Epidural Spinal Cord Stimulation Research Articles

Symptomatic Treatment of Myelopathy.

This article discusses the effects of myelopathy on multiple organ systems and reviews the treatment and management of some of these effects. Recent advances in functional electrical stimulation, epidural spinal cord stimulation, robotics, and surgical techniques such as nerve transfer show promise in improving function in patients with myelopathy. Ongoing research in stem cell therapy and neurotherapeutic drugs may provide further therapeutic avenues in the future. Treatment for symptoms of spinal cord injury should be targeted toward patient goals. If nerve transfer for upper extremity function is considered, the patient should be evaluated at around 6 months from injury to assess for lower motor neuron involvement and possible time limitations of surgery. A patient with injury at or above the T6 level is at risk for autonomic dysreflexia, a life-threatening condition that presents with elevated blood pressure and can lead to emergent hypertensive crisis. Baclofen withdrawal due to baclofen pump failure or programming errors may also be life-threatening. Proper management of symptoms may help avoid complications such as autonomic dysreflexia, renal failure, heterotopic ossification, and fractures.

Ergogenic effects of spinal cord stimulation on exercise performance following spinal cord injury.

Cervical or upper-thoracic spinal cord injury (SCI, ≥T6) often leads to low resting blood pressure (BP) and impaired cardiovascular responses to acute exercise due to disrupted supraspinal sympathetic drive. Epidural spinal cord stimulation (invasive, ESCS) and transcutaneous spinal cord stimulation (non-invasive, TSCS) have previously been used to target dormant sympathetic circuits and modulate cardiovascular responses. This case series compared the effects of cardiovascular-optimised ESCS and TSCS versus sham ESCS and TSCS on modulating cardiovascular responses and improving submaximal upper-body exercise performance in individuals with SCI. Seven males with a chronic, motor-complete SCI between C6 and T4 underwent a mapping session to identify cardiovascular responses to spinal cord stimulation. Subsequently, four participants (two ESCS and two TSCS) completed submaximal exercise testing. Stimulation parameters (waveform, frequency, intensity, epidural electrode array configuration, and transcutaneous electrode locations in the lumbosacral region) were optimised to elevate cardiovascular responses (CV-SCS). A sham condition (SHAM-SCS) served as a comparison. Participants performed arm-crank exercise to exhaustion at a fixed workload corresponding to above ventilatory threshold, on separate days, with CV-SCS or SHAM-SCS. At rest, CV-SCS increased BP and predicted left ventricular cardiac contractility and total peripheral resistance. During exercise, CV-SCS increased time to exhaustion and peak oxygen pulse (a surrogate for stroke volume), relative to SHAM-SCS. Ratings of perceived exertion also tended to be lower with CV-SCS than SHAM-SCS. Comparable improvements in time to exhaustion with ESCS and TSCS suggest that both approaches could be promising ergogenic aids to support exercise performance or rehabilitation, along with reducing fatigue during activities of daily living in individuals with SCI.

Spinal cord stimulation for chronic pain treatment following sacral chordoma resection: illustrative case.

Cancer-related or postoperative pain can occur following sacral chordoma resection. Despite a lack of current recommendations for cancer pain treatment, spinal cord stimulation (SCS) has demonstrated effectiveness in addressing cancer-related pain. A 76-year-old female with a sacral chordoma underwent anterior osteotomies and partial en bloc sacrectomy. She subsequently presented with chronic pain affecting both buttocks and posterior thighs and legs, significantly impeding her daily activities. She underwent a staged epidural SCS paddle trial and permanent system placement using intraoperative neuromonitoring. The utilization of percutaneous leads was not viable because of her history of spinal fluid leakage, multiple lumbosacral surgeries, and previous complex plastic surgery closure. The patient reported a 62.5% improvement in her lower-extremity pain per the modified Quadruple Visual Analog Scale and a 50% improvement in the modified Pain and Sleep Questionnaire 3-item index during the SCS trial. Following permanent SCS system placement and removal of her externalized lead extenders, she had an uncomplicated postoperative course and reported notable improvements in her pain symptoms. This case provides a compelling illustration of the successful treatment of chronic pain using SCS following radical sacral chordoma resection. Surgeons may consider this treatment approach in patients presenting with refractory pain following spinal tumor resection.

Standing Reactive Postural Responses of Lower Limbs With and Without Self-Balance Assistance in Individuals With Spinal Cord Injury Receiving Epidural Stimulation.

