Quantitative Evaluation of Denervation Potentials in Gastrocnemius of Rats Using Power Spectrum Analysis

ABSTRACT

OBJECTIVE: To evaluate the changes of maximum fibrillation potential amplitude and root- mean-square (RMS) value of denervation potential after nerve injury using power spectrum analysis. METHODS: The sciatic nerve was transected in 8 rats, and was compressed in 6 rats. Denervation potentials were collected in gastrocnemius using monopolar needle weekly after nerve injury. The change of RMS value of 1 second epoch of denervation potentials with time was evaluated and compared with the change of maximun fibrillation potential amplitude. RESULTS: In nerve-transected rat, the RMS value declined linearly with time after injury. On the contrary, the amplitude of fibrillation potentials declined much rapidly during first 3 weeks. In nerve-compressed rat, both the RMS value and amplitude of fibrillation potential increased for 2 weeks after injury, and declined thereafter. As the result of simple regression analysis, the changes of RMS value correlated better than changes of fibrillation amplitude in all 8 nerve-transected rat. CONCLUSION: The RMS value of denervation potentials correlated well with time after nerve injury in animal experiments. Measurement of the RMS value might be helpful to evaluate the time after peripheral nerve injury, but long-term human data should be essential for clinical application.