A resting tremor is a type of tremor that occurs when the affected body part is completely at rest and relaxed. Resting tremors are often the first and most noticeable sign of Parkinson’s disease, although not everyone with a resting tremor has Parkinson’s. Let’s explore what causes resting tremors and what conditions they may point to.
What is a resting tremor?
A resting tremor occurs when a body part shakes involuntarily while at complete rest. The classic example is a resting tremor in the hands. When the hands are resting on the lap, people with a resting tremor may see their fingers or hand shaking back and forth slowly and rhythmically.
The tremor usually disappears with action or movement and is not present during sleep. It tends to affect only one side of the body at first but often spreads to both sides over time. The tremor frequency is typically between 4-6 hertz, which means the affected body part trembles 4-6 times per second.
What causes a resting tremor?
Resting tremors develop when there are abnormalities in certain areas of the brain that control and coordinate movement. They are caused by dysfunctional communication between the cerebellum, basal ganglia, and thalamus.
The most common causes include:
- Parkinson’s disease – This progressive disorder causes dopamine-producing brain cells to die off. Dopamine helps transmit signals between the brain areas that coordinate movement. As dopamine levels decrease, it leads to tremor and other motor symptoms.
- Essential tremor – This is the most common movement disorder and runs in families. It is caused by mutations in genes that produce tremors during action or movement, although resting tremors may also occur.
- Dystonia – This disorder causes involuntary muscle contractions and abnormal postures. A tremor can occur if dystonia affects the muscles when they are at rest.
- Wilson’s disease – An accumulation of copper in the brain can lead to Parkinson’s-like tremors and other neurological symptoms.
- Drug side effects – Some drugs, like valproate for seizures or mood stabilizers, can cause enhanced physiological tremor or resting tremor as a side effect.
- Toxins – Exposure to heavy metals like mercury or manganese can damage the basal ganglia and cause a coarse resting tremor, often accompanied by muscle stiffness.
In some cases, doctors are unable to determine an exact cause for a resting tremor. These are termed isolated resting tremors.
What conditions are associated with resting tremors?
The most common conditions associated with resting tremors include:
Parkinson’s disease
A resting tremor in the hand is often the first visible symptom of Parkinson’s disease. Around 70% of people with Parkinson’s have a resting tremor at the time of diagnosis. Typically, the tremor starts on one side and persists even if the hands or legs are relaxed.
Parkinson’s resting tremors usually:
- Affect the hands, fingers, forearms, feet, lips, chin, jaw or legs
- Have a frequency between 4-6 Hz
- Worsen with stress or emotions
- Disappear with action and movement
- Affect only one side of the body initially
Along with tremors, Parkinson’s disease also causes other motor symptoms like slow movements, rigidity, and balance problems. Resting tremors due to Parkinson’s tend to occur in the early stages, while action tremors develop later as the disease progresses.
Essential tremor
Essential tremor is often confused with Parkinson’s tremor, but has some key differences:
- Usually involves shaking of both sides of the body, unlike Parkinson’s which begins unilaterally
- Worsens with intentional movement and action – unlike Parkinson’s where tremor improves with action
- Tends to affect the hands and arms more during action, although resting tremors may occur
- Generally does not cause other Parkinson’s symptoms like rigidity or slow movements
- May be accompanied by a mild postural tremor of the trunk or legs
Essential tremor is progressive, usually runs in families, and gets worse with age. Activities requiring fine precision like writing may be impaired.
Dystonia
Dystonia involves involuntary muscle contractions that cause twisting, repetitive movements or abnormal postures in the affected body part. If the dystonic contractions occur at rest, it can produce a tremor-like shaking of the affected area.
Common signs of dystonic tremor:
- Usually affects one body region only, like the neck, eyes, mouth, vocal cords, etc.
- Abnormal posture or twisting of the affected body part
- Tremor direction does not oscillate back and forth but often has a twisting or writhing quality
Dystonia has many causes including genetics, brain injury, medications, and neurological disease. Treatment involves medications, botulinum toxin injections, or deep brain stimulation in severe cases.
Cerebellar tremor
Damage to the cerebellum from stroke, tumor, multiple sclerosis or alcoholism can cause an intention tremor during movement. Sometimes cerebellar damage also produces a resting tremor that:
- Usually affects the arms, head, and trunk rather than hands
- Has a lower frequency (3-4 Hz) compared to Parkinson’s tremor
- Is accompanied by other cerebellar symptoms like loss of coordination, balance problems, and abnormal gait
Orthostatic tremor
This very rare tremor occurs when standing upright. The lower legs shake uncontrollably at a frequency of 14-18 Hz, which is much faster than Parkinson’s tremor. It makes standing difficult but disappears when sitting or walking. The exact cause is unknown but may involve abnormal signals from sensory receptors in the legs.
