Overview
Muscle weakness, common in Multiple Sclerosis (MS), can occur in any part of the body. The first step in managing weakness effectively is to determine the cause.
One of the main factors in weakness is the deconditioning of muscles, or loss of muscle tone. Deconditioning occurs with a lack of muscle use. With MS, a person’s overall activity level is reduced due to fatigue, pain, imbalance, or other symptoms. Lack of activity will cause weakness in the muscles affected by MS, as well as those that are not affected by the disease. For this type of weakness, progressive resistive exercise with weights can be very effective. A physical therapist can recommend a weight-training program that fits with your abilities and limitations.
One other cause of weakness is demyelination, or the resulting damage to the brain and spinal cord nerve fibers that stimulate the muscles. The muscles do not receiving the nerve impulses they require in order to work effectively – often resulting in decreased endurance. Because the source of this type of weakness is impaired nerve conduction, weight training to strengthen the affected muscles is not effective; in fact, it may even increase feelings of weakness and fatigue.
Medication
Ampyra®, Dalfampridine, 4-aminopyridine, 4 AP
This medication may improve the conduction of nerve messages through demyelinating plaques in people with multiple sclerosis (MS). It does not prevent multiple sclerosis relapses or progression nor does it repair damage from prior MS lesions. The FDA-approved version, Ampyra®, has an official indication to improve walking in patients with MS. Dalfampridine produced an increase in walking speed in clinical trials. Dalfampridine may also be used for other purposes (off label use) as its effects are not only on motor nerves. Dalfampridine may also be used by some neurologists in a compounded version known as 4-aminopyridine, or 4 AP. This form of the medication may be prepared with different size or dose capsules and used when the FDA approved version is either not covered by insurance or not available in the dose/form your neurologist desires. This version of the medication is felt to have a higher risk for seizures than Ampyra as the compounded capsules may not release the chemical as precisely as the FDA-approved version.
Risks of Ampyra®, Dalfampridine, 4-aminopyridine, 4 AP
You should not use Ampyra®, Dalfampridine, 4-aminopyridine, or 4 AP if you are allergic to any form of it, if you have moderate to severe kidney disease, if you have ever had a seizure (convulsion), or if you are also taking another version of it. Before you take Ampyra®, Dalfampridine, 4-aminopyridine, or 4 AP, tell your doctor if you have kidney disease. This medication increases your risk of seizures. This risk of seizures is felt to be less with the controlled release FDA version of the drug (Ampyra®) at its usual 10 mg twice per day dose than with the compounded version of the drug.
Please talk to your provider about the risks and benefits of this medication.