Long-term safety of spinal cord stimulation systems in a prospective, global registry of patients with chronic pain.

Aim: The availability of long-term (>2 years) safety outcomes of spinal cord stimulation (SCS) remains limited. We evaluated safety in a global SCS registry for chronic pain. Methods: Participants were prospectively enrolled globally at 79 implanting centers and followed out to 3 years after device implantation. Results: Of 1881 participants enrolled, 1289 received a permanent SCS implant (1776 completed trial). The annualized rate of device explant was 3.5% (all causes), and 1.1% due to inadequate pain relief. Total incidence of device explantation >3 years was 7.6% (n = 98). Of these, 32 subjects (2.5%) indicated inadequate pain relief as cause for removal. Implant site infection (11 events) was the most common device-related serious adverse event (<1%). Conclusion: This prospective, global, real-world study demonstrates a high-level of safety for SCS with low rate of explant/serious adverse events. Clinical Trial Registration: NCT01719055 (ClinicalTrials.gov).

Applicability and Validity of an e-Health Tool for the Appropriate Referral and Selection of Patients With Chronic Pain for Spinal Cord Stimulation: Results From a European Retrospective Study.

OBJECTIVES: To support rational decision-making on spinal cord stimulation (SCS), a European expert panel developed an educational e-health tool using the RAND/University of California at Los Angeles Appropriateness Method. This retrospective study aimed to determine the applicability and validity of the tool using data from patients for whom SCS had been considered. MATERIALS AND METHODS: A total of 12 European implant centers retrieved data from 25 to 50 consecutive patients for whom SCS was considered in 2018-2019. For each patient, data were captured on the clinical and psychosocial variables included in the e-health tool, center decisions on SCS, and patient outcomes. Patient outcomes included global perception of effect by the patient and observer, and pain reduction (numeric pain rating scale) at six-month follow-up. RESULTS: In total, 483 patients were included, of whom 133 received a direct implant, 258 received an implant after a positive trial, 32 had a negative trial, and 60 did not receive SCS for reasons other than a negative trial. The most frequent indication was persistent spinal pain syndrome type 1 and type 2 (74%), followed by neuropathic pain syndromes (13%), complex regional pain syndrome (12%), and ischemic pain syndromes (0.8%). Data on the clinical and psychosocial variables were complete for 95% and 93% of patients, respectively, and missing data did not have a significant impact on the study outcomes. In patients who had received SCS, panel recommendations were significantly associated with patient outcomes (p < 0.001 for all measures). Substantial improvement ranged from 25% if the e-health tool outcome was "not recommended" to 83% if SCS was "strongly recommended". In patients who underwent a trial (N = 290), there was 3% of trial failure when SCS was "strongly recommended" vs 46% when SCS was "not recommended". CONCLUSIONS: Retrospective application of the e-health tool on patient data showed a strong relationship between the panel recommendations and both SCS trial results and treatment outcomes.

Feasibility of therapeutic music listening in fibromyalgia: a randomised controlled pilot study.

BACKGROUND: Fibromyalgia patients can benefit from music approaches as complementary treatments. In the literature, it was shown that these interventions managed pain conditions as well as reduced complaints, increased relaxation, and improved moods. OBJECTIVE: This study aimed at evaluating music therapy, in the form of therapeutic music listening, specifically for patients with fibromyalgia, to treat chronic pain by reducing pain perception, increasing well-being, and improving quality of life. METHODS: Twenty-four patients with fibromyalgia were recruited to take part in this feasibility pilot study that adopted a between-subject and within-subject design. Participants were randomised into three groups: (1) standard care, (2) standard care plus preferred music listening, (3) standard care plus Melomics-Health music listening, composed by an algorithm. Participants in experimental groups listened to 30 min of music at home, twice a day for a month. Patients' perceptions of changes following the listening, the intensity of pain and its interference in their lives, physical and mental well-being, and reported attitudes towards listening to music were evaluated respectively through the patients' global impression of change, the brief pain inventory, the Short Form Healthy Survey-12, and the cognitive behavioural assessment-outcome evaluation. RESULTS: The study showed that music listening can significantly affect mental well-being compared to no music. Moreover, the effects in the Melomics-Health group are maintained at follow-up. No significant effect on pain perception was noted. CONCLUSIONS: The study provides information supporting a possible role of music listening in improving well-being of patients with fibromyalgia.

