Trick maneuvers in cervical dystonia: Investigation of movement- and touch-related changes in polymyographic activity

Antagonistic gestures or trick maneuvers are well-known clinical features t o reduce or abolish dystonic posturing in cervical dystonia (CD). The maneu vers typically consist of a finger touch to the facial skin but their physi ology remains unknown. To determine the temporal profile of geste maneuver performance, 25 patients with idiopathic CD were studied by means of polymy ography of six cervical muscles prior to any botulinum toxin treatment. Two piezoelectric elements fixed to a fingertip of the hand involved in the tr ick maneuver and to the facial target region, respectively, were used to re late the essential points of the trick maneuver time course (start of geste -arm movement, facial contact, end of contact, end of movement) to changes in polymyographic activity. Thirteen patients (52%) showed marked reduction s of electromyographic (EMG) activity (greater than or equal to 50% in at l east one muscle) during arm movement, definitely prior to contact between f ingers and facial target area; in the remaining 12 patients (48%), geste-re lated EMG effects were confined to facial-finger contact. These results mig ht indicate different physiological mechanisms in clinically indistinguisha ble antagonistic gestures.