Sensory problems, or disturbances in feeling, are often one of the earliest symptoms of MS and occur in 20 to 50 percent of individuals with the disease. Known as paresthesias, these abnormal sensations include numbness, tingling, burning, and increased sensitivity. Paresthesias may be caused by a number of other factors, including sitting or standing in one position for too long, certain medications, or lack of blood supply to the affected area. Itching, also known as pruritis, may occur as a sensory symptom of MS. While such itching causes the desire to scratch, the scratching can often intensify the itching and cause further damage to the skin. Feelings of tingling, burning or numbness, which are caused by lesions in the central nervous system, are known as dysesthesias. Literally translated from the Greek, this means “bad sensation.”
Numbness
One of the most common sensory problems associated with MS is numbness. Numbness occurs when the nerves that transmit sensations do not conduct information properly. As a result, sensations in that particular area are either lacking or nonexistent. Numbness is often one of the first symptoms experienced by people with MS and can affect a very small area, such as a spot on the face, or entire areas of the body, such as legs, feet, and arms. In most instances, numbness is a temporary symptom and remits without intervention. Consequently, numbness is often considered more of an annoyance than a disabling symptom.
However, in severe cases, numbness can interfere with a person’s ability to function normally. Caution is required for the individual to maintain safety and independence. For example, individuals with MS who have severe facial numbness must be careful when eating or chewing in order to avoid biting their mouth and/or tongue. They must exercise caution with temperature of food and drink to avoid burning their mouth. In addition, those who experience numbness in their arms and legs should be especially careful around fire, hot water, and other sources of heat to avoid being burned.
“Another form of numbness is the loss of position sense, or what we call proprioception,” said Ben Thrower, M.D., medical director of the MS Institute at Shepherd Center. “Normal proprioception is important for maintaining balance and coordination. If a person cannot tell that they are tilting in one direction or the other, they tend to walk like they are a little tipsy. There is also a higher risk of falling. This type of sensory loss is best treated by a physical therapist.”
With dysesthesias, such as burning or other uncomfortable sensations, there may be extreme hypersensitivity to even light touch. Some medications may help with dysesthesias. These include anti-seizure medications, like gabapentin (Neurontin®) and pregabalin (Lyrica®). Some anti-depressants may help with pain as well. These include amitriptyline (Elavil®), venlafaxine (Effexor®) and duloxetine (Cymbalta®).
MS, RLS or Both?
Restless leg syndrome – a neurological condition that causes the irresistible urge to move the legs – affects one in ten adults in the U.S. Interestingly, data suggest that individuals with MS are three times more likely than the general population to experience RLS. Cervical cord damage is a significant predictor for the co-occurrence of these conditions. The urge to move, which is sensory in nature, can be described as a crawling, creeping, tingling, or burning feeling. Moving the affected limb(s) somewhat eases the symptoms of RLS, but only for a short time. Fortunately, medications, such as Requip®, are available to treat RLS. If the symptoms of RLS are severe, a low dose of central nervous system depressants or anticonvulsants may be prescribed. In some instances, nondrug measures can help relieve symptoms.
Weakness
More than half of people with MS experience weakness. There are two fundamental causes of weakness in MS. First, weakness can be caused by spasms and fatigue. This type of weakness presents as loss of strength and control in the extremities. Second, weakness can result from damaged nerves, which prevent signals from reaching the extremities. This type of weakness does not result from diminished muscle strength. It is vital that the source of the weakness be understood in order to properly treat it.
Weakness due to spasms and fatigue generally responds best to exercise designed by a physical therapist. This type of weakness can also be significantly improved by treating the underlying causes of the weakness – the spasticity and fatigue. Antispasm medications, which make muscles less stiff, can decrease weakness. Antifatigue medications may also increase strength.
Prolonged exertion or heat exposure may worsen weakness temporarily. Cooling the body, either with a cold water bottle, air-conditioning or a cooling device, offers relief for many people. A class of drugs called aminopyridines may also offer some benefit. These drugs are not yet FDA-approved but can be prescribed by a physician and prepared by a compounding pharmacist. One of these drugs, Fampridine SR, is currently being tested in clinical trials.
A Word About the Disease-Modifying Drugs
It is important to note that while treatment with the disease-modifying drugs (Avonex®, Betaseron®, Copaxone®, Rebif®, Tysabri® and Novantrone®) does not reduce symptoms that are already present, their use may reduce the likelihood of new symptoms. Although these medications are not a cure for MS, early initiation of treatment may reduce short-term and potential long-term neurological impairment. The consistent use of these medications may lessen many of the symptomatic problems caused by MS.
Managing Sensory Symptoms
While sensory symptoms can be irritating and even debilitating, their affect on daily life can be minimized and the symptoms themselves can be managed to varying degrees. “Discuss your symptoms with your doctor and ask about treatment options,” advises Ben Thrower, M.D. “Besides medication, you may wish to try therapeutic massage, which provides relief for some people. Intermittent applications of heat or cold may provide some relief. Exercise, especially stretching, can help to maintain or improve range of motion. Finally, consider consulting with a physical or occupational therapist to learn compensatory strategies, such as visual cues, to promote safety and prevent injury.”
Ellen Guthrie practices pharmacy at Children’s Healthcare of Atlanta where she is a pediatric pharmacist. She is also a freelance medical writer and peer reviewer with the American Pharmacists Association and the Consortium of MS Centers. She has been a medical advisor to the MSF since 2002.
(Last reviewed 7/2009)