Intravenous lidocaine in central pain: a double-blind, placebo-controlled, psychophysical study. Dental impaction pain model as a potential tool to evaluate drugs with efficacy in neuropathic pain. A randomized double-blind crossover trial of intravenous lidocaine in the treatment of neuropathic cancer pain. Computer-controlled lidocaine infusion for the evaluation of neuropathic pain after peripheral nerve injury. Both intravenous lidocaine and morphine reduce the pain of postherpetic neuralgia. Lidocaine test in neuralgia. Concentration-effect relationship of intravenous lidocaine on the allodynia of complex regional pain syndrome types I and II. Systemic lidocaine in pain due to peripheral nerve injury and predictors of response. Capacity of the clinical picture to characterize low back pain relieved by facet joint anesthesia. Proposed criteria to identify patients with painful facet joints. The effectiveness of intravenous ketamine and lidocaine on peripheral neuropathic pain. Intravenous lidocaine, amantadine, and placebo in the treatment of sciatica: a double-blind, randomized, controlled study. Comparison of the efficacy of different local anesthetics and techniques of local anesthesia in therapeutic abortions. Lidocaine versus plain saline for pain relief in fractional curettage: a randomized controlled trial. Response to intravenous lidocaine infusion predicts subsequent response to oral mexiletine: a prospective study. A trial of intravenous lidocaine on the pain and allodynia of postherpetic neuralgia. Adjuvant use of intravenous lidocaine for procedural burn pain relief: a randomized double-blind, placebo-controlled, cross-over trial. Age-related response to lidocaine-prilocaine (EMLA) emulsion and effect of music distraction on the pain of intravenous cannulation. Sphenopalatine ganglion block for the treatment of myofascial pain of the head, neck, and shoulders. Evaluation of lidocaine as an analgesic when added to hypertonic saline for sclerotherapy. Topical lidocaine gel relieves postherpetic neuralgia. Analgesic effects of intravenous lidocaine and morphine on postamputation pain: a randomized double-blind, active placebo-controlled, crossover trial. A bilateral clinical model for the study of acute and chronic pain after breast-reduction surgery. The analgesic effect of intravenous ketamine and lidocaine on pain after spinal cord injury. Unpreserved lidocaine to control discomfort during cataract surgery using topical anesthesia. Lidocaine patch: double-blind controlled study of a new treatment method for post-herpetic neuralgia. Comparison of three modified lidocaine solutions for use in eyelid anesthesia.
To investigate the effects of systemic administration of lidocaine on different components of neuropathic central pains by quantitative sensory testing.
                The efficacy of systemic lidocaine (5 mg/kg IV over 30 minutes) was evaluated in a double-blind, placebo-controlled, and cross-over fashion, on both spontaneous ongoing pain and evoked pains (allodynia and hyperalgesia) in 16 patients with chronic poststroke (n = 6) or spinal cord injury (n = 10) related pain.
                Lidocaine was significantly superior to the placebo (saline) in reducing the intensity of spontaneous ongoing pain for up to 45 minutes after the injection: 10 of 16 patients (62.5%) receiving lidocaine showed a significant reduction in spontaneous pain, whereas only six patients showed this after the placebo. Lidocaine also significantly reduced the intensity of brush-induced allodynia and mechanical hyperalgesia, but was no better than the placebo against thermal allodynia and hyperalgesia. In general, the side effects were moderate and consisted mainly of lightheadedness (44%).
