Common misdiagnosis of a common neurological disorder : how are we misdiagnosing essential tremor?

Background: As a common neurological disorder, the diagnosis of essential tremor (ET) is considered routine. Despite this, previous work suggests that misdiagnoses may be common. Among other things, these misdiagnoses can lead to treatment errors. Objectives: To estimate how often other tremor disorders are misdiagnosed as ET and to identify factors that increase the odds of misdiagnosing ET and to precisely quantify the extent to which they do so. Design: Seventy-one consecutive patients underwent an evaluation at the Neurological Institute of New York, New York, between January 1, 2000, and December 31, 2005; these patients had a preevaluation diagnosis of ET. The criteria for ET were adapted from the consensus statement of the Movement Disorder Society. Results: Twenty-six patients (37%) were misdiagnosed as having ET ("false ET"). Their true diagnoses were Parkinson disease (11 patients [15%]), dystonia (6 patients [8%]), Parkinson disease with ET (5 patients [7%]), and other disorders (4 patients [6%]). Factors associated with misdiagnosed ET included unilateral arm tremor (odds ratio, 10.5; 95% confidence interval, 1.2-95.4; P=.02), spooning of the hands and other dystonic postures (odds ratio, 16.3; 95% confidence interval, 4.0-66.4; P<.001), and other unusual features (isolated thumb tremor, isolated leg tremor, and nonrhythmic tremor) (odds ratio, 49.4; 95% confidence interval, 2.7-895.0; P<.001). Conclusions: About 1 in 3 patients with tremor was misdiagnosed as having ET, with the most frequent false diagnoses being Parkinson disease and dystonia. Several factors that increased the odds of misdiagnosing ET were identified. These factors could be incorporated into improved diagnostic algorithms