Clonus and tremors are both involuntary movements, but they differ in their cause and appearance.
Clonus is a series of rhythmic, involuntary muscle contractions and relaxations that occur in response to a sudden stretch of a muscle. It is often a sign of an upper motor neuron lesion, such as a stroke or spinal cord injury. Clonus is typically seen in the ankles, feet, and wrists.
Tremors, on the other hand, are rhythmic oscillations or shaking of a body part. They can occur at rest, during movement, or when a person is trying to perform a specific task. Tremors can be caused by a variety of factors, including neurological conditions like Parkinson's disease, anxiety, medication side effects, and even caffeine or alcohol withdrawal.
Here's a table summarizing the key differences between clonus and tremors:
| Feature | Clonus | Tremor |
|---|---|---|
| Cause | Upper motor neuron lesion | Neurological conditions, anxiety, medication side effects, etc. |
| Appearance | Rhythmic contractions and relaxations in response to muscle stretch | Rhythmic oscillations or shaking of a body part |
| Location | Ankles, feet, wrists | Can occur anywhere in the body |
| Frequency | Typically faster than tremors | Can be slow or fast |
Examples:
- Clonus: A doctor tests for clonus by quickly flexing the foot upward. If clonus is present, the foot will rhythmically jerk upward and downward.
- Tremor: A person with Parkinson's disease may experience a resting tremor in their hands, causing their fingers to shake even when they are not moving.