Patient selection for spinal cord stimulation: The importance of an integrated assessment of clinical and psychosocial factors.

BACKGROUND: A previously developed educational e-health tool considers both clinical and psychosocial factors when selecting patients with chronic pain for spinal cord stimulation (SCS). The validity of the composite recommendations was evaluated in a retrospective study, demonstrating a strong relationship with patient outcomes after SCS. METHODS: An additional retrospective analysis was performed to determine the added value of a psychosocial evaluation as part of the decision-making process on SCS. Data concerned 482 patients who were considered for SCS in 2018-2019. The analysis focused on the relationship between the different layers of the tool recommendations (clinical, psychosocial, composite) with trial results and patient outcomes at 6 months after SCS. Of the initial study population, 381 patients underwent SCS and had follow-up data on at least one of three pain-related outcome measures. RESULTS: Pain improvement was observed in 76% of the patients for whom SCS was strongly recommended based on merely the clinical aspects. This percentage varied by the level of psychosocial problems and ranged from 86% in patients without any compromising psychosocial factors to 60% in those with severe problems. Similarly, the severity of psychosocial problems affected trial results in patients for whom SCS was either recommended or strongly recommended. CONCLUSIONS: The strong relationship between psychosocial factors embedded in the SCS e-health tool and patient outcomes supports an integrated and multidisciplinary approach in the selection of patients for SCS. The educational e-health tool, combining both clinical and psychosocial aspects, is believed to be helpful for further education and implementation of this approach. SIGNIFICANCE STATEMENT: This study confirms the relevance of the psychosocial factors embedded in the educational SCS e-health tool (https://scstool.org/). The strong relationship between the severity of psychosocial factors with patient outcomes supports conducting a comprehensive psychological and behavioural assessment when determining the eligibility of patients for SCS.

Pain diagnosis and treatment according to the pain generating factors.

SUMMARY: Chronic pain impacts on many aspects of patient life affecting autonomy, sleep, social activities and also employment. Adequate pain control is often challenging in patients with chronic pain, despite the availability of many medications and interventional techniques. Limitations to successful pain treatment are the poor understanding of contributing mechanisms and the lack of a mechanism based approach in clinical practice. The purpose of this article is to identify the factors contributing to pain generation in order to guide a personalized treatment. We analyze tissue specificity for chemical and physical stresses potentially causing pain, the changes that occur in the peripheral and central pain pathways during disease, the stimuli that, acting on a pathological pain pathway, can trigger pain. The pain generating factors should be recognized in each patient and addressed with pharmacological, rehabilitation and invasive interventions.

Genicular Nerve Pulsed Dose Radiofrequency (PDRF) Compared to Intra-Articular and Genicular Nerve PDRF in Knee Osteoarthritis Pain: A Propensity Score-Matched Analysis.

