Investigating Phantom Motor Execution as treatment of Phantom Limb Pain
Doktorsavhandling, 2021

Phantom Limb Pain (PLP) is commonly suffered by people with amputations and even though it has been studied for centuries, it remains a mysterious object of debate among researchers. For one thing, despite the vast number of proposed PLP treatments, no therapy has so far proved to be reliably effective. For another, studies attempting to provide a mechanistic explanation of the condition have produced mixed and inconsistent results, thus providing unreliable guidance for devising new treatment approaches.

Phantom Motor Execution (PME) – exertion of voluntary phantom limb movements – aims at restoring control over the phantom limb and the exercise of such control has been hypothesized to reverse neural changes implicated in PLP. Preliminary evidence supporting this hypothesis has been provided by clinical investigations on upper limb amputees. The main purpose of this doctoral thesis was to provide high quality and unbiased evidence for the use of PME as a treatment of PLP, by probing its efficacy with a Randomized Controlled Trial (RCT) on both upper and lower limb amputees. However, the implementation of this clinical investigation required of additional technology development related the extraction of motor volition via Myoelectric Pattern Recognition (MPR). In practice, this doctoral work consisted in the extension of PME technology to lower limb amputations by proposing and validating a new and more user-friendly recording method to acquire myoelectric signals. The use of PME was then shown to be efficacious in relieving PLP even in the lower limb population with a case study.

Another necessity for providing unbiased evidence was to ensure that the highest standards were met when designing, conducting, analysing and reporting the results of the RCT. For this reason, the protocol for the RCT and the prospective Statistical Analysis Plan (SAP) were designed and published. The RCT was established as an international, multi-center effort in 2017 and it is expected to reach its conclusion in September 2021. Preliminary results of the RCT regarding the primary outcome showed reduction of PLP above what is considered clinically relevant, and whereas a higher reduction was obtained with PME, this was not statistically significant over the control treatment. The available evidence at this stage indicates that the RCT will not be able to rule out the role of contextual factors other than PME in providing pain relief.

Having at hand a way to alleviate PLP provided a unique opportunity to investigate and identify its neural correlates, therefore this became a secondary aim of this thesis. In particular, patients suffering from PLP were followed regarding their pain trajectory through the therapy and brain imaging studies with functional Magnetic Resonance Imaging (fMRI) and electroencephalography (EEG) were performed. The present doctoral thesis reports part of this work by showing the early results of a cross-sectional study on the EEG correlates of PLP. The results show that it is possible to use machine-learning techniques to discriminate EEG recorded from patients with and without PLP. The findings further point to this technique as a promising target for future longitudinal research aiming at elucidating the neural mechanisms underlying PLP.

Phantom Limb Pain

EEG.

Phantom Motor Execution

Randomized Controlled Trial

Amputation

Phantom Limb Sensations

Opponent: Professor Jack Tsao, University of Tennessee, USA

Författare

Eva Lendaro

Chalmers, Elektroteknik, System- och reglerteknik, Bionik

Differential Activation of Biceps Brachii Muscle Compartments for Human-Machine Interfacing

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS,; Vol. 2018-July(2018)p. 4705-4709

Paper i proceeding

Seamless Integrated Textrode-Band for Real-time Lower Limb Movements Classification to Facilitate Self-Administrated Phantom Limb Pain Treatment

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS,; (2019)p. 1753-1756

Paper i proceeding

Lendaro E., Earley E. J., Ortiz Catalan - Statistical analysis plan for an international, double-blind, randomized controlled clinical trial on the use of phantom motor execution as a treatment for phantom limb pain.

Lendaro E., Balouji E., Baca K., Sheikh M. A., Ortiz-Catalan M- Common Spatial Pattern EEG decomposition for Phantom Limb Pain detection.

After amputation of a limb, most people report vivid sensations of the missing body part. Some can even move their missing foot or hand as if it were still there. For many amputees, though, these sensations are painful. This type of pain is known as Phantom Limb Pain (PLP) and is a considerable problem impacting a person’s overall life and well-being.

Why do people experience PLP? Even though it has been studied for centuries, this remains an unresolved question since current ideas on its origin cannot fully explain the clinical findings. Unfortunately, this lack of understanding translates in the fact that at present no effective PLP treatment is available.

More recently it has been proposed that exercising voluntary movements of the phantom limb could be an effective way to treat PLP. This treatment approach has been named Phantom Motor Execution (PME) and has been tested with non-controlled studies on upper limb amputees These studies however could not exclude that the pain relief reported by the patients was due to the placebo effect or factors other than the proposed treatment.

The main objective of this thesis was to test PME with a double-blind randomized controlled trial (RCT), which is considered as the gold standard for the evaluation of new treatment interventions. In this RCT, PME was tested against Phantom Motor Imagery where patients just imagine their phantom limb moving without exercising movement. During this investigation, patients in both groups got significantly better and the amount of pain relief was similar for both treatment approaches. These results are important because they tell us that the execution of phantom limb movements is probably not the main reason for the observed pain reduction. However, this also means that more research is needed in order to rule out the placebo effect.

Ämneskategorier

Medicinteknik

ISBN

978-91-7905-543-1

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5010

Utgivare

Chalmers tekniska högskola

Online

Opponent: Professor Jack Tsao, University of Tennessee, USA

Mer information

Senast uppdaterat

2021-09-16