Clinical Patient-Relevant Outcome Domains for Persistent Spinal Pain Syndrome-A Scoping Review and Expert Panels.

Large variation exists in the monitoring of clinical outcome domains in patients with persistent spinal pain syndrome (PSPS). Furthermore, it is unclear which outcome domains are important from the PSPS patient's perspective. The study objectives were to identify patient-relevant outcome domains for PSPS and to establish a PSPS outcomes framework. PubMed, CINAHL, Cochrane, and EMBASE were searched to identify studies reporting views or preferences of PSPS patients on outcome domains. The Arksey and O'Malley framework was followed to identify outcome domains. An expert panel rated the domains based on the importance for PSPS patients they have treated. A framework of relevant outcome domains was established using the selected outcome domains by the expert panel. No studies were found for PSPS type 1. Five studies with 77 PSPS type 2 patients were included for further analysis. Fourteen outcome domains were identified. An expert panel, including 27 clinical experts, reached consensus on the domains pain, daily activities, perspective of life, social participation, mobility, mood, self-reliance, and sleep. Eleven domains were included in the PSPS type 2 outcomes framework. This framework is illustrative of a more holistic perspective and should be used to improve the evaluation of care for PSPS type 2 patients. Further research is needed on the prioritization of relevant outcome domains.

Factors Predicting Clinically Relevant Pain Relief After Spinal Cord Stimulation for Patients With Chronic Low Back and/or Leg Pain: A Systematic Review With Meta-Analysis and Meta-Regression.

RATIONALE: To optimize results with spinal cord stimulation (SCS) for chronic low back pain (CLBP) and/or leg pain, including persistent spinal pain syndrome (PSPS), careful patient selection based on proved predictive factors is essential. Unfortunately, the necessary selection process required to optimize outcomes of SCS remains challenging. OBJECTIVE: This review aimed to evaluate predictive factors of clinically relevant pain relief after SCS for patients with CLBP and/or radicular leg pain, including PSPS. MATERIALS AND METHODS: In August 2023, PubMed, Cinahl, Cochrane, and EMBASE were searched to identify studies published between January 2010 and August 2023. Studies reporting the percentage of patients with ≥50% pain relief after SCS in patients with CLBP and leg pain, including PSPS at 12 or 24 months, were included. Meta-analysis was conducted to pool results for back, leg, and general pain relief. Predictive factors for pain relief after 12 months were examined using univariable and multivariable meta-regression. RESULTS: A total of 27 studies (2220 patients) were included for further analysis. The mean percentages of patients with substantial pain relief were 68% for leg pain, 63% for back pain, and 73% for general pain at 12 months follow-up, and 63% for leg pain, 59% for back pain, and 71% for general pain at 24 months follow-up assessment. The implantation method and baseline Oswestry Disability Index made the multivariable meta-regression model for ≥50% back pain relief. Sex and pain duration made the final model for ≥50% leg pain relief. Variable stimulation and implantation method made the final model for general pain relief. CONCLUSIONS: This review supports SCS as an effective pain-relieving treatment for CLBP and/or leg pain, and models were developed to predict substantial back and leg pain relief. To provide high-grade evidence for predictive factors, SCS studies of high quality are needed in which standardized factors predictive of SCS success, based on in-patient improvements, are monitored and reported.

Subcutaneous Stimulation as Add-on Therapy to Spinal Cord Stimulation in Patients With Persistent Spinal Pain Syndrome Significantly Increases the Total Electrical Charge per Second: Aspects on Stimulation Parameters and Energy Requirements of the Implanted Neurostimulators.

OBJECTIVE: In our previous multicenter randomized controlled trial, we demonstrated the clinical effectiveness of peripheral nerve field stimulation (PNFS) as add-on therapy to spinal cord stimulation (SCS) for the treatment of chronic back pain in patients with persistent spinal pain syndrome (PSPS) or failed back surgery syndrome (FBSS). To our knowledge, no previous study has investigated the effect of PNFS as an add-on to SCS on the energy consumption of the implanted neurostimulators. Therefore, in this study, we compared the specific stimulation parameters and energy requirements of a previously unreported group of patients with only SCS with those of a group of patients with SCS and add-on PNFS. We also investigated differences that might explain the need for PNFS in the treatment of chronic low back pain. MATERIALS AND METHODS: We analyzed 75 patients with complete sets of stimulation parameters, with 21 patients in the SCS-only group and 54 patients in the SCS + PNFS group. Outcome measures were average visual analog scale score, SCS parameters (voltage, frequency, and pulse width), SCS charge per second, and total charge per second. We analyzed baseline characteristics and differences between and within groups over time. RESULTS: Both groups had comparable patient characteristics at baseline and showed a significant decrease in back and leg pain. SCS charge per second did not significantly differ between the groups at baseline or at 12 months. The total charge per second was significantly higher in the active SCS + PNFS group than in the SCS-only group at baseline; in the SCS + PNFS group, this persisted for up to 12 months, and the SCS charge per second and total charge per second increased significantly over time. CONCLUSIONS: Our results show that add-on PNFS increases the total charge per second compared with SCS alone, as expected. However, further research is needed because our results do not directly explain why some patients require add-on PNFS to treat low back pain.

Spinal Cord Stimulation With Additional Peripheral Nerve/Field Stimulation Versus Spinal Cord Stimulation Alone on Back Pain and Quality of Life in Patients With Persistent Spinal Pain Syndrome.