BACKGROUND: Chronic knee osteoarthritic (OA) pain is a common and debilitating complaint in elderly patients. Despite numerous pharmaceutical options, the majority of patients still experience long-term pain. Genicular nerve (GN) radiofrequency has become increasingly popular as a treatment for knee pain. This retrospective study aimed to evaluate the effects of pulse dose radiofrequency (PDRF) in patients with chronic knee OA pain. PATIENTS AND METHODS: Propensity score matching analysis was performed in a retrospective cohort of 78 patients with moderate-severe knee OA pain unresponsive to conservative treatment who underwent PDRF GN or intra-articular (IA) and PDRF GN. Pain relief was measured using the numeric rating scale (NRS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Patient Global Impression of Change (PGIC) at 3 and 6 months post-intervention. RESULTS: A significant reduction in NRS scores was reported at 3 (p<0.001) and 6 months (p<0.001) after PDRF in both groups. NRS was lower in PDRF IA + GN than PDRF GN (p<0.0001). WOMAC pain was significantly reduced at 3 months in PDRF IA + GN group (baseline: 10.12±3.14, 3 months: 6.25±2.44, p=0.0001). WOMAC stiffness and function were improved only at 3 months in PDRF IA + GN compared to baseline (p=0.007 and p=0.006, respectively). A longer period of pain relief was reported after PDRF IA + GN (6.75±2.42 months) compared to PDRF GN (4.31±2.85 months, p<0.001) in association with higher PGIC scores. CONCLUSION: This is the first study that compared two different PDRF techniques. PDRF GN and PDRF IA + GN were both effective in reducing pain at 3 and 6 months follow-up. However, only PDRF IA + GN was able to improve WOMAC scores at 3 months after the treatment with a longer period of efficacy compared to PDRF GN alone.

Appropriate referral and selection of patients with chronic pain for spinal cord stimulation: European consensus recommendations and e-health tool.

BACKGROUND: Spinal cord stimulation (SCS) is an established treatment for chronic neuropathic, neuropathic-like and ischaemic pain. However, the heterogeneity of patients in daily clinical practice makes it often challenging to determine which patients are eligible for this treatment, resulting in undesirable practice variations. This study aimed to establish patient-specific recommendations for referral and selection of SCS in chronic pain. METHODS: A multidisciplinary European panel used the RAND/UCLA Appropriateness Method (RUAM) to assess the appropriateness of (referral for) SCS for 386 clinical scenarios in four pain areas: chronic low back pain and/or leg pain, complex regional pain syndrome, neuropathic pain syndromes and ischaemic pain syndromes. In addition, the panel identified a set of psychosocial factors that are relevant to the decision for SCS treatment. RESULTS: Appropriateness of SCS was strongly determined by the neuropathic or neuropathic-like pain component, location and spread of pain, anatomic abnormalities and previous response to therapies targeting pain processing (e.g. nerve block). Psychosocial factors considered relevant for SCS selection were as follows: lack of engagement, dysfunctional coping, unrealistic expectations, inadequate daily activity level, problematic social support, secondary gain, psychological distress and unwillingness to reduce high-dose opioids. An educational e-health tool was developed that combines clinical and psychosocial factors into an advice on referral/selection for SCS. CONCLUSIONS: The RUAM was useful to establish a consensus on patient-specific criteria for referral/selection for SCS in chronic pain. The e-health tool may help physicians learn to apply an integrated approach of clinical and psychosocial factors. SIGNIFICANCE: Determining the eligibility of SCS in patients with chronic pain requires careful consideration of a variety of clinical and psychosocial factors. Using a systematic approach to combine evidence from clinical studies and expert opinion, a multidisciplinary European expert panel developed detailed recommendations to support appropriate referral and selection for SCS in chronic pain. These recommendations are available as an educational e-health tool (https://www.scstool.org/).

Quantitative Sensory Testing (QST) Estimation of Regional Cutaneous Thermal Sensitivity During Waking State, Neutral Hypnosis, and Temperature Specific Suggestions.

This study aimed to determine the effects of neutral hypnosis and hypnotic temperature suggestions in thermal and pain thresholds compared to resting state. Sixteen healthy medium or high hypnotizable volunteers were enrolled. Hypnotizability was assessed with the Hypnotic Induction Profile (HIP); QST was checked in resting state, in neutral hypnosis, after suggestions of heat and cold, and after deinduction. A significant increase in heat threshold was recorded during hypnosis with both cold and heat suggestions compared to neutral hypnosis. HIP induction score showed a linear correlation with changes of temperature thresholds after heat and cold suggestions. Thermal suggestions may result in a significant increase of heat perception thresholds with respect to neutral hypnosis. HIP score is related to thermal threshold changes. QST is a valuable and manageable tool to measure temperature threshold change during hypnosis.

