Understanding and Treating Phantom Limb Pain: A Neurotechnological and Neuroscientific Perspective
Doctoral thesis, 2025
Phantom limb pain (PLP) affects up to 80% of amputees, remains difficult to treat, and is often associated with maladaptive cortical reorganization. This dissertation investigates plasticity-guided interventions that target abnormal sensorimotor processing through a unified framework combining transcranial direct current stimulation (tDCS), sensory discrimination training, and phantom sensorimotor execution (imagery and active movement). First, a systematic review of PLP and tDCS literature (Article I) establishes the therapeutic potential of neuromodulation while identifying gaps in mechanistic understanding. Further, controlled experimental work in able-bodied individuals (Articles II and III) demonstrates dissociable effects of task-specific sensory training on somatosensory plasticity. Discrimination-based training improved spatial acuity (two-point discrimination) in the stimulated skin areas (p = 0.047) with effects sustained at follow-up, while the control skin areas showed delayed yet comparable improvement. In contrast, detection sensitivity (monofilament force thresholds) demonstrated short-term state changes without persistent effects, suggesting distinct plasticity mechanisms: fine spatial discrimination engages lasting receptive-field sharpening, whereas detection sensitivity reflects transient excitability modulation. Concurrently, anodal tDCS enhanced motor learning in a cross-over study (Article IV) with the non-dominant limb showing a 28% increase in motor performance completion rate (p = 0.023), indicating mechanisms relevant to prosthesis control. Building on these mechanistic insights, a clinical protocol integrating tDCS with mindful sensor and motor training (Article V) is proposed for individuals with PLP to promote durable somatosensory map refinement and evaluate pain reduction. Collectively, this work introduces an integrated neuromodulatory and behavioral framework by demonstrating how task-specific sensory training and motor training interact with sensory acuity and motor learning, respectively, and potentially alleviate PLP. Rigorous validation through a clinically balanced trial design that controls for amputation level, pain severity, and demographic factors will be essential to confirm mechanism translation and achieve targeted and lasting relief from PLP.
motor cortex
Phantom limb pain
cortical reorganization
pain mechanisms
system neuroscience
precision medicine
somatosensory cortex
neuroplasticity
transcranial direct current stimulation
mirror therapy
sensorimotor training
Author
Shahrzad Damercheli
Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems
Imagine losing a limb but still feeling it and sometimes painfully. For many amputees, this phantom limb pain feels as if the missing hand or foot is cramping, burning, or frozen in place. Up to 80% of people who lose a limb experience it yet doctors still struggle to treat it effectively.
My research looks at the problem from the brain’s perspective. After an amputation, the brain’s internal “map” of the body becomes confused, and it continues to expect signals from the missing limb. This mismatch in communication may be what causes the pain in the missing limb. But because the brain is plastic (meaning it can rewire and adapt) it can also be retrained.
I explored ways to guide this plasticity using a combination of gentle brain modulation, tactile exercises that sharpen touch, and movements of the missing limb; yes, it can still feel moveable. The studies show that tactile exercises help refine the brain’s touch maps, while brain modulation enhances motor learning. Together, these methods support the restoration of healthy connections between the brain and body.
Building on these findings, I developed a therapy program that combines brain stimulation with mindful sensorimotor exercises. The goal is to help the brain “update” its body map, reduce confusion, and ultimately ease phantom pain. This work points toward a future where technology and training work hand in hand to help people not just live with limb loss but live comfortably again.
My research looks at the problem from the brain’s perspective. After an amputation, the brain’s internal “map” of the body becomes confused, and it continues to expect signals from the missing limb. This mismatch in communication may be what causes the pain in the missing limb. But because the brain is plastic (meaning it can rewire and adapt) it can also be retrained.
I explored ways to guide this plasticity using a combination of gentle brain modulation, tactile exercises that sharpen touch, and movements of the missing limb; yes, it can still feel moveable. The studies show that tactile exercises help refine the brain’s touch maps, while brain modulation enhances motor learning. Together, these methods support the restoration of healthy connections between the brain and body.
Building on these findings, I developed a therapy program that combines brain stimulation with mindful sensorimotor exercises. The goal is to help the brain “update” its body map, reduce confusion, and ultimately ease phantom pain. This work points toward a future where technology and training work hand in hand to help people not just live with limb loss but live comfortably again.
Subject Categories (SSIF 2025)
Nanotechnology for Electronic Applications
Rehabilitation Medicine
Neurosciences
Physiotherapy
Neurology
Other Medical Engineering
DOI
10.63959/chalmers.dt/5768
ISBN
978-91-8103-311-3
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5768
Publisher
Chalmers
EA salen, Hörsalsvägen 11, Chalmers
Opponent: Catherine Mercier, Laval University, Canada