Incidence Rates of Cranial Tremors in Essential Tremor: A Prospective, Longitudinal Study

Abstract

Background: Cranial (head, jaw) tremors develop in a sizable number of essential tremor (ET) patients. They are particularly important because they are a significant source of embarrassment and are especially resistant to treatment. There are no data on the rate at which ET patients develop these cranial tremors. Our aim was to estimate the incidence rate of head and jaw tremors in ET. Methods: Cases, enrolled in a prospective, longitudinal study, were evaluated at baseline and one follow-up visit. The in-person evaluation included questionnaires and a videotaped neurological examination, which was reviewed by a senior movement disorder neurologist for the presence/absence of head and jaw tremors. The mean time between baseline and follow-up assessments was 6.3 ± 2.4 (median = 6.0; range = 1.5-12.4 years). Results: Five (6.3%) of 79 cases developed head tremor by follow-up (incidence rate = 1,012 per 100,000 person years; 95% confidence interval [CI] = 0-3,219). Twelve (10.6%) of 113 cases developed jaw tremor by follow-up (incidence rate = 1,692 per 100,000 person years; 95% CI = 0-1,692). Conclusion: These epidemiological data were designed to assist physicians in counseling ET patients when they ask about their risks of developing cranial tremors.

Essential tremor: diagnosis and management

“…An estimated 1-2% of patients per year with essential tremor develop head or jaw tremor. The incidence rate for either tremor is 10-20% in a 10 year period 33. The presence of jaw tremor increases with disease severity, with a reported prevalence of 7.5% (95% confidence interval 3.9% to 14.2%) in a population study, 10.1% (6.8% to 14.7%) in a tertiary care center, and 18% (12.3% to 25.5%) in a brain bank of deceased patients with severe essential tremor (P=0.03) 34.…”

Longitudinal study of clinical and neurophysiological features in essential tremor

“…To date, only a few clinical longitudinal studies have characterized the progression of motor features in ET. Some studies estimated an annual tremor severity worsening of between 3.1% and 12% [ 8 , 9 ], with tremor spread to cranial structures [ 10 , 11 ]. Increased tremor severity over time may also depend on the higher prevalence of rest tremor observed in advanced disease stages [ 12 ].…”

Non‐motor symptoms are associated with midline tremor in essential tremor

“…Partly, tremor distribution differences contribute to the heterogeneity in ET syndrome. On the one hand, factors, such as female gender, late onset of tremor, advanced age, longer tremor duration, and more severe arm tremor, are significantly correlated with MT 4–11 . Therefore, the difference between an ET patient with, and without MT can mainly be explained by the progression of the disease.…”