Spinal cord epidural stimulation can promote the recovery of motor function in individuals with severe spinal cord injury (SCI) by enabling the spinal circuitry to interpret sensory information and generate related neuromuscular responses. This approach enables the spinal cord to generate lower limb extension patterns during weight bearing, allowing individuals with SCI to achieve upright standing. We have shown that the human spinal cord can generate some standing postural responses during self-initiated body weight shifting. In this study, we investigated the ability of individuals with motor complete SCI receiving epidural stimulation to generate standing reactive postural responses after external perturbations were applied at the trunk. A cable-driven robotic device was used to provide constant assistance for pelvic control and to deliver precise trunk perturbations while participants used their hands to grasp onto handlebars for self-balance support (hands-on) as well as when participants were without support (free-hands). Five individuals with motor complete SCI receiving lumbosacral spinal cord epidural stimulation parameters specific for standing (Stand-scES) participated in this study. Trunk perturbations (average magnitude: 17 ± 3% body weight) were delivered randomly in the four cardinal directions. Participants attempted to control each perturbation such that upright standing was maintained and no additional external assistance was needed. Lower limb postural responses were generally more frequent, larger in magnitude, and appropriately modulated during the free-hands condition. This was associated with trunk displacement and lower limb loading modulation that were larger in the free-hands condition. Further, we observed discernible lower limb muscle synergies that were similar between the two perturbed standing conditions. These findings suggest that the human spinal circuitry involved in postural control retains the ability to generate meaningful lower limb postural responses after SCI when its excitability is properly modulated. Moreover, lower limb postural responses appear enhanced by a standing environment without upper limb stabilization that promotes afferent inputs associated with a larger modulation of ground reaction forces and trunk kinematics. These findings should be considered when developing future experimental frameworks aimed at studying upright postural control and activity-based recovery training protocols aimed at promoting neural plasticity and sensory-motor recovery.

Current strategies for regenerative therapy of spinal cord injury

Spinal cord injury (SCI) is a leading cause of death and severe disability amongst young people. The incidence of SCI is 0.6–1.0 per 10,000 individuals. Unfortunately, there are no effective methods of restoring locomotor function for individuals with severe SCI. To address this issue, exoskeleton technology controlled using BCI is actively being developed for prosthetic locomotion. Despite the lack of encouraging data for severe spinal cord injuries, regenerative technologies continue to hold promise for spinal cord repair. The limited options for regenerating the central nervous system in humans necessitate creating new sources of neural stem cells for regeneration. Reprogramming autologous somatic cells neurologically can effectively serve as such a source [1]. Nevertheless, the constitution of neuroglial progenitors, which are necessary for regenerating damaged axons of the pyramidal tract, still requires clarification [2]. Some interesting efforts are underway to directly reprogram glial cells in situ using a variety of biotechnological approaches [3]. Overcoming or preventing the formation of a harsh scar tissue at the injury site is the key obstacle to successful regeneration therapy for SCI. Various scaffolds are being developed to facilitate axon regeneration, and several gene therapy agents are being tested to either knock down scar formation factors or activate extracellular matrix remodeling and reparative regeneration. Neuromodulation shows promise for SCI treatment. Studies indicate that epidural stimulation of the L2-S1 spinal cord in humans and mammals activates SPG neurons, aiding spinal walking generator functions. A potentially successful treatment approach involves scaffolds with reprogrammed cells and neuromodulation [4].

Consecutive Transcutaneous and Epidural Spinal Cord Neuromodulation to Modify Clinical Complete Paralysis—the Proof of Concept

ObjectiveTo evaluate the effect of transcutaneous (tSCS) and epidural electrical spinal cord stimulation (EES) in facilitating volitional movements, balance, and nonmotor functions, in this observational study, tSCS and EES were consecutively tested in 2 participants with motor complete spinal cord injury (SCI). Participants and MethodsTwo participants (a 48-year-old woman and a 28-year-old man), both classified as motor complete spinal injury, were enrolled in the study. Both participants went through a unified protocol, such as an initial electrophysiological assessment of neural connectivity, consecutive tSCS and EES combined with 8 wks of motor training with electromyography (EMG) and kinematic evaluation. The study was conducted from May 1, 2019, to December 31, 2021. ResultsIn both participants, tSCS reported a minimal improvement in voluntary movements still essential to start tSCS-enabled rehabilitation. Compared with tSCS, following EES showed immediate improvement in voluntary movements, whereas tSCS was more effective in improving balance and posture. Continuous improvement in nonmotor functions was found during tSCS-enabled and then during EES-enabled motor training. ConclusionResults report a significant difference in the effect of tSCS and EES on the recovery of neurologic functions and support consecutive tSCS and EES applications as a potential therapy for SCI. The proposed approach may help in selecting patients with SCI responsive to neuromodulation. It would also help initiate neuromodulation and rehabilitation therapy early, particularly for motor complete SCI with minimal effect from conventional rehabilitation.

