Reflex Training for Neuropathic Pain in Spinal Cord Injury
Recruiting in Palo Alto (17 mi)
Overseen byAiko Thompson, PhD
Age: 18+
Sex: Any
Travel: May Be Covered
Time Reimbursement: Varies
Trial Phase: Academic
Recruiting
Sponsor: Medical University of South Carolina
Disqualifiers: Motoneuron injury, Cardiac condition, Pregnancy, others
No Placebo Group
Approved in 1 Jurisdiction
Trial Summary
What is the purpose of this trial?
The purpose of the second part of the study is to examine the effect of reflex training in the leg to decrease neuropathic pain. For this, the researchers are recruiting 15 individuals with neuropathic pain due to spinal cord injury to participate in the reflex training procedure. The study involves approximately 50 visits with a total study duration of about 6.5 months (3 months for baseline and training phases followed by 1 month and 3 month follow-up visits).
Will I have to stop taking my current medications?
The trial requires that you keep taking your current medications without any changes for at least 3 months. If you are on anti-spasticity medication, you can continue using it as usual.
What data supports the effectiveness of the treatment Operant Conditioning of Cutaneous Reflexes for neuropathic pain in spinal cord injury?
Research on operant conditioning of spinal reflexes shows promising results in both animals and humans, indicating that this approach can help modify reflex behaviors through brain and spinal cord plasticity. This suggests potential benefits for managing neuropathic pain in spinal cord injury patients.12345
Is reflex training for neuropathic pain in spinal cord injury safe?
Research on reflex training, also known as operant conditioning of spinal reflexes, has been conducted in animals and humans, showing promising results without significant safety concerns. Studies have demonstrated that this method can safely modify reflexes in people with spinal cord injuries, suggesting it is generally safe for human use.46789
How does the Reflex Training Procedure treatment differ from other treatments for neuropathic pain in spinal cord injury?
The Reflex Training Procedure is unique because it uses operant conditioning to modify spinal reflexes, promoting plasticity (the ability to change and adapt) in the nervous system, which can improve motor function and potentially reduce pain. Unlike traditional treatments that may rely on medication, this approach focuses on retraining the body's reflex pathways to enhance recovery.18101112
Eligibility Criteria
This trial is for individuals with neuropathic pain in the lower leg due to spinal cord injury. They must be stable over a year post-injury, able to stand for at least 3 minutes, and on steady medication for 3 months. Excluded are those with motoneuron injuries, heart conditions, cognitive impairments or complete lack of sensation around the foot.Inclusion Criteria
My neuropathic pain affects my lower leg.
My spinal cord injury has been stable for over a year.
My current medication will stay the same for the next 3 months.
See 2 more
Exclusion Criteria
I use electrical stimulation on my leg every day.
I cannot feel anything in my foot.
I have severe nerve pain or tingling that is not under control.
See 5 more
Trial Timeline
Screening
Participants are screened for eligibility to participate in the trial
2-4 weeks
Baseline
Participants undergo baseline assessments including cutaneous reflex examination and sensation assessment
3 months
6 visits (in-person)
Conditioning
Participants complete 30 conditioning sessions to alter cutaneous reflexes and reduce neuropathic pain
3 months
30 visits (in-person)
Follow-up
Participants are monitored for safety and effectiveness after treatment
4 months
2 visits (in-person)
Treatment Details
Interventions
- Operant Conditioning of Cutaneous Reflexes (Behavioral Intervention)
Trial OverviewThe study tests reflex training aimed at reducing neuropathic pain after spinal cord injury. It involves about 50 sessions over roughly 6.5 months including baseline assessment, training phase and follow-up visits at one month and three months post-training.
Participant Groups
1Treatment groups
Experimental Treatment
Group I: Operant Conditioning of Cutaneous ReflexesExperimental Treatment1 Intervention
Each participant completes 6 baseline sessions and 30 conditioning sessions. In each of the 30 conditioning sessions, while the participant is standing nerves in the lower leg and ankle are stimulated to activate the reflex. The participant attempts to change the reflex activity based on visual feedback. In this way the cutaneous reflex (skin reflex) will be changed to decrease neuropathic pain resulting from spinal cord injury.