INTRODUCTION: Persistent spinal pain syndrome (PSPS) or failed back surgery syndrome (FBSS) refers to new or persistent pain following spinal surgery for back or leg pain in a subset of patients. Spinal cord stimulation (SCS) is a neuromodulation technique that can be considered in patients with predominant leg pain refractory to conservative treatment. Patients with predominant low back pain benefit less from SCS. Another neuromodulation technique for treatment of chronic low back pain is subcutaneous stimulation or peripheral nerve field stimulation (PNFS). We investigated the effect of SCS with additional PNFS on pain and quality of life of patients with PSPS compared with that of SCS alone after 12 months. MATERIALS AND METHODS: This is a comparative study of patients with PSPS who responded to treatment with either SCS + PNFS or SCS only following a multicenter randomized clinical trial protocol. In total, 75 patients completed the 12-month follow-up: 21 in the SCS-only group and 54 in the SCS + PNFS group. Outcome measures were pain (visual analog scale), quality of life (36-Item Short Form Survey [SF-36]), anxiety and depression (Hospital Anxiety and Depression Scale [HADS]), overall health (EuroQol Five-Dimension [EQ-5D]), disability (Oswestry Disability Index [ODI]), and pain assessed by the McGill questionnaire. RESULTS: There were no significant differences in baseline characteristics between the two groups. Both groups showed a significant reduction in back and leg pain at 12 months compared with baseline measurements. No significant differences were found between the groups in effect on both primary (pain) and secondary parameters (SF-36, HADS, EQ-5D, ODI, and McGill pain). CONCLUSION: In a subgroup of patients with chronic back and leg pain, SCS alone provided similar long-term pain relief and quality-of-life improvement as PNFS in addition to SCS. In patients with refractory low back pain not responding to SCS alone, adding PNFS should be recommended. CLINICAL TRIAL REGISTRATION: The Clinicaltrials.gov registration number for the study is NCT01776749.

Dorsal Root Ganglion Stimulation Normalizes Measures of Pain Processing in Patients with Chronic Low-Back Pain: A Prospective Pilot Study using Quantitative Sensory Testing.

BACKGROUND: Dorsal root ganglion stimulation (DRG-S) is used as a treatment for chronic low-back pain (CLBP), although its underlying mechanisms remain elusive. CLBP patients have been found to have reduced mechanoreceptive perception, reduced endogenous analgesia, as well as deep-tissue hyperalgesia when compared with healthy controls. Using quantitative sensory testing (QST), we studied if DRG-S in CLBP patients results in changes in pain processing. METHODS: Quantitative sensory testing was performed in patients before trial implantation of a DRG-S system for CLBP and just before the trial lead removal or at 1-month follow-up after the permanent implant. We determined the pressure pain threshold (PPT) and mechanical detection threshold (MDT) at the most painful lower-back location. PPT was also measured on the contralateral shoulder as a control. We obtained a measure of endogenous inhibitory pain modulation using conditioned pain modulation (CPM). RESULTS: We enrolled 11 patients (60 ± 16 years). Pain decreased from 8.5 ± 1.0 at baseline to 2.0 ± 1.5 on a 0-10 numerical rating scale with DRG-S (P < 0.01). From baseline to with DRG-S, PPT on the most painful location on the low back increased from 28.7 ± 13.6 to 43.4 ± 17.2 N/cm2 (P < 0.01). MDT on the same location decreased from 8.1 ± 10.4 to 3.4 ± 4.7 mN (P = 0.07). PPT on the control location and CPM did not change significantly. CONCLUSIONS: Our results suggest that DRG-S in CLBP patients reduces deep-tissue hyperalgesia in the low back, while improving mechanoreceptive perception. These changes in both neuropathic and nociceptive components of CLBP were accompanied by clinical improvements in pain and function.

Unilateral Dorsal Root Ganglion Stimulation Lead Placement With Resolution of Bilateral Lower Extremity Symptoms in Diabetic Peripheral Neuropathy.

Dorsal root ganglion stimulation (DRG-S) is a form of neuromodulation that can target specific dermatomes to obtain better coverage of the distal extremity. Previously proposed mechanisms of action for DRG-S focused on the dorsal root ganglion (DRG) itself, without consideration of orthodromic effects in the dorsal horn and antidromic effects on the nerve root and sympathetic chain. Diabetic peripheral neuropathy (DPN) is an axonal neuropathy that affects around half of all patients with diabetes mellitus, causing severe pain and sensory impairment in the distal extremities. We present a case of a patient with DPN in both feet, in addition to low back pain, who underwent a DRG-S trial with right T12 and S1 leads. The trial was performed unilaterally for seven days, allowing the patient to compare the treated versus the untreated (left) side. Pain, disability, general health status, and quality of life measures improved significantly. In addition to the significant pain relief in the low back and feet, the patient had near resolution of other DPN-related symptoms, including numbness, bluish discoloration, and allodynia of both feet. He also demonstrated functional and psychological benefits with only a single-sided lead. Overall, the placement of unilateral T12 and S1 DRG-S leads resulted in symmetric improvement of DPN symptoms. A possible mechanism of action is antidromic propagation of action potential signaling into the sympathetic chain to a central ganglion and then to the contralateral sympathetic chain. Given the DRG's ability to directly affect afferent sympathetic fibers with low-frequency stimulation, DRG-S may be an effective neuromodulatory treatment for DPN.