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Published on: March 25, 2014
Monophasic and biphasic stimulation evoke different responses
Edelle C Field-Fote1, Brent Anderson, Valma J Robertson
1Division of Physical Therapy, University of Miami School of Medicine, 5915 Ponce de Leon Blvd, Ste 500, Coral Gables, Florida 33146, USA. edee@miami.edu
Muscle & Nerve
|July 23, 2003
Summary
Sensory nerve action potentials (SNAPs) were studied using different electrical pulse types. Findings suggest biphasic pulses stimulate nerves more effectively at low intensities than previously thought.
Area of Science:
- Neuroscience
- Electrophysiology
Background:
- Understanding nerve stimulation is crucial for diagnostics and therapeutics.
- Electrical stimulation parameters, like pulse type, influence nerve response.
- Previous research has not fully elucidated the effect of biphasic pulse characteristics on sensory nerve action potentials (SNAPs).
Purpose of the Study:
- To compare sensory perception thresholds and SNAP waveforms elicited by monophasic and biphasic electrical stimuli.
- To investigate the impact of pulse duration and waveform on nerve excitability.
Main Methods:
- 31 subjects underwent psychophysiological testing and electrophysiological recording.
- Constant-current, 100-microsecond monophasic negative pulses were compared with biphasic symmetrical pulses (100 microseconds per phase).
- 200-microsecond monophasic negative pulses were also evaluated, with stimuli delivered to the index finger and SNAPs recorded from the median nerve.
Main Results:
- Perception thresholds differed significantly across the three stimulation conditions.
- At low intensities, biphasic stimuli produced SNAPs with two negative phases, while monophasic stimuli yielded a single negative phase.
- At higher intensities, all stimuli resulted in a single large negative phase SNAP, irrespective of waveform.
Conclusions:
- The trailing positive phase of a biphasic pulse exerts a stimulating effect at low intensities.
- This challenges historical assumptions regarding the efficacy of biphasic nerve stimulation.
- Results have implications for optimizing electrodiagnostic and therapeutic nerve stimulation techniques.
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