                Systemic lidocaine can induce a significant and selective reduction of several components of pain caused by CNS injuries. The observed preferential antihyperalgesic and antiallodynic effects of this drug suggest a selective central action on the mechanisms underlying these evoked pains. Intravenous lidocaine, a nonspecific Na-channel blocker, was used to assess the dental impaction model for evaluation of neuropathic pain drugs. Sixty patients, experiencing moderate or severe pain after removal of > or = 2 third molars, were randomized (2:2:1:1) to lidocaine (4 mg/kg; maximal dose 300 mg), oxycodone/acetaminophen (10/650 mg), placebo, and active placebo (diphenhydramine, 50 mg). Lidocaine provided a modest degree of pain relief. Predefined endpoints of total pain relief and sum of pain intensity at 2, 4, and 6 hours showed numerically, not statistically significantly, greater pain relief versus placebo. A significantly greater effect over placebo was observed in peak effect and at shorter time points (30 minutes and 1 hour), consistent with the pharmacokinetic profile (plasma concentration of approximately 2 mug/mL). Oxycodone/acetaminophen provided significantly greater analgesia versus placebo, validating study conduct, and significantly greater pain relief was observed versus lidocaine, which is consistent with a smaller portion of dental extraction pain being of neuropathic origin. In a randomized, double-blind, crossover study, we evaluated the effect of intravenous lidocaine (5 mg/kg body weight over 30 min) on the neuropathic pain of advanced cancer patients. Pain intensity, assessed by a visual analogue scale, did not show any significant difference between lidocaine and placebo infusion. The blinded choice of patients and investigators also suggested no significant improvement from lidocaine when given by this regimen. Intravenous lidocaine does not appear to have a significant analgesic effect on neuropathic cancer pain. Systemic lidocaine has been reported to be effective in treating several neuropathic pain syndromes. Few reports relate plasma lidocaine concentration to analgesia and the available studies have been complicated by labile plasma lidocaine concentrations. We used a computer-controlled infusion pump (CCIP) to target and maintain stable plasma lidocaine concentrations and study the effect of intravenous lidocaine on (1) pain scores, (2) current perception thresholds, (3) side effects, and (4) pain distribution in patients suffering from peripheral nerve injury pain.
                This study used a randomized double-blind placebo-controlled design. Eleven patients suffering from neuropathic pain after peripheral nerve injury received both a lidocaine and saline infusion in separate study sessions. The order of the study sessions was randomized and separated from each other by 1 week. The CCIP was programmed to target plasma lidocaine concentrations of 0.5, 1, 1.5, 2, and 2.5 micrograms/ml, each held for 10 min. Pain scores and pain distribution were assessed in the painful area, and electrical current perception thresholds (CPT) of the ring finger were measured using a cutaneous perception threshold neurometer (Neurometer CPT, Neurotron, Baltimore, MD). Side effects were recorded at fixed intervals. Plasma lidocaine concentrations were measured at 4 and 9 min after each step increase in infusion and correlated with the observed effects.
                Saline infusion had no effect. However, with lidocaine there was a significant plasma concentration-dependent decrease in pain scores starting at 1.5 micrograms/ml. This effect typically corresponded with a decrease in the size of the receptive field to which the pain was referred. For the electrical stimulus, there was no significant effect on cutaneous perception at 2000-Hz stimulation at the highest concentration examined; however, there was a significant increase in thresholds at 250-Hz (starting at 1.5 micrograms/ml) and 5-Hz (starting at 1.0 micrograms/ml) stimulation. There were no serious side effects. In all, 54.5% of patients reported lightheadedness (average plasma lidocaine concentration: 1.5 micrograms/ml) and one patient reported nausea (2.3 micrograms/ml).
