Common Causes
Among the most prevalent reasons for experiencing tremors are the following:
- Excessive caffeine consumption.
- Low blood sugar levels.
- Muscle weakness.
- Stress and anxiety.
- Advancing age.
- Certain medications such as corticosteroids and amphetamines.
- Alcohol dependence.
- Liver failure.
- Hyperthyroidism.
Medical Causes
The causes leading to tremors that are associated with specific medical conditions can be categorized as follows:
Movement Disorders
- Essential Tremor: This is the most common movement disorder, the exact cause of which remains unknown. However, genetic factors are believed to contribute to nearly half of the cases. This type of tremor typically affects both sides of the body, with more noticeable tremors in one hand.
- Dystonia: A movement disorder caused by the brain sending incorrect nerve signals, which leads to excessive muscle activity and abnormal postures. Young adults are often affected, and it can involve any muscle group.
Neurological Disorders
- Parkinson’s Disease: Over 25% of individuals with Parkinson’s experience tremors during movement (action tremor) as well as at rest (resting tremor) in one or both hands. The tremors typically start on one side of the body and may spread to the other side.
- Stroke: A stroke occurs when a blood vessel in the brain gets blocked by a blood clot, disrupting nerve pathways permanently, which may lead to tremors.
- Multiple Sclerosis: This condition damages areas in the central nervous system pathways that control movement, resulting in tremors.
- Traumatic Brain Injury: Refers to physical damage to the brain that can harm nerves responsible for motor coordination, such as causing hand tremors.
Types of Tremors
Tremors can be classified into two main types, as outlined below:
Action Tremor
The majority of tremor cases are classified as action tremors, which occur during voluntary muscle movement. These can be further divided into several overlapping categories:
- Intention Tremor: This occurs when performing a deliberate movement, such as touching the nose, worsening as the individual approaches the target.
- Kinetic Tremor: This tremor is associated with any voluntary muscle movement, such as opening and closing the eyes or moving the wrists up and down.
- Isometric Tremor: This manifests when a muscle is voluntarily contracted without accompanying movements, such as lifting heavy objects while standing still.
Resting Tremor
This type of tremor occurs while at rest, with no muscle movement, such as when resting the hands on the lap. Individuals diagnosed with Parkinson’s disease are particularly susceptible to this type of tremor, which is often described as a “pill-rolling tremor,” owing to the thumb’s movement resembling rolling small objects or pills within the hand.