Spinal cord stimulation in severe pharmacoresistant restless legs syndrome—two case reports

Restless legs syndrome is a prevalent, sleep-related sensorimotor disorder with relevant impact on the patients’ quality of life. For patients suffering from severe, pharmacoresistant restless legs syndrome, few therapeutic options remain to alleviate symptoms. In this case series, two patients with severe, pharmacoresistant restless legs syndrome were treated with epidural spinal cord stimulation and repeatedly assessed with polysomnography, including sleep structure and periodic limb movements as objective biomarkers not subject to placebo effects, during a 6-month follow-up period. One of the patients experienced excellent short- and long-term efficacy on subjective symptom severity (International RLS Study group rating scale 1 vs. 34 points at 3 months) and objective sleep parameters such as sleep architecture and periodic limb movements during sleep, while the second patient only reported short-term benefits from spinal cord stimulation. Ultimately, both patients opted for removal of the device for inefficacy. Based on the complex pathophysiology of restless legs syndrome and presumed mechanism of action of spinal cord stimulation in chronic pain disorders, we provide a detailed hypothesis on the possible modulating effect of spinal cord stimulation on the key symptoms of restless legs syndrome. Apart from describing a new therapeutic option for pharmacoresistant restless legs syndrome, our findings might also provide further insights into the pathophysiology of the syndrome.

Racial and Ethnic Disparities in Inpatient Interventional Pain Management for Lumbar Radiculopathy

BACKGROUND: Chronic pain is a common reason adults seek care; patients often feel that their pain is inadequately managed. Spine-related pain is the most common chronic pain concern, and lumbar radiculopathy is often the cause. Racial and ethnic disparities in the pharmacologic management of pain are well described, but less is known about these disparities regarding interventional procedures. OBJECTIVE: To study the utilization rates of physical therapy, epidural steroid injection, surgery, and spinal cord stimulation in hospitalized patients with lumbar radiculopathy across different races, ethnicities, and genders. STUDY DESIGN: A retrospective cross-sectional study design. METHODS: The National Inpatient Sample was used to identify 252,790 patients with lumbar radiculopathy, after sample weighting, from 2016-2019. Independent variables were race, ethnicity, age, gender, insurance, geography, year, and severity. Dependent variables were physical therapy, epidural steroid injection, spinal cord stimulator, or surgery (reference group). Conservative management was defined as nonoperative treatment ranging from physical therapy to epidural steroid injection. Data were analyzed with a logistic regression for complex surveys. Regressions were adjusted for age, insurance, geography, and other socioeconomic factors. RESULTS: Most patients were white (78.3%) and received surgery (95.0%). Severe disease was most common among African Americans (9.3%), but was similar across other races, ethnicities, and genders. Medicaid was more common among African Americans and Hispanics. An adjusted analysis showed that African Americans and Hispanics received more epidural steroid injections (odds ratio [OR] = 1.52; 95%CI, 1.3 – 1.8) and (OR = 1.43; 95%CI, 1.1 – 1.8) respectively; and physical therapy (OR = 1.65; 95%CI, 1.1 – 2.5) and (OR = 1.83; 95%CI, 1.2 – 2.8) respectively, than whites compared to surgery. African Americans received a spinal cord stimulator less often than whites compared to surgery (OR = 0.63; 95%CI. 0.4 – 0.9). Women received an epidural steroid injection more frequently than men compared to surgery (OR = 1.29; 95%CI, 1.2 – 1.4). LIMITATIONS: Generalizability is limited because conservative therapies are often outpatient treatments. CONCLUSION: Disparities were observed in lumbar radiculopathy treatment after independent variable adjustment. African Americans received conservative therapy more often than whites despite increased disease severity. Hispanics and women had similar disease severity compared to whites and men, respectively, but received more conservative therapies. Further investigation in outpatient settings is needed to definitively describe these disparities. KEY WORDS: Chronic pain, pain management, back pain, lumbar radiculopathy, epidural steroid injection, spinal cord stimulation, low back surgery, physical therapy, racial disparities, gender disparities

Spinal Cord Epidural Stimulation Improves Lower Spine Sitting Posture Following Severe Cervical Spinal Cord Injury.

