Submitted in partial compliance with the requirements for the Master’s Degree in Technology: Chiropractic, Durban University of Technology, Durban, South Africa, 2017. / Background to the study: Chronic low back pain (CLBP) is a common musculoskeletal complaint, which results in increased absenteeism from work and other disabilities. Interferential current (IFC) is one of the treatment modalities used by manual and physical therapists to alleviate CLBP. Interferential current involves electrical stimulation of medium frequency using two currents that cross over each other. There have been numerous mechanisms proposed on how IFC works with regard to pain inhibition; however, these remain unconfirmed. Common theories include those based on the gate control theory of pain and integrated pain theories. Although the placement of the electrodes used in the IFC application has been well defined, the optimum treatment time for CLBP has not been well researched. Therefore, this study aimed to determine what protocol regarding the duration of IFC is most appropriate in the treatment of CLBP. Aim: The aim of this study was to investigate the effect of interferential current in the treatment of chronic low back pain using variable time intervals Methodology: This study was a randomised single-blinded clinical trial which consisted of 45 participants residing in the eThekwini municipality, divided into three groups of 15 each. The participants were randomly assigned using concealed allocation to one of three treatment groups of 15 each viz. 15, 20 or 30 minutes of interferential current (IFC). Low back pain level was determined using a numerical pain rating scale (NRS-101). Pain pressure thresholds (PPT) were measured with a pain pressure algometer. The effect of low back pain on participants’ activities of daily living was assessed using the Oswestry low back questionnaire (OLBQ).The participants received three treatments over a two week period with the fourth consultation being used for the final subjective and objective measurements a week later. Results: Repeated measures ANOVA testing was used to examine the intra-group effect of time and the inter-group effect of treatment on the outcomes of NRS-101 and algometer readings. Profile plots were used to assess the direction and trends of the effects. An intra-group analysis revealed that, objectively and subjectively, all groups responded positively to treatment over time, with no significant time-group interaction. Conclusion: This study concluded that neither group is more effective than the other with respect to participants’ pain perception and the OLBQ. However, groups one and three showed the largest individual improvement between consultation one and three, compared to group two which showed consistent improvement throughout for the NRS-101 readings. Based on the results collected from this study, the shortest time frame of 15 minutes of IFC application can be used in the treatment of CLBP. / M

Mathematical models have been used to study the effects of various electrical stimuli on nerve. The applicability of the findings to electrocutaneous stimulation in man has been investigated experimentally. With the model of a nerve membrane the influence of variations in the stimulus parameters have been investigated. This was done for multiple bipolar pulses by considering selected cases and for single bipolar pulses with a systematic investigation. The main findings were i) that the threshold charge for a single bipolar pulses changes only slightly for different pulsewidths; ii) that the threshold charge monotonically decreases with pulsewidth and threshold charge also decreases monotonically with increasing delay of the symmetric negative pulse; iii) that threshold amplitude for multiple bipolar pulses was only slightly lower than the amplitude for a single bipolar pulse. The influence of different components involved in cutaneous stimulation, such as skin, electrode, and neuroanatomy, have been examined. Corresponding models for the passive components involved were selected. From these models the following limiting conditions for the stimulus were derived: i) the stimulus has to be current regulated; ii) it must be bipolar (no net charge transfer); and iii) the electrode voltage must remain below the skin break-down voltage. The aspect of the conversion of stimulus' energy into heat in the skin has been examined in detail. A review of mathematical models of the active nerve membrane is presented and the applicability of a nerve model to the stimulation of peripheral nerve fibres in man is discussed. Numerical methods were used to solve the model's differential equations. The effects on the solution of different integration methods and of different integration step sizes has been assessed. Experiments with electrocutaneous stimulation have been performed using single bipolar current stimuli. The duration of a pulse was less than 100 microseconds. For the experiments, an electrically isolated stimulator has been designed and built. It operated under the control of a PDP-12 computer. The sensations produced were slightly suprathreshold and painless. The thenar region of the hand was stimulated using a concentric electrode. The results of the experiments supported the theoretical predictions and indicated the possibility of using models to investigate the optimization of stimulus parameters within the range tested. The close correspondence between the experimental results and the nerve model calculations seems to provide some evidence for the hypothesis that in electrocutaneous stimulation the nerve fibres are stimulated directly. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The main purpose of this study was to observe the changes in muscular strength and endurance of the extensor muscles of the hand after the arm had been exposed to electrical stimulation. Twenty-four university students were chosen for this study. The subjects were divided into three groups of eight,, attempting to make each group homogeneous with respect to their Maximal Voluntary Iscitetric Contraction of the extensor muscles of the hand. All subjects were trained with the hand at 150 degrees with respect to the forearm (Position 1) . Group 1 (ES) received five minutes of electrical stimulation to the dorsal surface of the forearm each weekday for a four week period. The placement of the electrodes were at the musculotendonous area of the extensor muscles of the hand. The intensity of the faradic stimulation was just below the subjects pain threshold. Each contraction elicited by the electrical stimulation was for a duration of 880 msec, and the relaxation between each contraction was 1030 msec. Group 2 (VI) performed four sets of eight Maximal Voluntary Contractions, where each contraction was held for a duration of two seconds. Training took place on the Monday, Wednesday, and Friday of each week for a four week duration. Group 3 (ES+VIj performed the training of Groups 1 and 2 for four weeks. Subjects were tested for their Maximal Voluntary Contraction in both Position 1 and Position 2 (180 degrees with respect to the forearm). Endurance was calculated on the subjects fatigue curve. The time in seconds to 65% of their MVC (for each testing period) was used as a measure of their relative endurance. The testing of strength and endurance was done before any training took place, after two weeks of training, and at the duration of the four week period. Significant strength gains occurred in all three groups between the Pre test and Mid-Post in Position 1 and Position 2. During the Mid-Post training period only the ES+VI group had significant strength gains in Position 1; whereas in Position 2 both the ES and ES+VI groups yielded significant strength gains. It was illustrated that individual strength gains in the ES and VI groups were not additive in either position tested, and that one training method is not significantly better than another when observing mean strength gains over time. During the four week training period the endurance of the muscles did not alter significantly when locking at the mean of all three groups. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