                The computer-controlled delivery of intravenous lidocaine results in relatively stable plasma concentrations which allows a more thorough evaluation of the relationship between plasma concentration and patient response. This administration methodology for intravenous lidocaine may prove to be a valuable clinical and research tool. We studied the analgesic efficacy of an intravenous infusion of lidocaine and morphine in 19 adults with well-established postherpetic neuralgia in a three-session, randomized, double-blind, placebo-controlled trial. Compared with saline placebo, both lidocaine and morphine reduced pain intensity. Reductions in pain did not correlate with side effects produced by the infusions. For morphine, there was a significant correlation between reductions in pain intensity and blood level achieved. In the majority of subjects who reported definite pain relief, allodynia also disappeared. The results show that neuropathic pain can respond to opioids and to systemically administered local anesthetic drugs. Ten patients with organic nerve injury causing chronic neuropathic pain were tested for the effects of intravenous lidocaine versus saline upon psychophysical somatosensory variables. The variables assessed were the subjective magnitude of pain, area of mechanical hyperalgesia and presence and magnitude of thermal heat/cold hyperalgesia. The study methods applied to evaluate these conditions were the conventional testing of somatosensory submodalities with area mapping and the subjective magnitude estimation of spontaneous pain. It was found that spontaneous pain and mechanical hyperalgesia were consistently improved, transiently, by intravenous administration of lidocaine in all 10 patients; areas of hyperalgesia which extended beyond the territory of the nerve also improved transiently. Spontaneous pain and mechanical hyperalgesia, but not hypoesthesia, were transiently improved by injection of saline in only 1 of the 10 patients. This outcome is probably due to a placebo effect. This improvement is in keeping with the inhibition of anomalous neural impulses which can be generated anywhere along the sensory channels responsible for generating spontaneous pain and hyperalgesia. Thus, intravenous lidocaine is proposed as a diagnostic aid in the examination of patients complaining of complex sensory disorders associated with nerve injury. The transient pain relief may allow a fuller identification of the area of sensory loss. Several lines of evidence suggest that neuropathic pain (including Complex Regional Pain Syndrome [CRPS] I and CRPS II) is mediated in part by an increase in the density of voltage-sensitive sodium channels in injured axons and the dorsal root ganglion of injured axons. This study sought to characterize the effects of intravenous lidocaine (a sodium channel blocker) on acute sensory thresholds within the painful area and the size of the painful area in patients suffering from CRPS I and II.
                This study used a randomized, double-blind, placebo-controlled design in 16 subjects suffering from CRPS I and II with a prominent allodynia. Each subject received an intravenous infusion of lidocaine and diphenhydramine separated by 1 week. A computer-controlled infusion pump targeted stair-step increases in plasma levels of lidocaine of 1, 2, and 3 microg/ml. At baseline and at each plasma level, spontaneous and evoked pain scores and neurosensory testing within the painful area were measured. The neurosensory testing consisted of thermal thresholds, tactile thresholds and the area of allodynia to punctate, and stroking and thermal stimuli.
                Intravenous lidocaine and diphenhydramine had no significant effect on the cool, warm, or cold pain thresholds. However, lidocaine caused a significant elevation of the hot pain thresholds in the painful area. Intravenous lidocaine caused a significantly decreased response to stroking and cool stimuli in the allodynic area. There was also a significant decrease in pain scores to cool stimuli at all plasma levels and the spontaneous pain at the highest plasma level.
                This study demonstrates that intravenous lidocaine affects pain in response to cool stimuli more than mechanical pain in subjects with neuropathic pain. There is a lesser effect on spontaneous pain and pain induced by stroking stimuli and no effect on the pain induced by punctate stimuli. To investigate the effects of IV lidocaine on spontaneous and evoked pain (allodynia and hyperalgesia) due to peripheral nerve injury (postherpetic neuralgia or nerve trauma) using quantitative sensory testing.
                The authors randomized 22 patients to receive lidocaine 5 mg/kg IV during 30 minutes or placebo in a double-blind crossover design and 16 patients subsequently received mexiletine on an open basis titrated from 400 to 1,000 mg per day (mean 737 mg/day).
                Lidocaine induced a significant decrease in ongoing pain for up to 6 hours with a peak effect 60 to 120 minutes postinjection. The drug also decreased mechanical dynamic allodynia and static (punctate) mechanical allodynia/hyperalgesia, but not thermal allodynia and hyperalgesia. The effects of lidocaine and mexiletine on spontaneous pain intensity were significantly higher in patients with concomitant mechanical allodynia in comparison with those without allodynia.
