Written by Stephanie Watson | Published on May 20, 2015
Medically Reviewed by Natalie Butler, RD, LD on May 20, 2015
Part 1 of 4: Causes
Causes of Muscle Weakness in Multiple Sclerosis
The reason you’re able to walk, put on your clothes, and grab a glass off your kitchen shelf is because of the connection between your brain and muscles. Your brain controls the action, sending electrical signals from your brain to your muscles via a network of nerves. Those signals tell your muscles to move.
When you have multiple sclerosis (MS), your immune system attacks your nerves. It destroys myelin, an insulating substance that surrounds and protects nerve fibers. As myelin is damaged, scar tissue can form on the nerves. This can prevent nerve signals from traveling correctly from your brain to certain parts of your body.
Nerve damage can leave your muscles stiff or weak, reducing your ability to move and perform everyday activities. The weakness often occurs only on one side of your body or just in your legs or trunk. Weakness, like other MS symptoms, may come and go as you experience flare-ups and remissions during the course of the disease.
Part 2 of 4: Types
Types of Muscle Weakness
When nerve fibers are damaged, your brain can’t effectively send your muscles the signals they need to flex or contract. As a result, you won’t be able to properly use these muscles. Also, your muscles weaken when you don’t use them. Even muscles that aren’t directly affected by MS can become weak if symptoms like fatigue and pain prevent you from moving and exercising them. Over time, your muscles can get weaker and weaker.
Some people with MS find that their muscles tire more easily than usual. For example, someone with MS might find that their legs might start to feel unstable or they may have trouble moving them after periods of exercise, like walking.
Sometimes MS affects the muscles of the foot, making it hard to walk in a normal heel-toe pattern. As a result, your foot may drag on the ground when you walk. This is called drop foot or foot drop.
Part 3 of 4: Coping
How to Treat Muscle Weakness
The main treatments for MS will focus on slowing the disease progression, preventing nerve-damaging attacks, and relieving your symptoms. Medications that accomplish these goals may be mainstays of your MS therapy. These may include:
•interferon beta therapy
•glatiramer acetate (Copaxone)
MS: Treatment Overview »
Exercise is another important component of your treatment. A combination of cardio and strength-training exercises can combat muscle weakness and give you more energy. If your muscles have become weak from lack of use, resistance exercises using weights can strengthen them. A physical therapist can help you develop an exercise program that meets your ability level and accommodates any limitations you might have. The therapist can also show you how to do the exercises correctly so you don’t get injured or overly tired.
MS: Exercises for Better Balance and Coordination »
When your weakness is caused by damage to nerve fibers, the treatment strategy is a bit different. The goal will be to use the affected muscles as much as possible by staying more active. Then you’ll learn weight-training exercises to strengthen the muscles around the ones that have been damaged.
In this case, the therapist will teach you ways to minimize the effects of muscle weakness. You’ll learn how to use assistive devices like a cane, walker, or braces if you need them. For foot drop, the therapist can prescribe an ankle splint (orthosis) to prevent your foot from dragging while you walk. You may also need occupational therapy to learn new strategies for getting around in your home and at work.
In addition, the following steps can help relieve MS symptoms:
•maintaining an adequate sleep and rest routine
•keeping your body temperature cool
•eating a healthy, balanced diet
Part 4 of 4: Your Doctor
Working with Your Doctor
MS symptoms aren’t one size fits all. Everyone experiences the disease a little differently. That’s why it’s important to address your muscle weakness with your doctor and physical therapist and find solutions together.
You may need to try different treatments until you find one that relieves your muscle weakness and other symptoms. Those treatments may include a combination of medicine, physical therapy, and assistive devices. If one type of therapy isn’t effective, go back to your doctor with any concerns. Through a period of trial and error, you may be able to find another therapy that will work better for you.
MS is a challenging disease. Without support you may start to feel isolated. To avoid this, stay connected with friends and family, join a support group, and engage in enjoyable activities and hobbies.