Typescript (photocopy) / Digitized by Kansas Correctional Industries

The well-known field of engineering psychology, also known as human factors engineering, utilizes psychologists to solve Engineering's problems that concern the behavior of humans in their operation and control of engineering systems such as military aircraft. To limit psychology's relation to engineering this way is, however, counterproductive. Psychology requires a broader conceptualization of engineering psychology, a subfield of psychology, within which the psychologist's major concern is with the behavior of psychoengineering systems that affect the reliability, validity and safety of psychological research and practice. In contrast with human-factor systems, the psychoengineering systems include healthy and unhealthy, human and animal subjects. The affiliated problems are not those of the engineering industry. This study in engineering psychology concerned the safety of two electrical stimulation systems that are used on animals, chiefly dogs, in punishment and escape/avoidance conditioning procedures of psychology. The study referenced two safety questions. First, is the electricity, when applied externally to the ventral neck of the animal, capable of stimulating carotide sinus and vagus nerves to the point of dangerously disrupting systemic blood pressure and sinus rhythm? Second, is the electricity capable of damaging the epidermis when it is applied repeatedly to the same two points of contact? Of forty-two anesthetized dogs, half were tested with a punishment system; the remainder were tested with an escape/avoidance system. Each was stimulated for five seconds, five times, at each of five intensities. Inter-stimulus interval was about thirty seconds. Systemic blood pressures and electrocardiograms (ECG) were recorded. Control and experimental biopsies were taken for histological examinations of electrified and unelectrified specimens. Each animal's neck was examined grossly each day for ten days following the stimulation runs. None of the gross examination reports was positive. An exact binomial test supported the hypothesis that tissue samples from control and experimental biopsies did not differ histologically. Repeated measure ANOVAs were used to detect significant differences in systolic pressures, diastolic pressures, and R to R intervals of the ECG throughout stimulation runs. While there were some statistically significant results, there was no clinical significance, especially with regard to safety hazards.

Electrical stimulation of retinal neurons is known to elicit visual sensations. When applied to the retina in a spatial pattern, electrical stimulation may be capable of providing rudimentary patterned vision that may be of benefit to sufferers of degenerative retinal disorders. No such device has yet been devised to provide for chronic study of the psychophysical perceptions elicited from a prosthesis for retinal stimulation. In this study, steps towards achieving this goal have been successfully carried out. Foregoing research was reviewed such that appropriate stimulation parameters were incorporated in the design of a 100 stimulation channel, complimentary metal oxide semiconductor (CMOS) integrated circuit, small enough in size so as to be capable of being implanted within the ocular anatomy or surrounding orbit. The device, and its associated external hardware and software were designed, modeled, fabricated, and interfaced with stimulating electrodes in acute testing in a highorder mammal (Ovis aries) so as to assess the capabilities of the device to elicit cortical potentials as a direct result of stimulation of the neural retina. Testing was performed under conditions similar to those anticipated in chronic in-situ configurations wherein radio-frequency telemetry was used to deliver power and configuration parameters to the device thus avoiding the passage of wires through tissue in order to communicate to the implant circuit. The results of the testing indicate that the circuit is indeed capable of eliciting physiological responses in the animal and evidence is present that these responses could be elicited in patterned form. Further work undertaken includes the development of surgical methods for implantation, and application of the prosthesis circuit in functional electronic stimulation.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Stuart A. Binder-Macleod, Dept. of Physical Therapy. Includes bibliographical references.

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: Stuart A. Binder-Macleod, Dept. of Physical Therapy. Includes bibliographical references.

Thesis (Ph. D.)(Electronic Eng.)--University of Pretoria, 2004. / Includes bibliographical references.

Electrical stimulation of retinal neurons is known to elicit visual sensations. When applied to the retina in a spatial pattern, electrical stimulation may be capable of providing rudimentary patterned vision that may be of benefit to sufferers of degenerative retinal disorders. No such device has yet been devised to provide for chronic study of the psychophysical perceptions elicited from a prosthesis for retinal stimulation. In this study, steps towards achieving this goal have been successfully carried out. Foregoing research was reviewed such that appropriate stimulation parameters were incorporated in the design of a 100 stimulation channel, complimentary metal oxide semiconductor (CMOS) integrated circuit, small enough in size so as to be capable of being implanted within the ocular anatomy or surrounding orbit. The device, and its associated external hardware and software were designed, modeled, fabricated, and interfaced with stimulating electrodes in acute testing in a highorder mammal (Ovis aries) so as to assess the capabilities of the device to elicit cortical potentials as a direct result of stimulation of the neural retina. Testing was performed under conditions similar to those anticipated in chronic in-situ configurations wherein radio-frequency telemetry was used to deliver power and configuration parameters to the device thus avoiding the passage of wires through tissue in order to communicate to the implant circuit. The results of the testing indicate that the circuit is indeed capable of eliciting physiological responses in the animal and evidence is present that these responses could be elicited in patterned form. Further work undertaken includes the development of surgical methods for implantation, and application of the prosthesis circuit in functional electronic stimulation.