Experimental study of the correlation between amplitude of fibrillation potential and positive sharp wave and functional recovery of muscles after nerve repair

Abstract

Objective To observe the changing pattern of fibrillation potential amplitude and positive sharp wave amplitude in a rat soleus muscle denervation model, and investigate its correlation with functional recovery of the muscle after nerve repair of different post - traumatic intervals. Methods Soleus muscle denervation model was set up in 54 male SD rats by transecting the tibial nerve. 12 rats were used to measure the amplitude of fibrillation potential and positive sharp wave of the soleus muscle after different denervation intervals, that is immediately after, 48 hours, 72 hours, 1 week, 2 weeks, 4 weeks, 8 weeks, 12 weeks, and 16 weeks after nerve transection. The other 42 rats were randomly divided into 7 groups, with 6 each. The tibial nerve was repaired 1, 2, 4, 8, 12, and 16 weeks after nerve transection respectively. 12 weeks following nerve repair, wet muscle weight and muscle fiber cross - sectional area of the soleus muscle was measured. A group without nerve repair served as control. Results After muscle denervation, positive sharp wave appeared prior to fibrillation potential. Amplitude of fibrillation potential reached peak level 1 week following denervation, maintained at this level for 4 weeks, gradually declined from 8 weeks on, and disappeared at 16 weeks after denervation. Positive sharp wave was present 48 hours following denervation, its amplitude being highest in 8 weeks. 16 weeks following denervation, positive sharp wave disappeared in half of the rats. There was no significant difference of muscle weight and fiber size among groups in which the tibial nerve was repaired within 8 weeks. Significant difference was found when the nerve was repaired after 12 weeks. Conclusions Fibrillation potential amplitude and positive sharp wave amplitude were closely correlated with recovery of muscle function. It thus can be used as a quantitative parameter to determine whether denervation atrophy of skeletal muscle is reversible or not.