Find a Clinic Near You
Research Locations NearbySelect from list below to view details:
Medical University of South CarolinaCharleston, SC
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Who Is Running the Clinical Trial?
Medical University of South CarolinaLead Sponsor
References
Longitudinal study of wind-up responses after graded spinal cord injuries in the adult rat. [2013]The main objectives of this work were to evaluate the development of neuropathic pain after spinal cord injuries of different severities, and to assess changes in central excitability and plasticity by means of wind-up responses and withdrawal reflexes.
A novel affective-motivational-based Overground System for detecting spinal cord injury-associated thermal and mechanical hypersensitivity in rats. [2019]Preclinical research for neuropathic pain has depended primarily on the use of behavioural nociceptive testing that is sensory-discriminatory-based and reflexive in nature. This can be particularly problematic in spinal cord injury (SCI)-associated neuropathic pain research where hyperreflexia may develop thus confounding interpretation of reflexive responses as pain symptoms. To address this, we have designed an affective-motivational-based Overground System that has interchangeable floors to allow examination of nociceptive behaviours in response to mechanical and cold stimuli prior to and following spinal cord injury.
Promoting Gait Recovery and Limiting Neuropathic Pain After Spinal Cord Injury. [2018]Most persons living with a spinal cord injury experience neuropathic pain in the months following their lesion, at the moment where they receive intensive gait rehabilitation. Based on studies using animal models, it has been proposed that central sensitization in nociceptive pathways (maladaptive plasticity) and plasticity related to motor learning (adaptive plasticity) share common neural mechanisms and compete with each other. This article aims to address the discrepancy between the growing body of basic science literature supporting this hypothesis and the general belief in rehabilitation research that pain and gait rehabilitation represent two independent problems. First, the main findings from basic research showing interactions between nociception and learning in the spinal cord will be summarized, focusing both on evidence demonstrating the impact of nociception on motor learning and of motor learning on central sensitization. Then, the generalizability of these findings in animal models to humans will be discussed. Finally, the way potential interactions between nociception and motor learning are currently taken into account in clinical research in patients with spinal cord injury will be presented. To conclude, recommendations will be proposed to better integrate findings from basic research into future clinical research in persons with spinal cord injury.
Operant conditioning of spinal reflexes: from basic science to clinical therapy. [2022]New appreciation of the adaptive capabilities of the nervous system, recent recognition that most spinal cord injuries are incomplete, and progress in enabling regeneration are generating growing interest in novel rehabilitation therapies. Here we review the 35-year evolution of one promising new approach, operant conditioning of spinal reflexes. This work began in the late 1970's as basic science; its purpose was to develop and exploit a uniquely accessible model for studying the acquisition and maintenance of a simple behavior in the mammalian central nervous system (CNS). The model was developed first in monkeys and then in rats, mice, and humans. Studies with it showed that the ostensibly simple behavior (i.e., a larger or smaller reflex) rests on a complex hierarchy of brain and spinal cord plasticity; and current investigations are delineating this plasticity and its interactions with the plasticity that supports other behaviors. In the last decade, the possible therapeutic uses of reflex conditioning have come under study, first in rats and then in humans. The initial results are very exciting, and they are spurring further studies. At the same time, the original basic science purpose and the new clinical purpose are enabling and illuminating each other in unexpected ways. The long course and current state of this work illustrate the practical importance of basic research and the valuable synergy that can develop between basic science questions and clinical needs.
