Clinical characteristics of essential tremor in Mersin, Turkey--a population-based door-to-door study.

Objective: To describe the clinical features of essential tremor (ET) in a population.

Background: With few exceptions, clinical data on ET are derived from patients who attend specialty clinics. Most (> 90%) population-dwelling ET cases do not seek neurological attention.

Methods: 89 ET cases living in the Mersin province, Turkey were matched to 89 controls from the same population. All were examined by neurologists. Standardized scales included the Hamilton Depression Scale (HDS) and Hamilton Anxiety Scale (HAS).

Results: Eight-one (91%) of 89 cases previously had not been diagnosed as ET and 96.6% were untreated. Despite this,more than half (51.7%) of the cases answered "yes" to the question "are you disabled in some way by your tremor". Cases had more psychiatric symptomatology than controls (mean HDS scores = 11.4 +/- 8.2 vs. 7.9 +/- 6.1, p = 0.003 and mean HAS scores = 12.0 +/- 8.8 vs. 6.9 +/- 7.1, p < 0.001). Among ET cases, HDS scores (r = 0.24, p = 0.03) and HAS scores (r = 0.27, p = 0.01) were correlated with tremor severity.

Conclusions: We present the clinical findings of a group of largely undiagnosed and untreated population-dwelling ET cases that would not otherwise have come to neurological attention. Approximately one-half reported functional difficulty and psychiatric symptoms were over-represented in these ET cases compared with matched controls. These findings suggest that ET, as it exists in the population, is not a completely benign entity.