Tremor is a rhythmic oscillation of a body part.
There are 6 main types of tremor:
1 – Physiologic tremor (frequency 10-12 Hz)
This is a common tremor. Almost everyone has experienced this tremor. There is likely a lowered threshold for this type of tremor in certain families. It is seen more prominently when triggered by anxiety, fever, hyperthyroidism, physical exhaustion, low blood sugar. Some medications and some chemicals (e.g. theophylline, caffeine, alcohol withdrawal) will accentuate physiologic tremor.
Often no treatment is necessary other than reassurance once the diagnosis is made. Triggering factors should be removed (eg. reducing caffeine intake, getting adequate sleep and avoid going hungry). If severe enough, medications including B-blockers or anxiolytics, can be prescribed.
2 – Essential tremor (frequency 4-12 Hz)
This is the most common movement disorder. It has been reported to affect 3% of the population. It is an inherited condition and the trait for this tremor can be passed from generation to generation. Fifty percent of children of an affected parent will inherit the tendency to get the tremor (autosomal dominant inheritance). The tremor will usually affect both sides of the body but may be somewhat asymmetric. The tremor severity slowly worsens with age (frequency slows, amplitude increases) with some stable phases occasionally lasting years.
The tremor most often affects the hands, but may affect arms, legs (~30%), voice, jaw and/or head. This tremor typically stops with rest or relaxation of the arms. It is more apparent when the patient holds their arms out straight (posturing) or when they are performing activities (intention) such as holding a cup, drinking soup with a spoon, or writing.
It is worse when triggered by anxiety, fever, hyperthyroidism, physical exhaustion or low blood sugar. Some medications and some chemicals (e.g. theophylline, caffeine, alcohol withdrawal) will also accentuate essential tremor. Click here for treatment information
3 – Basal Ganglia tremor (Parkinsonism) (frequency 4-5 Hz)
This is the type of tremor seen as part of the features of Parkinson’s disease and other illnesses damaging the basal ganglia. The basal ganglia is a group of brain cells (ganglia) deep within the brain. This type of tremor is most evident at rest, and unlike essential tremor tends to improve with posturing or action, then re-emerges after a period of time. Approximately 30% of patients with Parkinson’s disease can have an associated action tremor (6-12 Hz). These tremors start on one side and will usually progress to the other side within 2 years; typically one side is always more affected.
The medications typically used to treat Parkinson’s disease often help to suppress tremor. However, some patients will suffer from medically unresponsive (refractory) tremor. The main medications used include but are not limited to: levodopa, dopamine agonists, amantadine, and anticholinergics.
When this type of tremor occurs as the result of other diseases which affect the basal ganglia (eg. stroke) it is less responsive to medication. Click here for more information about Parkinson’s disease
4 – Cerebellar tremor (frequency 3-4 Hz)
Tremors can result from damage to the cerebellum. This type of tremor is associated with poor coordination or ataxia. The cerebellum is a structure attached to the back of the brain. It is made up of two halves, the hemispheres. The main function of the cerebellum is to coordinate motor activity. When one hemisphere is damaged there is a loss of coordination on the same side of the body.
Tremor can result by damage to the cerebellar outflow pathways; it will be absent at rest, and maximal with activity. Some cerebellar tremors called Holme’s tremor are more obvious with posturing and at rest (“rubral” or red nucleus tremors). Cerebellar tremors due to lesions of the hemispheres of the cerebellum tend to be more irregular, erratic and non rhythmic “tremors” with action.
Cerebellar tremors are very difficult to treat. Weighting the arms by placing something heavy around the wrists can help. Surgical treatment results are not as good in general (by comparison to essential tremor) but can still be considered for cerebellar tremors. Surgery does not help the poor coordination (ataxia) associated with a cerebellar lesion.
Although no medication works well, Topamax (topiramate), isoniazid, clonazepam, Tegretol (carbamazepine), amantadine and buspirone have shown limited benefit in some patients. Click here for more information about Ataxia
5 – Dystonic tremor
Not infrequently dystonic movements can be associated with a rhythmic oscillation. This combination of movements would be called Dystonic tremor. The main treatment approach would be to treat the dystonia. Click here for more information about Dystonia
6 – Functional tremor
The exact way this type of tremor develops is still under investigation. There are cases where stress is clearly a contributor but often no trigger is identified. It can affect any body part and patients with this type of tremor can take years and undergo extensive diagnostic testing without being advised of the cause of their tremor. Techniques employed by skilled clinicians during the exam can result in marked or complete brief resolution of the tremor allowing the diagnosis to become more clearly established, which then allows successful treatment programs to be set up. Click her for more information about Functional Movement Disorders
7 – Other types of tremor
Some tremors persist at rest, with posture, and with action. These tremors are usually associated with medication side effects, hepatic failure (eg. Wilson’s Disease), or are due to Functional Movement Disorders.
Other rare conditions that can mimic tremors are:
- Rhythmic Myoclonus
- Epilepsia Partialis Continua
- Head bobbing with 3rd ventricular cysts
- Orthostatic tremor – is a tremor that only occurs with standing and mainly affects the legs and causes those affected to feel like their legs will give way.
- Unspecified tremor – is a term some specialists use when the features of the tremor do not clearly fit one of the above categories and individuals presenting with this type are usually watched over time until the diagnosis becomes more clearly established.