Spinal-, brainstem- and cerebrally mediated responses at- and below-level of a spinal cord contusion in rats: evaluation of pain-like behavior. [2021]Pain is a frequent consequence of spinal cord injury (SCI) which may profoundly impair the patients' quality of life. Valid experimental models and methods are therefore desirable in the search for better treatments. Usually, experimental pain assays depend on stimulus-evoked withdrawal responses; however, this spinal-mediated reflex response may be particularly problematic when evaluating below-level SCI pain due to the development of hyperactive reflex circuitries. In this study, we applied and compared assays measuring cold (acetone), static (von Frey filaments), and dynamic mechanical (soft brush) hypersensitivity at different levels of the neuroaxis at and below the level of injury in a rat model of SCI. We induced an experimental SCI (MASCIS 25 mm weight-drop) and evaluated the development of spinal reflexes (withdrawal), spinal-brainstem-spinal reflexes (licking, guarding, struggling, vocalizing, jumping, and biting) and cerebral-dependent behavior (place escape/avoidance paradigm (PEAP)). We demonstrated increased brainstem reflexes and cerebrally mediated aversive reactions to stimuli applied at the level of SCI, suggesting development of at-level evoked pain behavior. Furthermore, stimulation below-level increased innate reflex responses without increasing brainstem reflexes or aversive behavior in the PEAP, suggesting development of the spasticity syndrome rather than pain-like behavior. While spinal reflex measures are acceptable for studying changes in the spinal reflex pathways and spinal cord, they are not suited as nociceptive behavioral measures. Measuring brainstem organized responses eliminates the bias associated with the spastic syndrome, but pain requires cortical involvement. Methods depending on cortical structures, as the PEAP, are therefore optimal endpoints in animal models of central pain.
The simplest motor skill: mechanisms and applications of reflex operant conditioning. [2021]Operant conditioning protocols can change spinal reflexes gradually, which are the simplest behaviors. This article summarizes the evidence supporting two propositions: that these protocols provide excellent models for defining the substrates of learning and that they can induce and guide plasticity to help restore skills, such as locomotion, that have been impaired by spinal cord injury or other disorders.
Operant conditioning of spinal stretch reflexes in patients with spinal cord injuries. [2022]Hyperactive spinal stretch reflexes (SSRs) often occur with spinal cord injuries (SCI). These altered SSRs may impair movement. Recent studies in monkeys and human subjects have indicated that the magnitude of SSRs can be modulated using operant conditioning. The purpose of this study was to determine whether hyperactive biceps brachii SSRs could be operantly conditioned downward. Seventeen chronic (> 1 year postlesion) spinal cord-injured patients participated. Subjects were trained to keep biceps background (prestretch) electromyographic (EMG) activity and elbow angle at predetermined levels prior to having the elbow rapidly extended by a torque motor to elicit the biceps SSR. All subjects participated in six baseline sessions over a 2-week period. Then, subjects were randomly assigned to either control or training groups for the next 24 sessions over an 8-week period. By the end of the study, training subjects had significantly reduced biceps SSRs (t test, P 0.05). The reduced SSRs persisted for up to 4 months following cessation of training. The results of this study support the hypothesis that hyperactive SSRs can be operantly conditioned downward in SCI patients.
Targeted neuroplasticity for rehabilitation. [2018]An operant-conditioning protocol that bases reward on the electromyographic response produced by a specific CNS pathway can change that pathway. For example, in both animals and people, an operant-conditioning protocol can increase or decrease the spinal stretch reflex or its electrical analog, the H-reflex. Reflex change is associated with plasticity in the pathway of the reflex as well as elsewhere in the spinal cord and brain. Because these pathways serve many different behaviors, the plasticity produced by this conditioning can change other behaviors. Thus, in animals or people with partial spinal cord injuries, appropriate reflex conditioning can improve locomotion. Furthermore, in people with spinal cord injuries, appropriate reflex conditioning can trigger widespread beneficial plasticity. This wider plasticity appears to reflect an iterative process through which the multiple behaviors in the individual's repertoire negotiate the properties of the spinal neurons and synapses that they all use. Operant-conditioning protocols are a promising new therapeutic method that could complement other rehabilitation methods and enhance functional recovery. Their successful use requires strict adherence to appropriately designed procedures, as well as close attention to accommodating and engaging the individual subject in the conditioning process.
Afferent stimulation inhibits abnormal cutaneous reflex activity in patients with spinal cord injury spasticity syndrome. [2018]Tibialis Anterior (TA) cutaneous reflex (CR) activity evoked following cutaneous stimulation of the plantar (Pl) surface (Pl-TA CR) has demonstrated hyperreflexia and damage of inhibitory mechanisms in subjects with spinal cord injury (SCI) and spasticity.
