Autoimmune Disorders of the Joints and Nerves

Autoimmune disorders occur when the body’s own immune system mistakenly starts attacking healthy tissue. More than 80 different types of diseases are believed to be autoimmune, according to the National Institutes of Health. Because there are so many conditions under this umbrella, symptoms can vary and may affect organs and tissues throughout the body. Autoimmune disorders that specifically affect the muscles, joints, and nerves include rheumatoid arthritis (RA) and multiple sclerosis (MS). Polymyalgia rheumatica, which also involves the joints, is thought to be an autoimmune condition, according to the Arthritis Foundation.

Polymyalgia Rheumatica

Polymyalgia rheumatica, an inflammatory disorder, causes symptoms of muscle pain and stiffness, typically in the neck, shoulder, arms, or hip areas. Pain is generally worse in the morning. Polymyalgia rheumatica usually occurs in people 65 and older, rarely occurring in those under 50, according to Mayo Clinic, and women are 2 to 3 times more likely to develop the disorder. Polymyalgia rheumatica predominantly affects white people with Scandinavian or northern European ancestry, notes the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).

Patients with this disorder may also have signs of inflammatory arthritis. Moreover, about 15 percent of people with polymyalgia rheumatica develop a condition known as giant cell arteritis, according to the Arthritis Foundation. In this disorder, inflammation narrows or blocks blood vessels, restricting blood flow.

Corticosteroids, at the lowest dose possible, are the mainstay of treating polymyalgia rheumatica, notes NIAMS. But sarilumab (Kevzara), a biologic approved by the U.S. Food and Drug Administration (FDA) to treat moderate to severe rheumatoid arthritis was also approved in 2023 to treat polymyalgia rheumatica in people for whom corticosteroids don’t work well, according to a press release.

RELATED: FDA Approves Steroid-Free Treatment for Polymyalgia Rheumatica

Multiple Sclerosis

Commonly referred to as MS, multiple sclerosis affects the central nervous system — the brain and spinal cord. MS involves injury to the protective covering that surrounds nerve cells. This protective covering is called the myelin sheath and when it’s damaged, nerve impulses slow down. This is why MS is considered to be an autoimmune condition — the body’s immune system is what attacks the myelin sheath, through inflammation.

MS symptoms vary in severity from person to person, ranging from limb numbness and muscle weakness to paralysis. The disease is considered progressive, meaning it gets worse over time, but the rate of progression also varies widely. The cause of MS remains unknown, but most research points to a genetic predisposition combined with exposure to certain environmental conditions, such as smoking or the Epstein-Barr virus.

According to the National Multiple Sclerosis Society, nearly one million people in the United States are living with MS. It is most commonly diagnosed between ages of 20 and 50, and it’s 3 times more common in women than men.

Treatment for MS is typically multifaceted, involving disease-modifying drugs; steroids; physical therapy and lifestyle modification; as well as therapeutic support for mood disorders.

RELATED: What Multiple Sclerosis Looks Like in Your Brain

Rheumatoid Arthritis

This form of arthritis, unlike osteoarthritis, is an autoimmune disorder. When the body’s immune system attacks itself, inflammation results, which causes joint linings to thicken, leading to pain and swelling. If RA goes untreated, the inflammation can become so severe that it causes bone damage or joint deformities.

The joints most commonly affected are in the following areas:

  • Wrists
  • Fingers
  • Knees
  • Feet
  • Ankles

Joint pain and swelling are the signature symptoms of RA, but the disease can affect organs throughout the body. RA patients may also experience fatigue, general weakness, muscle weakness, flu-like symptoms, loss of appetite, depression, weight loss, and anemia. Advanced RA can make those with the disorder more susceptible to infections.

In the United States, RA affects more than 1.3 million people according to the American College of Rheumatology (ACR). Onset typically occurs between ages 30 and 50, though it can happen at any age. About 75 percent of RA cases are in women, per the ACR, and 1 to 3 percent of women may get rheumatoid arthritis.

RELATED: How to Choose a Rheumatologist

Treatment for RA aims to stop the progression of the disease. This involves reducing symptoms, controlling inflammation, minimizing joint and organ damage, and improving physical function. Treatment includes medication — disease-modifying anti-rheumatic drugs (DMARDs) as well as biologics and JAK inhibitors — and physical therapy. Early, aggressive measures can help keep complications from developing.

Additional reporting by Deborah Shapiro.

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