A Socioeconomic Survey of Spinal Cord Stimulation (SCS) Surgery

Objective: We evaluated trends in inpatient spinal cord stimulation (SCS) for the 14‐year period from 1993 to 2006. Materials and Methods: We utilized the Nationwide Inpatient Sample data base from the Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality. Results: A total of 57,486 patients underwent inpatient placement of SCS systems from 1993 to 2006. Length of stay steadily decreased from 4.0 days in 1993 to 2.1 days in 2006. Average cost increased from $15,342 in 1993 to nearly $58,088 in 2006. The National Bill for SCS surgery in 2006 alone totaled nearly $215MM. Medicare accounted for 35% of payers, while private insurance accounted for 41% of claims. Conclusions: Given the expense of these systems, it is important to assess not only the efficacy of novel neuromodulatory interventions, but also their cost. Future studies should be designed with these important outcome measures in mind.     

Evaluating optimized temporal patterns of spinal cord stimulation (SCS)

BackgroundTemporal patterns of stimulation represent a novel dimension for improving the efficacy of spinal cord stimulation to treat chronic neuropathic pain.ObjectiveWe hypothesized that nonregular temporal patterns of stimulation designed using a computational model would be superior to conventional stimulation at constant frequencies or completely random patterns of stimulation.MethodsUsing a computational model of the dorsal horn network and an optimization algorithm based on biological evolution, we designed an optimized pattern of spinal cord stimulation with comparable efficacy and increased efficiency relative to constant frequency (CF) stimulation. We evaluated the effect of different temporal patterns on individual neurons recorded in the dorsal horn of urethane-anesthetized rats.ResultsThe optimized pattern and 50 Hz CF stimulation produced greater inhibition of spontaneously firing neurons recorded in vivo than random 50 Hz stimulation or a pattern designed intentionally with poor fitness. Spinal Cord Stimulation (SCS) led to significant changes in the firing patterns of recorded units, and stimulation patterns that generated significant inhibition also tended to reduce entropy and regularize the firing patterns of units, suggesting that patterns of dorsal horn neuron activity may be important for pain perception in addition to the firing rate.ConclusionsThese results demonstrate that the computational model can be used as a tool for optimizing stimulation parameters and suggest that optimized temporal patterns may increase the efficacy of spinal cord stimulation.     

The Effect of Spinal Cord Stimulation (SCS) on Static Balance and Gait

Objectives: To investigate whether spinal cord stimulation (SCS) has a negative effect on static balance and gait, which is implicated by the increased incidence of falls leading to frequently occurring lead migrations. Materials and Methods: A controlled trial is performed with 11 subjects (four female, seven male) with a mean age of 46 years old. A baseline measurement consisting of static balance and gait tests was performed. Within two weeks after implantation of a spinal cord stimulator, subjects performed the same tests with both stimulation switched on and off. Static balance was assessed with eyes open and eyes closed on hard surface and foam surface. The velocity of the center of pressure and weight symmetry were the main outcome parameters. Kinematics and spatiotemporal outcome parameters were used to analyze gait. ANOVAs were used to compare between baseline, stimulation on, and stimulation off. Results: Spinal cord stimulation resulted in significant pain relief as scored on a Visual Analog Scale (p < 0.001). Gait width decreased and this change (indicative of improvement in balance) was significant (p = 0.007). No other significant group differences were found between stimulation baseline and post‐surgery measurements. SCS did not influence static balance or gait when group effects were analyzed. Four subjects showed significant differences in static balance between stimulation on and off. Conclusions: The lack of group differences in normal gait and static balance cannot explain the increased incidence of falls. However, four subjects showed an effect of SCS on static balance. Further research to clarify why only a part of the subjects experienced balance problems is recommended and assessments of more demanding balance and gait tasks are desirable.     

Spinal Cord Stimulator (SCS) Placement: Examining Outcomes Between the Open and Percutaneous Approach

