This interesting article dealt with the behavior of the pelvic floor following pelvic surgery. The article compared pre-and postoperative pelvic floor EMG activities, using quantitative EMG registration with a concentric needle. A changed pattern was recorded, and a peripheral nerve lesion, caused by TURP surgery, was proposed as the explanation for the changed EMG pattern.
Similar findings were reported by Zermann et al. [1997]. Pelvic floor function was studied using eight surface EMG electrodes before, 10 days, and 6 months after radical retropubic prostatectomy (RRP). A changed activation pattern was recorded only within the dynamic interval of increasing voluntary muscle recruitment. There was a decrease in the mean frequency of EMG activity when compared to the preoperative EMG-voluntary recruitment pattern (Friedman test; P < 0.001). At rest, and during the sustained phase of maximum voluntary contraction, no significant changes of EMG amplitude and frequency could be found. These differences had disappeared by the 6-month evaluation.
In addition to the peripheral nerve hypothesis proposed by the authors, there are also possible central explanations that might be considered.
The central nervous system is very prone to instability. Complete and partial peripheral nerve injuries have been shown to produce sustained changes in dorsal horn (spinal cord) neuron excitability [Kajander et al., 1990]. This phenomenon is now well-recognized and described as windup and/or long-term potentiation [Pockett, 1995]. Instability within spinal cord dorsal horn circuitry could account for the changes in EMG activity noted. The cause may be attributed to alterations in spinal cord neurotransmitter expression, consequent to wound-related (TURP or RRP) nociceptive afferent feedback into the spinal cord dorsal horns.
In addition to peripheral nerve injury, it is important to consider plasticity phenomena within the central nervous system as a consequence of pelvic surgery. Both peripheral nerve injury, and induced changes within the spinal cord, can reverse with time. However, it is also possible for induced spinal cord (i.e., central nervous