Frequency- and amplitude-transitioned waveforms mitigate the onset response in high-frequency nerve block

Abstract

High frequency alternating currents (HFAC) have proven to be a reversible and rapid method of blocking peripheral nerve conduction, holding promise for treatment of disorders associated with undesirable neuronal activity. The delivery of HFAC is characterized by a transient period of neural firing at its inception, termed the "onset response". The onset response is minimized for higher frequencies and higher amplitudes, but requires larger currents. However, complete block can be maintained at lower frequencies and amplitudes, using lower currents. In this in-vivo study on whole mammalian peripheral nerves, we demonstrate a method to minimize the onset response by initiating the block using a stimulation paradigm with a high frequency and large amplitude, and then transitioning to a low frequency and low amplitude waveform, reducing the currents required to maintain the conduction block. In five of six animals it was possible to transition from a 30 kHz to a 10 kHz waveform without inducing any transient neural firing. The minimum transition time was 0.03 sec. Transition activity was minimized or eliminated with longer transition times. The results of this study show that this method is feasible for achieving a nerve block with minimal onset responses and current amplitude requirements. KeywordsHigh frequency nerve block; functional electrical stimulation; onset response; in-vivo model

A Simulation Study of the Combined Thermoelectric Extracellular Stimulation of the Sciatic Nerve of the Xenopus Laevis: The Localized Transient Heat Block

“…Gating variables n and p are modeled by equivalent set of equations to (4)- (8). Values for Q 10 are in Table III.…”

“…DC monophasic waveforms [5]) or high frequency alternating currents (HFAC) [6]. Several recent studies have examined the biophysics of HFAC techniques in both myelinated and unmyelinated fibres, optimal electrode design and optimal waveforms [7][8]. In practice, conventional selectivity methods have exhibited limited success so far, as they require high stimulus currents and have a limited resolution evoking unwanted neural activity that can result in side effects, but they constantly pursue improvements [8].…”

“…Several recent studies have examined the biophysics of HFAC techniques in both myelinated and unmyelinated fibres, optimal electrode design and optimal waveforms [7][8]. In practice, conventional selectivity methods have exhibited limited success so far, as they require high stimulus currents and have a limited resolution evoking unwanted neural activity that can result in side effects, but they constantly pursue improvements [8]. Overall, neurostimulation for blocking is very desirable; either directly, to avert undesirable neural activity, or for refining the selectivity of activating stimulation methods.…”

An Implantable Neuroprosthetic Device to Normalize Bladder Function after SCI

“…However these blocking methods could cause significant nerve damage in clinical applications. A recent study [26] also showed that the initial firing can be significantly reduced by first applying a 30 kHz stimulation and then shifting the stimulation to a lower frequency (10 kHz). Our current study indicates that in small unmyelinated axons (i.e., the nociceptive C-fibers) the initial nerve firing can be eliminated at the stimulation frequency above 30 kHz (Figs.…”

“…One of the advantages of using higher frequencies such as 300 kHz (see Fig.3) to block the myelinated axons is that the initial nerve firing induced by the high-frequency stimulation can be eliminated (see , which is very desirable for clinical applications (Camilleri et al 2009;Gerges et al 2010;Nashold et al 1982;Tai et al 2004;Wattaja et al 2011). …”