MS, as outlined in a report published in Neurology.

Clinically Isolated Syndrome (CIS): This is the initial episode of neurologic symptoms (via National MS Society). With CIS, a person exhibits classic symptoms of MS for at least 24 hours, although this doesn't necessarily mean they will go on to develop MS. If the episode is accompanied by brain lesions as seen on an MRI scan, they are more likely to have a second episode.

Relapse-remitting MS (RRMS): This is the most common course of MS, as 85% of people diagnosed with MS are first diagnosed with RRMS. In this form, regular attacks (or relapses) occur with periods of remission following them. Symptoms can become worse or remain the same during relapses, but the disease does not progress during remission.

Secondary progressive MS (SPMS): SPMS is similar to RRMS, except that neurologic function worsens over time. Some people with RRMS eventually transition to SPMS. While there can still be periods of stability in SPMS, disability will gradually increase.

Primary progressive MS (PPMS): In this form of MS, neurologic function worsens with no early periods of relapse or remission. Of those who have MS, approximately 15% are diagnosed with PPMS.