Analgesic effect of paired associative stimulation in a tetraplegic patient with severe drug-resistant neuropathic pain: a case report. [2021]There is no effective evidence-based non-pharmacological treatment for severe neuropathic pain after spinal cord injury (SCI). Paired associative stimulation (PAS) has been used in motor rehabilitation of patients after SCI. In the SCI-PAS protocol for tetraplegic patients, peripheral and central nerve tracts are activated with subject-specific timing, such that ascending and descending signals appear simultaneously at the cervical level. The effect on motor rehabilitation is thought to arise via strengthening of cervical upper and lower motoneuron synapses. We have observed an analgesic effect of PAS on mild-to-moderate neuropathic pain in tetraplegic patients receiving PAS for motor rehabilitation. Here, we applied PAS to a patient with severe drug-resistant neuropathic pain.
Modulation in spinal circuits and corticospinal connections following nerve stimulation and operant conditioning. [2020]Neural plasticity occurs throughout adult life. In healthy individuals, different spinal pathways are differently modulated during different daily activities. Drastic changes to nervous system activity and connections caused by injuries or diseases alter spinal reflexes, and this is often related to disturbed motor functions. In both health and disease, spinal reflexes are subject to substantial modifications. Plasticity in supraspinal descending connections is even more remarkable; corticospinal connectivity has been shown to be extremely plastic. In this session, we describe two approaches for possibly improving recovery after central nervous system (CNS) lesions. They are very different, but both involve repetitive nerve stimulation and CNS plasticity. The first approach is functional electrical stimulation (FES) of the common peroneal nerve, which has been used to treat foot drop in patients with CNS lesions. The second approach is operant conditioning of a spinal reflex. Spinal reflex operant conditioning studies in animal models have shown plastic changes in spinal cord neurons associated with this form of learning and improved locomotor function in incomplete spinal cord injured rats. Thus, reflex conditioning might be a robust approach to inducing plasticity at spinal and supraspinal levels. As a first step in establishing this approach and characterizing its effects in the human adult CNS, we are currently investigating the extent and time course of operant conditioning of the soleus H-reflex in healthy subjects. In results to date, all subjects (n=5) have changed reflex size in the correct direction to various degree (16-36%) over 2-3 months of conditioning, indicating possibility that H-reflex conditioning can occur in humans. At the same time, the substantial inter-subject variation in the time course and extent of conditioning suggest that additional data are needed to establish its principal features. We hope that studying modulation and modification o- f the CNS by different approaches will help us further understand the plasticity of the human adult nervous system.
Noxious radiant heat evokes bi-component nociceptive withdrawal reflexes in spinal cord injured humans-A clinical tool to study neuroplastic changes of spinal neural circuits. [2023]Investigating nocifensive withdrawal reflexes as potential surrogate marker for the spinal excitation level may widen the understanding of maladaptive nociceptive processing after spinal cord injury (SCI). The aim of this prospective, explorative cross-sectional observational study was to investigate the response behavior of individuals with SCI to noxious radiant heat (laser) stimuli and to assess its relation to spasticity and neuropathic pain, two clinical consequences of spinal hyperexcitability/spinal disinhibition. Laser stimuli were applied at the sole and dorsum of the foot and below the fibula head. Corresponding reflexes were electromyography (EMG) recorded ipsilateral. Motor responses to laser stimuli were analyzed and related to clinical readouts (severity of injury/spasticity/pain), using established clinical assessment tools. Twenty-seven participants, 15 with SCI (age 18-63; 6.5 years post-injury; AIS-A through D) and 12 non-disabled controls, [non-disabled controls (NDC); age 19-63] were included. The percentage of individuals with SCI responding to stimuli (70-77%; p < 0.001), their response rates (16-21%; p < 0.05) and their reflex magnitude (p < 0.05) were significantly higher compared to NDC. SCI-related reflexes clustered in two time-windows, indicating involvement of both A-delta- and C-fibers. Spasticity was associated with facilitated reflexes in SCI (Kendall-tau-b p ≤ 0.05) and inversely associated with the occurrence/severity of neuropathic pain (Fisher's exact p < 0.05; Eta-coefficient p < 0.05). However, neuropathic pain was not related to reflex behavior. Altogether, we found a bi-component motor hyperresponsiveness of SCI to noxious heat, which correlated with spasticity, but not neuropathic pain. Laser-evoked withdrawal reflexes may become a suitable outcome parameter to explore maladaptive spinal circuitries in SCI and to assess the effect of targeted treatment strategies. Registration: https://drks.de/search/de/trial/DRKS00006779.