Multiple Sclerosis (MS) is a chronic disease that affects the central nervous system, disrupting the flow of information between the brain and body. Tremor, an involuntary, rhythmic shaking, is a common symptom of MS, affecting an estimated 25% to 60% of people with the condition. The duration of MS tremors is highly variable and depends on individual circumstances and the type of tremor experienced. Tremors can range from a minor inconvenience to a severe, sustained symptom that significantly impacts daily life.
The Different Kinds of MS Tremors
MS tremors are generally classified based on when they occur, with the two most prevalent forms being action tremors: intention and postural types. Intention tremor is the most common and often the most disabling form of MS tremor, occurring only during voluntary, purposeful movement. This shaking develops and becomes more pronounced as an individual attempts to reach for an object, often worsening as the target is approached.
Postural tremor presents when a person is actively maintaining a position against gravity, such as holding the arms outstretched or sitting upright. This type of tremor ceases when the body part is fully supported or at rest. The physical disruption of these action tremors stems from damage to the cerebellum and its connecting pathways, the regions of the brain responsible for coordinating smooth movement.
A third type, resting tremor, is characterized by shaking that is greatest when the affected body part is completely supported and at rest, diminishing with voluntary movement. While this tremor is more commonly associated with conditions like Parkinson’s disease, a small percentage of individuals with MS may also experience it. The location of the demyelinating lesions in the brain determines the specific type of tremor a person experiences.
Why Tremor Duration Varies
The duration of MS tremors is rarely constant, often presenting as episodic events influenced by internal and external factors. The location and severity of the MS lesion, particularly in the cerebellar pathways, dictates the potential for tremor, but triggers determine its persistence. For example, a tremor may be absent for a period, only to become noticeable and sustained for minutes or hours following a specific activity or physiological change.
Fatigue is an internal factor that consistently increases the frequency and severity of tremors. As the body’s energy reserves deplete, the stability and control provided by the motor system decrease, allowing the tremor to emerge or intensify. Emotional stress and anxiety can also activate the nervous system, leading to a temporary increase in tremor amplitude and duration.
External triggers, particularly body temperature, play a role in tremor variability. Heat sensitivity can cause neurological symptoms, including tremor, to worsen, potentially sustaining the shaking until the body is cooled. The episodic nature means a tremor might only last for the duration of a stressful meeting or an overheated environment, but in severe cases related to advanced disease progression, the tremor may become almost continuous.
Management Approaches to Minimize Tremor Persistence
Managing MS tremors involves reducing the frequency and severity of episodes. Lifestyle adjustments focus on mitigating known triggers, starting with fatigue management through activity pacing and scheduled rest periods. Regulating body temperature, such as using cooling vests or avoiding intense heat, can prevent the physiological worsening of tremors.
Physical and occupational therapy offer practical, non-pharmacological strategies to improve control and function. Therapists may recommend adaptive equipment, such as weighted utensils or wrist braces, which add inertia to the limb to dampen involuntary movement. Task-oriented training and exercises to improve core stability can help the body compensate for the coordination deficit.
Pharmacological options are available, though no single medication is specifically designed for MS tremor, and effectiveness varies widely. Medications initially used for other conditions, such as beta-blockers or anti-seizure drugs, may be prescribed to reduce tremor severity. These treatments aim to calm the overactive nerve signals that contribute to the rhythmic shaking.
For the most severe, debilitating cases that do not respond to other treatments, surgical options like deep brain stimulation (DBS) may be considered. DBS involves implanting electrodes in the brain to deliver targeted electrical impulses, which can reduce tremor amplitude by disrupting the abnormal signals. While this is a major intervention, it represents an option for long-term tremor reduction when other approaches have failed to provide functional relief.