A Systematic Evaluation of Burst Spinal Cord Stimulation for Chronic Back and Limb Pain

Efficacy of the latest new stimulation patterns of spinal cord stimulation for intractable neuropathic pain compared to conventional stimulation: study protocol for a clinical trial

BACKGROUND

Spinal cord stimulation (SCS) is one of the neuromodulation therapies for chronic neuropathic pain. The conventional paresthesia-based SCS involves the application of tonic stimulation that induces a sense of paresthesia. Recently, new SCS stimulation patterns without paresthesia have been developed. Differential target multiplexed (DTM) stimulation and fast-acting subperception therapy (FAST) stimulation are the latest paresthesia-free SCS patterns.

METHODS

A single-center, open-label, crossover, randomized clinical trial to investigate the superiority of SCS using the latest new stimulation patterns over conventional tonic stimulation for neuropathic pain is planned. This study consists of two steps: SCS trial (first step) and SCS system implantation (second step). In the SCS trial, participants will be randomly assigned to 4 groups receiving stimulation, including tonic, DTM, and FAST. Each stimulation will then be performed for 2 days, and a visual analog scale (VAS) for pain will be evaluated before and after each stimulation pattern. A stimulation-off period for 1 day is set between each stimulation pattern to wash out the residual previous stimulation effects. Pain improvement is defined as more than 33% reduction in the pain VAS. The primary analysis will compare pain improvement between the new stimulation patterns and the conventional tonic stimulation pattern in the SCS trial. The secondary outcomes will be evaluated as follows: (1) the relationships between causative disease and improvement rate by each stimulation pattern; (2) comparison of pain improvement between the DTM and FAST stimulation patterns in all cases and by causative disease; (3) changes in assessment items preoperatively to 24 months after the implantation; (4) preoperative factors associated with long-term effects defined as continuing for more than 12 months; and (5) adverse events related to this study 3 months after the implantation.

DISCUSSION

This study aims to clarify the effectiveness of the latest new stimulation patterns compared to the conventional tonic stimulation. In addition, which stimulation pattern is most effective for which kind of causative disease will be clarified.

TRIAL REGISTRATION

Japan Registry of Clinical Trials (jRCT) 1,042,220,094. Registered on 21 November 2022, and last modified on 6 January 2023. jRCT is an approved member of the Primary Registry Network of WHO ICTRP.

Precise management system for chronic intractable pain patients implanted with spinal cord stimulation based on a remote programming platform: study protocol for a randomized controlled trial (PreMaSy study)

BACKGROUND

Spinal cord stimulation (SCS) is a surgical technique used in patients with chronic intractable pain, and its effectiveness and safety have been validated by multiple studies. However, to maintain an optimal and steady long-term effect is still challenging. Here, we report a new management paradigm integrating smartphone application and remote programming. Chronic pain patients with SCS implants can monitor their pain status on the phone and change stimulation parameters accordingly. The PreMaSy study is a randomized controlled trial to evaluate the clinical effectiveness and safety of this precise management system.

METHODS

Patients with chronic intractable pain will be screened for eligibility, and 82 participants are anticipated to be enrolled in this trial. After the electrode implantation, the stimulation effectiveness will be tested. Participants with a reduction of more than 50% in the visual analog scale (VAS) will receive implantation of an implantable pulse generator and randomized (1:1) into the experimental group or control group. All participants will be asked to take online follow-ups and complete assessments using a smartphone application. Daily pain characteristic assessments and monthly quality of life questionnaires are integrated into the App, and participants will be required to complete these assessments. The daily VAS for pain intensity will be monitored and a threshold will be set based on baseline VAS score. The interventional appointment will be scheduled once the threshold is reached. The primary outcome is the health condition and quality of life assessed by the five-level EuroQol five-dimensional questionnaire (EQ-5D-5L). Utility values of EQ-5D-5L will be assessed at baseline and 1, 3, and 6 months post-operative.

DISCUSSION

The PreMaSy study aims to evaluate the effectiveness and safety of a novel App-based, patient-centered, self-assessment management system for chronic intractable pain. A randomized controlled trial is designed to test the non-inferiority of this precise management system compared to the monthly online follow-ups. It is also expected to yield valuable experiences regarding precision medicine.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05761392. Registered on March 07, 2023.

Burst stimulation for refractory angina pectoris - A case report

BACKGROUND

Refractory angina pectoris (RAP) is a chronic, severe chest pain associated with coronary artery disease that cannot be resolved using optimal medical or surgical approaches. Spinal cord stimulation (SCS) is a suitable treatment option. Conventional waveforms of SCS have shown a potent effect on the tempering of RAP. However, SCS is associated with undesired paresthesia. The new burst SCS waveforms have been reported to have fewer adverse effects.

CASE

We reviewed a case in which RAP was successfully treated with burst SCS in a middle-aged male, with a tonic waveform employed for breakthrough pain as needed.

CONCLUSIONS

Appropriate use of tonic and burst stimulations according to the symptoms is expected to maximize the effect of relieving chest pain induced by RAP.

Differential target multiplexed spinal cord stimulation using a paddle-type lead placed at the appropriate site for neuropathic pain after spinal cord injury in patients with past spinal surgical histories: study protocol for an exploratory clinical trial

BACKGROUND

Neuropathic pain after spinal cord injury (SCI), both traumatic and non-traumatic, is refractory to various treatments. Spinal cord stimulation (SCS) is one of the neuromodulation therapies for neuropathic pain, although SCS has insufficient efficacy for neuropathic pain after SCI. The reasons are presumed to be inappropriate locations of SCS leads and conventional tonic stimulation itself does not have a sufficient analgesic effect for the pain. In patients with past spinal surgical histories, the cylinder-type leads are likely to be placed on the caudal side of the SCI because of surgical adhesions. Differential target multiplexed (DTM) stimulation is one of the latest new stimulation patterns that is superior to conventional stimulation.

METHODS

A single-center, open-label, randomized, two-way crossover trial is planned to investigate the efficacy of SCS using DTM stimulation placing a paddle lead at the appropriate site for neuropathic pain after SCI in patients with spinal surgical histories. The paddle-type lead delivers energy more efficiently than a cylinder-type lead. This study consists of two steps: SCS trial (first step) and SCS system implantation (second step). The primary outcome is rates of achieving pain improvement with more than 33% reduction 3 months after SCS system implantation. The secondary outcomes are to be evaluated as follows: (1) effectiveness of DTM and tonic stimulations during the SCS trial; (2) changes of assessment items from 1 to 24 months; (3) relationships between the result of the SCS trial and the effects 3 months after SCS system implantation; (4) preoperative factors associated with a long-term effect, defined as continuing for more than 12 months; and (5) whether gait function improves from 1 to 24 months.

