An interventional study of Trans Direct-Cranial Stimulation (tDCS) and Mirror therapy in Phantom Limb Pain After Amputation, sponsored by University of Haifa. Recruiting at 3 sites in Israel. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-09-08.
Sponsored by University of Haifa · Not applicable, Interventional, and Treatment
Background: Most amputees experience phantom limb pain (PLP), for years after amputation. Virtually all PLP research to date has focused on the mechanisms of chronic PLP, ignoring the mechanisms of chronification. This research project will focus on combined neuromodulatory interventions of mirror therapy (MT) and trans direct-cranial stimulation (tDCS), applied for the first time at the acute state of PLP, with an aim to prevent its chronification and chronicity. In PLP, maladaptive plasticity associated with sensory deafferentation following an amputation is one of the contributors for excessive pain.
MT is a well-accepted yet limited option, which is thought to counterbalance abnormal plasticity. tDCS is an emerging approach believed to affect the membrane potential and activity threshold of cortical neurons. tDCS analgesic effectiveness, however, is mild and short, rendering it a noneffective stand-alone treatment. The researchers' objectives are to investigate whether the combined therapy of MT and tDCS will prevent chronic PLP and improve its related clinical characteristics. In addition, the researchers will investigate the behavioral manifestations effects of the combined treatment. The investigators expect that the combined treatment applied at the acute stage of PLP will have synergistic effects on PLP intensity and thus avert its chronification. In addition, it will reduce phantom sensations, and negative affect, and will improve the sense of body ownership and agency and endogenous inhibition efficiency.
Research design: This randomized-controlled double-blinded study will be held at Israel's 3 largest rehabilitation centers. The study consists of 3 randomized patient arms (36 in each): (1) no-intervention, natural-course group; (2) MT + sham tDCS; (3) MT + real tDCS.
MT and tDCS neuromodulatory interferences will be self-administered and consist of 20 sessions, completed during 4 weeks. The researchers outcome measures include: primary outcome: pain intensity, network-related behavioral markers, and amputation-related clinical characteristics. The data gathered will be collected at 5 timepoints.
Research novelty and innovation: The researchers proposed model will provide insights on the prevention of PLP and, potentially, other neurological pathologies involving the dysfunction of sensory systems and integration and body perception.
Approximately 80% of amputees experience PLP, often severe, for years after amputation and most amputees will experience phantom limb sensations, including kinetic, proprioceptive (i.e. feeling of length or volume) and exteroceptive sensations (e.g. touch, pressure, itching). Treatment options for PLP have generally been limited, and there is no clear consensensus on the optimal treatment regimen. In PLP maladaptive plasticity associated with sensory defferentation following an amputation is one of the contributors for excessive pain.
This research project will focus on combined known neuromodulatory interventions of MT and tDCS, applied for the first time at the acute state of PLP in traumatic and non-traumatic amputees, with an aim to prevent maladaptive plasticity associated with PLP chronification and chronicity.
MT and tDCS related literature is based on data collected from patients who already developed PLP for years, before enrollment in the study. The investigators suggest that tDCS and MT applied at the acute stage of PLP will have synergistic effects on PLP intensity and thus avert its chronification. The researchers rationale is based on recent evidence from basic neuroscience on the phantom perception of other non-pain sensory modalities and the neuroscience of chronification of other pain conditions.
The fundamental mechanism for PLP suggests initial changes at the peripheral nervous system, including loss of afferent somatosensory input and exaggerated input from ectopic activity generated in the axotomized nociceptive neurons. Subsequent central changes include thalamic and cortical functional reorganization in the sensorimotor cortex, manifested as maladaptive cortical reorganization: an "invasion" of neighboring areas to the representation of the amputated limb.