                These data indicate modality-specific antihyperalgesic effects of IV lidocaine in patients with peripheral nerve injury. Patients with mechanical allodynia may be good candidates for treatment with local anesthetic-like drugs and possibly with other sodium-channel blockers. Prospective randomized study to compare the efficacy of facet joint injection with lidocaine and facet joint injection with saline in two groups of patients with low back pain, with and without clinical criteria that were determined in a previous study to implicate the facet joint as the primary source of the pain.
                To assess the efficacy of single facet joint anesthesia versus placebo (saline injections) and to determine clinical criteria that are predictive of significant relief of LBP after injection.
                There is no syndrome that discriminates between lower back pain caused by facet joint and that caused by other structures. Single or double facet joint anesthesia, and single photon emission computed tomography are expensive and time-consuming procedures for selecting patients in controlled clinical trials with large populations.
                Results of a previous study showed that seven clinical characteristics were more frequent in patients who responded to facet joint anesthesia than in those who did not. In the current study, a group of 43 patients with lower back pain who met at least five criteria were compared with 37 patients who met fewer criteria. Patients randomly received injection of either lidocaine or saline into the lower facet joints. The result was considered positive if more than 75% pain relief was determined by visual analog scale. The patient, the radiologist, and the investigator were blinded. An analysis of variance was used to seek an interaction between clinical group effect and injection effect, and logistic regression analysis to select the best set of variables that would be predictive of minimum pain relief of 75% after the injection.
                There was a significant interaction between clinical group and injection effect (P = 0.003). In patients with back pain, lidocaine provided greater lower-back pain relief than saline (P = 0.01). Lidocaine also-provided greater pain relief in the back pain group than in the nonpain group (P = 0.02). The presence of five among seven variables (age greater than 65 years and pain that was not exacerbated by coughing, not worsened by hyperextension, not worsened by forward flexion, not worsened when rising from flexion, not worsened by extension-rotation, and well-relieved by recumbency), always including the last item, distinguished 92% of patients responding to lidocaine injection and 80% of those not responding in the lidocaine group.
                A set of five clinical characteristics can be used in randomized studies to select lower back pain that will be well relieved by facet joint anesthesia. These characteristics should not, however, be considered as definite diagnostic criteria of lower back pain originating from facet joints. Neuropathic pain is often severe and resistant to pharmacological treatment. The aims of the present study were to assess the analgesic effect of ketamine and lidocaine and to investigate if measurement of different variables of sensibility could be used to identify responders. We also wanted to study if treatment resulted in changes of sensibility.
                Twelve patients with long-lasting peripheral neuropathic pain of traumatic origin were included. The effects of ketamine hydrochloride (Ketalar, Parke Davis) 0.4 mg/kg and lidocaine hydrochloride (Xylocain, Astra) 2.5 mg/kg were investigated. Saline was used as placebo. The intensity of continuous pain was measured by a visual analogue scale (VAS). Warm and cold perception as well as heat and cold pain thresholds were assessed. Sensibility to touch was also tested. Systemic plasma concentrations of lidocaine and ketamine were assessed.
                The mean reduction in VAS-scores was 55%, 34% and 22% for ketamine, lidocaine and placebo, respectively. A significant difference was registered between ketamine and placebo (P = 0.009). Response to treatment (50% reduction in VAS-score during infusion) was recorded in 7/12 in the ketamine, 4/12 in the lidocaine and 2/12 in the placebo group. Quantitative sensory testing (QST) of thermal sensitivity and sensory tests for mechanical stimuli could not separate responders from non-responders and neither were the results from these assessments changed by the infusion of the drugs. Lidocaine and particularly ketamine were associated with frequent side-effects, the most common being somnolence and dizziness.