DISCUSSION

A paddle-type lead placed on the rostral side of SCI and using DTM stimulation may provide significant pain relief for patients with intractable neuropathic pain after SCI in patients with past spinal surgical histories.

TRIAL REGISTRATION

Japan Registry of Clinical Trials (jRCT) jRCT 1042220093. Registered on 21 November 2022, and last modified on 6 January 2023. jRCT is approved as a member of the Primary Registry Network of WHO ICTRP.

Role of patient selection and trial stimulation for spinal cord stimulation therapy for chronic non-cancer pain: a comprehensive narrative review

Background/importance

Patient selection for spinal cord stimulation (SCS) therapy is crucial and is traditionally performed with clinical selection followed by a screening trial. The factors influencing patient selection and the importance of trialing have not been systematically evaluated.

Objective

We report a narrative review conducted to synthesize evidence regarding patient selection and the role of SCS trials.

Evidence review

Medline, EMBASE and Cochrane databases were searched for reports (any design) of SCS in adult patients, from their inception until March 30, 2022. Study selection and data extraction were carried out using DistillerSR. Data were organized into tables and narrative summaries, categorized by study design. Importance of patient variables and trialing was considered by looking at their influence on the long-term therapy success.

Findings

Among 7321 citations, 201 reports consisting of 60 systematic reviews, 36 randomized controlled trials (RCTs), 41 observational studies (OSs), 51 registry-based reports, and 13 case reports on complications during trialing were included. Based on RCTs and OSs, the median trial success rate was 72% and 82%, and therapy success was 65% and 61% at 12 months, respectively. Although several psychological and non-psychological determinants have been investigated, studies do not report a consistent approach to patient selection. Among psychological factors, untreated depression was associated with poor long-term outcomes, but the effect of others was inconsistent. Most RCTs except for chronic angina involved trialing and only one RCT compared patient selection with or without trial. The median (range) trial duration was 10 (0–30) and 7 (0–56) days among RCTs and OSs, respectively.

Conclusions

Due to lack of a consistent approach to identify responders for SCS therapy, trialing complements patient selection to exclude patients who do not find the therapy helpful and/or intolerant of the SCS system. However, more rigorous and large studies are necessary to better evaluate its role.

Relief of Central Poststroke Pain Affecting Both the Arm and Leg on One Side by Double-independent Dual-lead Spinal Cord Stimulation Using Fast-acting Subperception Therapy Stimulation: A Case Report

Central poststroke pain is a chronic, intractable, central neuropathic pain. Spinal cord stimulation is a neuromodulation therapy for chronic neuropathic pain. The conventional stimulation method induces a sense of paresthesia. Fast-acting subperception therapy is one of the latest new stimulation methods without paresthesia. A case of achieving pain relief of central poststroke pain affecting both the arm and leg on one side by double-independent dual-lead spinal cord stimulation using fast-acting subperception therapy stimulation is presented. A 67-year-old woman had central poststroke pain due to a right thalamic hemorrhage. The numerical rating scale scores of the left arm and leg were 6 and 7, respectively. Using dual-lead stimulation at the Th 9-11 levels, a spinal cord stimulation trial was performed. Fast-acting subperception therapy stimulation achieved pain reduction in the left leg from 7 to 3. Therefore, a pulse generator was implanted, and the pain relief continued for 6 months. Then, two additional leads were implanted at the C 3-5 levels, and pain in the arm decreased from 6 to 4. Independent setting and adjustments of the dual-lead stimulation were required because the thresholds of paresthesia perception were significantly different. To achieve pain relief in both the arm and leg, double-independent dual-lead stimulation placed at cervical and thoracic levels is an effective treatment. Fast-acting subperception therapy stimulation may be effective for central poststroke pain, especially in cases where the paresthesia is perceived as uncomfortable or the conventional stimulation itself is ineffective.

Posterior Cord Syndrome After Spinal Cord Stimulation Electrode Lead Insertion: A Case Report

Chronic neuropathic pain after spinal cord injury is often refractory to conventional treatments. Spinal cord stimulation (SCS) is used to manage intractable chronic neuropathic pain. A 42-year-old man presented with chronic neuropathic pain in his right lower extremity for 5 years. He had undergone posterior fusion from T11 to L3 for a burst fracture of L1 vertebra and conus medullaris syndrome. Conservative treatment with medications, pain blocks, and physical therapy did not relieve the neuropathic pain in the right lower limb. A paddle-type SCS electrode lead was inserted at the level of T9-11 vertebrae for test stimulation. Postoperatively, the patient immediately complained of decreased proprioception, while the motor and sensory neurologic states did not change. Since his neurological deficit did not recover spontaneously, we had to remove the epidural SCS electrode to resolve the neurological symptoms.

Spinal Cord Stimulation for Neuropathic Pain following a Spinal Cord Lesion with Past Spinal Surgical Histories Using a Paddle Lead Placed on the Rostral Side of the Lesion: Report of Three Cases

Spinal cord parenchymal lesions may induce intractable neuropathic pain. However, the efficacy of conventional spinal cord stimulation for the neuropathic pain following spinal cord lesions remains to be controversial. In this study, we present three cases of spinal cord stimulation using a paddle lead at the rostral side of the spinal lesion causing pain symptoms. Good pain reductions were achieved using conventional stimulation in one case and using differential target multiplexed stimulation in two cases. Case 1: A 55-year-old man presented with neuropathic pain affecting his bilateral upper extremities due to a traumatic cervical spinal cord injury. Conventional stimulation via a paddle-type electrode was able to reduce the pain from 8 to 4 via a visual analog scale. Case 2: A 67-year-old man had undergone three spinal surgeries. He presented with pain and numbness of bilateral lower extremities due to a spinal cord lesion by thoracic disc herniation. Differential target multiplexed stimulation via a paddle-type electrode achieved excellent pain reduction, that is, from 9 to 2 on the visual analog scale. Case 3: An 80-year-old man presented with pain in his bilateral upper extremities due to a cervical spinal cord lesion caused by compression and spinal canal stenosis. Posterior cervical decompression and paddle-type electrode placement were performed simultaneously. Differential target multiplexed stimulation was able to achieve excellent pain reduction, from 7 to 2 on the visual analog scale. Spinal cord stimulation using a paddle lead at the rostral side of the spinal lesion and differential target multiplexed stimulation may provide significant opportunities for patients with intractable neuropathic pain following spinal cord lesions.

Tonic, Burst, and Burst-Cycle Spinal Cord Stimulation Lead to Differential Brain Activation Patterns as Detected by Functional Magnetic Resonance Imaging

OBJECTIVE

The objective of this preclinical study was to examine the responses of the brain to noxious stimulation in the presence and absence of different modes of spinal cord stimulation (SCS) using blood-oxygen-level-dependent functional magnetic resonance imaging (BOLD-fMRI).