BackgroundSpinal cord stimulator (SCS) placement has been gaining traction as an approach to modulate pain levels for several different chronic pain conditions. This procedure can be performed via a percutaneous or open approach. Data regarding SCS complications are relatively limited.ObjectiveThe purpose of this study was to leverage a large national database to examine outcomes between the percutaneous and open SCS placement approaches. Outcomes in this study include length of stay (LOS), complication rates, reoperation rates, and 1-year readmission rates.Materials and MethodsInclusion criteria for the current study is SCS placement between 2015 and 2020, with receipt of an SCS using either a percutaneous approach or an open laminectomy based approach. Encounters included were limited to true SCS placement, such that trial placements were not included in the study. Univariate statistics and multivariable logistic regression was performed to compare outcomes between cohorts.ResultsTotal SCS case volumes were 9935 between the percutaneous (n = 4477, 45.1%) and open (n = 5458, 54.9%) approach. Patients receiving the percutaneous approach were found to have a mean decrease in LOS of 9.91 hours when compared to those receiving the open approach. The percutaneous approach was significantly associated with the need for reoperation within one year compared to the open approach (odds ratio [OR]: 0.663, p < 0.001), as well as with the need for readmission within 30 days (51.2% vs 40.2%, OR: 0.759, p < 0.001).ConclusionThe open approach, when compared to the percutaneous approach, had a longer mean LOS, lower outpatient discharge rates, and higher odds of experiencing an operative complication in comparison to the percutaneous approach. The percutaneous approach had relatively increased odds of thirty-day readmission, although no significant difference in one-year readmission or removal was demonstrated.     

Spatial Filtering of Electroencephalography Reduces Artifacts and Enhances Signals Related to Spinal Cord Stimulation (SCS)

ObjectivesHow spinal cord stimulation (SCS) in its different modes suppresses pain is poorly understood. Mechanisms of action may reside locally in the spinal cord, but also involve a larger network including subcortical and cortical brain structures. Tonic, burst, and high-frequency modes of SCS can, in principle, entrain distinct temporal activity patterns in this network, but finally have to yield specific effects on pain suppression. Here, we employ high-density electroencephalography (EEG) and recently developed spatial filtering techniques to reduce SCS artifacts and to enhance EEG signals specifically related to neuromodulation by SCS.Materials and MethodsWe recorded high-density resting-state EEGs in patients suffering from pain of various etiologies under different modes of SCS. We established a pipeline for the robust spectral analysis of oscillatory brain activity during SCS, which includes spatial filtering for attenuation of pulse artifacts and enhancement of brain activity potentially modulated by SCS.ResultsIn sensor regions responsive to SCS, neuromodulation strongly reduced activity in the theta and low alpha range (6–10 Hz) in all SCS modes. Results were consistent in all patients, and in accordance with thalamocortical dysrhythmia hypothesis of pain. Only in the tonic mode showing paresthesia as side effect, SCS also consistently and strongly reduced high-gamma activity (>84 Hz).ConclusionsEEG spectral analysis combined with spatial filtering allows for a spatially and temporally specific assessment of SCS-related, neuromodulatory EEG activity, and may help to disentangle therapeutic and side effects of SCS.     

Using Lower Amplitudes to Maintain Effective High Dose Spinal Cord Stimulation Therapy (SCS Dosing Pilot Study)

ObjectiveSpinal cord stimulation is an effective therapy for chronic back and/or leg pain. Amplitude dose–response studies are lacking; therefore, little guidance exists regarding the minimum amplitude requirements with specific high dose parameters. This study characterized the minimum amplitude level that maintained SCS therapy satisfaction and pain relief when stimulating at 1000 Hz and 90 μsec.Materials and MethodsQualified patients had back and leg pain, an implanted neurostimulator programmed to 1000 Hz and 90 μsec, and were very or somewhat satisfied with the therapy, and an average overall VAS pain score ≤ 4 from a daily diary. Patients received four blinded amplitudes (titrated from 80%, 60%, 40%, and 20% of baseline perception threshold), approximately two weeks each, with 1000 Hz and 90 μsec and position-adaptive stimulation enabled. Patients’ satisfaction and overall VAS pain scores were collected for each period. All patients continued through the study, even after reporting lack of therapy satisfaction or pain relief.ResultsThe minimum amplitude, which maintained therapy satisfaction, was 80% of perception threshold for two patients, 60% for one patient, and 20% for 21 patients. Additionally, six patients lost satisfaction changing from their baseline amplitude to 80% perception threshold. The minimum amplitude level, which maintained overall pain relief, was 80% perception threshold for three patients, 60% perception threshold for one patient, 40% perception threshold for two patients, and 20% perception threshold for 19 patients. Five patients required the setting they were programmed to during the baseline period.ConclusionThe qualified study patients defined an implanted population reporting good pain relief and satisfaction using HD SCS therapy at baseline. The majority of these patients were able to maintain therapy satisfaction and pain relief (70% and 63.3%, respectively) with 20% perception threshold amplitude. Amplitudes below perception threshold could potentially maintain effective SCS therapy with HD stimulation in a subset of patients.     