Cervical spinal cord injury (SCI) leads to impaired trunk motor control, negatively impacting the performance of activities of daily living in the affected individuals. Improved trunk control with better sitting posture has been previously observed due to neuromuscular electrical stimulation and transcutaneous spinal stimulation, while improved postural stability has been observed with spinal cord epidural stimulation (scES). Hence, we studied how trunk-specific scES impacts sitting independence and posture. Fourteen individuals with chronic, severe cervical SCI with an implanted neurostimulator performed a 5-min tall-sit task without and with trunk-specific scES. Spine posture was assessed by placing markers on five spine levels and evaluating vertical spine inclination angles. Duration of trunk manual assistance was used to assess independence along with the number of independence changes and average independence score across those changes. With scES, the sacrum-L1 inclination and number of independence changes tended to decrease by 1.64 ± 3.16° (p = 0.07; Cohen's d = 0.53) and 9.86 ± 16.8 (p = 0.047; Cohen's d = 0.59), respectively. Additionally, for the participants who had poor sitting independence without scES, level of independence tended to increase by 12.91% [0%, 31.52%] (p = 0.38; Cohen's d = 0.96) when scES was present. Hence, trunk-specific scES promoted improvements in lower spine posture and lower levels of trunk assistance.

Student Competition (Knowledge Generation) ID 1985158

Background Spinal cord injury (SCI) affects locomotion and quality of life. Two spinal cord stimulation approaches are currently under investigation for restoring standing and walking following SCI: epidural spinal cord stimulation (ESCS) and intraspinal microstimulation (ISMS). In ESCS, electrodes are placed on the dura mater and in ISMS, ultrafine wires are inserted into the cord. These modalities likely activate the locomotor regions in the ventral horn through different pathways. Objective The goal of this study is to examine the difference in the distribution of neuronal activation and the type of neurons activated by ESCS and ISMS. Methods The first step was to establish the needed immunohistochemical (IHC) staining protocols. Domestic pigs were divided into naïve (n=2) and positive control (n=1) groups. The naïve control animals were anesthetized for 5 hrs. The positive control animal was anesthetized for 2 hrs and injected with hypertonic saline in hindlimb muscles. The animals were then euthanized, and the spinal cord removed for IHC analysis. Antibodies against cFos, a maker of neuronal activation, and NeuN, a neuronal marker were used. Results Preliminary results indicate that ESCS activates neurons in the dorsal horn with scattered activation in the intermediate and ventral regions. ISMS primarily activates neurons in the intermediate and ventral regions where locomotor-related networks reside. Significance To the best of our knowledge, this is the first time the type and sites of activation of ESCS and ISMS are investigated. This will provide a foundational understanding of the mechanism of action of these stimulation modalities.

Student Competition (Knowledge Generation) ID 1985170

Background/Objectives Functional electrical stimulation (FES)-assisted arm and leg (A&L) cycling is an effective rehabilitative intervention for improving walking following an incomplete spinal cord injury (SCI). The goal of this study was to assess the potential benefits of combining transcutaneous spinal cord stimulation (tSCS) with A&L cycling to potentially improve functional mobility and activities of daily living for persons living with motor complete SCI. Methods This is a case study of a participant with AIS B SCI. The participant has been undergoing FES-assisted A&L cycling training combined with cervical and lumbar tSCS (1 hr/day, 5 days/week) for 37 weeks. Assessments were performed pre-training and every 6 weeks thereafter and include the International Standards for Neurological Classification of SCI (ISNCSCI), time able to stand while assisted, and training load of each exercise session. Results Although there were no changes in the ISNCSCI scores, the duration of assisted standing increased from 10s per-training to 33.5s at 36 weeks post-training. Interestingly, the addition of tSCS enhanced standing duration to 38.5s. Moreover, the total power output exerted by the participant consistently increased over time. Conclusion This study provides, for the first time, evidence that FES-assisted A&L cycling paired with non-invasive tSCS can be safely completed after severe SCI and leads to improvements in training load and assisted standing. Additional assessments will be incorporated to further identify improvements in function and quality of life. Future work will assess the benefits of using epidural spinal cord stimulation combined with A&L cycling after motor complete SCI.