MATERIALS AND METHODS

Sprague-Dawley rats were randomized to groups based on the mode of SCS delivered which included tonic stimulation (n = 27), burst stimulation (n = 30), and burst-cycle stimulation (n = 29). The control (sham) group (n = 28) received no SCS. The SCS electrode was inserted between T10 and T12 spinal levels prior to fMRI session. The experimental protocol for fMRI acquisition consisted of an initial noxious stimulation phase, a treatment phase wherein the SCS was turned on concurrently with noxious stimulation, and a residual effect phase wherein the noxious stimulation alone was turned on. The responses were statistically analyzed through paired t-test and the results were presented as z-scores for the quantitative analysis of the fMRI data.

RESULTS

The treatment with different SCS modes attenuated the BOLD brain responses to noxious hindlimb stimulation. The tonic, burst, and burst-cycle SCS treatment attenuated BOLD responses in the caudate putamen (CPu), insula (In), and secondary somatosensory cortex (S2). There was little to no corresponding change in sham control in these three regions. The burst and burst-cycle SCS demonstrated greater attenuation of BOLD signals in CPu, In, and S2 compared to tonic stimulation.

CONCLUSION

The high-resolution fMRI study using a rat model demonstrated the potential of different SCS modes to act on several pain-matrix-related regions of the brain in response to noxious stimulation. The burst and burst-cycle SCS exhibited greater brain activity reduction in response to noxious hindlimb stimulation in the caudate putamen, insula, and secondary somatosensory cortex compared to tonic stimulation.

Effects of Noninvasive Low-Intensity Focus Ultrasound Neuromodulation on Spinal Cord Neurocircuits In Vivo

Although neurocircuits can be activated by focused ultrasound stimulation, it is unclear whether this is also true for spinal cord neurocircuits. In this study, we used low-intensity focused ultrasound (LIFU) to stimulate lumbar 4–lumbar 5 (L4–L5) segments of the spinal cord of normal Sprague Dawley rats with a clapper. The activation of the spinal cord neurocircuits enhanced soleus muscle contraction as measured by electromyography (EMG). Neuronal activation and injury were assessed by EMG, western blotting (WB), immunofluorescence, hematoxylin and eosin (H&E) staining, Nissl staining, enzyme-linked immunosorbent assay (ELISA), immunohistochemistry (IHC), somatosensory evoked potentials (SEPs), motor evoked potentials (MEPs), and the Basso–Beattie–Bresnahan locomotor rating scale. When the LIFU intensity was more than 0.5 MPa, LIFU stimulation induced soleus muscle contraction and increased the EMG amplitudes (P < 0.05) and the number of c-fos- and GAD65-positive cells (P < 0.05). When the LIFU intensity was 3.0 MPa, the LIFU stimulation led to spinal cord damage and decreased SEP amplitudes for electrophysiological assessment (P < 0.05); this resulted in coagulation necrosis, structural destruction, neuronal loss in the dorsal horn by H&E and Nissl staining, and increased expression of GFAP, IL-1β, TNF-α, and caspase-3 by IHC, ELISA, and WB (P < 0.05). These results show that LIFU can activate spinal cord neurocircuits and that LIFU stimulation with an irradiation intensity ≤1.5 MPa is a safe neurostimulation method for the spinal cord.

Management of Phantom Limb Pain through Thalamotomy of the Centro-Median Nucleus

Background: Phantom limb syndrome is defined as the perception of intense pain or other sensations that are secondary to a neural lesion in a limb that does not exist. It can be treated using pharmacological and surgical interventions. Most medications are prescribed to improve patients’ lives; however, the response rate is low. In this case report, we present a case of phantom limb syndrome in a 42-year-old female with a history of transradial amputation of the left thoracic limb due to an accidental compression one year before. The patient underwent placement of a deep brain stimulator at the ventral posteromedial nucleus (VPM) on the right side and removal secondary to loss of battery. The patient continued to have a burning pain throughout the limb with a sensation of still having the limb, which was subsequently diagnosed as phantom limb syndrome. After a thorough discussion with the patient, a right stereotactic centro-median thalamotomy was offered. An immediate response was reported with a reduction in pain severity on the visual analogue scale (VAS) from a value of 9–10 preoperative to a value of 2 postoperative, with no postoperative complications. Although phantom limb pain is one of the most difficult to treat conditions, centro-median thalamotomy may provide an effective stereotactic treatment procedure with adequate outcomes.

Stable softening bioelectronics: A paradigm for chronically viable ester-free neural interfaces such as spinal cord stimulation implants

Polymer toughness is preserved at chronic timepoints in a new class of modulus-changing bioelectronics, which hold promise for commercial chronic implant components such as spinal cord stimulation leads. The underlying ester-free chemical network of the polymer substrate enables device rigidity during implantation, soft, compliant, conforming structures during acute phases in vivo, and gradual stabilization of materials properties chronically, maintaining materials toughness as device stiffness changes. In the past, bioelectronics device designs generally avoided modulus-changing and materials due to the difficulty in demonstrating consistent, predictable performance over time in the body. Here, the acute, and chronic mechanical and chemical properties of a new class of ester-free bioelectronic substrates are described and characterized via accelerated aging at elevated temperatures, with an assessment of their underlying cytotoxicity. Furthermore, spinal cord stimulation leads consisting of photolithographically-defined gold traces and titanium nitride (TiN) electrodes are fabricated on ester-free polymer substrates. Electrochemical properties of the fabricated devices are determined in vitro before implantation in the cervical spinal cord of rat models and subsequent quantification of device stimulation capabilities. Preliminary in vivo evidence demonstrates that this new generation of ester-free, softening bioelectronics holds promise to realize stable, scalable, chronically viable components for bioelectronic medicines of the future.

The Effectiveness of Spinal Cord Stimulation for the Treatment of Axial Low Back Pain: A Systematic Review with Narrative Synthesis

OBJECTIVE

Determine the effectiveness of spinal cord stimulation (SCS) for the treatment of axial low back pain (LBP) with or without leg pain.

DESIGN

Systematic review.

SUBJECTS

Persons aged ≥18 with axial LBP with or without accompanying leg pain.

INTERVENTION

Traditional low-frequency, burst, or high-frequency SCS.

COMPARISON

Sham, active standard of care treatment, or none.

OUTCOMES

The primary outcome was ≥50% pain improvement, and the secondary outcome was functional improvement measured six or more months after treatment intervention.

METHODS

Publications in PubMed, MEDLINE, and Cochrane databases were reviewed through September 19, 2019. Randomized or nonrandomized comparative studies and nonrandomized studies without internal controls were included. The Cochrane Risk of Bias Tool and GRADE system were used to assess individual study characteristics and overall quality.

