PubMed · 11030809
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E D Louis. 2000. Essential tremor.. https://doi.org/10.1001/archneur.57.10.1522
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UNLABELLED: Teaching videotapes, developed to aid in the evaluation of several movement disorders, have not been used in essential tremor research. As part of the Washington Heights-Inwood Genetic Study of Essential Tremor (WHIGET), we developed a reliable and valid tremor rating scale. Because this rating scale is currently being used by investigators at other centers, we developed a teaching videotape to aid in the consistent application of this scale. OBJECTIVE: To develop a teaching videotape for a revised version of the WHIGET Tremor Rating Scale and to assess the interrater agreement among raters who used this videotape to rate tremor. METHODS: The revised WHIGET Tremor Rating Scale was used to rate action tremor from 0 to 4 during six tests: arm extension, pouring, drinking, using a spoon, finger-to-nose, and drawing spirals. A 22-minute teaching videotape was developed that includes a 29-item educational section and a self-assessment section consisting of 20 examples of tremor ratings chosen by the two WHIGET study neurologists. Eight raters, including senior movement disorder specialists, movement disorder fellows, general neurologists, and a movement disorder nurse practitioner, independently viewed the videotape and rated tremor during the self-assessment section. Interobserver reliability was assessed with weighted kappa statistics (kappa(w)). RESULTS: Eight raters each rated 20 items (160 ratings total). Total kappa(w) was 0.97 (nearly perfect agreement). Interrater reliability was as follows: kappa(w) = 0.99 (movement disorder specialists), kappa(w) = 0.98 (movement disorder fellows), and kappa(w) = 0.97 (general neurologists); all kappa(w) were nearly perfect. CONCLUSIONS: This teaching videotape may be used to improve the uniform application of the revised WHIGET Tremor Rating Scale by raters with various levels of experience in movement disorders.
Surgical treatment for essential tremor (ET) has been used since the early 1950s. Initially, different areas were targeted for tremor control. However, the optimal target was eventually determined to be the ventralis intermedius (VIM) nucleus of the thalamus. Thalamotomy improves contralateral tremor in more than 90% of patients. Long-term studies of thalamotomy indicate that the benefits continue in most patients. Persistent morbidity associated with thalamotomy, which occurs in less than 10% of patients, includes dysarthria, dysequilibrium, weakness, and cognitive impairment. Bilateral thalamotomy is associated with substantial morbidity and is usually avoided. Studies demonstrate that chronic stimulation of the VIM is safe and effective for tremor. Adverse effects of chronic stimulation include paresthesia, dysarthria, dysequilibrium, and localized pain. In many patients, bilateral thalamic stimulation is performed without a substantial increase in morbidity. ET patients with disabling medication-resistant tremor are reasonable candidates for these stereotactic procedures.