Continuous Stimulation of Transected Distal Nerves Fails to Prolong Action Potential Propagation

Department of Orthopaedic Surgery, SUNY at Downstate, Brooklyn, New York 11203, USA.
Clinical Orthopaedics and Related Research (Impact Factor: 2.88). 07/2006; 447(447):209-13. DOI: 10.1097/01.blo.0000203481.11797.0f
Source: PubMed

ABSTRACT Wallerian degeneration of the distal portion of a cut nerve is considered irreversible. A possible reason for degeneration is lack of axon stimulation in the distal, cut nerves. We hypothesized greater rates of stimulation of distal nerve stumps would prolong time to action potential propagation failure, and uncut nerves would not be damaged by implanted nerve stimulators. We also hypothesized that action potentials measured from the body of the sciatic nerve would show similar response as motor-evoked potentials measured in the muscles innervated by branches of the sciatic nerve. We implanted a nerve stimulator onto distal cut sciatic nerves of rats and recorded motor-evoked potentials. Three groups were stimulated at 1 Hz (once per second), 0.1 Hz (once per 10 seconds), and 0.01 Hz (once per 100 seconds) respectively. Motor-evoked potentials progressively declined after nerve transection, failing faster at 1 Hz (26.8 hours +/- 108 minutes) and 0.1 Hz (22 hours +/- 66 minutes) compared with stimulation at 0.01 Hz (36.75 hours +/- 83 minutes). Intact axons were not damaged by implanted nerve stimulators. Action potentials recorded directly from nerves were equivalent to motor- evoked potentials. Failure of motor-evoked potential transmission in a transected nerve is accelerated by a greater rate of continuous stimulation of the distal stump.

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    • "Several investigators have reported that a low-frequency electrical stimulation is a promise approach to accelerate nerve regeneration after injury2,12). However, a high frequency of electrical stimulation may increase failure of nerve regeneration16). Hence, these results cannot exclude potential beneficial effects of sacral nerve stimulation in other models of SCI with different treatment protocols, the disappointing outcomes in this study were limited by the treatment protocol. "
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    • "Immobilization studies using MS at 50 to 100 Hz have shown to minimize the reduction of the cross-sectional area of muscle fiber and to restore mechanical properties (Kim et al., 2007). Stimulation of distal nerve stumps had similar action potential response between normal and muscle innervated (O'Gara et al., 2006). Although the response of ImP and bone mass by MS under such periphery nerve block conditions is still remained unknown, MS could serve as a mitigating agent to retain bone mass under chronic nerve damage conditions, e.g., spinal cord injury. "
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    • "We used a linear array electrode for all nerve recordings (O'Gara et al., 2006). The array electrode consists of four platinum/iridium wires embedded in a small epoxy trough. "
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