Essential tremor (sometimes called benign essential tremor) is the most common cause of non-physiological tremor. It has no identified pathology, though recent research links some cases to a genetic abnormality or to cerebellar damage.
Course of manifestations
Essential tremor is mild in many cases, and remains this way. However, in other individuals, it is progressive, starting on one side of the body but becoming bilateral over the next few years. In most patients, it first affects the hands, but other parts of the body may also be involved. This includes the head, tongue, vocal cords, upper and lower extremities, and the trunk.
The hand tremor occurs upon doing something (action tremor). The head tremor is usually of the nodding or shaking type. Mild abnormalities of the gait are also often present.
While the frequency of essential tremor often decreases with age, its severity increases. This means that the individual may eventually find it difficult to carry out their routine activities, including eating, shaving, or writing, among others. This naturally creates much emotional turbulence, and embarrassment at one’s increasing need for help, which may result in depression as well.
Head tremors are also likely to create initial miscommunications, as the nodding or shaking of the head may be mistakenly thought to convey agreement or disagreement with the speaker during a conversation.
In addition, the person may be advised to cut down or avoid aspects of lifestyle which may exacerbate the intensity of the tremor. This includes:
- Situations which evoke strong feelings
- Extreme fatigue
This may mean that the person not only develops a disability but feels forced to abstain from many small pleasures, increasing the feeling of loss and deprivation.
When one person in a family suffers from essential tremor, others may also be affected. Half the people who have essential tremor have other family members with the condition, especially parents. The mode of inheritance is dominant in these cases. One of the genes identified so far is the LINGO1 gene, which is not, however, uniformly present in all persons with the condition, and has also been found in people who do not have tremor.
The severity of the tremor varies from case to case, even within the same family, as does the age of onset.
Finally, individuals with essential tremor have an increased risk of developing Parkinson disease, and hearing loss. This is especially true if the tremor first started over the age of 65 years.
In short, the main difficulties to be envisaged for a patient with progressive essential tremor include:
- Social embarrassment which may limit activities outside the home
- Professional incompetence in situations where public performances are required, as in the case of a musician or a speaker
- Difficulty in completing tasks which require a steady hand, such as drawing, typing, writing, eating, shaving, or drinking
- Increased fatigue due to the effort expended to complete daily activities
- Stress and anger at the decreased quality of life
- Mood changes
- Development of other neurological conditions such as Parkinson disease
Reviewed by Afsaneh Khetrapal BSc (Hons)