National Italian Register of Implantable Systems for Spinal Cord Stimulation (SCS): Analysis of Preliminary Data

The aim of this work is to assess quality of treatment and to monitor drawbacks of SCS implantation systems through a National Observational Center. Data were obtained through a questionnaire sent by post or via telephone to each patient. All patients were affected by chronic‐‘vascular’ and “neuropathic” pain. Questionnaires were handed out to 463 patients. So far the returned questionnaires have accounted for 72% (with men accounting for 58% and women for 42%). The data obtained concern the decade between 1988 and 1999. Eighty‐one percent of patients reported a positive assessment for pain control with neurostimulation; there was a lowering of drug needs in 71% of patients after implantation; 10% of patients reported problems with the use of their stimulator; an improvement in quality of life was reported by 63% of patients; 94% of patients enrolled in the registry expressed a positive judgement on their pain therapy center; and 87% of patients would make the same choice again, considering SCS to be a valid treatment for their condition. We conclude that the methodology used is consistent with that of previous studies on nonmalignant chronic pain. The data obtained also reveal implantation hardware reliability, regardless of clinical outcome. A low percentage of complications and a high degree of patient satisfaction are also to be stressed.     

Spinal Cord Stimulation (SCS) in Conjunction With Peripheral Nerve Field Stimulation (PNfS) for the Treatment of Complex Pain in Failed Back Surgery Syndrome (FBSS)

Background: Failed back surgery syndrome (FBSS) is a well‐defined pathologic condition observed over many years. Design: We have investigated the effect of spinal cord stimulation (SCS) with peripheral nerve field stimulation (PNfS) in eight patients with FBSS Outcome Measure: The following parameters were collected and analyzed: The pain intensity score on a 0–10 numbering rating scale (NRS), the psychologic profile with Beck Depression Inventory (BDI), the pain quality with McGill Pain Questionnaire—short form (MGPQ‐sf), the back pain with Oswestry scale score (OS), and the health general quality pattern with QualityMetric's SF‐36v2^® Health Survey. Patients: Eight patients with low back and radicular pain in FBSS are reported. The mean duration of pain was 6.7 months, and the mean NRS score was 9.5, BDI 28.8, MGPQ‐sf 16.8, OS 44.5, and SF‐36 score was 72.8. The average drug intake of opioids was 250 mg/day. Intervention: In six patients, two octopolar leads were placed in epidural space at D7‐D8 and D8‐D9, in conjunction with two octopolar leads placed in lumbar‐sacral subcutaneous space (Precision System, Boston Scientific, Valencia, CA, USA), and in two patients, a two tetrapolar leads was placed in epidural space at D8‐D9 with two tetrapolar leads (Pisces Quad, Plus, Medtronic Inc., Minneapolis, MN, USA) placed in lumbar‐sacral subcutaneous space (Restore Ultra, Medtronic Inc., Minneapolis, MN, USA). Results: After one year mean of follow‐up, the mean NRS score was 4, BDI 8, MGPQ‐sf 5, OS 21, and the SF‐36 score was increased at 108.5. The mean drug intake of opioids was decreased at 20 mg/day. Conclusion: The combination of SCS and PNfS, using the latest rechargeable systems, may be a valid therapeutic strategy in FBSS.     

Electric Spinal Cord Stimulation (SCS) in the Treatment of Angina Pectoris: A Cost‐Utility Analysis

For the last 15 years electric spinal cord stimulation (SCS) has been employed in patients with confirmed ischemic heart disease who suffer from refractory angina pectoris despite maximum medical/surgical treatment. The purpose of this investigation was to assess not only the economic consequences of SCS treatment (cost‐utility analysis) but also altered quality of life in SCS patients. The retrospective study includes 18 consecutive patients, six women and 12 men, with an average age of 56.5 years (range 50–68), submitted to implantation of a SCS system at Odense University Hospital. Before implantation of the SCS system, the patients were in a transcutaneous electric nerve stimulation (TENS) treatment 2–11 months. At the submission all patients were in New York Heart Association functional group III/IV. The results are based on cost data from the year prior to start of TENS treatment compared with the year after implantation of the SCS system. Medical records of the patients were examined and data concerning use of general practitioners and emergency services were collected from a nationwide database. Quality of life data were collected using identical questionnaires (perception of pain, mobility, function in daily life, and physical activity) related to the period immediately before start of the TENS treatment and one year after SCS implant. Savings were found at hospital level (reduction in number of admissions) and for non‐hospital related expenses (such as medication and visits at general practitioners). In addition, improvements were registered in all respects which constituted assessment of the quality of life of the patients. The study is a repetition of a similar analysis with identical results made in 1990 and including the 16 first angina pectoris patients treated with SCS at Odense University Hospital. SCS is effective in reducing hospital and non‐hospital related expenses and improving quality of life of the patients. SCS is a simple treatment for the patient to use. The implantation technique is not more invasive than permanent cardiac pacing. The decisive part of the procedure is the insertion of the electrode and follow‐up with support and adjustments of the stimulation.