Hardware Failures in Spinal Cord Stimulation for Failed Back Surgery Syndrome

Spinal cord stimulation (SCS) is an efficient means for treatment of the postsurgical lumbar spine condition known as failed back surgery syndrome (FBSS). Although the devices and the implantation techniques are well established and the technology is sophisticated, there are some complications caused by hardware failures. This study was aimed at identifying the most frequent types of hardware failures and their causes in FBSS patients treated with SCS. In a retrospective analysis, a group of 42 FBSS patients using single lead SCS for 6–74 months was evaluated. Only hardware failures were considered in the analysis, and parameters such as occurrence of failure after primary implantation of the device, frequency and site of failure, stimulation time to failure (TF), and overall time of SCS usage were recorded. In the patient group studied, 12 surgical corrections of the hardware were carried out in 10 patients. In eight patients there was a single corrective procedure, in two additional cases there were two surgically corrected hardware failures each. The most often encountered type of hardware failure was lead breakage or disruption of insulation (percutaneously placed Quad leads only) leading to short circuiting and dysfunction (n= 8). Second in frequency were receiver (model 3470) failures due to insulation leakage at the plug connection site (n= 2). In one case, extension cable breakage caused dysfunction of the system, and another dysfunction was caused by distal extension cable disconnection. In conclusion, SCS is a low‐complication procedure for treatment of benign low‐back pain, but seems to be prone to lead and insulation failures.     

Spinal Cord Stimulation for Failed Back Surgery Syndrome

Objective. The purpose of this study is to evaluate the effectiveness of modern spinal cord stimulation (SCS) for the treatment of failed back surgery syndrome (FBSS). Materials and Methods. Thirty patients were treated with SCS between December 1992 and January 1998 for low back and radicular pain after multiple failed back surgeries. Permanent systems were implanted if trial stimulation led to > 50% pain reduction. Median long‐term follow‐up was 34 months (range, 6–66 months). Severity of pain was determined postoperatively by a disinterested third party. Results. Overall, 12 of the 16 patients (75%) who received permanent implants continued to report at least 50% relief of pain at follow‐up. All six patients who underwent placement of laminectomy‐styled electrode for SCS in the thoracic region had > 50% pain relief at long‐term follow‐up. Visual analog scores decreased an average of 3.2 (from 8.6 preoperatively to 5.4 postoperatively). Patients undergoing SCS placement via laminectomy in the thoracic region experienced an average decrease of 4.9 in VAS, whereas those who underwent percutaneous placement of thoracic leads had an average decrease of 2.5. Conclusions. SCS is an effective treatment for chronic low back and lower extremity pain which is refractory to conservative therapy and which is not amenable to corrective anatomic surgery. Though our patient population is small, our results imply that the laminectomy‐style electrodes in the thoracic region achieve better long‐term effectiveness than percutaneous leads.     

Spontaneous Resolution of Nausea Induced by Spinal Cord Stimulation for Failed Back Surgery Syndrome

Introduction: Spinal cord stimulation (SCS) is used for treatment of pain arising from a variety of pathologies. Reported side‐effects related to SCS are most commonly technical complications including malfunction, lead migration, or severance. Up to date, only a few cases of gastrointestinal side‐effects have been reported. Materials and Methods: A 54‐year‐old man with a 20‐year history of low back pain developed persistent and refractory nausea following spinal cord stimulator implantation. Results: The nausea resolved spontaneously within eight weeks allowing continued use of the spinal cord stimulator. Conclusions: In this case report, we described the uncommon side‐effect of nausea because of SCS that resolved over time allowing continued neurostimulation therapy in a patient with arachnoiditis and failed lumbar back surgery syndrome. We encourage other providers to report similar cases to help elucidate the mechanism of these seemingly underreported side‐effects to allow continuation of the therapeutic effects of SCS.     

Treatment of Failed Back Surgery Syndrome

Objectives. To evaluate the long‐term results of different therapies for failed back surgery syndrome (FBSS). Materials and Methods. From 1992 to 1997, 49 patients were treated for FBSS. Twenty patients were treated medically. Twenty‐four patients, who did not respond to medical therapy, underwent spinal cord stimulator (SCS) implant and five underwent further spine surgery. All patients were evaluated by VAS, PDI, and the Oswestry Scales before treatment and at follow‐up. Leg pain, back pain, work status or daily activities, drug side effects, and use of analgesic medications after implantation were examined. Follow‐up ranged from 24 to 84 months (mean 42 months). Results. At last follow‐up, the patients treated medically demonstrated good results on leg and low back pain in eight cases; in other cases, good results were transitory and several therapeutic courses were necessary to control the pain. Two patients treated medically had substantial side effects. All but two patients treated with SCS demonstrated good results for their leg pain; whereas those treated for back pain with SCS had poor results. Two patients still needed continuous drug administration. Conclusions. Medical therapy is effective for leg and back pain; nevertheless, several courses of therapy may be necessary. SCS is an effective treatment for leg pain, however, its effectiveness on back pain appears to be inadequate.     

