Iranian Journal of Medical Physics

Iranian Journal of Medical Physics

Asymmetric Rectangular Waveform in Stimulation with High Frequency Alternating Current Reduces the Threshold for Neural Conduction Block

Document Type : Original Paper

Authors
Alireza Arianfar
Amin Mahnam
Biomedical Engineering Deptartment, University of Isfahan, Isfahan, I.R. Iran
10.22038/ijmp.2013.915
Abstract
Introduction
Abnormal neural impulses in the nervous system may lead to various diseases and disabilities. High frequency alternating currents (HFAC) has been used to block the propagation of such impulses and improve the symptoms or disabilities. The technique is safe, reversible, and relatively selective, and its reliability, the optimum stimulation parameters, and elimination of the onset response have been the focus of related studies in the last decade. In this work, a series of computational simulations were performed to evaluate the performance of asymmetric biphasic rectangular waveforms for HFAC.
Materials and Methods
Computer simulations were carried out in NEURON software based on the MRG model, a detailed model of mammalian peripheral nerve fibers. The current threshold for the block and the injected charge per phase were assess for different forms of this waveform and compared with symmetric rectangular, sinusoidal, DC, and monophasic stimulations. The effect of fiber diameter and the stimulation frequency were also evaluated for this waveform.
Results
The threshold charge per phase to induce nerve conduction block was significantly lower for the proposed asymmetric biphasic stimulation. The minimum thresholds were achieved for the waveforms with short anodic long cathodic phases. The threshold was reduced with increasing the asymmetry of the waveform and reduction of the frequency.
Conclusion
Simulations performed in this study demonstrated that the proposed stimulation with asymmetric biphasic rectangular waveforms significantly reduces the current threshold and requires much less charge injection per phase to induce nerve conduction block. This is very important for clinical use due to less damage to the tissue.
Keywords
Asymmetric Biphasic Waveform
High Frequency Alternating Current
Nerve Conduction Block
Subjects
Iranian Journal of Medical Physics
Volume 10, Issue 1 - Serial Number 1
Winter & Spring 2013
March and April 2013
Pages 22-30

  • Receive Date 10 July 2013
  • Revise Date 09 December 2012
  • Accept Date 06 April 2013