Intention Tremor
Intention tremor happens when the body starts to shake during a purposeful action, like reaching for a glass or touching a button. Damage or dysfunction in the cerebellum, the part of the brain that controls coordination and balance, often causes this tremor. This type of tremor is different from shaking that occurs at rest, because it only appears or worsens when someone tries to move with precision.
Several health conditions can cause intention tremor, including multiple sclerosis, stroke, or brain injury. Other factors such as alcohol use disorder, infections, or vitamin deficiencies may also play a role. Even stress and fatigue can make the shaking more noticeable, showing that not all causes are tied to permanent disease.
Definition of Symptom
An intention tremor is a type of shaking that appears during purposeful movement, such as reaching for an object. The tremor becomes more noticeable as the hand or limb approaches the target.
This symptom is a form of kinetic tremor, which means shaking that occurs while a body part is in motion. Because intention tremor happens during directed movement, it also falls under the broader category of action tremors.
Unlike a rest tremor, which occurs when muscles are relaxed and not moving, intention tremor only appears with activity. It also differs from a postural tremor, which develops when holding a position against gravity, such as extending the arms.
Key Features of Intention Tremor
- Appears during voluntary, goal-directed movement.
- Worsens as the target is approached.
- Often broad and coarse in motion.
- Commonly affects arms, legs, and sometimes speech muscles.
The tremor usually has a slower rhythm compared to other tremor types. This slower, back-and-forth movement can interfere with tasks that require precision, such as writing, buttoning clothes, or carrying a drink.
| Tremor Type | When It Occurs | Example Situation |
|---|---|---|
| Intention | During purposeful movement. | Reaching for a glass. |
| Kinetic | With any voluntary movement. | Moving an arm in any direction. |
| Rest | When muscles are relaxed. | Hand shaking while sitting still. |
| Postural | When holding a position. | Arms extended in front. |
Possible Causes/Diseases Condition
Intention tremor, also called cerebellar tremor, often develops from problems in the cerebellum or its pathways. These brain regions control coordination, so damage here can lead to shaking during purposeful movement. Neurological conditions commonly cause intention tremor:
- Multiple Sclerosis (MS): MS can damage nerve pathways in the cerebellum and cause tremors.
- Stroke: A stroke that affects the cerebellum may result in lasting tremor symptoms.
- Brain Injury or tumors: Trauma or growths in this area can disrupt normal movement control.
Some genetic and metabolic disorders also play a role. Wilson disease, which causes copper buildup in the body, may damage the brain and lead to tremor. Other diseases and conditions sometimes linked to intention tremor include:
- Parkinson disease (though its tremors are usually at rest, intention tremor can appear in some cases).
- Infections such as West Nile virus or rubella.
- Vitamin deficiencies that affect nerve and brain function.
Medications and toxins can also trigger tremor. For example, the antibiotic isoniazid, used to treat tuberculosis, can cause tremor in some people. Exposure to heavy metals like mercury may also contribute.
| Cause Type | Examples | Notes |
|---|---|---|
| Neurological | MS, stroke, cerebellar tumors | Damage to cerebellum pathways |
| Genetic/Metabolic | Wilson disease | Copper buildup affects brain tissue |
| Other Diseases | Parkinson disease, infections | May vary in severity and frequency |
| Medications/Toxins | Isoniazid, mercury | Side effect or toxic exposure |
Other Non-Disease Causes
Not all intention tremors come from chronic diseases. In some cases, outside factors or temporary conditions can trigger similar shaking during purposeful movement.
- Radiation exposure can affect brain tissue and pathways linked to movement control. People who have undergone radiation treatment for tumors near the brain may develop tremors later on.
- A psychogenic tremor is another non-disease cause. This type often appears during stress or emotional strain and may lessen when the person is distracted. Unlike neurological tremors, psychogenic tremors can vary in speed and pattern.
Doctors may use tests such as the heel-to-shin test to check coordination and rule out disease-based causes. Imaging studies like magnetic resonance imaging (MRI) can help confirm whether the tremor stems from structural brain changes or from non-disease factors.
Other tests, such as an echocardiogram, can help rule out circulation or heart-related issues that might indirectly affect brain function. These tests help separate functional or temporary tremors from those linked to long-term conditions.
Examples of Non-Disease Related Factors
- Stress or anxiety episodes.
- Fatigue or lack of sleep.
- Side effects of certain medications.
- Past exposure to radiation.
- Psychogenic tremor linked to emotional causes.
How It Causes the Symptom
Intention tremor occurs when the cerebellum or its pathways are damaged. The cerebellum helps coordinate smooth, accurate movements. When it cannot process signals correctly, voluntary movement becomes shaky and less controlled.
When reaching for an object or performing a task, tremors often worsen as the hand approaches the target. The brain struggles to fine-tune the movement. Key factors that contribute to the symptom include:
- Dysfunction in the cerebellum impairs coordination.
- Diminished awareness of limb positioning.
- Disrupted feedback between the brain and muscles.
These problems make it harder for the body to adjust muscle activity during motion. Without accurate feedback, the nervous system overshoots or corrects too strongly, leading to rhythmic shaking.
At times, intention tremor can also impact one’s ability to walk effectively. This may appear as an unsteady gait, where steps become less stable and balance is reduced. The same coordination issues that affect the arms can also disturb leg movement.
The tremor can also involve speech muscles, creating a shaky or uneven voice. Each of these symptoms shows the cerebellum’s central role in controlling voluntary movement and keeping actions coordinated.
Possible Complications
Intention tremor can disrupt daily tasks such as eating, writing, or dressing. The shaking often worsens during precise movements, which may lead to frustration and reduced independence.
Mobility can also be affected. Some people develop an unsteady gait, making walking less stable and increasing the risk of falls. Speech may become difficult when tremors affect muscles used for talking. Fine motor skills, like buttoning clothes or using utensils, may decline over time.
When to Seek Medical Attention
Contact a doctor if tremors start suddenly or get worse quickly. Sudden changes may point to a new or serious problem in the brain or nervous system. Get medical help if tremors make it hard to do daily tasks like eating, writing, or walking safely. Seek help if tremors happen with other symptoms such as:
- Difficulty speaking or swallowing.
- Loss of balance or coordination.
- Numbness, weakness, or vision changes.
See a doctor if tremors show up after a head injury, stroke, or starting a new medication. These situations may need urgent testing and treatment. If tremors affect your quality of life, even without other symptoms, getting medical advice can still help. Treatment may include physical therapy, medication, or managing another health issue.