Immediate Effects of Anti-Spastic Epidural Cervical Spinal Cord Stimulation on Functional Connectivity of the Central Motor System in Patients with Stroke- and Traumatic Brain Injury-Induced Spasticity: A Pilot Resting-State Functional Magnetic Resonance Imaging Study.

Spinal cord stimulation (SCS) is one approach to the potential improvement of patients with post-stroke or post-traumatic spasticity. However, little is known about whether and how such interventions alter supraspinal neural systems involved in the pathogenesis of spasticity. This pilot study investigated whether epidural spinal cord stimulation at the level of the C3-C5 cervical segments, aimed at reducing spasticity, alters the patterns of functional connectivity of the brain. Eight patients with spasticity in the right limbs as a result of left cerebral hemisphere damage (due to hemorrhagic and ischemic stroke or traumatic and anoxic brain injury) were assessed with fMRI immediately before and immediately after short-term (1 to 6 days) test cervical epidural SCS therapy. Eight demographically and clinically comparable patients with spasticity in the right extremities due to a left hemisphere ischemic stroke and brain injury who received conventional therapy were examined as a control group. All patients also had paresis of one or two limbs and hyperreflexia. After the SCS therapy, there were three main findings: (1) higher functional connectivity of the brainstem to the right premotor cortex and changes in functional connectivity between cortical motor areas, (2) increased functional connectivity between the right and left lateral nodes of the sensorimotor network, and (3) a positive correlation between decreased spasticity in the right leg and increased functional connectivity within the right hemisphere sensorimotor cortex. All these changes in functional connectivity occurred with a statistically significant decrease in spasticity, as assessed using the modified Ashworth scale. The control group showed no decrease in spasticity or increase in functional connectivity in any of the seeds of interest. On the contrary, a decrease in functional connectivity of the brainstem and right postcentral gyrus was observed in this group during the observation period. We were thus able to detect intrinsic brain connectivity rearrangements that occurred during spasticity mitigation following short epidural SCS therapy. The clinical results obtained confirmed the efficacy of short-term anti-spastic SCS therapy. The obtained data on functional rearrangements of the central motor system may shed light on the mechanism of antispastic action of this procedure.

Spinal cord stimulation for spinal cord injury – Where do we stand? A narrative review

Recovery of function following a complete spinal cord injury (SCI) or an incomplete SCI where recovery has plateaued still eludes us despite extensive research. Epidural spinal cord stimulation (SCS) was initially used for managing neuropathic pain. It has subsequently demonstrated improvement in motor function in otherwise non-recovering chronic spinal cord injury in animal and human trials. The mechanisms of how it is precisely effective in doing so will need further research, which would help refine the technology for broader application. Transcutaneous spinal cord stimulation (TSCS) is also emerging as a modality to improve the functional outcome in SCI individuals, especially when coupled with appropriate rehabilitation. Apart from motor recovery, ESCS and TSCS have also shown improvement in autonomic, metabolic, genitourinary, and pulmonary function. Since the literature on this is still in its infancy, with no large-scale randomised trials and different studies using different protocols in a wide range of patients, a review of the present literature is imperative to better understand the latest developments in this field. This article examines the existing literature on the use of SCS for SCI individuals with the purpose of enabling functional recovery. It also examines the voids in the present research, thus providing future directions.

Mid-lumbar (L3) epidural stimulation effects on bladder and external urethral sphincter in non-injured and chronically transected urethane-anesthetized rats

Recent pre-clinical and clinical spinal cord epidural stimulation (scES) experiments specifically targeting the thoracolumbar and lumbosacral circuitries mediating lower urinary tract (LUT) function have shown improvements in storage, detrusor pressure, and emptying. With the existence of a lumbar spinal coordinating center in rats that is involved with external urethral sphincter (EUS) functionality during micturition, the mid-lumbar spinal cord (specifically L3) was targeted in the current study with scES to determine if the EUS and thus the void pattern could be modulated, using both intact and chronic complete spinal cord injured female rats under urethane anesthesia. L3 scES at select frequencies and intensities of stimulation produced a reduction in void volumes and EUS burst duration in intact rats. After chronic transection, three different subgroups of LUT dysfunction were identified and the response to L3 scES promoted different cystometry outcomes, including changes in EUS bursting. The current findings suggest that scES at the L3 level can generate functional neuromodulation of both the urinary bladder and the EUS in intact and SCI rats to enhance voiding in a variety of clinical scenarios.