Evidence in the literature suggests that the 2 noninvasive neuromodulation techniques- MT and tDCS applied to motor cortex (M1-tDCS)-may interfere with the maladaptive plasticity accompanied PLP and respectively will reduced PLP and negative affects. With MT, the moving, healthy limb reflected in the mirror makes the missing limb appear intact and functioning. The analgesic effect attributed to MT likely results from enhanced coherence between sensory feedback and motor command, counterbalancing the amputation-induced maladaptive neuroplasticity. In chronic PLP, MT conducted over several weeks reversed sensorimotor reorganization and reduced PLP intensity, suggesting a correlation between reorganization and PLP. MT also modulates the activity of the multisensory integration network to resolve the post-amputation perceptual incongruence, and modulates the activity of networks which help integrate the perceptual and motor areas to affect the sense of body ownership and agency. Indeed, an improved sense of agency has been reported after MT. Yet, these studies examined patients with chronic PLP and found mild analgesic effects. The investigators argue that MT applied at the acute PLP stage may interfere with the maladaptive plasticity of the multisensory integration network, and accordingly will improve the sense of agency and ownership over phantom limb, and reduce PLP intensity.
Motor areas (M1) stimulation through neuromodulation techniques alters the functional connectivity between brain areas, thus modulating brain networks rather than just affecting the local stimulation target. Specifically, it modulates ascending sensory input; brain areas of the fronto-striatal circuit, limbic brain areas, and midbrain nuclei involved in descending pain inhibition. Thus, tDCS applied to M1 may modulate brain areas composed of the subcircuits connected to mPFC and the salience network , i.e., areas presumably involved in pain chronification and chronicity. Although the electrical current only affects the cortex below the electrode, remote cortical and subcortical connected areas are affected as well. Previous work has described two putative analgesic effects of anodal M1 tDCS: 1) modulation of thalamic activity by descending corticothalamic pathways originating in the primary motor cortex and 2) inhibition of the primary somatosensory cortex via corticocortical pathways. Clinically, tDCS has immediate, sustained, and long-term analgesic effects. The investigators expect that M1-tDCS will restore the function of the mPFC and the salience network, and will thus improve endogenous pain inhibition, reduce PLP intensity and negative affect, yet will not eliminate pain chronification.
Because MT and tDCS, when given alone, produced only mild analgesic effects, their clinical adoption was limited. Soler et al. were the first to study the analgesic effects of a combination of visual illusion (similar to MT) and tDCS on neuropathic pain after spinal cord injury. The investigators found that the combination reduced pain intensity significantly more than did any single intervention; this effect lasted at least 12 weeks post-treatment. Gunduz et al. found no cumulative effect of MT and tDCS on patients with limb amputation. Whether studies examined the clinical effects of MT, tDCS, or a combination of both, the entire literature is based on data collected from patients with chronic PLP and did not consider time since amputation as an exclusion criterion. Therefore, time since amputation might be a key factor in the efficacy of these treatments. In patients who had only recently undergone amputation, the abnormal neuroplasticity might not yet be fixated; therefore, counterbalancing it should be easier. A preliminary study from Treister's lab is the first to show that a combination of MT and tDCS applied at the acute stage of PLP can prevent PLP chronification. Considering Treister's preliminary results and given that MT and M1-tDCS exert neuroplastic effects on different neural networks with similar outcome (i.e., PLP intensity), the investigators expect that a combination of MT and tDCS applied at the acute stage of PLP will have synergistic effects on PLP intensity and thus avert its chronification.
163 studies on the registry are indexed under Phantom Limb; 35 are open to participants now.
This study's planned enrollment of 108 is above the median of 30 across 125 interventional studies indexed under Phantom Limb.
Browse Phantom Limb studies →University of Haifa is the lead sponsor of 105 studies on the registry; 27 are open to participants now.
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Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
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Both MT and tDCS neuromodulatory interferences (separately or combined) will consist of 20 sessions, each lasting 20 min, completed during 4 weeks, once daily (excluding weekends). The neuromodulatory interferences will be self-administered by the participants. The first 2 sessions (at the clinic) will include training to familiarize participants (and their primary caregivers) with the procedure and to instruct them on the self-administering techniques that the researchers and others successfully employed. After training, neuromodulatory interferences will be applied either at the clinic (during hospitalization) or at home (after discharge). This approach promotes participants' retention and reduces dropouts, especially when the study constitutes multiple sessions.
