PROGRAM

13:00: Opening by the Moderator Andrew James Thomas Stevenson

13:05: PhD lecture by Armita Faghani Jadidi

13:50: Break

14:00: Questions and comments from the Committee

15:30: Questions and comments from the audience at the Moderator’s discretion

16:00 Conclusion of the session by the Moderator

EVALUATION COMMITTEE

The Faculty Council has appointed the following adjudication committee to evaluate the thesis and the associated lecture: 

Jonas Duun-Henriksen, UNEEG™ medical A/S, Alleroed, Denmark
Professor André Mouraux, Institute of Neuroscience, University Catholique de Louvain, Belgium

Chairman:
Associate Professor Laura Petrini Department of Health Science and Technology, Aalborg University

Moderator:
Associate Professor Andrew James Thomas Stevenson Department of Health Science and Technology, Aalborg University

HOW TO PARTICIPATE

The Ph.D. Defense is online via ZOOM.. 

Please click here to participate via Zoom.

ABSTRACT

Following amputation, almost two-thirds of amputees experience painful sensations localized in or around the area of the lost limb, referred to as phantom limb pain (PLP), diminishing the quality of their life. Amputation deprives the nervous system of sensory input leading to anatomical and physiological changes at the peripheral and central levels, contributing to the mechanisms generating PLP. While the underlying mechanisms of PLP are not fully understood, several therapeutic interventions have been suggested with the goal of PLP alleviation. Transcutaneous electrical nerve stimulation (TENS) is one of these approaches as a non-invasive, drug-free pain treatment. To enhance rehabilitation efficacy, the literature has recently laid more focus on alternative temporal stimulation patterns like burst and pulse width modulated (PWM) rather than conventional TENS. However, the mechanism of modulated TENS on the cortical and corticospinal level, which might lead to improvement of the PLP alleviation, is not explored yet. The objective of this Ph.D. project was, therefore, to investigate possible cortical plasticity following modulated TENS.  

The Ph.D. thesis consists of four studies. Studies I-III were carried out in healthy subjects, while a pilot study included one PLP patient. Study I was conducted to compare the effect of modulated TENS patterns with the classical TENS on the corticospinal (CS) activity as maladaptive cortical plasticity has been mentioned to play a major role in PLP. We investigated motor evoked potentials (MEP) evoked by transcranial magnetic stimulation (TMS) for the assessment. The results revealed significant facilitation of CS excitability and expansion of cortical motor map of stimulated muscle following the PWM intervention, which were suggested as the possible desired effects to reduce PLP. In Study II, we utilized somatosensory evoked potentials (SEPs) to investigate the possible alteration in cortical activity at the somatosensory cortex and the perceived sensation by PWM TENS intervention and conducted comparative analysis with induced changes by non-modulated TENS. Our findings showed that suppression of SEP components following the PWM TENS pattern was associated with a higher perceived sensation reduction. In Study III, functional brain network from eight brain areas corresponding to pain and sensation across seven frequency bands was examined. The results demonstrated significant changes in local and global brain network indices following the application of PWM TENS compared to classical TENS. Induced cortical plasticity by PWM TENS in healthy subjects was evaluated in PLP patient over two separate experimental sessions in Study IV, and the finding indicated the same changes in cortical response.

In conclusion, the underlying mechanism of modulated TENS on cortical and corticospinal pathway, and how this may be correlated with pain alleviation were studied. As such, this work provides further evidence for the potentials of PWM TENS as the alternative pattern in PLP treatment.