What is Intention Tremor?
An intention tremor, otherwise known as a rubral or cerebellar tremor, is a rhythmic, back-and-forth shaking that gets worse when you’re aiming to reach a specific target, like when moving your hand towards something. This happens due to problems in the part of your brain called the cerebellum. It can even disrupt precise coordination required for talking and moving your arms and legs. The cerebellum and its connections to the rest of the brain help manage motor coordination, posture, and balance. When these connections are disrupted, it triggers kinetic energy – mistakes in movement, especially when precision is involved.
Back in 1868, a man named Jean-Martin Charcot first documented the phenomena of intention tremors. He noticed that patients with multiple sclerosis (or MS), a condition that affects the nervous system, showed different types of tremors compared to those with Parkinson’s disease. MS is now known as the most frequent cause of intention tremor. Charcot observed that MS patients not only had intention tremors but also had nystagmus – rapid involuntary eye movement, and ‘scanning speech’ – a speaking disorder. These three symptoms are collectively known as the Charcot’s triad.
What Causes Intention Tremor?
Intention tremors, which are shakiness in your body when you try to do something on purpose, can come from different causes:
* Emotional or physical state: This includes things like stress, fear, anger, or just feeling tired.
* Medication side effects: Certain drugs used for seizures like phenytoin and carbamazepine may cause these tremors.
* Blood flow issues: For instance, a cerebellar infarct, which happens when blood supply to the part of the brain that controls balance and coordination (cerebellum), is blocked.
* Injuries: Especially injuries that affect many parts of the brain, known as diffuse axonal injury.
* Autoimmune condition: Multiple sclerosis, a condition where the body’s immune system attacks the protective covering of nerves, can cause intention tremor.
* Metabolic problems: An example is hepatocerebral degeneration, which is a disorder that affects the brain and liver.
* Substances: Overuse or dependence on certain substances like alcohol, sleeping pills (barbiturates), or exposure to mercury can lead to tremors.
* Genetic disorders: An example is Wilson disease, a rare genetic disorder that causes copper to build up in the body.
Risk Factors and Frequency for Intention Tremor
Understanding the spread of intention tremors can be difficult as they show up in various diseases at different rates. They can appear in certain parts of the body at varying instances – 9% in the head, 50% in the arms, and 27% in the legs. Interestingly, about 38.5% of patients with essential tremor also experience intention tremor. This situation is often linked to having the essential tremor for a long time and a younger age when the tremor first began. Amongst people with essential tremor, the prevalence of intention tremor can be as high as 44%. However, with Parkinson’s disease (PD), intention tremor is quite rare, being present in just 4% of the cases.
- Intention tremors manifest in various diseases at different rates.
- They appear 9% in the head, 50% in the arms, and 27% in the legs.
- About 38.5% of patients with essential tremor also have an intention tremor.
- The co-occurrence of essential and intention tremor often indicates longer duration of the condition and a younger age at onset.
- In patients with essential tremor, up to 44% can also show signs of intention tremor.
- Intention tremors are very rare in Parkinson’s disease cases, appearing in just about 4% of patients.
Signs and Symptoms of Intention Tremor
People with intention tremors may have trouble managing day-to-day activities. This could involve difficulty in actions like drinking from a cup, holding eating utensils, focusing their sight on an object, or walking. They may also encounter other related issues, such as involuntary eye movement, miscalculation of distance during voluntary movement, inability to perform rapid, alternating movements, muscle weakness, loss of sense of body-awareness, and unsteady movements.
During a physical exam:
- Tests like touching the nose with a finger or moving the heel up and down along the shin can help identify tremors that worsen as the patient’s hand or leg reaches the target, particularly when these tests are done quickly.
- Monitor fine movements of fingers for coordination and speed during tasks such as tapping fingers or feet, buttoning/unbuttoning a shirt, or grabbing objects like a cup or pencil. The tremor often amplifies when their hand is close to the target.
- An observation is also that the tremor’s wavering intensity might reduce when a person closes their eyes.
- Rapid shifting between movements may be used to spot the inability to make rapid, alternating movements.
- The person may also show impaired sense of positioning of the big toes. Walking tests might show a wide-based, unsteady walk, troubles with walking in a straight line (tandem gait), and a positive Romberg’s sign (loss of balance when eyes are closed).
- Their eye movements might be slow, and they may experience involuntary eye movements.
Depending on the cause of the tremors, patients may exhibit overactive reflexes and a positive Babinski reflex (extension of the big toe upon stimulating the sole of the foot).
Testing for Intention Tremor
An MRI, or magnetic resonance imaging, is often used as the go-to method to examine the brain and cerebellum to identify causes of certain diseases. This tool helps in getting detailed images of the organs and tissues.
Let’s look at some specific causes and how they are evaluated:
1. Physiological/psychiatric: If the cause is believed to be physiological or psychiatric, your doctor will examine your medical history and current health condition. They might check your metabolic function with a complete metabolic panel (CMP), which includes various blood tests. It’s important to discuss mental health history, regular coping mechanisms, and any stressful situations you’re experiencing.
2. Iatrogenic: This term refers to health issues triggered by medical treatments or advice. Your doctor will look closely at your medications and when you started or stopped them, to see if these could have initiated the tremor.
