Quantitative assessment of botulinum toxin treatment in 43 patients with head tremor

We treated 43 patients who had head tremor as the major complaint with local botulinum toxin type A (Btx A) injections into neck muscles: 29 patients were classified as suffering from tremulous cervical dystonia (TCD), and 14 had head tremor without dystonia (HT). All patients were clinically assessed by means of the Tsui scale and a 4-point pain scale at baseline and follow-up visit. Quantitative recordings of head tremor with a bidirectional accelerometer system (horizontal and vertical planes) placed on the forehead were obtained before and 2-3 weeks after Btx A injections. Muscle selection for an injection was based on the visible and palpable tremor oscillation in the involved neck muscles and on analysis of standardized simultaneous electromyographic recordings of six cervical muscles. Patients with HT received mean total doses of 400 units (U) of Dysport (Btx A) (range, 160-560 U) distributed between the two splenius capitis muscles. Patients with TCD received a mean total dose of 500 U Dysport (range, 320-720 U) injected into a mean of 3 muscles (range, 2-4 muscles). The condition of all patients with HT and of 26 of the 29 patients with TCD improved subjectively. The total on the Tsui scale as well as pain scores decreased significantly (p < 0.05) following treatment. Latency of onset, duration of improvement, and side effects showed no significant difference in HT and TCD. Amplitude of HT decreased significantly for both groups following treatment. The mean dominant peak frequency in TCD and HT was slightly less than 5 Hz and did not change significantly after treatment.