Intention tremor —generally is greatest during physical movement; there is no shaking when a person is at rest. The tremor develops and becomes more pronounced as the person tries to grasp or reach for something, or move a hand or foot to a precise spot. This is the most common and generally most disabling form of tremor that occurs in people with MS.
Postural tremor —generally is greatest when a limb or the whole body is being supported against gravity. For example, a person who has a postural tremor will shake while sitting or standing, but not while lying down.
Resting tremor —generally is greatest when the body part is at rest and is diminished with movement. More typical of Parkinson's disease than MS.
Nystagmus —produces jumpy eye movements.
Tremor occurs because there are plaques—damaged areas—along the complex nerve pathways that are responsible for coordination of movements. People with MS who have tremors may also have associated symptoms such as difficulty in speaking ( dysarthria ) or difficulty in swallowing ( dysphagia )—activities that are governed by many of the same pathways involved in coordinating movement.
Tremor is One of the Most Difficult MS Symptoms to Treat
Tremor is considered by physicians and other health professionals to be one of the most difficult symptoms to treat. To date, there have been no reports of consistently effective drugs for tremor. Varying degrees of success have been reported with agents such as: the anti-tuberculosis agent, isoniazid (INH); the antihistimines Atarax® and Vistaril® ( hydroxyzine ); the beta-blocker Inderal® (propranolol); the anticonvulsive medication Mysoline® (primidone); a diuretic Diamox® (acetazolamide); and anti-anxiety drugs Buspar® (buspirone) and Klonopin® ( clonazepam ).
Weights and other devices can also be attached to a limb to inhibit or compensate for tremors. An occupational therapist is the health professional who can best advise about assistive devices to aid in the management of tremor.
More recently, deep brain stimulation (using electrodes implanted surgically into various brain areas) has been shown to be effective for the management of tremor in Parkinson's disease. This has also been tried in MS patients (with varying degrees of success) although, at the moment, this therapeutic approach should be regarded as experimental.
Tremor can have significant emotional and social impact, especially when people choose to keep to themselves rather than be embarrassed by tremor. Isolation can lead to depression and further psychological problems. A psychologist, social worker, or counselor may be able to help a person with MS deal with these issues and become more comfortable in public.
Controversy continues over the role of alcohol or tetrahydro-cannabinol (THC), the active ingredient in marijuana, in treating tremor. Only small studies have been done, characterized by conflicting results. Marijuana remains a controlled substance under current policies of the U.S. Drug Enforcement Agency.