                Ketamine showed a significant analgesic effect. The clinical usefulness is, however, limited by disturbing side-effects. Sciatica is a neuropathic pain syndrome caused by compression and/or inflammation of spinal nerve roots by herniated disc material, and its treatment is therefore usually aimed at reducing compression and inflammation. Studies have shown that both systemic local anesthetics and N-methyl-D-aspartate (NMDA) receptor antagonists may produce analgesia in a variety of neuropathic pain syndromes. The present study evaluated the analgesic efficacy of i.v. infusions of the local anesthetic lidocaine, the NMDA receptor antagonist amantadine, and a placebo in sciatica.
                Thirty patients with sciatica, as confirmed by physical examination and imaging studies, were enrolled in a randomized, double-blind, three-arm crossover trial. Infusions of amantadine (2.5 mg/kg), lidocaine (5 mg/kg), and a placebo were administered over a 2-hour period, 2-7 days apart from each other. Spontaneous pain (visual analog scale) and evoked pain (straight leg raise) were measured every 30 minutes for 3 hours.
                Lidocaine reduced spontaneous pain as compared with amantadine and with the placebo for all measurements and at a significant level at the 30 (P < .05), 120, and 180 (P < .01) minute time points. Maximal pain reduction from the baseline was 62 +/- 7% for lidocaine, 43 +/- 7% for amantadine, and 47 +/- 7% for the placebo. Straight leg raise test also significantly improved with lidocaine (from 30 to 37 degrees; P < .05), as compared to amantadine (34-36 degrees) and to the placebo (32-34 degrees). All three treatments were relatively well tolerated.
                Intravenous lidocaine, rather than amantadine, reduces both spontaneous and evoked sciatic pain. The objectives of this study were to determine whether carbonated or plain lidocaine provides better pain control during abortions and to determine whether deep injections of lidocaine provide better pain control than regular injections of lidocaine.
                Phase 1 was a prospective, randomized, double-blind trial comparing 10 cm3 of 2% carbonated lidocaine with plain lidocaine. In phase 2 the plain lidocaine group in phase 1 was compared prospectively with the next group of patients, in whom a new technique of deep injection was used. A pain scale was administered by the counselor after dilatation and at the end of the procedure.
                The improvement in pain scores with carbonated lidocaine was 8%. The improvement with the deep injection technique was 25%.
                The improvement in pain scores with deep injection was clinically significant and is recommended. To compare the efficiency of lidocaine with that of plain saline for paracervical pain relief during fractional curettage.
                This double-blind, randomized, controlled trial included 140 women who underwent fractional curettage. Seventy women were allocated to the lidocaine group and 70 to the plain saline group. The main outcome measure was the intensity of pain measured by visual analog scale during and after the procedure.
                The intensity of pain was significantly lower in the lidocaine group than in the plain saline group over the course of the procedure (P = .02), especially during fractional curettage. There were no serious adverse effects in this study.
                Lidocaine is more effective than plain saline for paracervical pain relief during fractional curettage. The anesthetic mechanisms of lidocaine are mechanical distention of tissue and peripheral nerve block. The local anesthetic sodium-channel blockers lidocaine and mexiletine reduce spontaneous and evoked activity in experimental neuroma models and have been reported to relieve a variety of clinical neuropathic pain conditions. The predictive value of relief from an intravenous lidocaine infusion (IVL) for subsequent relief from a 4-week trial of oral mexiletine was assessed in a prospective study of nine subjects with chronic neuropathic pain of peripheral origin. Subjects received IVL, 2 mg/kg and 5 mg/kg, over 45 min during separate sessions in random order under double-blind conditions. One week later, a 4-week titrating trial of oral mexiletine was initiated. Both doses of IVL significantly reduced pain visual analogue scores (VAS) scores. Although IVL 5 mg/kg produced significantly higher pain relief scores than IVL 2 mg/kg, subjects responded in a highly consistent manner to the two IVL. Subsequent response to oral mexiletine was significantly correlated with the average response to the two IVL. Mexiletine dose and blood levels were not correlated