RESULTS

Query identified 262 publications; 17 were suitable for inclusion. For high-frequency SCS, the only level 1 study showed that 79% (95% confidence interval = 70-87%) of patients reported ≥50% pain improvement. For low-frequency SCS, the only level 1 study reported no categorical data for axial LBP-specific outcomes; axial LBP improved by a mean 14 mm on the visual analog scale at six months. Meta-analysis was not performed due to study heterogeneity.

CONCLUSIONS

According to GRADE, there is low-quality evidence that high-frequency SCS compared with low-frequency SCS is effective in patients with axial LBP with concomitant leg pain. There is very low-quality evidence for low-frequency SCS for the treatment of axial LBP in patients with concomitant leg pain. There is insufficient evidence addressing the effectiveness of burst SCS to apply a GRADE rating.

Differential modulation of excitatory and inhibitory populations of superficial dorsal horn neurons in lumbar spinal cord by Aβ-fiber electrical stimulation

Activation of Aβ-fibers is fundamental to numerous analgesic therapies, yet its effects on dorsal horn neuronal activity remain unclear. We used multiphoton microscopy of the genetically encoded calcium indicator GCaMP6s to characterize the effects of Aβ-fiber electrical stimulation (Aβ-ES) on neural activity. Specifically, we quantified somatic responses evoked by C-fiber intensity stimulation before and after a 10-minute train of dorsal root Aβ-ES in superficial dorsal horn (SDH) neurons, in mouse lumbar spinal cord. Aβ-ES did not alter C-fiber-evoked activity when GCaMP6s was virally expressed in all neurons, in an intact lumbar spinal cord preparation. However, when we restricted the expression of GCaMP6s to excitatory or inhibitory populations, we observed that Aβ-ES modestly potentiated evoked activity of excitatory neurons and depressed that of inhibitory neurons. Aβ-ES had no significant effects in a slice preparation in either SDH population. A larger proportion of SDH neurons was activated by Aβ-ES when delivered at a root rostral or caudal to the segment where the imaging and C-fiber intensity stimulation occurred. Aβ-ES effects on excitatory and inhibitory populations depended on the root used. Our findings suggest that Aβ-ES differentially modulates lumbar spinal cord SDH populations in a cell type- and input-specific manner. Furthermore, they underscore the importance of the Aβ-ES delivery site, suggesting that Aβ stimulation at a segment adjacent to where the pain is may improve analgesic efficacy.

[Spinal cord stimulation in the treatment of chronic pain]

Despite the numerous analgesic drugs, the prevalence of intractable neuropathic pain remains high making up about 5%. Intervention methods, including methods of chronic electrostimulation, are used to treat these patients. Spinal cord stimulation (SCS) is the most common surgical method worldwide that replaced destructive and ablation procedures. Currently, common tonic SCS, HF-10 stimulation and burst SCS are applied, and the choice of method is based on clinical and neurophysiological data. Also, the introduction of nanomaterial-enabled neural stimulation could significantly minimize surgery risk.

Burst Spinal Cord Stimulation: A Systematic Review and Pooled Analysis of Real-World Evidence and Outcomes Data

Objective

This review provides a comprehensive assessment of the effectiveness of burst spinal cord stimulation (SCS). Ratings of pain intensity (visual analog scale or numeric rating scale) and patient-reported outcomes (PROs) on functional/psychometric domains such as depression (Beck Depression Index), catastrophizing (Pain Catastrophizing Scale), surveillance (Pain Vigilance and Attention Questionnaire), and others are addressed.

Design

Articles were identified and selected from the literature according to prospective, replicable methods. Effectiveness data—pain scores and PRO ratings—were weighted by study sample sizes and pooled. The effects of burst SCS were compared against values at baseline and with tonic SCS. For PROs, published population norms were used for comparison.

Results

Fifteen articles, with a combined sample size of 427, were included. Follow-up ranged from a few hours to two years. A variety of prospective designs were employed, including crossover studies, single-arm cohorts, and a randomized controlled trial, as well as retrospective case reports. The weighted pooled mean pain rating across articles at baseline was 76.7 (±27.4). With tonic SCS, this was reduced to 49.2 (±12.9), and with burst SCS it was further reduced to 36.7 (±11.6), a 12.5-point difference between tonic and burst values. Psychometric analyses of PROs noted preferential improvement with burst SCS. In addition, 65% of subjects stated a preference for burst SCS.

Conclusions

In pooled analyses that incorporated all available published evidence, the improvement over baseline for burst SCS was shown to have a clinically important incremental benefit over tonic SCS. In addition, burst SCS may support resolution of the emotional or cognitive aspects of pain that are mediated by medial thalamo-cortical pathways. This study highlights the value in considering the entire knowledge base in therapeutic assessments as well as adopting a consistent set of outcome variables within neuromodulation. Burst SCS is a valuable intervention, providing both analgesia and psychometric benefits that warrant further thoughtful applications.

Spinal cord stimulation in chronic pain: technical advances

Chronic severe pain results in a detrimental effect on the patient’s quality of life. Such patients have to take a large number of medications, including opioids, often without satisfactory effect, sometimes leading to medication abuse and the pain worsening. Spinal cord stimulation (SCS) is one of the most effective technologies that, unlike other interventional pain treatment methods, achieves long-term results in patients suffering from chronic neuropathic pain. The first described mode of SCS was a conventional tonic stimulation, but now the novel modalities (high-frequency and burst), techniques (dorsal root ganglia stimulations), and technical development (wireless and implantable pulse generator-free systems) of SCS are becoming more popular. The improvement of SCS systems, their miniaturization, and the appearance of new mechanisms for anchoring electrodes results in a significant reduction in the rate of complications and revision surgeries, and the appearance of new waves of stimulation allows not only to avoid the phenomenon of addiction, but also to improve the long-term results of chronic SCS. The purpose of this review is to describe the current condition of SCS and up-to-date technical advances.

Early high-frequency spinal cord stimulation treatment inhibited the activation of spinal mitogen-activated protein kinases and ameliorated spared nerve injury-induced neuropathic pain in rats

BACKGROUND

Neuromodulation therapies offer a treatment option that has minimal side effects and is relatively safe and potentially reversible. Spinal cord stimulation (SCS) has been used to treat various pain conditions for many decades. High-frequency SCS (HFSCS) involves the application of a single waveform at 10,000 Hz at a subthreshold level, therefore providing pain relief without any paresthesia.

METHODS

We tested whether early HFSCS treatment attenuated spared nerve injury (SNI)-induced neuropathic pain. The phosphorylation profile of mitogen-activated protein kinases (MAPKs), i.e., extracellular signal-regulated kinases (ERKs), c-Jun N-terminal kinases (JNKs), and p38, was evaluated to elucidate the potential underlying mechanism.