Device: Trans Direct-Cranial Stimulation (tDCS) · Behavioral: Mirror therapy
Both MT and tDCS neuromodulatory interferences (separately or combined) will consist of 20 sessions, each lasting 20 min, completed during 4 weeks, once daily (excluding weekends). The sham tDCS will be identical to the real tDCS, except no current will be applied. However, as recommended, during the first and last 30 sec, the current will be ramped up to 1.5 mA and immediately back to 0 to induce scalp sensations similar to those in real tDCS, further supporting blinding
Device: Trans Direct-Cranial Stimulation (tDCS) · Behavioral: Mirror therapy
The participants will receive the regular treatment regimen at the rehabilitation center, including physical-therapy and pharmacological treatment, without intervention of Mirror-therapy and tDCS.
The tDCS electrodes will be inserted into 5×7 cm (35 cm2) sponges soaked with saline (0.9 M) and placed as follows: anode over the M1 contralateral to the amputated limb (adjusted based on lower/upper amputation), and cathode over the forehead, contralateral to the anode (ipsilateral to amputated limb). Total stimulation duration will be 20 min, with a rise and decline time of 30 sec and stimulus intensity of 1.5 mA for the real tDCS real. The intensity of 1.5 mA is in the midrange of recommended intensities (1-2 mA) and supports successful blinding. The sham tDCS will be identical to the real tDCS, except no current will be applied. However, as recommended, during the first and last 30 sec, the current will be ramped up to 1.5 mA and immediately back to 0 to induce scalp sensations similar to those in real tDCS, further supporting blinding. The Mini-CT tDCS Stimulator device has been developed for home use and allows double-blind administration.
Participants will be seated with a portable mirror between their limbs so that the unaffected limb is reflected in the mirror. The participants will focus their attention on the reflection in the mirror and perform the following movements: plantarflexion and dorsiflexion and inversion and eversion of the foot, flexion and extension of the wrist and ulnar and radial deviation, for lower and upper limp amputates, respectively. The participants will continue performing the 2 sets of movements for 20 minutes (with short intermissions if needed)
A 0-100 VAS of mean pain intensity during one week
completed during 7 days, will be used to capture the weekly average of pain intensity (0 = no pain to 100 = the worst imaginable pain, via pain diary). This data will be used either in its raw, continuous form or as a transformed dichotomous variable, yes/no chronic PLP. A cutoff value of PLP intensity ≤20/100 will be used, because from a clinical perspective, pain intensity ≤20 is considered low and will seldom prompt a request for analgesic treatment.
Time frame: Pain will be compared between baseline and 4 weeks after the end of the 4 weeks intervention (meaning, comparing baseline to timepoint number 3, which is exactly 8 weeks from the end of the baseline week)
Sense of ownership and agency over phantom limb
Sense of ownership and agency over phantom limb will be a behavioral marker for function of the multisensory integration network. It will be evaluated using a self-report questionnaire with demonstrated sensitivity to detect changes after MT. Six of the questionnaire's 8 items (on a 5-point Likert scale) will be used to assess sense of ownership and agency of upper limb and will be adjusted for the lower limb. Mean scores of 3 questions will evaluate the sense of ownership, and 3 others, the sense of agency, as recommended.
Time frame: Sense of ownership and agency over phantom limb will be compared between baseline and 4 weeks after the end of the 4 weeks intervention (meaning, comparing baseline to timepoint number 3, which is exactly 8 weeks from the end of the baseline week)
The Hospital Anxiety and Depression Scale (HADS)
The researchers' marker for function of the fronto-striatal-amygdala circuit, will be assessed via the Hospital Anxiety and Depression Scale (HADS), a self-report 14-item questionnaire focusing on nonphysical symptoms, which measures anxiety and depression, both demonstrated associations with changes in fronto-striatal connectivity. The HADS uses a 0-21 scoring scale, with each item rated on a 4-point Likert scale (0-3). A score of 0-7 is considered normal, 8-10 indicates a mild disorder, 11-14 suggests a moderate disorder, and 15-21 points to a severe disorder.