Evaluation of a Dual Quadripolar Surgically Implanted Spinal Cord Stimulation Lead for Failed Back Surgery Patients with Chronic Low Back and Leg Pain

Objectives. Recent publications on dual program spinal cord stimulation (SCS) system demonstrate more flexible electrode programming, which helps to steer paresthesias towards all of the affected areas including the low back area. Materials and Methods. The following data were retrospectively sought from 20 nonrandomized failed back surgery patients at two centers treated by a dual quadripolar surgically implanted SCS lead: pain and paresthesia, VAS ratings, medication use, sleep patterns, daily activities, hardware problems, and willingness to repeat the procedure. The data were analyzed by the Wilcoxon signed rank test (p value < 0.05). Results. The average paresthesia coverage was 76%. After SCS implantation, analgesic use was decreased in 59% of the patients, sleeping time augmented, and quality of sleep improved. The number of patients taking benzodiazepines decreased. Sixty percent reported increased participation in social activities. Conclusions. This dual program surgical SCS technique is simple, respects patients’ autonomy, and provides adequate analgesia with an increase in quality of life.     

Factors Associated with the Success of Trial Spinal Cord Stimulation in Patients with Chronic Pain from Failed Back Surgery Syndrome

Objective

Spinal cord stimulation (SCS) is an effective means of treatment of chronic neuropathic pain from failed back surgery syndrome (FBSS). Because the success of trial stimulation is an essential part of SCS, we investigated factors associated with success of trial stimulation.

Methods

Successful trial stimulation was possible in 26 of 44 patients (63.6%) who underwent insertion of electrodes for the treatment of chronic pain from FBSS. To investigate factors associated with successful trial stimulation, patients were classified into two groups (success and failure in trial). We investigated the following factors : age, sex, predominant pain areas (axial, limb, axial combined with limbs), number of operations, duration of preoperative pain, type of electrode (cylindrical/paddle), predominant type of pain (nociceptive, neuropathic, mixed), degree of sensory loss in painful areas, presence of motor weakness, and preoperative Visual Analogue Scale.

Results

There were no significant differences between the two groups in terms of age, degree of pain, number of operations, and duration of pain (p>0.05). Univariate analysis revealed that the type of electrode and presence of severe sensory deficits were significantly associated with the success of trial stimulation (p<0.05). However, the remaining variable, sex, type of pain, main location of pain, degree of pain duration, degree of sensory loss, and presence of motor weakness, were not associated with the trial success of SCS for FBSS.

Conclusion

Trial stimulation with paddle leads was more successful. If severe sensory deficits occur in the painful dermatomes in FBSS, trial stimulation were less effective.     

Treatment of Chronic Pain in Failed Back Surgery Patients with Spinal Cord Stimulation: a Review of Current Literature and Proposal for Future Investigation

Objective. The authors attempted to design and conduct a randomized, prospective study to investigate the efficacy of spinal cord stimulation (SCS) for patients with chronic back and leg pain following at least one previous surgery. While the scientific advantages of the randomized, prospective trial are considerable, the authors encountered numerous practical and ethical difficulties with conducting these trials. These are reviewed and an alternative investigative technique proposed. Materials and Methods. The literature on interventional and minimally invasive treatments for this population group is reviewed, and the strengths and weaknesses of different methodologies for conducting clinical research in an interventional setting are examined. Results. The difficulties inherent in a randomized, prospective study for an intervention vs. a nonintervention group are addressed, and an alternative methodology is proposed—that of a randomized interventional design. In this design, patients are assigned to a given treatment group, with each treatment exclusively available at different centers. Conclusions. By utilizing a randomized interventional study design, problems of comparability of procedures, provider reluctance to participate in randomized clinical trials, provider bias, detection bias, and transfer bias are eliminated. It is suggested that future investigations, particularly those which are interventionally or device‐based, conform to this particular model.     

1.2 kHz High-Frequency Stimulation as a Rescue Therapy in Patients With Chronic Pain Refractory to Conventional Spinal Cord Stimulation

ObjectivesWe aimed to investigate the efficacy of new subperception stimulation paradigms including 1.2 kHz-high-frequency stimulation (HFS) and advanced-HFS field-shaping algorithm (dorsal horn HFS [DHHFS]) in refractory cases which initially benefited from conventional spinal cord stimulation (SCS) and lost the effect throughout time.Materials and MethodsIn the context of a rescue-therapy, patients underwent externalization of the implanted SCS-leads and were tested with multiple combinations of new SCS paradigms. Pain intensity was analyzed using the numeric rating scale (NRS), and data were collected preoperatively and at multiple postoperative follow-ups.ResultsThirty-seven patients underwent externalization of the leads. Mean preoperative NRS-score was 8.1/10 points (SD ± 0.9) for the ON-stimulation period. Patients received a combination of either tonic, burst and 1.2 kHz-HFS, or burst and 1.2 kHz-HFS, DHHFS, or 1.2 kHz-HFS and DHHFS, or 1.2 kHz-HFS alone. The mean postoperative NRS-score after the testing-phase was 3.8/10 points (SD ± 2.5), showing a 48.0% mean reduction (p < 0.001). In total, 29 patients reported a significant reduction above 50% in NRS-scores and therefore were reimplanted with new generators that could deliver the new paradigms. Eight patients underwent full SCS-system explantation. The patients who continued with the new paradigms (n = 29) reported mean NRS-scores of 3.5/10 points (SD ± 1.7) 12 months postoperatively, still showing a significant reduction of 43.3% when compared to preoperative scores (p < 0.001).ConclusionRescue-therapy with combination of multiple waveforms, including tonic, burst, 1.2 kHz-HFS, and DHHFS, was associated with a significant pain relief in patients with failed conventional SCS. This approach is a safe and efficient and should be considered before explantation of the SCS-system.