Abstract
Background: An estimated 30–50% of essential tremor (ET) diagnoses are incorrect, and the true diagnosis in those patients is often Parkinson’s disease (PD) or other tremor disorders. There are general statements about the tremor in these ET and PD, but published data on the more subtle characteristics of tremor are surprisingly limited. Postural tremor may occur in both disorders, adding to the difficulty. There are several anecdotal impressions regarding specific features of postural tremor in ET vs. PD, including joint distribution (e.g., phalanges, metacarpal-phalangeal joints, wrist), tremor directionality (e.g., flexion-extension vs. pronation-supination), and presence of intention tremor. However, there is little data to support these impressions.Methods: In this cross-sectional study, 100 patients (ET, 50 PD) underwent detailed videotaped neurological examinations. Arm tremor was rated by a movement disorder neurologist who assessed severity and directionality across multiple joints.Results: During sustained arm extension, ET patients exhibited more wrist than metacarpal-phalangeal and phalangeal joint tremor than did PD patients (p < 0.001), and more wrist flexion-extension tremor than wrist pronation-supination tremor (p < 0.001). During the finger-nose-finger maneuver, intention tremor was present in approximately one in four (28%) ET patients vs. virtually none (4%) of the Parkinson’s patients (p < 0.001).Conclusions: We evaluated the location, severity, and directionality of postural tremor in ET and PD, and the presence of intention tremor, observing several clinical differences. We hope that detailed phenomenological data on tremor in ET and PD will help practicing physicians delineate the two diseases.
Highlights
The phenomenology of tremor is complex and the diagnosis of the variety of tremor disorders can be difficult
During the finger-nose-finger maneuver, intention tremor was present in approximately one in four (28%) essential tremor (ET) patients vs. virtually none (4%) of the Parkinson’s patients (p < 0.001)
We hope that detailed phenomenological data on tremor in ET and Parkinson’s disease (PD) will help practicing physicians delineate the two diseases
Summary
The phenomenology of tremor is complex and the diagnosis of the variety of tremor disorders can be difficult. Even in the case of essential tremor (ET), often considered a clinically bland disorder, the diagnosis can be surprisingly challenging. As many as 30–50% of ET diagnoses are incorrect, with the true diagnosis in those cases often being Parkinson’s disease (PD), dystonia, and other tremor disorders (Schrag et al, 2000; Jain et al, 2006). Published data on the more clinically subtle characteristics of tremor in ET and PD are surprisingly limited. An estimated 30–50% of essential tremor (ET) diagnoses are incorrect, and the true diagnosis in those patients is often Parkinson’s disease (PD) or other tremor disorders. There are general statements about the tremor in these ET and PD, but published data on the more subtle characteristics of tremor are surprisingly limited.
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