Time frame: Anxiety and Depression will be compared between baseline and 4 weeks after the end of the 4 weeks intervention (meaning, comparing baseline to timepoint number 3, which is exactly 8 weeks from the end of the baseline week)
The Short Form McGill Pain Questionnaire
The researchers' marker for function of the fronto-striatal-amygdala circuit, will also be assessed via the Short Form McGill Pain Questionnaire, which assesses various affective qualities of pain and has demonstrated validity in neuropathic populations. Four affective descriptors rated on a 0-10 numerical rating scale will be summarized.
Time frame: The Affective qualities of pain will be compared between baseline and 4 weeks after the end of the 4 weeks intervention (meaning, comparing baseline to timepoint number 3, which is exactly 8 weeks from the end of the baseline week)
The Conditioned Pain Modulation (CPM)
Endogenous pain inhibition will be a psychophysical marker for function of the fronto-PAG circuit. It will be evaluated by the conditioned pain modulation (CPM) paradigm, based on the systemic pain-inhibits-pain phenomenon. The conditioning stimulus will be administrated by immersing the palm in a cold-water bath (14°C). The test stimulus applied on the contralateral (to the conditioning stimulus) lower leg will include individually calibrated heat pain stimulus applied for 20 sec, while averaging pain intensity scores on a VAS Scale (0=no pain, 100= the worst imaginable pain) reported at time 0, 10, and 20 sec. CPM is calculated by subtracting pain scores of the test stimulus given alone from those given with the conditioning stimulus, as recommended.
Time frame: The CPM score will be compared between baseline and 4 weeks after the end of the 4 weeks intervention (meaning, comparing baseline to timepoint number 3, which is exactly 8 weeks from the end of the baseline week)
Frequency of PLP paroxysms
Frequency of PLP paroxysms, known to be correlated with PLP intensity or to be affected by neuromodulation techniques applied in PLP, will be evaluated daily for 1 week. Paroxysm will be defined as a period when PLP clearly increases above background pain level; frequency will be evaluated by the average value of the daily score on a 0-100 VAS (0="never during the day" to 100="very frequently").
Time frame: Frequency of PLP paroxysms will be compared between baseline and 4 weeks after the end of the 4 weeks intervention (meaning, comparing baseline to timepoint number 3, which is exactly 8 weeks from the end of the baseline week)
Stump pain
Stump pain, known to be correlated with PLP intensity or to be affected by neuromodulation techniques applied in PLP, will be evaluated daily for 1 week. It will be evaluated by the average value of the daily score on a 0-100 VAS (0="not painful at all" to 100="the worst imaginable pain").
Time frame: Stump pain will be compared between baseline and 4 weeks after the end of the 4 weeks intervention (meaning, comparing baseline to timepoint number 3, which is exactly 8 weeks from the end of the baseline week)
Phantom sensations
Phantom sensations, known to be correlated with PLP intensity or to be affected by neuromodulation techniques applied in PLP, will be evaluated daily for 1 week. It will be evaluated by the average value of the daily score on a 0-100 VAS (0="no sensations" to 100="very intense").
Time frame: Phantom sensations be compared between baseline and 4 weeks after the end of the 4 weeks intervention (meaning, comparing baseline to timepoint number 3, which is exactly 8 weeks from the end of the baseline week)
Telescoping
Telescoping, known to be correlated with PLP intensity or to be affected by neuromodulation techniques applied in PLP, will be evaluated daily for 1 week. Telescoping will be evaluated by the average value of the daily score on a 0-100 VAS (0="no telescoping sensations" to 100="very intense telescoping sensations").
Time frame: Telescoping be compared between baseline and 4 weeks after the end of the 4 weeks intervention (meaning, comparing baseline to timepoint number 3, which is exactly 8 weeks from the end of the baseline week)
Plan to share: Yes
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