Comparison of Tonic vs. Burst Spinal Cord Stimulation During Trial Period.

BACKGROUND: Spinal cord stimulation (SCS) is a well-known treatment in patients with failed back surgery syndrome (FBSS). Burst stimulation is a recently developed stimulation modality that seems to be superior to tonic stimulation. METHODS: This observational multicenter study compared tonic and burst stimulation during a trial period in patients with FBSS or radiculopathy. All the patients enrolled underwent two weeks of tonic stimulation followed by another two weeks of BurstDR stimulation, without randomization. The primary outcome was the reduction of pain in the legs and back. Health-related quality of life (EQ-5D) and the pain catastrophizing scale (PCS) were assessed before and after the trial. Patients were reevaluated after 12 months. RESULTS: We recruited 23 patients, 57% of whom had FBSS and 43% had radiculopathies. Five patients failed both the tonic and burst stimulation trials. While tonic stimulation reduced leg pain (p < 0.05), the burst mode added an extra pain reduction (ΔNRS 1.2 ± 1.5) (p < 0.01). No significant reduction in back pain was found (p 0.29). Pain on movement was reduced only by BurstDR (p < 0.01). Both stimulation modalities increased EQ-5D and reduced PCS from the baseline (p < 0.0001). At the end of the SCS trial phase, 26% patients chose tonic SCS, while 74% preferred burst. On 12-month follow-up examination, the benefits recorded at the end of the trial were maintained. CONCLUSIONS: Burst stimulation confers a greater reduction in leg pain intensity at rest and on movement. Reducing axial pain is still a challenge. Further studies are needed in order to provide each patient with the most appropriate stimulation paradigm.

Benefits in pain perception, ability function and health-related quality of life in patients with failed back surgery syndrome undergoing spinal cord stimulation in a clinical practice setting.

BACKGROUND: Failed back surgery syndrome (FBSS) represents one main cause of chronic neuropathic or mixed pain, functional disability and reduced Health Related Quality of Life (HRQoL). Spinal Cord Stimulation (SCS) can be a value for money option to treat patients refractory to conventional medical management (CMM). We estimated from real-world data: 1) the amount of reduced levels of HRQoL of target patients compared to general population, 2) the relationship between pain intensity, functional disability, and overall HRQoL, and 3) the improvement of patients' health from SCS intervention, and 4) we give some insights and make some suggestions on the selection of a battery of patients' reported health instruments for use in routine clinical practice. METHODS: At recruitment (before SCS) and every 6 months for 2 years after SCS a battery of questionnaires/tests were completed: the generic EQ-5D and SF-36 for HRQoL, the specific Numerical Rating Scale (NRS) to measure pain intensity, and Oswestry Disability Index (ODI) to measure functional disability. We conducted multilevel regression analyses to investigate the association of HRQoL with the NRS and ODI indexes; multiple regression analyses to compare EQ-5D data with those of the general population adjusted for age, sex and education, and statistical tests to compare the changes of HRQoL, NRS and ODI estimates at baseline with those measured during the follow-up. RESULTS: Eighty patients (40% male, mean age = 58 years) participated. HRQoL was significantly worse in the patients than in the corresponding general population. Pain, functional disability and HRQoL significantly related each other during follow-up, Significant improvements (p < 0.001) in pain intensity, functional capability and HRQoL were reached after 6 months from SCS and generally remained stable during follow-up. Specific instruments provided detailed information on disability and pain, while generic instruments assessed the overall HRQoL and allowed a comparison with the general population's one. CONCLUSIONS: SCS + CMM treatment reaches a statistically significant and probably a clinically relevant improvement in pain perception, functional disability and HRQoL in patients with FBSS refractory to CMM. An appropriate selection of instruments for use in clinical practice is crucial for a routine assessment of health perception in patients, aimed to guide decisions for optimal treatment.

Effect of Botulinum Toxin on Disabling Neuropathic Pain: A Case Presentation Suggesting a New Therapeutic Strategy.