RESULTS

SNI of rat unilateral sciatic nerves induced mechanical hyperalgesia in the ipsilateral hind paws. Rats were assigned to SCS sessions with HFSCS (frequency 10 kHz; pulse width 30 μs; pulse shape of charge-balanced, current controlled; delivered continuously for 72 h), or sham stimulation immediately after SNI. Tissue samples were examined at 1, 3, 7, and 14 days after SNI. Behavioral studies showed that HFSCS applied to the T10/T11 spinal cord significantly attenuated SNI-induced mechanical hyperalgesia compared with the sham stimulation group. Moreover, western blotting revealed a significant attenuation of the activation of ERK1, ERK2, JNK1, and p38 in the dorsal root ganglia and the spinal dorsal horn.

CONCLUSION

Application of HFSCS provides an effective treatment for SNI-induced persistent mechanical hyperalgesia by attenuating ERK, JNK, and p38 activation in the dorsal root ganglia and the spinal dorsal horn.

Burst and Tonic Spinal Cord Stimulation Both Activate Spinal GABAergic Mechanisms to Attenuate Pain in a Rat Model of Chronic Neuropathic Pain

BACKGROUND

Experimental and clinical studies have shown that tonic spinal cord stimulation (SCS) releases gamma-aminobutyric acid (GABA) in the spinal dorsal horn. Recently, it was suggested that burst SCS does not act via spinal GABAergic mechanisms. Therefore, we studied spinal GABA release during burst and tonic SCS, both anatomically and pharmacologically, in a well-established chronic neuropathic pain model.

METHODS

Animals underwent partial sciatic nerve ligation (PSNL). Quantitative immunohistochemical (IHC) analysis of intracellular GABA levels in the lumbar L4 to L6 dorsal spinal cord was performed after 60 minutes of burst, tonic, or sham SCS in rats that had undergone PSNL (n = 16). In a second pharmacological experiment, the effects of intrathecal administration of the GABA_A antagonist bicuculline (5 μg) and the GABA_B antagonist phaclofen (5 μg) were assessed. Paw withdrawal thresholds to von Frey filaments of rats that had undergone PSNL (n = 20) were tested during 60 minutes of burst and tonic SCS 30 minutes after intrathecal administration of the drugs.

RESULTS

Quantitative IHC analysis of GABA immunoreactivity in spinal dorsal horn sections of animals that had received burst SCS (n = 5) showed significantly lower intracellular GABA levels when compared to sham SCS sections (n = 4; P = 0.0201) and tonic SCS sections (n = 7; P = 0.0077). Intrathecal application of the GABA_A antagonist bicuculline (5 μg; n = 10) or the GABA_B antagonist phaclofen (5 μg; n = 10) resulted in ablation of the analgesic effect for both burst SCS and tonic SCS.

CONCLUSIONS

In conclusion, our anatomical and pharmacological data demonstrate that, in this well-established chronic neuropathic animal model, the analgesic effects of both burst SCS and tonic SCS are mediated via spinal GABAergic mechanisms.

Comparison of Neural Activity in Chronic Pain Patients During Tonic and Burst Spinal Cord Stimulation Using Fluorodeoxyglucose Positron Emission Tomography

OBJECTIVE

Burst spinal cord stimulation (SCS) is a novel stimulation paradigm that seems to provide better pain relief compared to the classic tonic SCS with minimal paresthesia sensation. Based on source localized electroencephalography and clinical data, it has been proposed that burst stimulation as defined by Dirk De Ridder exerts this greater effect by not only modulating the lateral and the descending pain-inhibitory pathways (similar to tonic SCS) but also modulating the medial pain pathway, which encodes the affective, motivational aspects of pain.

MATERIAL AND METHODS

The current study evaluates the supraspinal differences between burst and tonic stimulation with another functional imaging technique, namely fluorodeoxyglucose positron emission tomography (FGD-PET) scanning, in seven patients, who underwent both burst and tonic SCS, to confirm this notion of medial pain pathway modulation.

RESULTS

The results of the current FGD-PET study show that burst stimulation, in contrast to tonic stimulation, indeed modulates the dorsal anterior cingulate cortex (i.e., medial pain pathway) more than tonic stimulation.

DISCUSSION

Our data suggest an inherent difference in the central neural mechanisms during burst and tonic stimulation, which could potentially alter the patient's perception of pain.

CONFLICT OF INTEREST

Dr. Yearwood, Dr. De Ridder, Dr. Falowski, and Dr. Vanneste are the consultants of Abbott. Dr. Venkatesan is an employee of Abbott. Hye Bin Yoo and Dr. Wing Ting To have no conflicts of interest to report.

Burst and Tonic Spinal Cord Stimulation in the Mechanical Conflict-Avoidance System: Cognitive-Motivational Aspects

BACKGROUND

Clinical research suggests that a novel spinal cord stimulation (SCS) waveform, known as Burst-SCS, specifically targets cognitive-motivational aspects of pain. The objective of the present study was to assess the cognitive-motivational aspects of Tonic- and Burst SCS-induced pain relief, by means of exit latency in the mechanical conflict-avoidance system (MCAS), in a rat model of chronic neuropathic pain.

METHODS

Exit latency on the MCAS operant testing setup was evaluated at various probe heights for rats (n = 26) with chronic neuropathic pain induced by a partial sciatic nerve ligation (PSNL). Von Frey paw withdrawal analysis was performed to assess mechanical hypersensitivity. In a second experiment (n = 12), the behavioral effect of Tonic SCS or biphasic Burst SCS on both Von Frey analysis and MCAS exit latency was assessed.

RESULTS

Burst SCS exit latencies differed significantly from Tonic SCS exit latencies at 4 mm probe height (3.8 vs. 5.8 sec, respectively; p < 0.01) and 5 mm probe height (3.2 vs. 5.4 sec respectively; p < 0.05). This difference was not detected with reflex-based Von Frey testing (Tonic-SCS vs. Burst-SCS at 30 min stimulation: p = 0.73, and at 60 min stimulation; p = 0.42).

CONCLUSIONS

Testing of MCAS exit latency allows for detection of cognitive-motivational pain relieving aspects induced by either Tonic- or Burst-SCS in treatment of chronic neuropathic rats. Our behavioral findings strongly suggest that Burst-SCS specifically affects, much more than Tonic-SCS, the processing of cognitive-motivational aspects of pain.