ID: 214352 Microdissection of the Swine Spinal Cord to Reveal Lumbar and Thoracic Rootlets

Spinal cord epidural stimulation (SCS) is a safe and effective therapy of chronic pain. The most common complication for SCS is lead migration, resulting in inefficient stimulation. In addition, the shunting of current or activation of the dorsal rootlets may result in contraction of back muscles, via activation of motor fibers recruited at lower stimulation amplitudes. Activation of these rootlets could cause electromyography (EMG) bleed-through into the evoked compound action potential (ECAPs) recordings, as well as cause side effect during SCS therapy. In some cases, motor activation may limit the range of stimulation to levels below what is required for pain therapy.

ID: 221565 EEG Signatures of Epidural Spinal Cord Stimulation: A Dosing and Mechanism of Action Study

The neurophysiological process by which epidural spinal cord stimulation (SCS) relieves pain and the relationship of paresthesia perception to analgesia are still poorly understood. While the gate control theory of pain processing[1] suggests that SCS-induced sensory paresthesia interferes with ascending pain processing, a wealth of evidence contradicts this notion.[2] Studies indicate that SCS may produce analgesia at sub-paresthesia amplitudes by modulating key brain circuits[3] despite similar effects at spinal levels.[4] To date, there are limited human studies evaluating the effect of SCS on chronic pain states and endogenous neural patterns as measured by electroencephalography (EEG).

ID: 206155 Rapid Adaption of Dorsal Horn Inhibitory Populations to Dorsal Column Stimulation

Epidural spinal cord stimulation (SCS) has been used for over 50 years to treat refractory pain and avoid addictive opioid therapies. However, there is an incomplete understanding of how these neuromodulatory devices mediate pain relief, which has precluded effective clinical implementation. One of the mechanisms of SCS-mediated pain relief is through activation of inhibitory superficial dorsal horn circuits, as elegantly proposed in the Gate Control Theory (GCT). The properties of sustained Aβ-fiber stimulation evoked responses in molecularly defined inhibitory dorsal horn populations remain poorly defined and were investigated here using an optical approach.

ID: 202712 Loss of Conduction Fidelity in Dorsal Column Axons During Spinal Cord Stimulation With Conventional Frequencies

Epidural spinal cord stimulation (SCS) is an effective therapy for chronic pain, but there remains an opportunity to increase efficacy and response rates. Conventional paresthesia-producing SCS delivers pulse repetition frequencies < 200 Hz. SCS produces analgesia by activating large dorsal column axons which innervate inhibitory interneurons in the dorsal horn (Gate control theory). This understanding and contemporary research presume that dorsal column (DC) axons propagate faithfully every time a stimulation pulse is delivered. However, recent computational studies suggested that there may be a loss of conduction fidelity, or faithful propagation of an action potential for each stimulation pulse, depending on the stimulation frequency. We measured the response of single dorsal column axons to epidural SCS in healthy urethane-anesthetized Sprague-Dawley rats.

ID: 213423 Changes in Evoked Responses During Epidural Spinal Cord Stimulation Generated by Minimal Movement of Leads

Lead migration is a frequent problem with Spinal Cord Stimulation (SCS) for chronic pain. The role of lead migration in efficacy of pain control is unclear. Using a large animal model, we investigated if a movement of stimulation lead could cause change in the evoked response, which could place impact on the evoked compound action potential (ECAP) component, seeking a way to notify and quantify lead migration during SCS.

ID: 211552 Quantification of Lead Sensing Differences Along Rostral-Caudal Axis During Spinal Cord Stimulation

Electrical epidural spinal cord stimulation (EES) has been successfully implemented to relieve chronic pain. Variations in the effect of EES to suppress chronic pain can be attributed to multiple factors such as exact location of the electrode contacts, patient position, and others. Evoked responses triggered during EES, provides a way that may measure and quantify these variations. These evoked responses, including evoked compound action potential (ECAP) from neuronal fiber activation as a major component, still have an enormous number of questions related to the response registration needed to be addressed. This study is focused on evoked response registration related to the latency, amplitude in Area Under the Curve (AUC), and the effect of displacement of the stimulation and recording leads along rostral caudal axis.