Essential tremor is a dominant hereditary disorder with incomplete penetration manifested in action, postural tremor with no signs of parkinsonism, cerebellar lesions or other neurological signs [1]. The diagnosis of essential tremor is established on the basis of the clinical picture, and is greatly variable and insufficiently defined [5].
Material and methods: The study concerned patients with the diagnosis of essential tremor established by the International Association for Tremor Studies in 1995 where tremor was classified into definite++, possible and probable [6]. All patients were subjected to a special questionnaire including demographic and clinical characteristics of tremor. Detailed neurological examinations focusing the presence of extrapyramidal signs were carried out. Fischer's Exact test was used for statistical analysis.
Results: The study comprised 107 patients (55 males, 41 females), aged 17-84 years (57.3 +/- 15.6) and 7-77 (46.3 +/- 17.9) at onset of the disease. Postural tremor was present in 36% of patients, postural tremor with intentional deterioration in 16%, statopostural tremor in 21% and continuous tremor in 17% of subjects. Extrapyramidal signs were present in 31% of patients, and clumsiness in fine alternating movements was present in 17 patients. The patients with longer duration of illness were significantly more clumsy in fine alternating movements (Fischer's Exact test; p = 0.507 < 0.05), but not in the presence of extrapyramidal signs (Fischer's Exact test; p = 0.507 > 0.05).
Discussion: Essential tremor is described as a dominant inherited postural tremor. Koller et al. [9] describe dominantly kinetic tremor occurring with movements, while Martinelli et al. [10] describe continuous tremor manifested at rest, posture and with movements. Static tremor was considered as a result of the disease progression [8]. In our patients those with longer duration of the disease were frequently more clumsy in fine alternating movements, but not in manifestation of extrapyramidal signs. Continuous tremor is probably a subgroup of essential tremor; suggests a more pronounced role of cerebellum in its genesis.