with pain relief. The results suggest that IVL may be a valuable tool in selecting patients for oral therapy with analogous drugs. This study investigated the effect of intravenous lidocaine at two doses (1 mg/kg and 5 mg/kg over 2 hours) and an intravenous saline placebo on the pain and allodynia of postherpetic neuralgia (PHN). Twenty-four patients were studied using a randomized, double-blind, within-patient crossover design. Each patient received normal saline, lidocaine 0.5 mg/kg/h, and lidocaine 2.5 mg/kg/h for a 2-h period. The McGill Pain Questionnaire Short Form, visual analogue scores (VAS), and area of allodynia were measured at intervals during the infusions. Free plasma lidocaine levels were also measured. The results were statistically analyzed using Student's t-test for paired data. The VAS for ongoing pain showed a significant reduction after all the infusions (P < 0.05). For dynamic pressure-provoked pain, the VAS was unaffected by placebo but showed a reduction at an equal level of significance with both lidocaine infusions (P < 0.05). The area of allodynia of PHN, as mapped by brush stroke, declined in association with intravenous lidocaine (0.5 mg/kg/h = P < 0.05; 2.5 mg/kg/h = P < 0.001). Placebo had no significant effect on the area of allodynia. These findings demonstrate a positive effect on pain and allodynia following a brief intravenous infusion of lidocaine. The higher dose infusion may produce plasma levels in the toxic range, with no significant clinical increase in response. Pain is a major issue for patients with severe burn. High dose intravenous opioids form the mainstay of procedural burns pain management; however it was suggested that intravenous lidocaine assists with minimising the pain experience. This study aimed to evaluate whether intravenous lidocaine improved analgesic efficacy and decreased opioid consumption during a burn wound care procedure.
                A prospective double-blind randomized crossover study compared intravenous lidocaine versus placebo alongside patient controlled analgesia (PCA) in 45 patients with severe burn undergoing wound care procedures (i.e. dressing change±debridement) on two consecutive days. Subjects were randomised to either the intervention or control condition on the first dressing day, and received the alternate condition on the second dressing day. During the intervention condition, subjects received lidocaine of 1.5 mg/kg/body weight followed by two boluses of 0.5 mg/kg at 5-min intervals followed by a continuous infusion. During the control condition, 0.9% sodium chloride was administered at an equivalent volume, dose and rate to that of lidocaine. Primary end points included pain intensity as measured by verbal rating scale (VRS), time to rescue analgesia, opioid requests and consumption and overall anxiety and level of satisfaction.
                Changes in the VRS score was significantly lower for lidocaine [difference (95% CI)=0.36 (0.17-0.55)] as compared to placebo. However, there were no significant clinical or statistical differences regarding the effects of lidocaine and placebo on opioid requests and consumption, anxiety or level of satisfaction during the first and second dressing procedures.
                In this study, the clinical benefit of intravenous lidocaine for pain relief during burn wound dressing changes in terms of overall pain scores and opioid consumption was unremarkable. Further investigations using different lidocaine regimes for the management of procedural burn pain are warranted.
                Copyright © 2011 Elsevier Ltd and ISBI. All rights reserved. To compare the efficacy of a local anesthetic cream and music distraction in reducing or preventing pain from needle puncture (intravenous cannulation) in children. A secondary aim was to examine the influence of age on the pain report and behavior and on the therapeutic outcome.
                Children aged 4 to 16 years (N = 180) who were to undergo surgery under general anesthesia via intravenous cannulation were randomly allocated to one of three interventions. The comparison of lidocaine-prilocaine emulsion (EMLA, Astra) and a placebo emulsion was double-blind. Stratification by age group (4 to 6, 7 to 11, 12 to 16) ensured an equal number of children (20) in each intervention/age group category. A global assessment of the behavioral reaction to the procedure was made by the principal investigator, taking into account vocal, verbal, facial, and motor responses. The child was asked to assess pain severity on the Faces Pain Scale (FPS) and a visual analogue toy (VAT). The scales were applied conservatively as ordinal scales: FPS 0 to 6; VAT 0 to 10.
