The standard electrical stimulation waveform used for electrical activation of nerve
is a rectangular pulse or a charge balanced rectangular pulse, where the pulse width is
typically in the range of ∼100 µsec through ∼1000 µsec. In this work, we explore the
effects of a continuous sinusoidal waveform with a frequency ranging from 5 through
20 Hz, which was named the Low Frequency Alternating Current (LFAC) waveform.
The LFAC waveform was explored in the Bioelectronics Laboratory as a novel means
to evoke nerve block. However, in an attempt to evoke complete nerve block on a
somatic motor nerve, increasing the amplitude of the LFAC waveform unexpectedly
produced nerve activation, and elicited a strong non-fatiguing muscle contraction in
the anesthetized rabbit model (unpublished observation). The present thesis aimed to
further explore the phenomenon to measure the effect of LFAC waveform frequency
and amplitude on nerve activation.<div><br></div><div>In freshly excised canine cervical vagus nerve (n=3), it was found that the LFAC
waveform at 5, 10, and 20 Hz produced burst modulated activity. Compound action
potentials (CAP) synchronous to the stimuli was absent from the electroneurogram
(ENG) recordings. When applied <i>in-vivo</i>, LFAC was capable of activating the cervical
vagus nerve fibers in anaesthetized swine (n=5) and induced the Hering-Breuer reflex.
Additionally, when applied <i>in-vivo</i> to anesthetized Sprague Dawley rats (n=4), the
LFAC waveform was able to activate the left sciatic nerve fibers and induced muscle
contractions.</div><div><br></div><div>The results demonstrate that LFAC activation was stochastic, and asynchronous
to the stimuli unlike conventional pulse stimulation where nerve and muscle response
simultaneously and synchronously to stimulus. The activation thresholds were found
to be frequency dependent. As the waveform frequency increases the required current
amplitude decreases. These experiments also implied that the LFAC phenomenon was
most likely to be fiber type-size dependent but that more sophisticated exploration
should be addressed before reaching clinical applications. In all settings, the LFAC
amplitude was within the water window preventing irreversible electrochemical reactions and damages to the cuff electrodes or nerve tissues. This thesis also reconfirms
the preliminary LFAC activation discovery and explores multiple methods to evaluate
the experimental observations, which suggest the feasibility of the LFAC waveform
at 5, 10, and 20 Hz to activate autonomic and somatic nerve fibers. LFAC appears
to be a promising new technique to activate peripheral nerve fibers.</div>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12730652 |
| Date | 05 August 2020 |
| Creators | Awadh Mubarak M Al Hawwash (9179432) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Relation | https://figshare.com/articles/thesis/A_NOVEL_APPROACH_TO_PERIPHERAL_NERVE_ACTIVATION_USING_LOW_FREQUENCY_ALTERNATING_CURRENTS/12730652 |
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