6. Persistent spinal pain syndrome type 2.

INTRODUCTION: Persistent Spinal Pain Syndrome (PSPS) refers to chronic axial pain and/or extremity pain. Two subtypes have been defined: PSPS-type 1 is chronic pain without previous spinal surgery and PSPS-type 2 is chronic pain, persisting after spine surgery, and is formerly known as Failed Back Surgery Syndrome (FBSS) or post-laminectomy syndrome. The etiology of PSPS-type 2 can be gleaned using elements from the patient history, physical examination, and additional medical imaging. Origins of persistent pain following spinal surgery may be categorized into an inappropriate procedure (eg a lumbar fusion at an incorrect level or for sacroiliac joint [SIJ] pain); technical failure (eg operation at non-affected levels, retained disk fragment, pseudoarthrosis), biomechanical sequelae of surgery (eg adjacent segment disease or SIJ pain after a fusion to the sacrum, muscle wasting, spinal instability); and complications (eg battered root syndrome, excessive epidural fibrosis, and arachnoiditis), or undetermined. METHODS: The literature on the diagnosis and treatment of PSPS-type 2 was retrieved and summarized. RESULTS: There is low-quality evidence for the efficacy of conservative treatments including exercise, rehabilitation, manipulation, and behavioral therapy, and very limited evidence for the pharmacological treatment of PSPS-type 2. Interventional treatments such as pulsed radiofrequency (PRF) of the dorsal root ganglia, epidural adhesiolysis, and spinal endoscopy (epiduroscopy) might be beneficial in patients with PSPS-type 2. Spinal cord stimulation (SCS) has been shown to be an effective treatment for chronic, intractable neuropathic limb pain, and possibly well-selected candidates with axial pain. CONCLUSIONS: The diagnosis of PSPS-type 2 is based on patient history, clinical examination, and medical imaging. Low-quality evidence exists for conservative interventions. Pulsed radiofrequency, adhesiolysis and SCS have a higher level of evidence with a high safety margin and should be considered as interventional treatment options when conservative treatment fails.

Comparing the Efficacy of Dorsal Root Ganglion Stimulation With Conventional Medical Management in Patients With Chronic Postsurgical Inguinal Pain: Post Hoc Analyzed Results of the SMASHING Study.

OBJECTIVES: Approximately 10% of patients who undergo inguinal hernia repair or Pfannenstiel incision develop chronic (> three months) postsurgical inguinal pain (PSIP). If medication or peripheral nerve blocks fail, a neurectomy is the treatment of choice. However, some patients do not respond to this treatment. In such cases, stimulation of the dorsal root ganglion (DRG) appears to significantly reduce chronic PSIP in selected patients. MATERIALS AND METHODS: In this multicenter, randomized controlled study, DRG stimulation was compared with conventional medical management (CMM) (noninvasive treatments, such as medication, transcutaneous electric neurostimulation, and rehabilitation therapy) in patients with PSIP that was resistant to a neurectomy. Patients were recruited at a tertiary referral center for groin pain (SolviMáx, Eindhoven, The Netherlands) between March 2015 and November 2016. Suitability for implantation was assessed according to the Dutch Neuromodulation Association guidelines. The sponsor discontinued the study early owing to slow enrollment. Of 78 planned patients, 18 were randomized (DRG and CMM groups each had nine patients). Six patients with CMM (67%) crossed over to DRG stimulation at the six-month mark. RESULTS: Fifteen of the 18 patients met the six-month primary end point with a complete data set for a per-protocol analysis. Three patients with DRG stimulation had a negative trial and were lost to follow-up. The average pain reduction was 50% in the DRG stimulation and crossover group (from 6.60 ± 1.24 to 3.28 ± 2.30, p = 0.0029). Conversely, a 13% increase in pain was observed in patients with CMM (from 6.13 ± 2.24 to 6.89 ± 1.24, p = 0.42). Nine patients with DRG stimulation experienced a total of 19 adverse events, such as lead dislocation and pain at the implantation site. CONCLUSIONS: DRG stimulation is a promising effective therapy for pain relief in patients with PSIP resistant to conventional treatment modalities; larger studies should confirm this. The frequency of side effects should be a concern in a new study. CLINICAL TRIAL REGISTRATION: The Clinicaltrials.gov registration number for the study is NCT02349659.

Prospective Cohort Analysis of DRG Stimulation for Failed Back Surgery Syndrome Pain Following Lumbar Discectomy.

INTRODUCTION: Surgical lumbar discectomy is a commonly performed routine spinal procedure that is usually undertaken to alleviate lumbar radicular symptoms caused by a herniated intervertebral disc. Surgical lumbar discectomy can also lead to chronic postsurgical leg and/or back pain (failed back surgery syndrome [FBSS]), a condition that can be refractory to conventional medical management. Early clinical results on the use of dorsal root ganglion (DRG) stimulation for FBSS have supported the use of this treatment alternative. METHODS: A multicenter, single-arm, observational cohort study enrolled patients who had chronic pain following surgical lumbar discectomy, had failed conservative treatments, and reported pain intensity of at least 6 out of 10 in the primary region of pain. Data were collected on pain, quality of life, disability, and mood at baseline and through 12 months. RESULTS: Thirteen patients underwent a trial of DRG stimulation; 11 (84.6%; 95% confidence interval = 57.8% to 95.7%) had good outcomes and underwent permanent device placement. Pain was reduced from a score of 8.64 (±0.92) at baseline to 2.40 (±2.38; n = 9) after 12 months of treatment, a 72.05% average reduction (P < 0.001). Similar improvements were observed across the secondary clinical measures, and safety data were in line with published rates. DISCUSSION: These results suggest that DRG stimulation induces pain relief in subjects diagnosed with FBSS. These reductions in pain were also associated with improvements in quality of life and disability. Additional prospective studies are warranted to further investigate this potential application of DRG stimulation, as well as to optimize patient selection, lead placement, and programming strategies.

