On the use of Phantom Motor Execution for the treatment of Phantom Limb Pain

Licentiate thesis, 2020

Phantom limb pain (PLP) is a common complaint among amputees and despite having been studied
for centuries, it remains a mysterious object of debate among researcher. To date, a vast number of
ways to treat PLP has been proposed in the literature, however none of them has proven to be
universally effective, thus creating uncertainty on how to operate clinically. The uncertainty is largely
attributable to the scarcity of well conducted randomized controlled trials (RCTs) to prove the efficacy
of PLP treatments.
Phantom Motor Execution (PME) -exertion of voluntary phantom limb movements – aims at restoring
the 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 Licentiate thesis was to
enable a RCT on the use of PME for the treatment of PLP in order to provide robust and unbiased
evidence for clinical practice. However, the implementation and kick-off of this clinical investigation
required to complete few preparatory steps. For example, most amputees and PLP patients have lower
limb amputation, thus PME needed to be adapted and validated for this population. Further, the RCT
protocol needed to be carefully planned and made openly accessible, as per guidelines for conducting
and publishing clinical RCT. Finally, a secondary aim of this thesis emerged with the need of providing
long term relief from PLP to patient. Preliminary evidence seemed to indicate that in order to maintain
pain relief, periodic rehearsal of the phantom motor skills acquired through PME is necessary. This
raised the question of whether it is beneficial and possible to translate the technology from clinic to
home use, question that was explored employing both quantitative and qualitative methods from
engineering, medical anthropology, and user interface design.
The work conducted within this thesis resulted in the extension of PME to lower limb patients by
proposal and validation of a new and more user-friendly recording configuration to record EMG signals.
The use of PME was then shown to be efficacious in relieving PLP with a case study on a patient. The
protocol for the RCT was then designed and published. These two first steps permitted the
establishment of the RCT, which is currently ongoing and expected to close in March 2021. With regard
to the secondary aim of this thesis, the work conducted enabled PME to be used by the patients in the
comfort of their home, while it also allowed investigate the benefits and challenges generally faced
(not only by PME) in the transition from the clinic to home and its effects on treatment adherence. The
work conducted is presented in the three appended publications.
Future work includes the presentation of the results of the RCT. Further, having a way to modulate PLP
is an incredibly useful tool to study the neural basis of PLP. By capitalizing on this tool, we are currently
conducting brain imaging studies using fMRI and electroencephalography that are the main focus of
the work that lies ahead.