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.

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Background and aims Peripheral neuropathic pain (PNeP) is a chronic and disabling condition for which no predictors of response to treatment have yet been identified. Clinical studies show that while many patients with PNeP respond positively to treatment with the capsaicin 8% patch, others do not. This study used quantitative sensory testing (QST) to determine whether any patient characteristics can predict response to treatment with the capsaicin 8% patch. Methods This was a prospective, non-placebo-controlled, observational study. Patients used the Visual Analogue Scale (VAS) to assess their pain at baseline and then on Days 1, 7-10 (from here referred to as Day 7/10), 28 and 84 following treatment with the capsaicin 8% patch. QST was undertaken at the same timepoints on the painful area at the region of maximum PNeP and on a contralateral, control area. In addition, the size of the painful area was assessed at baseline and Days 7/10, 28 and 84. Results A total of 57 patients were treated. Among 54 evaluable patients, 19 (35.2%) achieved a ≥30% reduction in VAS pain score at Day 7/10 post-treatment compared with baseline - these were defined as 'responders'. Analysis of the QST data showed that the PNeP area in responders, but not in non-responders, had a significantly lower pressure pain threshold compared with the control area at baseline (median 320 kPa vs. 480 kPa, respectively; p = .004). Furthermore, non-responders had approximately three times greater degree of allodynia at baseline compared with responders across tests using brush, cotton wool and Q-tip. These differences were significant for tests using brush and cotton wool (p = .024 and p = .046, respectively) and approached significance in the test using Q-tip (p = .066). Following treatment with the capsaicin 8% patch, responders showed a trend towards a reduction in warm perception and also appeared to show normalization of the pinprick hyperalgesia at some stimulus levels. Responders to therapy had significantly greater reductions than non-responders in the size of the painful area at Day 28 (p = .011) and Day 84 (p = .005) following treatment. However, both responders and non-responders had meaningful reductions in the size of the painful area compared with baseline values. Conclusions This study suggests that differences can be identified in the sensory profiles of patients with PNeP who respond to the capsaicin 8% patch and those who do not, specifically pressure pain threshold and degree of allodynia. Notably, both responders and non-responders experienced meaningful reductions in the size of the painful area following treatment. Implications The findings warrant further investigation in a larger number of patients and in prospective trials.

Intraspinal drug infusion using implantable pumps and catheter systems is a safe and effective therapy for selected pain patients with severe chronic pain. It improves pain relief, reduces drug-related side effects, decreases the need for oral analgesia and enhances quality of life in a segment of chronic pain patients whose pain has not been controlled with more conservative therapies. Intrathecal drug therapy has therefore established its role in the treatment of malignant pain, benign pain and severe spasticity.Careful patient selection and management as well as a multidisciplinary approach are determinants of successful treatment. Current practices for patient selection and management, screening, drug selection, dosing and implantation for intrathecal drug delivery systems are discussed.

Background Capsaicin 8% patch reduces peripheral neuropathic pain. Based on the concept of neuropathic pain (NeP) in mixed low back pain (LBP) it is hypothesized, that an exclusively lumbar capsaicin 8% patch is an effective treatment of mixed LBP. The aim is a proof of this concept and to identify predictors of responsiveness. Methods This prospective stratified study included 54 chronic, mixed, LBP patients with spontaneous pain >3/10 on the NRS (0-10) and a painDETECT Questionnaire (PDQ) score >12 meaning possible or likely (>18) NeP. Pain intensity, PDQ, and quantitative sensory testing (QST) were assessed at baseline. After a one-hour capsaicin 8% treatment on the low back, follow-up was carried out regularly over three months. Response was determined at one month (≥30% pain reduction) and predictors were compared accordingly. Results The average change in pain intensity at week four was -1.1 (-0.50;-1.71, 95%CI, p < 0.001). Twenty-one (39%) patients responded at one month with a mean pain reduction of -3.1 (-4.0;-2.3, 95%CI) and even 10 of the 21 responders showed a ≥ 50% pain reduction. No pain reduction was seen in 33 (61%) patients (p = 0.42). Responders and non-responders did not differ at any baseline parameter: NRS (p = 0.85), PDQ score (p = 0.47), duration of pain (median of 48 and 36 months) nor QST profiles. Conclusions Lumbar capsaicin 8% patch is an effective treatment in about 40% of chronic patients with mixed neuropathic LBP. However, predictors for response could not be identified.