EFFECTS OF TRH ON BALLISTIC WRIST MOVEMENTS IN CEREBELLAR CORTICAL ATROPHY - IMPROVEMENT OF 2 GENUINE DEFICIENCIES BUT NOT OF THE MAJOR ONE

Thyrotropin-releasing hormone (TRH) has been claimed to improve cerebe llar ataxia in patients with idiopathic sporadic cerebellar cortical a trophy (CCA). We analysed the effects of intravenous administration of TRH (1 mg) in ballistic wrist flexions movements in 10 healthy subjec ts and in eight patients with CCA. The associated agonist and antagoni st electromyographic (EMG) activities were recorded. In healthy subjec ts, TRH did modify neither the movement amplitudes, nor the intensity of the agonist and antagonist EMG activities. Before TRH administratio n, patients with CCA exhibited a hypermetria which was associated with a delayed onset of the antagonist activity. Moreover, the intensity o f EMG activity in both the agonist and the antagonist muscles were red uced. After TRH, the hypermetria and the delayed onset latencies of th e antagonist EMG activities were unchanged but the intensity of both t he agonist and the antagonist EMG activities increased. TRH could incr ease the magnitude of agonist and antagonist EMG activities in patient s with CCA by exerting an excitatory effect directly on motoneurons or by modulating at the supraspinal level the central commands to agonis t and antagonist motoneuron pools. (C) 1998 Rapid Science Ltd.