This case presentation describes a 47-year-old woman who developed complex regional pain syndrome type II with severe neuropathic pain following iatrogenic transection of the tibial nerve at the ankle. The pain and disability progressively worsened over time, markedly impaired ambulation, and were not relieved despite various analgesic treatments. After injection of botulinum toxin (abobotulinumtoxinA, BoNT-A) in the leg muscles the tendons of which pass through the tarsal tunnel (together with the tibial nerve), her pain decreased and her walking capacity improved. This case suggests a new therapeutic role for botulin toxin in treating peripheral neuropathic pain caused by movement-evoked ectopic potentials. LEVEL OF EVIDENCE: V.

Dynamic Mechanical Allodynia--One Clinical Sign, Several Mechanisms: Five Illustrative Cases.

Pain evoked by tangential movement across the skin is usually defined as dynamic mechanical allodynia (DMA). Some patients complain of DMA as troublesome as spontaneous pain and refer a marked interfering with activities of daily living and sleep. Pathophysiology of DMA is complex and can be related to several mechanisms, both nociceptive and neuropathic. Five exemplificative clinical cases of DMA are presented, each associated to a possible specific mechanism: injured skin DMA, peri-injured skin DMA, far injury DMA, nerve-confined DMA and fear DMA (pseudo allodynia). The identification of these subcategories of DMA can stimulate further studies aimed at evaluating the usefulness of a mechanism-based therapy for the different clinical forms of DMA.

Inhibition of Somatosensory Evoked Potentials During Different Modalities of Spinal Cord Stimulation: A Case Report.

BACKGROUND: Although the number of patients with chronic neuropathic pain treated by spinal cord stimulation (SCS) is continuously increasing, its analgesic mechanism remains to be elucidated. Previous studies have demonstrated that classical SCS (low stimulation frequency evoking paresthesia) inhibits the somatosensory evoked potentials (SEPs). CASE PRESENTATION: We describe here the results of a series of SEPs recordings performed in a female patient with chronic pain, using four different types of SCS: the classical SCS (60 Hz, 250 µsec) and three paresthesia free SCS modalities: high frequency (10 kHz, 20 µsec) and two types of high-density SCS (500 Hz, 500 µsec and 200 Hz, 1000 µsec). All the tested SCS modalities completely inhibited the SEPs cortical responses, with an immediate recovery of the inhibition after turning the stimulator off. CONCLUSIONS: All the tested SCS modalities are able to inhibit SEPs and thus the lemniscal system. In particular, both paresthesia and paresthesia free SCS affect SEPs in the same manner. The presence of this inhibitory effect during paresthesia free modalities suggests that it is independent from the generation of action potentials, with a probable mechanism acting at the stimulation site. Further studies investigating the relationship between the inhibition of the lemniscal system and the analgesic effect of the SCS are, therefore, warranted.

Cost-Effectiveness and Cost-Utility Analysis of Spinal Cord Stimulation in Patients With Failed Back Surgery Syndrome: Results From the PRECISE Study.

OBJECTIVE: To assess the cost-effectiveness and cost-utility of Spinal Cord Stimulation (SCS) in patients with failed back surgery syndrome (FBSS) refractory to conventional medical management (CMM). MATERIALS AND METHODS: We conducted an observational, multicenter, longitudinal ambispective study, where patients with predominant leg pain refractory to CMM expecting to receive SCS+CMM were recruited in 9 Italian centers and followed up to 24 months after SCS. We collected data on clinical status (pain intensity, disability), Health-Related Quality-of-Life (HRQoL) and on direct and indirect costs before (pre-SCS) and after (post-SCS) the SCS intervention. Costs were quantified in € 2009, adopting the National Health Service's (NHS), patient and societal perspectives. Benefits and costs pre-SCS versus post-SCS were compared to estimate the incremental cost-effectiveness and cost utility ratios. RESULTS: 80 patients (40% male, mean age 58 years) were recruited. Between baseline and 24 months post-SCS, clinical outcomes and HRQoL significantly improved. The EQ-5D utility index increased from 0.421 to 0.630 (p < 0.0001). Statistically significant improvement was first observed six months post-SCS. Societal costs increased from €6600 (pre-SCS) to €13,200 (post-SCS) per patient per year. Accordingly, the cost-utility acceptability curve suggested that if decision makers' willingness to pay per Quality-Adjusted-Life-Years (QALYs) was €60,000, SCS implantation would be cost-effective in 80% and 85% of cases, according to the NHS's and societal point of views, respectively. CONCLUSIONS: Our results suggest that in clinical practice, SCS+CMM treatment of FBSS patients refractory to CMM provides good value for money. Further research is encouraged in the form of larger, long-term studies.

