A cross-over clinical and electromyographic assessment of treatment for parkinsonian tremor

Background: Whether dopaminergic and anticholinergic drugs exert influence on parkinsonian rest and postural tremor is a subject of debate. Different types of tremor may be influenced differently by the drugs. The aim of this study was to reevaluate the differential effects of levodopa and anticholi nergic drugs on parkinsonian tremor in different limb positions and on diff erent types of postural tremor. Methods: Thirty-eight patients with parkinsonian resting tremor and postura l tremor were included in this study. Patients were divided into two groups according to the electromyographic pattern of the postural tremor. We foun d fast synchronous postural tremor (>7 Hz) in 16 patients, and slow alterna ting postural tremor in 22 patients. The tremor was scored clinically in ea ch limb position using the Webster Tremor Scale. Surface electromyographic recordings from the most involved limb in all positions were also performed . The patients were randomly assigned to levodopa (one 250/50-mg tablet), o r to biperiden (one 3-mg tablet). Tremor was assessed by clinical and elect romyographic examinations at base line 1 h following ingestion of the drug. The subjective tremor improvement was also assessed. Results: We found that levodopa had a good effect on the amplitude of the r esting tremor, while the effect of biperiden was weaker. Both levodopa and biperiden has less effect on postural tremor. However, levodopa's effect wa s better than that of biperiden. Levodopa and biperiden had better effect o n slow alternating postural tremor than on fast synchronous postural tremor . They had no effect on kinetic and intention tremors. Conclusions: Levodopa and anticholinergic drugs have differing effects on b oth resting and postural tremor Also, the different categories of postural tremor respond differently to treatment. The mechanisms underlying resting parkinsonian tremor may be different from those underlying postural, kineti c and intention tremor. Moreover, the mechanisms underlying different types of postural tremor may be different. (C) 2001 Elsevier Science Ltd. All ri ghts reserved.