Quantification of sensory trick impact on tremor amplitude and frequency in 60 patients with head tremor

Head tremor with an obvious head deviation is the typical clinical picture of tremulous cervical dystonia (TCD), whereas head tremor without any signi ficant head deviation allows for the differential diagnosis of dystonic hea d tremor (DHT) as well as essential head tremor (EHT). Clinical and polyele ctromyographic (poly-EMG) studies have shown a suppression of dystonic musc le activity in patients with TCD performing a maneuver called geste antagon istique. The effect of these trick maneuvers on head tremor has not been in vestigated in patients with DHT and EHT. We studied the impact of sensory t rick maneuvers on head tremor amplitude and frequency clinically by using t he tremor subscore of the Tsui scale and by means of computer-based acceler ometry in 60 patients with head tremor as their major disorder. Based on cl inical data (modified Tsui scale: rating of spontaneous head deviation [rot ation + lateroflexion + ante-/retroflexion]), pharmacologic response of tre mor (propranolol, primidone, or alcohol), family history (postural hand tre mor in first-degree relatives), and poly-EMG findings (reciprocal inhibitio n in neck muscles during voluntary head rotation), 34 patients were diagnos ed as having TCD, 14 were classified as having DHT, and 12 patients were di agnosed as having EHT. Using a clinical rating scale, head tremor amplitude s showed a significant decrease compared with baseline during the performan ce of sensory trick maneuvers in patients with TCD and DHT, but not in pati ents with EHT. This clinically observed effect was accompanied by a signifi cant reduction in the mean peak power of the dominant frequency in patients with TCD (decrease by 83%, p = 0.0001) and DHT (decrease by 90%, p = 0.01) , but not in patients with EHT (decrease by 6%, p = 0.6). Head tremor frequ encies showed no significant changes in relation to the trick maneuvers. We conclude that a significant reduction of head tremor amplitude during a se nsory trick maneuver is a useful quantitative criterion to distinguish TCD and DHT from EHT.