Tremor causes, symptoms and treatment options

A tremor is a rhythmic and uncontrollable shaking of all or part of the body due to a partial muscle contraction.

Tremors trigger involuntary repetitive movements, usually when performing an action and commonly in the arms or legs. They are considered to be serious if their debilitating effects have a significant impact, with ordinary tasks such as holding a pen becoming frustratingly difficult. Tremors can seriously affect work, social participation, mental health and many activities of daily living.

Types of tremor

Tremors can be divided into two types, resting and action.

A resting tremor occurs when a body part is fully relaxed, often seen with Parkinson’s.

An action tremor occurs when muscles are contracted voluntarily, and has a number of sub-types:

• Postural tremor occurs when holding a position against gravity, for example with outstretched arms.
• Kinetic tremor is associated with deliberate movement, such as using a knife and fork.
• Intention tremor is a tremor which worsens as a body part approaches a target, such as reaching to pick up a book.
• Isometric tremor is when a voluntary muscle contraction happens with a rigid object – like gripping a heavy weight.
• Task-specific tremor is rare and occurs during skilled, repetitive activities such as playing an instrument, taking part in a sport, writing or even speaking. 

What causes a tremor?

There are numerous tremor causes. These include non-neurological ones such as fear, stress or anxiety, an overload of caffeine, reaction to medication, vitamin B12 deficiency, low blood sugar and thyroid problems.

However, there is a difference between this type and a neurological tremor like essential tremor (ET), which is the world’s most prevalent movement disorder, or a tremor which comes on due to Parkinson’s disease.

Main types of neurological tremor, their causes and symptoms

Essential tremor is the most common and is usually an action tremor. It’s bilateral and usually presents in the hands, head and voice. It’s caused by genetic factors (roughly 50% of cases are inherited) and abnormal brain activity.

Parkinsonian tremor is a resting tremor, unilateral, and tending to affect hands, limbs and jaws. Parkinson’s damages the nerve cells in the brain which make dopamine, and this subsequent reduction in dopamine causes the symptoms, including tremor. However, exactly how these tremors develop is still not fully understood. Between 70% and 90% of people with Parkinson’s experience a tremor.

Cerebellar Tremor isa slow shaking of limbs getting worse as a sufferer finishes a movement. The primary tremor cause is damage to the cerebellum from a stroke, a neurodegenerative disease like MS, a tumour, traumatic brain injury or hereditary degenerative disease like Friedreich’s Ataxia.

Dystonic Tremor occurs in conjunction with dystonia and is characterised by jerky movements. The tremor cause is often abnormal signalling in the basal ganglia of the brain, and tends to be associated with underlying neurological issues, brain injuries or genetic factors.

Diagnosing the type of tremor

A neurologist will examine the patient’s medical and family history and take blood and urine tests. A physical examination establishes whether the tremor is resting or action, and tests such as handwriting analysis help clinicians assess tremor severity.

A neurological exam will look at tremor location, frequency and amplitude. An electromyogram measures involuntary muscle movement and the response of muscles to nerve stimulation. Imaging such as a CT scan, MRI scan or SPECT (Single-Photon Emission Computed Tomography) helps rule out secondary causes.

Treatment options

Medication

Medication is usually the first option, with beta-blockers like propranolol, anti-seizure meds like primidone, and levodopa or anticholinergics for Parkinsonian tremor. Botox can be utilised for head and voice tremors.

Medication is not always successful, and up to half of all patients come off it because of side effects such as fatigue, light headedness or nausea.

Surgical options

Radiofrequency ablation (RFA)

A surgical procedure which uses heat from radio waves to treat lesions in the brain causing ET or tremor-dominant Parkinson’s. It can be very effective but has possible side effects such as balance and coordination issues.

Deep brain stimulation (DBS)

DBS is used to treat several neurological conditions, most commonly Parkinson’s. It is also highly effective for ET and an established treatment for dystonia.

Electrodes are implanted into specific brain regions responsible for movement control, connected to a small battery which is placed under the skin in the chest. The system delivers electrical stimulation to regulate abnormal brain signals.

A key advantage is its adjustability. Doctors can fine-tune the stimulation settings over time to match changes in symptoms or disease progression.

MRgFUS (MR-Guided Focused Ultrasound)

MRgFUS is a safe, non-invasive, incisionless procedure which uses high-intensity focused ultrasound waves to create a precise lesion in a targeted area of the brain. MRI imaging is used throughout the procedure to ensure accuracy. Many patients experience noticeable symptom relief straight away.

MRgFUS takes about three to four hours, and patients remain awake so the team can monitor response to treatment in real time and make immediate adjustments.

During MRgFUS, the patient will be moved into and out of the MRI machine and asked to do simple neurological tasks to help assess improvement. This step-by-step approach, individually tailored to each patient’s particular requirements and responses, is what gives MRgFUS its precision and safety.

MRgFUS is primarily used to treat ET and is also an option for tremor-dominant Parkinson’s, offering significant improvement when symptoms are unilateral.

Further precision – FAT1 imaging

The part of the brain which is targeted during MRgFUS is the Ventral Intermediate Nucleus (Vim). FAT1 imaging is a new type of brain scan which combines two separate types of MRI to create a much clearer picture of the Vim. It allows doctors to target the area they need to treat based on each patient’s specific brain anatomy.

Where can I find a treatment centre for a tremor?

It’s important to make contact with a neurologist who specialises in movement disorders to look into tremor causes. Queen Square Imaging Centre’s exceptional team of neurosurgeons are renowned globally for their highly effective and outstanding care. To learn more or discuss your options for essential tremor, contact us – we’re here to guide you every step of the way.