[Essential tremor].

BACKGROUND

Essential tremor is probably the most common movement disorder. Still, the mechanisms underlying this condition are largely unknown. We have reason to believe that essential tremor is under-diagnosed, and that many patients because of this do not receive adequate treatment.

MATERIAL AND METHODS

This review is based on own clinical experience, non-systematic search in the PubMed database, and on the available international consensus documents.

RESULTS AND DISCUSSION

Essential tremor usually presents as action tremor with postural tremor as the most prominent feature. It typically starts in the arms, but may spread and include head tremor in one third of the patients. Tremor in other parts of the body is seen less frequently. Ethanol may relieve the tremor. Essential tremor usually starts in adults and progresses with age. The prevalence is unknown, but is probably in the range 0.4-3.9%. The cause is unknown, but many families seem to have an autosomal dominant inheritance. Three associated loci have been found, but genes have not been identified. Essential tremor is often considered a neurodegenerative disorder, but receptor mechanisms may also be important. Some patients also show other neurological signs like cerebellar ataxia. New findings indicate that there are two neuropathological types of essential tremor, one is associated with cerebellar Purkinje cell pathology and one with brain stem Lewy bodies. Treatment is only symptomatic. Propranolol and primidone are the first choice drugs, but at least 30% of the patients have insufficient symptomatic relief from drug therapy. Neurosurgical treatment with thalamic deep brain stimulation is an effective alternative for the most severely disabled patients.