Supplementary Material for: Validity of a Self-Report Information on Cranial Tremors in Essential Tremor: Analysis of Data from a Large, Prospective Cohort

Background/objective: Cranial (i.e., head and voice) tremors are highly prevalent in essential tremor (ET). They may be disabling and they often drive treatment. Furthermore, their appearance may provide insights about disease severity and staging. Several features of these tremors make self-report data complex. There are no data on the validity of self-reported information on cranial tremors in ET. We evaluated the validity of self-reported cranial tremor in ET. Methods: ET cases, enrolled in a prospective evaluation, were queried about the presence of head and voice tremor. A detailed neurological examination was performed, and the presence of head or voice tremor was assessed by an experienced movement disorders neurologist. Results: There were 185 ET cases. The prevalence of voice tremor on examination was 50.8%, and of head tremor was 49.7%. Cases under-reported voice and head tremors (sensitivity = 13.8% - 59.3%); however, the positive predictive value of self-reported voice and head tremor was moderate (61.9% to 84.2%). Overall, the validity of self-reported data was lower for voice than head tremor. Self-reported voice tremor was the least valid when that tremor was mild. Conclusions: We provide the only data we are aware of, of the validity of self-reported cranial tremors in ET. Self-reports were a poor screen to ascertain cranial tremors; however, if a case did report these tremors, the information was likely to be valid. These data emphasize the importance of a thorough neurological examination. Although this requires a greater investment of time/resources, it reduces the number of false negatives.