Psychogenic (functional) tremor
This may resemble a resting or action tremor but is caused by psychiatric disorders rather than neurodegenerative disease. Clues that the tremor may be psychogenic include:
- Sudden onset after a stressful event
- Inconsistent tremor direction and severity
- Unusual conditions like shaking intensity increasing when lying down
- Patient is able to temporarily suppress the tremor
Treatment involves therapy and psychiatric medications rather than drugs for movement disorders.
How are resting tremors diagnosed?
Doctors will perform a physical exam to check for tremor characteristics and associated symptoms that may point to an underlying cause:
- Observe tremor location – Resting tremor in hands suggests Parkinson’s disease
- Note which body parts are affected – Lower leg tremor may indicate orthostatic tremor
- Check tremor frequency – High frequency suggests dystonia rather than Parkinson’s
- Look for associated symptoms – Slow movements and rigidity indicate Parkinson’s disease
- Test reflexes – Impaired reflexes occur in Parkinson’s disease
Other tests that help confirm the diagnosis are:
- Blood tests – Check for thyroid abnormalities, liver disease, and signs of Wilson’s disease.
- Brain imaging – MRI and CT scans help rule out structural abnormalities like stroke or tumor.
- DaTscan – SPECT imaging of dopamine transporters can confirm dopamine deficiency typical of Parkinson’s disease.
A neurologist may also administer drugs that amplify or reduce tremors to observe the response and clarify the cause.
How are resting tremors treated?
Treatment focuses first on addressing any underlying condition causing the tremor, such as Parkinson’s disease or dystonia. Other treatment approaches include:
Medications
- Levodopa – The mainstay of Parkinson’s treatment helps replace lost dopamine.
- Dopamine agonists – These mimic dopamine effects and may reduce tremor.
- Beta blockers – Propranolol helps lower adrenaline and reduce tremor amplitude.
- Benzodiazepines – Alprazolam and clonazepam have a calming effect on tremors.
- Topiramate and primidone – Anticonvulsants that may lessen essential tremor severity.
- Botulinum toxin – Injected to reduce dystonic tremor by weakening overactive muscles.
Lifestyle changes
Avoiding stimulants like caffeine and getting regular exercise may help reduce tremor severity in some people. Reducing stress through yoga, meditation, or other relaxation techniques can also help in several types of tremor.
Surgery
Surgical implants like deep brain stimulation (DBS) can reduce tremor from Parkinson’s, essential tremor, and dystonia that are severe and resistant to medications. DBS sends electrical impulses to modulate abnormal nerve signals causing the tremor.
Another surgical option is a thalamotomy, which destroys a tiny part of the thalamus involved in transmitting tremor signals.
Physical therapy
Sometimes weighted wrist braces can dampen hand tremor during rest. Occupational therapy helps identify adaptations and techniques to manage tremor-related disability.
What is the prognosis for someone with a resting tremor?
The prognosis greatly depends on the cause of the resting tremor:
- Parkinson’s disease – Resting tremor is an early symptom that responds well to dopamine medications initially. But the disease progresses over 10-15 years and can cause significant disability.
- Essential tremor – This slowly worsens over time and may severely limit hand function in advanced cases. Lifespan is normal.
- Dystonia – Symptoms are gradual but progressive. Severe cases can affect speech and swallowing.
- Cerebellar tremor – Depends on the underlying cause. Stroke or MS related tremor may improve initially and then plateau.
- Orthostatic tremor – Usually persistent but does not severely impact health or longevity.
- Psychogenic tremor – Typically resolves once the psychiatric disorder is successfully treated.
While bothersome, a resting tremor itself does not impact life expectancy. But focusing on managing the underlying condition is key to maintain quality of life and function.
Key takeaways
- A resting tremor occurs when the affected body part shakes involuntarily while at complete rest.
- Common causes include Parkinson’s disease, essential tremor, dystonia, cerebellar disorders, orthostatic tremor, and side effects from certain medications.
- Parkinson’s disease is the most common condition associated with resting tremor, seen in up to 70% of patients.
- Doctors diagnose resting tremors based on physical exam findings and response to certain drugs. Brain imaging and blood tests help rule out other causes.
- Treatment involves medications, surgery, and lifestyle changes to manage the underlying cause of the tremor.
- Prognosis varies depending on the cause but resting tremor alone does not impact lifespan.