Spinal Cord Stimulation for Loin Pain Hematuria Syndrome: Clinical Report

Loin pain hematuria syndrome (LPHS) is a rare condition characterized by cryptogenic debilitating flank pain and microscopic or macroscopic hematuria. The pathophysiology of LPHS remains poorly understood, and diagnosis is made largely by exclusion of alternate pathology. Management strategies can vary widely and include chronic opioid medication and a variety of invasive procedures, including regional nerve blocks, transcutaneous electrical nerve stimulation, local capsaicin infusion, and surgical renal denervation. Neuromodulation may provide a new paradigm of treatment for LPHS, potentially sparing patients from long-term complications of opiate therapy and invasive surgery. This report demonstrates the first case of successful symptomatic management of LPHS using spinal cord stimulation.

Spinal Cord Stimulation for Pain Treatment After Spinal Cord Injury

In addition to restoration of bladder, bowel, and motor functions, alleviating the accompanying debilitating pain is equally important for improving the quality of life of patients with spinal cord injury (SCI). Currently, however, the treatment of chronic pain after SCI remains a largely unmet need. Electrical spinal cord stimulation (SCS) has been used to manage a variety of chronic pain conditions that are refractory to pharmacotherapy. Yet, its efficacy, benefit profiles, and mechanisms of action in SCI pain remain elusive, due to limited research, methodological weaknesses in previous clinical studies, and a lack of mechanistic exploration of SCS for SCI pain control. We aim to review recent studies and outline the therapeutic potential of different SCS paradigms for traumatic SCI pain. We begin with an overview of its manifestations, classification, potential underlying etiology, and current challenges for its treatment. The clinical evidence for using SCS in SCI pain is then reviewed. Finally, future perspectives of pre-clinical research and clinical study of SCS for SCI pain treatment are discussed.

Burst SCS Microdosing Is as Efficacious as Standard Burst SCS in Treating Chronic Back and Leg Pain: Results From a Randomized Controlled Trial

INTRODUCTION

The burst waveform, a recent innovation in spinal cord stimulation (SCS), can achieve better outcomes than conventional tonic SCS, both for de novo implants and as a salvage therapy. Burst stimulation delivers more energy per second than tonic stimulation, which is a consideration for battery consumption. The clinical effectiveness of an energy-conserving strategy was investigated.

METHODS

Subjects were experienced users of BurstDR SCS for back and leg pain. Three 2-week stimulation paradigms were presented in blinded random order: standard (continuously delivered) BurstDR, microdosing A: 5 sec of BurstDR alternating with 5 sec of no stimulation, and microdosing B: 5 sec of BurstDR alternating with 10 sec of no stimulation. The primary outcome for each paradigm was change in pain ratings, and secondary outcomes included changes in scores for quality of life, satisfaction, and preference.

RESULTS

Twenty-five subjects assessed all three stimulation paradigms. There were no significant differences in pain (visual analog scale) or quality of life (EQ-5D) when comparing standard burst outcomes with those of microdosing A and, separately, microdosing B. Microdosing paradigms were graded with slightly higher level of satisfaction and were generally preferred above standard burst stimulation.

DISCUSSION

These results suggest that the use of energy-efficient burst microdosing stimulation paradigms with alternating stimulation-on and stimulation-off periods can provide clinically equivalent results to standard burst stimulation. This is important for extending SCS battery life. Further research is needed to comprehensively characterize the clinical utility of this approach and the neurophysiological mechanisms for the maintenance of pain relief during stimulation-off periods.

Comparison of Tonic vs. Burst Spinal Cord Stimulation During Trial Period

BACKGROUND

Spinal cord stimulation (SCS) is a well-known treatment in patients with failed back surgery syndrome (FBSS). Burst stimulation is a recently developed stimulation modality that seems to be superior to tonic stimulation.

METHODS

This observational multicenter study compared tonic and burst stimulation during a trial period in patients with FBSS or radiculopathy. All the patients enrolled underwent two weeks of tonic stimulation followed by another two weeks of BurstDR stimulation, without randomization. The primary outcome was the reduction of pain in the legs and back. Health-related quality of life (EQ-5D) and the pain catastrophizing scale (PCS) were assessed before and after the trial. Patients were reevaluated after 12 months.

RESULTS

We recruited 23 patients, 57% of whom had FBSS and 43% had radiculopathies. Five patients failed both the tonic and burst stimulation trials. While tonic stimulation reduced leg pain (p < 0.05), the burst mode added an extra pain reduction (ΔNRS 1.2 ± 1.5) (p < 0.01). No significant reduction in back pain was found (p 0.29). Pain on movement was reduced only by BurstDR (p < 0.01). Both stimulation modalities increased EQ-5D and reduced PCS from the baseline (p < 0.0001). At the end of the SCS trial phase, 26% patients chose tonic SCS, while 74% preferred burst. On 12-month follow-up examination, the benefits recorded at the end of the trial were maintained.

CONCLUSIONS

Burst stimulation confers a greater reduction in leg pain intensity at rest and on movement. Reducing axial pain is still a challenge. Further studies are needed in order to provide each patient with the most appropriate stimulation paradigm.

Ovine model of neuropathic pain for assessing mechanisms of spinal cord stimulation therapy via dorsal horn recordings, von Frey filaments, and gait analysis

Background

It is becoming increasingly important to understand the mechanisms of spinal cord stimulation (SCS) in alleviating neuropathic pain as novel stimulation paradigms arise.

Purpose

Additionally, the small anatomic scale of current SCS animal models is a barrier to more translational research.

Methods

Using chronic constriction injury (CCI) of the common peroneal nerve (CPN) in sheep (ovine), we have created a chronic model of neuropathic pain that avoids motor deficits present in prior large animal models. This large animal model has allowed us to implant clinical grade SCS hardware, which enables both acute and chronic testing using von Frey filament thresholds and gait analysis. Furthermore, the larger anatomic scale of the sheep allows for simultaneous single-unit recordings from the dorsal horn and SCS with minimal electrical artifact.

Results

Detectable tactile hypersensitivity occurred 21 days after nerve injury, with preliminary indications that chronic SCS may reverse it in the painful limb. Gait analysis revealed no hoof drop in the CCI model. Single neurons were identified and discriminated in the dorsal horn, and their activity was modulated via SCS. Unlike previous large animal models that employed a complete transection of the nerve, no motor deficit was observed in the sheep with CCI.

Conclusion

To our knowledge, this is the first reported large animal model of chronic neuropathic pain which facilitates the study of both acute and chronic SCS using complementary behavioral and electrophysiologic measures. As demonstrated by our successful establishment of these techniques, an ovine model of neuropathic pain is suitable for testing the mechanisms of SCS.

