OBJECTIVE: To assess the effect of antidopaminergic antipsychotic medication on the electromyographic (EMG) responses of thenar muscles to transcranial magnetic stimulation (TMS) of the motor cortex in schizophrenic patients. METHODS: A group of nine drug naive schizophrenic patients was compared with a group of nine schizophrenic patients established on neuroleptic medication. Surface EMG recordings were made from the thenar muscles while patients maintained a weak isometric voluntary contraction. TMS was applied using a 9 cm circular stimulating coil centred over the vertex. The EMG responses to up to 50 magnetic stimuli were rectified and averaged. RESULTS: There was no difference in threshold TMS strength for eliciting compound motor evoked potentials (cMEPs), or in their latency, in drug naive and medicated patients. In some patients the silent period (SP) was clearly made up of two parts and the percentage of control levels of voluntary EMG was measured in each component. During the early component of the SP there was a weaker (P<0.05) suppression of EMG in the medicated patients (mean 73.9 (SEM) 5.5% of control levels) compared with the drug naive patients (54.7 (SEM) 7.3% of control levels). This resulted in the latency of maximum suppression of voluntary EMG being longer (P<0.05) in the medicated patients (38.3 (2.4) ms) than in the drug naive patients (28.2 (0.7) ms). During the late component of the SP voluntary EMG was reduced to similar levels (P>0.05) in both medicated (48.2 (7.7)% of control levels) and drug naive (58 (7.8)% of control levels) patients. CONCLUSION: The results are discussed with reference to the disrupted inhibition seen in the early part of the SP in Parkinson's disease and drug induced parkinsonism. The future uses of motor responses to TMS as a marker for the status of antipsychotic medication are considered.
OBJECTIVE: To assess the effect of antidopaminergic antipsychotic medication on the electromyographic (EMG) responses of thenar muscles to transcranial magnetic stimulation (TMS) of the motor cortex in schizophrenicpatients. METHODS: A group of nine drug naive schizophrenicpatients was compared with a group of nine schizophrenicpatients established on neuroleptic medication. Surface EMG recordings were made from the thenar muscles while patients maintained a weak isometric voluntary contraction. TMS was applied using a 9 cm circular stimulating coil centred over the vertex. The EMG responses to up to 50 magnetic stimuli were rectified and averaged. RESULTS: There was no difference in threshold TMS strength for eliciting compound motor evoked potentials (cMEPs), or in their latency, in drug naive and medicated patients. In some patients the silent period (SP) was clearly made up of two parts and the percentage of control levels of voluntary EMG was measured in each component. During the early component of the SP there was a weaker (P<0.05) suppression of EMG in the medicated patients (mean 73.9 (SEM) 5.5% of control levels) compared with the drug naive patients (54.7 (SEM) 7.3% of control levels). This resulted in the latency of maximum suppression of voluntary EMG being longer (P<0.05) in the medicated patients (38.3 (2.4) ms) than in the drug naive patients (28.2 (0.7) ms). During the late component of the SP voluntary EMG was reduced to similar levels (P>0.05) in both medicated (48.2 (7.7)% of control levels) and drug naive (58 (7.8)% of control levels) patients. CONCLUSION: The results are discussed with reference to the disrupted inhibition seen in the early part of the SP in Parkinson's disease and drug induced parkinsonism. The future uses of motor responses to TMS as a marker for the status of antipsychotic medication are considered.
Authors: Tony W Wilson; Erin Slason; Olivia O Hernandez; Ryan Asherin; Martin L Reite; Peter D Teale; Donald C Rojas Journal: Psychiatry Res Date: 2009-09-23 Impact factor: 3.222
Authors: Thomas Wobrock; Alkomiet Hasan; Berend Malchow; Claus Wolff-Menzler; Birgit Guse; Nicolas Lang; Thomas Schneider-Axmann; Ullrich K H Ecker; Peter Falkai Journal: Psychopharmacology (Berl) Date: 2009-12-09 Impact factor: 4.530
Authors: B K Puri; H C Smith; I J Cox; J Sargentoni; G Savic; D W Maskill; H L Frankel; P H Ellaway; N J Davey Journal: J Neurol Neurosurg Psychiatry Date: 1998-11 Impact factor: 10.154
Authors: N J Davey; H C Smith; E Wells; D W Maskill; G Savic; P H Ellaway; H L Frankel Journal: J Neurol Neurosurg Psychiatry Date: 1998-07 Impact factor: 10.154