Excessive daytime sleepiness in patients on intrathecal analgesia for chronic pain.

OBJECTIVES: Intrathecal (IT) drug administration is an advanced technique in pain treatment algorithm for patients poorly responsive to systemic pharmacological treatment or less invasive techniques. The aim is to improve analgesia lowering side effects; despite this premise, many side effects of long-term IT therapy have been described, mainly related to opioid administration. We observed, in some of the patients regularly followed for pump refills in our Pain Unit, the appearance of excessive daytime sleepiness (EDS) interfering with daily life and work activity; this study aims to investigate the incidence of EDS in patients on IT analgesia with opioid or non-opioid drugs and its possible relationship with respiratory problems during sleep. MATERIALS AND METHODS: 21 patients on IT therapy for chronic pain answered the Epworth Sleepiness Scale (ESS). The incidence of EDS in patients receiving IT opioids was compared to a control group not receiving opioids. In 10 patients, who performed polysomnography (PSG) and maintenance of wakefulness test (MWT) for sleep complaints, we studied the relationship between PSG data and ESS scores and we verified the concordance of ESS and MWT results. RESULTS: 38% of the patients reported EDS, according to ESS data; all the patients with EDS were receiving an IT opioid. Even if some patients presented sleep apneas, we failed to correlate this data with daytime sleepiness. Subjective sleepiness is confirmed by the results of MWT. CONCLUSION: Our data demonstrate that EDS is a frequent and important side effect of IT analgesia and it seems related to opioids administration.

[Pain in urology: pathophysiological aspects of pain and chronicity.] / Il dolore in ambito urologico: aspetti fisiopatologici del dolore e della cronicità

Chronic pain has been traditionally defined by pain duration, but this approach has limited empirical support and does not account for chronic pain multidimensionality. Defining chronic pain solely by duration is based on the view that acute pain signals potential tissue damage, whereas chronic pain results from central sensitization in which pain is sustained after nociceptive inputs have diminished. Chronic urological pain is a prevalent condition, which can represent a major challenge to health care providers due to its complex aetiology and poor response to therapy. In most cases, clear signs of on-going tissue trauma, inflammation or infection are not present. Despite this, more underhanded pathophysiological mechanisms, affecting the urinary system or other pelvic organ systems (musculoskeletal, neurologic, urologic, gynaecologic) and some psychological aspects may be present. In this article, some pathophysiological aspects of visceral pain are discussed; the definition of 'chronic pain', the mechanism of action of drugs used in the treatment of pain and the rationale for association therapy are also reviewed.

Chronic pain therapy and hypothalamic-pituitary-adrenal axis impairment.