Spinal Cord Stimulation: Clinical Efficacy and Potential Mechanisms

Spinal cord stimulation (SCS) is a minimally invasive therapy used for the treatment of chronic neuropathic pain. SCS is a safe and effective alternative to medications such as opioids, and multiple randomized controlled studies have demonstrated efficacy for difficult-to-treat neuropathic conditions such as failed back surgery syndrome. Conventional SCS is believed mediate pain relief via activation of dorsal column Aβ fibers, resulting in variable effects on sensory and pain thresholds, and measurable alterations in higher order cortical processing. Although potentiation of inhibition, as suggested by Wall and Melzack's gate control theory, continues to be the leading explanatory model, other segmental and supraspinal mechanisms have been described. Novel, non-standard, stimulation waveforms such as high-frequency and burst have been shown in some studies to be clinically superior to conventional SCS, however their mechanisms of action remain to be determined. Additional studies are needed, both mechanistic and clinical, to better understand optimal stimulation strategies for different neuropathic conditions, improve patient selection and optimize efficacy.

Evaluation of an innovative spinal cord stimulator platform for the treatment of chronic pain

Spinal cord stimulation (SCS) is an ever-evolving therapy for the treatment of chronic pain. Currently, there are four main companies offering a variety of options for SCS. The Intellis™ system is the latest offering from Medtronic (MN, USA). Intellis offers the smallest implantable SCS pulse generator available and is capable of multiple different modes of stimulation, some of which can be run simultaneously. With an intrinsic accelerometer, the device is capable of sensing various patient positions and can automatically adjust stimulation intensity. Intellis also offers the most comprehensive MRI conditionality to date. Additionally, the new Samsung/Android^® (Seoul, South Korea) clinician programmer allows for easier programming than previous Medtronic programing systems. The programer can also generate patient activity and usage reports from implantable pulse generator data.

Burst Spinal Cord Stimulation: Review of Preclinical Studies and Comments on Clinical Outcomes

BACKGROUND

Burst spinal cord stimulation (SCS) technology uses a novel waveform that consists of closely packed high-frequency electrical impulses followed by a quiescent period. Within the growing field of neuromodulation, burst stimulation is unique in that it mimics the natural burst firing of the nervous system, in particular the thalamo-cingulate rhythmicity, resulting in modulation of the affective and attentional components of pain processing (e.g., medial thalamic pathways).

STUDY DESIGN

A review of preclinical and clinical studies regarding burst SCS for various chronic pain states.

METHODS

Available literature was reviewed on burst stimulation technology. Data sources included relevant literature identified through searches of PubMed, MEDLINE/OVID, SCOPUS, and manual searches of the bibliographies of known primary and review articles.

OUTCOME MEASURES

The primary outcome measure was to understand the mechanisms of action with regards to burst stimulation and to review clinical data on the indications of burst SCS for various chronic pain states.

RESULTS

We present both mechanisms of action and review uses of burst stimulation for various pain states.

CONCLUSIONS

Burst stimulation offers a novel pain reduction tool with the absence of uncomfortable paresthesia for failed back surgery syndrome, diabetic neuropathic pain, and anesthesia dolorosa. Preclinical models have emphasized that the potential mechanisms for burst therapy could be related to neural coding algorithms that mimic the natural nervous system firing patterns, resulting in effects on both the medial and lateral pain pathways. Other mechanisms include frequency dependent opioid release, modulation of the pain gate, and activation of electrical and chemical synapses.

Conventional-SCS vs. Burst-SCS and the Behavioral Effect on Mechanical Hypersensitivity in a Rat Model of Chronic Neuropathic Pain: Effect of Amplitude

OBJECTIVE

Various spinal cord stimulation (SCS) modes are used in the treatment of chronic neuropathic pain disorders. Conventional (Con) and Burst-SCS are hypothesized to exert analgesic effects through different stimulation-induced mechanisms. Preclinical electrophysiological findings suggest that stimulation intensity is correlated with the effectiveness of Burst-SCS. Therefore, we aimed to investigate the relation between amplitude (charge per second) and behavioral effects in a rat model of chronic neuropathic pain, for both Conventional Spinal Cord Stimulation (Con-SCS) and biphasic Burst-SCS.

MATERIALS AND METHODS

Animals (n = 12 rats) received a unilateral partial sciatic nerve ligation, after which they were implanted with quadripolar electrodes in the epidural space at thoracic level 13. Mechanical hypersensitivity was assessed using paw withdrawal thresholds (WTs) to von Frey monofilaments, at various SCS intensities (amplitudes) and multiple time points during 60 minutes of stimulation and 30 minutes post stimulation.

RESULTS

Increasing amplitude was shown to improve the efficacy of Con-SCS, whereas the efficacy of Burst-SCS showed a non-monotonic relation with amplitude. Con-SCS at 66% MT (n = 5) and Burst-SCS at 50% MT (n = 6) were found to be equally effective in normalizing mechanical hypersensitivity. However, in the assessed time period Burst-SCS required significantly more mean charge per second to do so (p < 0.01). When applied at comparable mean charge per second, Con-SCS resulted in a superior behavioral outcome (p < 0.01), compared with Burst-SCS.

CONCLUSION

Biphasic Burst-SCS requires significantly more mean charge per second in order to achieve similar pain relief, as compared with Con-SCS, in an experimental model of chronic neuropathic pain.

Trial Design and Endpoint Evaluation in Clinical Studies Addressing Chronic Back Pain

STUDY DESIGN

A review of the literature evaluating clinical trials of chronic back pain.

OBJECTIVE

To assist physicians in assessing the quality of clinical trial data to make the most informed treatment decisions.

SUMMARY OF BACKGROUND DATA

Chronic pain is a tremendous public health issue, affecting close to 100 million adults in the United States, and costs the American people billions of dollars. One traditional treatment approach, the long-term use of opiate medications, has recently come under intense scrutiny for problems with complications, diversion, abuse, addiction, and lack of efficacy. In addition, the Centers for Disease Control and Prevention has recognized that overprescribing opiates has enabled an overdose crisis, and written guidelines that are intended to limit their use. It is for this reason that physicians must have a comprehensive understanding of the range of drug-free alternative therapies available and have the tools needed to rigorously evaluate the chronic pain literature so they can make appropriate treatment decisions.

METHODS

An evaluation of how clinical trials are designed and ranked, outcome measures, and costs for a variety of therapies is necessary to determine which treatment option is the most efficacious for an individual patient.

RESULTS

Clinical trial data demonstrate that spinal cord stimulation (SCS) is a safe and effective treatment option for many types of chronic pain, including back pain. The last 10 years has brought tremendous advances in the field of neuromodulation. Today, several treatment modalities exist for SCS requiring the physician to be able to critically evaluate and interpret the literature and determine which modality has the strongest evidence. When evaluating clinical trial data of patients with chronic back pain, emphasis must be placed on well designed, randomized controlled trials with long-term follow-up producing level I evidence. These data are obtained in a rigorous manner and are likely to have less bias when compared with lower level studies.

