Peripheral nerve field stimulation (PNFS) in chronic low back pain: a prospective multicenter study.

OBJECTIVES: The goal of this study was to evaluate the long-term efficacy and safety of peripheral nerve field stimulation (PNFS) for chronic low back pain (cLBP). MATERIALS AND METHODS: In this prospective, multicenter observational study, 118 patients were admitted to 11 centers throughout Austria and Switzerland. After a screening visit, all patients underwent a trial stimulation period of at least seven days before implantation of the permanent system. Leads were placed in the subcutaneous tissues of the lower back directly in the region of greatest pain. One hundred five patients were implanted with a permanent stimulating system. Patients' evaluation of pain and functional levels were completed before implantation and one, three, and six months after implantation. Adverse events, medication usage, and coverage of the painful area and predictive value of transcutaneous electrical nerve stimulation (TENS) were monitored. RESULTS: All pain and quality-of-life measures showed statistically significant improvement during the treatment period. These included the average pain visual analog scale, the Oswestry Disability Questionnaire, the Becks Depression Inventory, and the Short Form-12 item Health survey. Additionally, medication usage with opioids, nonsteroidal anti-inflammatory drugs, and anti-convulsants showed a highly significant reduction. Complications requiring surgical intervention were reported in 9.6% of the patients. The degree of coverage of painful areas seems to be an important criterion for efficacy of PNFS, whereas TENS is presumably no predictor. CONCLUSIONS: This prospective, multicenter study confirms that PNFS is an effective therapy for the management of cLBP. Significant improvements in many aspects of the pain condition were measured, and complications were minimal.

Subcutaneous target stimulation (STS) in chronic noncancer pain: a nationwide retrospective study.

Stimulation of primary afferent neurons offers a new approach for the control of localized chronic pain. We describe the results with a new neurostimulation technique, subcutaneous target stimulation (STS), for the treatment of chronic focal noncancer pain. STS applies permanent electrical stimulation directly at the painful area via a percutaneous-placed subcutaneous lead. We reported the clinical outcomes of 111 patients with focal chronic, noncancer pain treated with STS in this first nationwide, multicenter retrospective analysis. The indications for STS were low back pain (n = 29) and failed back surgery syndrome (back pain with leg pain) (n = 37), cervical neck pain (n = 15), and postherpetic neuralgia (n = 12). Pain intensity was measured on a numerical rating scale (NRS) before and after implantation. Data on analgesic medication, stimulation systems, position, and type of leads and complications were obtained from the patients' records. After implantation, the mean pain intensity improved by more than 50% (mean NRS reduction from 8.2 to 4.0) in the entire patient group (P = 0.0009). This was accompanied by a sustained reduction in demand for analgesics. In all the patients, the STS leads were positioned directly at the site of maximum pain. Lead dislocation occurred in 14 patients (13%), infections in 7 (6%), and in 6 cases (5%), lead fractures were observed. The retrospective data analysis revealed that STS effectively provided pain relief in patients suffering from refractory focal chronic noncancer pain and that STS is an alternative treatment option. Prospective controlled studies are required to confirm these retrospective findings. This article presents a new minimally invasive technique for therapy-resistant focal pain.