Sex and tremor location: Similarities between essential tremor and cervical dystonia

Are patients with limb and head tremor a clinically distinct subtype of essential tremor?

BACKGROUND

Essential tremor (ET) is the most common tremor disorder in adults. In addition to upper limbs, the tremor in ET may also involve head, jaw, voice, tongue, and trunk. Though head tremor (HT) is commonly present in patients with ET, large comparative studies of ET patients with HT (HT+) and without HT (HT-) are few.

METHODS

To determine whether ET with HT is a distinct clinical subtype by comparing ET patients with and without HT, a chart review of 234 consecutive patients with ET attending the neurology clinics of the National Institute of Mental Health and Neurosciences, India, was done. A movement disorder specialist confirmed the diagnosis of ET in all patients using the National Institutes of Health collaborative genetic criteria.

RESULTS

HT was present in 44.4% of the patients. Comparison between HT+ and HT- showed that the HT+ group patients: (1) were older, (2) had later onset of tremor, (3) had unimodal distribution of age at onset with a single peak in the fifth decade, (4) had more frequent voice tremor, and (5) were more likely to have mild cervical dystonia. HT was part of presenting symptoms in nearly two thirds of the ET patients and in the rest it was detected during clinical examination.

CONCLUSIONS

Several demographic and clinical variables suggest that ET patients with HT have a distinct clinical phenotype.

Prevalence of essential tremor in the territory of Lake Trasimeno, Italy: Results of a population-based study

Because of the great variability in previous epidemiological data, and in light of the more accurate definition and diagnostic criteria recently formulated, we designed the present study to evaluate the prevalence of essential tremor (ET) in an Italian population. The study population included 13,604 individuals, who represented all patients of 11 family doctors working in the Territory of Lake Trasimeno in central Italy. Assessment of the sample and selection of the suspected cases were carried out by the same family doctors, previously trained to apply the inclusion and exclusion criteria for the definition of ET based on the Classification Criteria of the Movement Disorder Society (1998) and the Guidelines of the Ad Hoc Committee (2000). The total population was assessed over a period of 12 months. The age-adjusted prevalence of ET was 1.21% (95% confidence interval, 0.83-1.76). The probability of presenting with ET tended to increase with age and males showed a 50% greater risk for developing ET (male/female ratio = 1.5 for each age class). Our results are in line with the most recent epidemiological findings, which suggest a lower prevalence of ET than in older studies. These results can be attributed to the application of more stringent diagnostic criteria.