CONCLUSION

The level I studies performed to date have provided evidence that treatment with SCS results in sustainable pain reduction and improvements in scores measuring quality of life and patient functioning in those patients with chronic intractable back pain.

LEVEL OF EVIDENCE

5.

Best Practices in Spinal Cord Stimulation

STUDY DESIGN

A review of clinical best practices for spinal cord stimulation (SCS).

OBJECTIVE

The aim of this study is to summarize published and evidence based guidelines with regards to utilizing SCS, including patient selection, disease indication, perioperative management, complication mitigation strategies, and device selection. Additional focus has been provided on quality care to individual patients by acknowledging the importance of durable outcomes and care delivery costs.

SUMMARY OF BACKGROUND DATA

For more than 30 years, SCS has successfully alleviated patient suffering and enhanced the lives of patients with refractory pain conditions. Prospective studies of SCS have consistently demonstrated benefits through reduction of pain, improvement in function, and reduced healthcare expenditures in select patient diagnosis groups. Although the benefits of SCS are well-supported, the clinical application of this therapy varies widely based on physician training and experience, regional clinical practice variations, and insurance coverage.

METHODS

This article provides a summary of published studies, case reports, evidence-based guidelines and expert consensus, with the intent of increasing physician competency and enhancing patient care through improved clinical outcomes.

RESULTS

A guide to SCS implantation, appropriate patient selection, ranked recommendations for diseases that may most benefit for SCS treatment, complication mitigation strategies, and finally, indications for choosing the most efficacious modality of SCS therapy for specific patients and pain conditions.

CONCLUSION

Although SCS has been shown to be safe and effective for a number of pain conditions, emerging SCS modalities promise even greater efficacy over traditional SCS. To achieve this promise, physicians must carefully select and manage their patients and the SCS device.

LEVEL OF EVIDENCE

N\A.

Evidence Gaps in the Use of Spinal Cord Stimulation for Treating Chronic Spine Conditions

STUDY DESIGN

A review of literature.

OBJECTIVE

The aim of this study was to define and explore the current evidence gaps in the use of spinal cord stimulation (SCS) for treating chronic spine conditions.

SUMMARY OF BACKGROUND DATA

Although over the last 40 years SCS therapy has undergone significant technological advancements, evidence gaps still exist.

METHODS

A literature review was conducted to define current evidence gaps for the use of SCS. Areas of focus included 1) treatment of cervical spine conditions, 2) treatment of lumbar spine conditions, 3) technological advancement and device selection, 4) appropriate patient selection, 5) the ability to curb pharmacological treatment, and 6) methods to prolong efficacy over time. New SCS strategies using advanced waveforms are explored.

RESULTS

The efficacy, safety, and cost-effectiveness of traditional SCS for chronic pain conditions are well-established. Evidence gaps do exist. Recently, advancement in waveforms and programming parameters have allowed for paresthesia-reduced/free stimulation that in specific clinical areas may improve clinical outcomes. New waveforms such as 10-kHz high-frequency have resulted in an improvement in back coverage. To date, clinical efficacy data are more prevalent for the treatment of painful conditions originating from the lumbar spine in comparison to the cervical spine.

CONCLUSION

Evidence gaps still exist that require appropriate study designs with long-term follow-up to better define and improve the use of this therapy for the treatment of chronic spine pain in both the cervical and lumbar regions.

LEVEL OF EVIDENCE

N/A.

Clinical Evidence for Spinal Cord Stimulation for Failed Back Surgery Syndrome (FBSS): Systematic Review

STUDY DESIGN

A systematic review.

OBJECTIVE

A systematic literature review of the clinical data from prospective studies was undertaken to assess the efficacy of spinal cord stimulation (SCS) in the treatment of failed back surgery syndrome (FBSS) in adults.

SUMMARY OF BACKGROUND DATA

For patients with unrelenting back pain due to mechanical instability of the spine, degenerative disc disease, spinal injury, or deformity, spinal surgery is a well-accepted treatment option; however, even after surgical intervention, many patients continue to experience chronic back pain that can be notoriously difficult to treat. Clinical evidence suggests that for patients with FBSS, repeated surgery will not likely offer relief. Additionally, evidence suggests long-term use of opioid pain medications is not effective in this population, likely presents additional complications, and requires strict management.

METHODS

A systematic literature review was performed using several bibliographic databases, prospective studies in adults using SCS for FBSS were included.

RESULTS AND CONCLUSION

SCS has been shown to be a safe and efficacious treatment for this patient population. Recent technological developments in SCS offer even greater pain relief to patients' refractory to other treatment options, allowing patients to regain functionality and improve their quality of life with significant reductions in pain.

LEVEL OF EVIDENCE

N/A.

Burst or High-Frequency (10 kHz) Spinal Cord Stimulation in Failed Back Surgery Syndrome Patients With Predominant Back Pain: One Year Comparative Data

OBJECTIVES

Burst and 10 kHz spinal cord stimulation (SCS) demonstrated improvement for failed back surgery syndrome (FBSS) with predominant, refractory back pain. Here, we report the long-term follow-up of a previously published study comparing the safety and efficacy of burst vs. 10 kHz SCS for predominant back pain (70% of global pain) of FBSS patients.

METHODS

This comparative, observational study extended the follow-up period up to 20 months evaluating both SCS modalities. Pain intensity (visual analog scale [VAS_B , VAS_L ]), functional capacity (Pittsburgh Sleep Quality Index [PSQI]; depression (Beck Depression Inventory [BDI]), stimulation parameters and hardware and/or stimulation associated adverse events were recorded and analyzed over time.

RESULTS

Overall VAS_B (t_1,12  = 66.76, p < 0.001) and VAS_L (t_1,12  = 4.763, p < 0.049; p < 0.001) declined over time. Burst significantly decreased VAS_B by 87.5% (±17.7) (mean 8 ± 0.76 to 1 ± 1.41; t₁ =12.3, p < 0.001), and 10 kHz significant decreased VAS_B by 54.9% (±44) (mean 8 ± 0.63 to 3.5 ± 3.27; t₁ =3.09, p = 0.027). No significant differences for between SCS types were revealed (t₁ =1.75, p = 0.13). VAS_L was significantly suppressed for burst (burst: 3.6 ± 1.59 to 1.5 ± 1.06; t₁  = 3.32, p = 0.013). A significant effect of time was found for functional outcome with no significant differences between SCS types (PSQI: t_1,12  = 8.8, p = 0.012; and BDI: t₁  = 53.3, p < 0.001). No stimulation/hardware-related complications occurred.

DISCUSSION

Long-term data of this comparative study suggests that burst responsiveness was superior to 10 kHz in our small-scale cohort, thus a larger, randomized-controlled comparative study design is highly recommended.