Opiates and/or nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most effective therapies for chronic pain, but their prolonged time of use can affect health conditions through physical and psychological side effects. They include the very common gastrointestinal effects and changes that can induce osteoporosis, depression, impaired cognition and a generally poor quality of life, which per se can induce and maintain a chronic painful condition. For this reason it is becoming imperative to expand our knowledge of the interaction of these substances with body functions apparently not directly involved in nociception and pain, such as neuroendocrine functions. The purpose of this study was to determine, in male and female patients suffering from chronic pain, the effect of conventional pain therapy (opiates, NSAIDs) on hypothalamic-pituitary-adrenal (HPA) axis function. This was assessed by measuring the blood levels of adrenal-related hormones (adrenocorticotrophin hormone, ACTH; cortisol; dehydroepiandrosterone, DHEA and dehydroepiandrosterone sulfate, DHEAS). The second purpose of the study was to test the hypothesis that these hormones are associated with the psychological profile shown by the chronic pain patients. The results showed significant changes induced by pain therapy on the HPA axis: ACTH, cortisol, DHEA and DHEAS blood levels decreased in all subjects taking opiates or NSAIDs to treat pain. Moreover these changes showed significant correlations with psychological features of the subjects depending on age and sex.

Italian registry on long-term intrathecal ziconotide treatment.

BACKGROUND: Ziconotide is commonly used for intrathecal (IT) therapy of chronic pain, and has been recently indicated as a first-line IT drug. It is also extremely useful for patients intolerant or refractory to the common IT drugs (such as morphine). The literature, excluding registration studies, mostly includes small samples, and gives only fragmentary evidence on the long-term risks and benefits of ziconotide. OBJECTIVE: To collect data on safety and efficacy of long-term ziconotide IT infusion in Italian pain centers. STUDY DESIGN: Retrospective cohort study on the use of ziconotide in Italy. The study was designed and coordinated by the Foundation ISAL (Algological Sciences Research and Training Institute). Patients treated with ziconotide from several pain therapy and neurosurgery units were included in the study, allowing the creation of the first Italian Registry of Ziconotide. SETTING: Seventeen Italian public and private pain and neurosurgery centers. METHODS: Patients suffering from cancer or non-cancer intractable chronic pain who had been treated with ziconotide IT infusion for at least one month. Efficacy was analyzed considering changes on the visual analog scale of pain intensity from baseline observation. Safety was assessed by monitoring the number and intensity of adverse events. RESULTS: Currently, 104 patients are included in the Italian Registry of Ziconotide. Ziconotide was administered as the first IT drug choice to 55 patients. Seventy-two patients reported at least a 30% pain intensity reduction with a mean dose of 4.36 ug/d. The sustained analgesic effect (P < 0.001) of the ziconotide IT therapy was observed in a group of 45 patients who remained in the study over 6 months without treatment interruptions and with relatively stable doses. Sixty-six patients reported at least one side effect related to ziconotide. However, adverse events have not always been decisive for treatment interruptions. LIMITATIONS: Data were collected retrospectively from different pain centers that used different methods for ziconotide treatment and clinical forms for its data collection; for this reason there is an absence of standardized methodologies and a placebo-controlled group, and some data were missing. CONCLUSIONS: Ziconotide IT therapy is a treatment option commonly used for clinical practice in 17 Italian pain therapy and neurosurgery units. It might give relief to patients with refractory chronic pain, and it seems to have a safe profile. Long-term studies and controlled trials are required.

Peripheral subcutaneous neurostimulation in the management of neuropathic pain: five case reports.

Introduction. Spinal cord stimulation (SCS) is an effective treatment option for neuropathic pain. However, because of the obvious procedural issues, SCS is unable to reach certain areas, such as the face, thorax, coccyx, the cervico-dorsal and lumbar areas, and the sacral, abdominal, and inguinal regions. On the other hand, these areas are easily reached by subcutaneous field stimulation. Methodology. We report the analgesic results, using a visual analog scale (VAS), of five patients with neuropathic pain treated with subcutaneous field stimulation to the area. We also discuss the probable mechanism of action, and highlight the technical issues inherent to this approach. Results. Significant pain reduction and reduction in analgesic medication were reported in all patients during the study period, with VAS scores consistently lowered by more than 50% from baseline levels. As a result of pain reduction, the patients' quality of life improved. There were no adverse events reported except for early electrode array displacement in two of our patients. Conclusion. When SCS is not appropriate for certain neuropathic pain syndromes, subcutaneous field stimulation may be used with some degree of efficacy.