electrophysiological-methods-to-assess-peripheral-pain-block-an

Electrophysiological Methods to Assess Peripheral Pain Block in an Anesthetized Rat

In vivo electrophysiological recordings from the lumbar region of the rat spine can be used to study the activation of sensory neural signals in the ...

The MetroHealth System

Case Western Reserve University School of Medicine

Direct current (DC) can briefly produce a reversible nerve conduction block in acute experiments. However, irreversible reactions at the electrode-tissue interface have prevented its use in both acute and chronic settings. A high capacitance material (platinum black) using a charge-balanced waveform was evaluated to determine whether brief DC block (13 s) could be achieved repeatedly (>100 cycles) without causing acute irreversible reduction in nerve conduction. Electrochemical techniques were used to characterize the electrodes to determine appropriate waveform parameters. In vivo experiments on DC motor conduction block of the rat sciatic nerve were performed to characterize the acute neural response to this novel nerve block system. Complete nerve motor conduction block of the rat sciatic nerve was possible in all experiments, with the block threshold ranging from -0.15 to -3.0 mA. DC pulses were applied for 100 cycles with no nerve conduction reduction in four of the six platinum black electrodes tested. However, two of the six electrodes exhibited irreversible conduction degradation despite charge delivery that was within the initial Q (capacitance) value of the electrode. Degradation of material properties occurred in all experiments, pointing to a possible cause of the reduction in nerve conduction in some platinum black experiments .

Characterization of high capacitance electrodes for the application of direct current electrical nerve block.

Nerve conduction block using implanted electrodes is being used increasingly for clinical applications. Alternatively, non-invasive electrical nerve block would be beneficial for applications including pain block and muscle spasticity. Here we developed a novel means of non-invasive electrical nerve conduction blockade - transcutaneous direct current block (tDCB) - that produces direct block of nerve conduction.

Block of motor nerve conduction via transcutaneous application of direct current.

. Direct current (DC) electrical block of peripheral nerve conduction shows promise for clinical applications to treat spasticity, pain, and cardiac arrhythmias. Most previous work has used invasive nerve cuffs. Here we investigate the potential of non-invasive transcutaneous DC motor block (tDCB).. In anesthetized rats, force output from the tibialis and peroneus muscles was measured in response to stimulation proximally on the sciatic nerve. DC blocking waveforms were delivered via a surface electrode placed distally on the skin over the common peroneal nerve. The efficacy of the block was observed as the reduction/abolition of muscle force. Experiments using this model were performed with two different electrode types. A range of DC amplitudes and durations were used to elucidate the temporal properties of block.. Higher levels of DC resulted in a larger block percentage. The amount of time needed to induce block depended on the level of DC, with smaller amplitudes resulting in longer induction times. When block was applied for a longer period of time (120s), the block was sustained following DC delivery. This 'recovery period' was longer for higher amplitudes of block. In addition to the block thresholds and temporal effects, two additional evaluations were made: In some animals the efficacy of tDCB to block tetanic muscle contractions was successfully verified. Finally, the effect of tDCB on the stability of nerve conduction was verified using a second distal electrode for comparison.. In this study, tDCB has been shown to reversibly block action potentials in peripheral motor nerves. A subthreshold amplitude applied for a longer duration could produce complete or partial block following a brief induction time. Also, a higher amplitude was associated with a longer recovery time. These temporal properties are important considerations for potential clinical applications.

Article	Year
Characterization of high capacitance electrodes for the application of direct current electrical nerve block. Medical & biological engineering & computing\| PubMed ID: 26358242	2016
Block of motor nerve conduction via transcutaneous application of direct current. Bioelectronics in medicine\| PubMed ID: 39301195	2018
Temporal properties of transcutaneous direct current motor conduction block. Journal of neural engineering\| PubMed ID: 39883954	2025

Tina L. Vrabec

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