Through the use of stereotactic neurosurgical operation, some authors have employed chronic electrical stimulation of the dentate nucleus reduce spasticity and each trial on spastic patients has show marked clinical improvement.
We investigated the eletrophysiological changes of cats after stereotactic electrical stimulation of the dentate nucleus to elucidate the possibility of clinical application and to evaluate the clinical results.
The M-wave is an initial response and the F-wave is a late response in the electromyography of a muscle, which is stimulated by its original controlling nerve itself. There is evidence that the size of the F-wave is dependent on motor neuron
excitability and its amplitude is increased significantly at spastic condition.
If such a relationship exists, procedures which are carried out to relieve spasticity might be exerted to change the F-wave size and thus it might be possible to use the F-wave as an objective monitor during electrical stimulation of the dentate
nucleus.
We investigated this possibility in experiments on 10 cats weighing between 2.7kg and 4.4kg. We studied the changes of M and F waves, recorded in EMG, after stereotactic stimulation to cerebellar dentate nucleus in cats.
@ES The results were as follows:
@EN 1) The change of mean value of M-wave amplitude was not significant (control group, 3591±1029μV; stimulation group, 3424±927μV, p>0.05).
2) The mean value of F-wave amplitude was significantly reduced about 56.7% after the dentate stimulation (control group, 443.2±119μV; stimulation group, 251.3±99.4μV, p<0.05).
3) The F/M ratio also significantly reduced, about 56.8% after the dentate stimulation (control group, 12.5±1.9%, stimulation group, 7.1±1.2%, p<0.05).
Our experimental results demonstrated that the dentate stimulation markedly decreased the size of F-wave amplitude and F/M ratio in the experimental cats and we concluded that these electrophysiological changes can be applied as a parameter of
clinical
evaluation of electrical dentate stimulation for the spasticity.
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