Electrophysiological Changes During Cerebellar Dentatotomy in Cats.

Son, Byung Cheul; Kim, Moon Chan; Kang, Joon Ki; Choi, Chang Rak

Original Article

Journal of Korean Neurosurgical Society 1993;22(9): 953-959.

Byung Cheul Son, Moon Chan Kim, Joon Ki Kang, Chang Rak Choi

Department of Neurosurgery, Catholic University Medical College, Seoul, Korea.

ABSTRACT

Spasticity is a wide variety of motor problems to connote difficulty with coordinated movements, involuntary spasma, rigidity. Abnormal primitive reflexes and hyperactive reflexes. Electrophysiologically, spasticity is represented as the involuntary firing of motor units on a reflex basis at a polysynaptic spinal cord level, associated with interruption of descending cortical pathways. Although many procedures have been tried over the years to combat this spasticity, and the multitude of procedures indicates that none are entirely satisfactory, the reduction in spasticity produced by dentatotomy has been confirmed in many neurological centers. The F-wave is a late response recorded in the electromyography of a muscle following stimulation of its nerve supply. There is evidence that the size of the F-wave is dependent on motor neuron excitability. If such a relationship exists, procedures which are carried out to relieve motor neuron excitability might be expected to change F-wave size and it might therefore be possible to use the F-wave as an objective monitor during stereotactic dentatotomy. We have investigated this possiblity in 10 cats, weighing 2.8 to 3.7kg each. The size of F-wave Amplitude in experimental animals were devided into 2 groups, normal control group values(10 cats, before dentatotomy) and the dentatotomy group values(10 cats after dentatotomy). The F-wave size and F/M ratio were recorded from right tibialis anterior muscle after application of supramaximal stimulation(250 V. 100 mA. 2 Hz. 10 times) on the right peroneal nerve. The results were as follows: 1) The size of M-wave amplitude did not change significantly in experimental models(before dentatotomy, 2805.5+/-1012.3 microV;dentatotomy group, 2555.5+/-725.9 microV, P>0.05). 2) The individual size of F-wave showed a wide variability from each stimulus, which emphasizes the importance of using 0 stimulating responses. The mean value of F-wave amplitude before dentatotomy was 436.5+/-113.2microV. 3) The size of F-wave amplitude was significantly reduced after dentatotomy(before dentatotomy, 436.5+/-113.2microV;after dantatotomy: 212.5+/-49.3microV, P<0.05). The size of F-wave amplitude decreased about 48.6% after dentatotomy. 4) The F/M ratio also significantly reduced after dentatotomy(before dentatotomy, 17.1+/-6.6%;after dentatotomy, 8.5+/-1.2%, P<0.05) and mean reduction was 49.7%. The results demonstrated that the dentatotomy markedly decreased the size of F-wave amplitude in experimental cats and indicated that the monitoring of F-wave amplitude during dentatotomy might be useful as an objective monitor for the relief of spasticity.