3. Vascular: If the concern is about possible damage due to problems with blood flow (also called vascular issues), your doctor will examine your health history along with physical check-ups and assess risk factors related to blood vessels. You might undergo various tests including A1C, lipid panel, blood pressure monitoring, and imaging of the brain and its associated blood vessels. This could include CT scans, MRI, or 2D Echocardiogram with bubble study, which uses sound waves to picture the heart, and Holter monitoring, which tracks your heart’s activity.
4. Trauma: For trauma-induced health issues, your doctor will opt for a thorough blood count, coagulation (clotting) tests, and imaging studies to check for any damage or injuries. These could be CT scans, MRI, or electromyography, which is a diagnostic procedure for assessing the health of muscles and the nerve cells that control them.
5. Neuroinflammatory, autoimmune or paraneoplastic: If your condition might have been triggered by inflammation, autoimmune responses, or cancer-related actions in your body, you will need a series of tests. These involve blood counts, metabolic panels, and various specialized tests to check for inflammatory markers and possible cancer indicators. You might also need imaging of your head, spine, and other body parts. In some cases, you might also need a lumbar puncture, often known as a spinal tap, to collect fluid from the spine for laboratory examination.
6. Metabolic: If your condition is suspected as metabolic, tests like complete blood counts, metabolic panels, checking for vitamin deficiencies, ammonia levels, and imaging of abdomen or pelvis might be needed. You may also get an ultrasound scan of your liver.
7. Toxic: If toxins are suspected as a cause, urine toxicology tests, ethanol level tests, and heavy metal tests might be done.
8. Hereditary: If your condition might be a result of heredity, complete blood count, metabolic panels, inflammatory markers, and tests specific to genetic disorders will be executed. You can also expect imaging tests like CT and MRI, genetic testing, or an eye examination to determine the level of copper in your body.
Your doctor will guide you through the appropriate method based on your specific situation. It’s essential to openly communicate your symptoms and any potential causes to receive the best treatment.
Treatment Options for Intention Tremor
The primary course of action for treating intention tremor, a type of shaky movement that happens when you try to do something on purpose, is to handle the medical condition that’s causing it.
Noninvasive techniques, or treatments that do not require going under the skin or into the body, can be helpful. These might include exercises to improve walking (gait rehabilitation), methods guided by sight (visually guided techniques), shaking the muscles in a precise way (tendon vibration), adding weight to the limbs (weighting extremities), methods for placing and moving the body (positioning techniques), and hands-on approaches (manual techniques). All these methods can contribute to helping you get back to your routine activities.
There’s no one-size-fits-all drug treatment for intention tremor. Even though isoniazid is frequently used for patients with multiple sclerosis (MS), a disorder of the nervous system, it works only for about half of them. Other drugs like botulinum toxin A (commonly used in botox), levetiracetam (an anticonvulsant), 4-aminopyridine (used for walking in MS), and cannabis have also been tried.
Lastly, more aggressive or invasive techniques are also options. Thalamic deep brain stimulation is one such procedure that can lessen the tremor in MS patients, leading to better function. This involves implanting a small device in the brain which sends out electrical impulses. Stereotactic radiosurgery thalamotomy is another technique that has shown good results. It involves pinpointing and damaging a small part of the brain called the nucleus ventralis intermedius with radiation. While it has been beneficial, radiofrequency thalamotomy, a procedure using heat to destroy a part of the thalamus in the brain, has largely been replaced by radiosurgery and deep brain stimulation due to their lower side effects.
What else can Intention Tremor be?
When a patient has an intention tremor (a shaking that gets worse when you try to do something with your hand), it could be due to a medical condition called ‘essential tremor’. In fact, up to 38.5% of people with essential tremor also experience intention tremor.
Different causes of this tremor require different treatments. The most common cause is the use of certain drugs (also called “iatrogenic” causes). However, in order to tell whether the tremor is caused by other factors such as metabolism issues, infections of the brain, inflammation of brain tissues, or cancer-related causes, doctors may use a variety of tests. These can include blood tests, brain scans, or tests on the cerebrospinal fluid (the fluid around your brain and spinal cord).
What to expect with Intention Tremor
The outlook for intention tremor, a type of trembling that commonly happens when you’re moving purposefully, greatly depends on what’s causing it. However, with proper rehabilitation, non-drug treatments, and medication, the condition should gradually get better. However, keep in mind that permanent damage to parts of the brain called cerebellar structures and tracts, which help control our movements, may lead to unchangeable imbalances in movement (dysmetria) and intention tremors.
Possible Complications When Diagnosed with Intention Tremor
If the root cause is not dealt with, intention tremors can interfere with a person’s day-to-day activities, causing great frustration. However, it’s reassuring to know there are no life-threatening complications related to intention tremors.
Affected day-to-day activities:
- Basic self-care tasks
- Professional tasks
- Social interactions
Preventing Intention Tremor
If patients suddenly and intensely experience symptoms, they should immediately go to the emergency room. This swift action is crucial to quickly rule out life-threatening conditions like ischemic stroke, which is a blockage in the blood supply to the brain, and malignancy, or cancer. If symptoms appear slowly or come and go, patients should see their family doctor. The doctor can then refer them to a neurologist, a doctor who specializes in disorders of the nervous system, for further assessment and possible treatment.
