Head tremor in essential tremor: “Yes–yes”, “no–no”, or “round and round”?

• Head tremor is present in 1/3 of cases of ET remains under-studied.
• A mixed direction is more common than horizontal or vertical head tremor in ET.
• Head tremor direction correlates with duration, severity, and continuity of tremor.

IntroductionEssential tremor (ET) is a common yet frequently misdiagnosed movement disorder. One contributing factor may be the dearth of studies that focus on the nuances of clinical phenomenology. A clinical feature that has received relatively little attention is head tremor. Indeed, there is no consensus regarding the predominant direction of head tremor in ET, and no study has examined the clinical correlates of directionality.MethodsWe identified 51 ET cases with head tremor enrolled in a clinical-epidemiological study of ET at Columbia University. Each had a videotaped neurological examination. Videotapes were viewed and coded by a movement disorders neurologist for head tremor direction (“no–no”, “yes–yes”, or mixed) and continuity (continuous, intermittent, or rare). Direction was correlated with a wide range of clinical features.ResultsFourteen cases (27.5%) had “no–no” tremor, 9 (17.6%) had “yes–yes” tremor, and 28 (54.9%) had a mixed tremor. Mixed and “yes–yes” cases were older (p = 0.004) and had a longer tremor duration (p = 0.018) than “no–no” cases. Tremor severity (arms) was higher for mixed cases than for “yes–yes” and “no–no” cases (p = 0.04). More mixed cases had continuously present tremor while more “no–no” cases had rare head tremor (p < 0.001).ConclusionsHead tremor in ET seems to start as an infrequent tremor in one direction (esp. “no–no”) and becomes more frequent while acquiring additional directionality and a mixed phenotype as the disease progresses. These findings add to our understanding of the clinical spectrum of ET.