Durability of Evoked Compound Action Potential (ECAP)-Controlled, Closed-Loop Spinal Cord Stimulation (SCS) in a Real-World European Chronic Pain Population.

INTRODUCTION: Closed-loop spinal cord stimulation (CL-SCS) is a recently introduced system that records evoked compound action potentials (ECAPs) from the spinal cord elicited by each stimulation pulse and uses this information to automatically adjust the stimulation strength in real time, known as ECAP-controlled SCS. This innovative system compensates for fluctuations in the distance between the epidural leads and the spinal cord by maintaining the neural response (ECAP) at a predetermined target level. This data collection study was designed to assess the performance of the first CL-SCS system in a real-world setting under normal conditions of use in multiple European centers. The study analyzes and presents clinical outcomes and electrophysiological and device data and compares these findings with those reported in earlier pre-market studies of the same system. METHODS: This prospective, multicenter, observational study was conducted in 13 European centers and aimed to gather electrophysiological and device data. The study focused on the real-world application of this system in treating chronic pain affecting the trunk and/or limbs, adhering to standard conditions of use. In addition to collecting and analyzing basic demographic information, the study presents data from the inaugural patient cohort permanently implanted at multiple European centers. RESULTS: A significant decrease in pain intensity was observed for overall back or leg pain scores (verbal numerical rating score [VNRS]) between baseline (mean ± standard error of the mean [SEM]; n = 135; 8.2 ± 0.1), 3 months (n = 93; 2.3 ± 0.2), 6 months (n = 82; 2.5 ± 0.3), and 12 months (n = 76; 2.5 ± 0.3). Comparison of overall pain relief (%) to the AVALON and EVOKE studies showed no significant differences at 3 and 12 months between the real-world data release (RWE; 71.3%; 69.6%) and the AVALON (71.2%; 73.6%) and EVOKE (78.1%; 76.7%) studies. Further investigation was undertaken to objectively characterize the physiological parameters of SCS therapy in this cohort using the metrics of percent time above ECAP threshold (%), dose ratio, and dose accuracy (µV), according to previously described methods. Results showed that a median of 90% (40.7-99.2) of stimuli were above the ECAP threshold, with a dose ratio of 1.3 (1.1-1.4) and dose accuracy of 4.4 µV (0.0-7.1), based on data from 236, 230, and 254 patients, respectively. Thus, across all three metrics, the majority of patients had objective therapy metrics corresponding to the highest levels of pain relief in previously reported studies (usage over threshold > 80%, dose ratio > 1.2, and error < 10 µV). CONCLUSIONS: In conclusion, this study provides valuable insights into the real-world application of the ECAP-controlled CL-SCS system, highlighting its potential for maintaining effective pain relief and objective neurophysiological therapy metrics at levels seen in randomized control trials, and potential for quantifying patient burden associated with SCS system use via patient-device interaction metrics. CLINICAL TRIAL REGISTRATION: In the Netherlands, the study is duly registered on the International Clinical Trials Registry Platform (Trial NL7889). In Germany, the study is duly registered as NCT05272137 and in the United Kingdom as ISCRTN27710516 and has been reviewed by the ethics committee in both countries.

Inflammatory response and optimalisation of perioperative fluid administration during hyperthermic intraoperative intraperitoneal chemotherapy surgery.

BACKGROUND: Surgical cytoreduction and simultaneous hyperthermic intraoperative intraperitoneal chemotherapy (HIPEC) for peritoneal carcinomatosis has a high incidence of postoperative complications. Inadequate intraoperative volume therapy is a known risk factor for the development of postoperative complications. Another possible risk factor is the inflammatory response due to surgery and HIPEC. The aim of this observational pilot study was to monitor fluid intake in the first 24 hours peri- and postoperative by using a non-invasive cardiac output indicator. Furthermore, we measured circulating cytokines and evaluated the possible relation of these changes of inflammatory response with the non-invasive monitored fluid management. METHODS: Twenty-four patients undergoing cytoreductive surgery and HIPEC for peritoneal carcinomatosis were included. Patients were randomised into either a liberal fluid management group using intra-arterial blood pressure and central venous pressure measurement or a restrictive group by using intra-arterial blood pressure and central venous pressure measurement with FloTrac/Vigileo monitoring. Cytokines were measured with multiplex immunoassays. RESULTS: We found no difference in the amount of fluid administration in patients undergoing HIPEC surgery with FloTrac/Vigileo monitoring compared to standard care. Furthermore, there was no difference in mortality, ICU and hospital length of stay between both groups. A severe inflammatory response was seen in all patients after the HIPEC procedure with a rapid increase of interleukins and C-reactive protein (CRP). There was however no difference between our intervention and control group in the severity of this reaction. Finally, we found no relation between the severity of the inflammatory response and mortality, or a composite end-point of mortality and severe complications within 30 days postoperative. CONCLUSIONS: FloTrac/Vigileo monitoring does not lead to a more restrictive fluid administration and does not influence short-term clinical course in patients undergoing HIPEC surgery. The procedure itself leads to a severe inflammatory response, which is not affected by the use of FloTrac/Vigileo. Our data do not support the use of FloTrac/Vigileo monitoring in patients undergoing HIPEC surgery concerning fluid restrictive management.