                Children who received lidocaine-prilocaine emulsion reported less pain (mean FPS score = 1.42) compared with placebo emulsion (mean FPS score = 2.58) and with music distraction (mean FPS = 2.62). There was a highly significant therapeutic effect (P < .001) on the self-report and behavioral scores. Younger children, regardless of intervention, reported significantly more pain than the older children (mean FPS scores: 2.85, 2.33, 1.43 for age groups 4 to 6, 7 to 11, and 12 to 16 respectively; P < .001). The superiority of the local anesthetic emulsion was maximal in the youngest age group (4 to 6) almost eliminating pain-related behavior, and multiple regression analysis confirmed significant age and treatment effects and revealed interaction between therapeutic effect and age. Although a trend favoring the active emulsion was evident in the older children (7 to 11, 12 to 16) the differences were not significant. The pain scores were influenced by the type (gauge) of cannula, but this did not affect the conclusion regarding therapeutic and age effects. There was no influence of sex, experience with venipuncture, or whether the child was anxious on arrival in the operating room.
                The results show that lidocaine-prilocaine emulsion is highly effective in preventing pain from venipunctures in young children, the group in most need of prevention. This study examined the effectiveness of sphenopalatine ganglion block (SPGB) for myofascial pain syndrome of the head, neck, and shoulders using a double-blind, placebo-controlled, crossover study design with comparison to an internal standard consisting of trigger point injections (TPI).
                Patients (n = 23) were randomly assigned to receive either: (1) SPGB with 4% lidocaine, then TPI with 1% lidocaine, and finally SPGB with saline placebo or (2) SPGB with saline placebo, then TPI with 1% lidocaine, and finally SPGB with 4% lidocaine. Each respective treatment within each protocol was given sequentially at 1-week intervals for both groups. Prior to the first treatment, all patients assessed their average intensity of pain and pain at that particular moment using a visual analog pain scale. Pain intensity and pain relief were reassessed 30 minutes after each treatment and at 6 hours, 24 hours and 1 week using visual analog pain and pain relief scales. Pain intensity and pain relief data were transformed into natural logarithm units, and the statistical significance of SPGB with 4% lidocaine versus SPGB with placebo, SPGB with 4% lidocaine versus TPI, and TPI versus SPGB with placebo were tested by mixed-model analysis of variance. The magnitude of the differences in pain intensity and pain relief ratings were also compared via computation of 95% confidence intervals.
                The analgesic effect of SPGB with 4% lidocaine was no better than placebo. Mixed-model analysis of variance revealed improved analgesia with administration of TPIs as compared to SPGB with 4% lidocaine and placebo over the entire week of observations (pain relief scores).
                This study suggests that SPGB with 4% lidocaine is no more efficacious than placebo and less efficacious than administration of standard trigger point injections in the treatment of myofascial pain of the head, neck, and shoulders. The efficacy of sclerosing agents for the treatment of telangiectasias and reticular veins is well established. The injection of these agents is often associated with pain, and it is not uncommon for sclerotherapists to include lidocaine with the sclerosants in an attempt to reduce the pain associated with treatment. However, there are concerns that this may reduce the overall efficacy of the treatment because of dilution of the sclerosant. Patient comfort and overall outcome associated with treatment using HS with lidocaine (LIDO) versus that using HS alone was compared.
                Forty-two patients were prospectively entered into the study and randomized blindly to sclerotherapy with 23.4% HS or 19% LIDO. Study subjects and treating physicians were blinded to the injection solution used. Injection sites were chosen for veins ranging in size from 0.1 to 3 mm. Photographs of the area to be treated were taken, and the patients rated their pain. They were then observed at regular intervals for four months, and clinical data was collected. Thirty-five subjects completed the full follow-up period, and photographs of the injected area were taken again. Three investigators blinded to the treatment assignment then evaluated the photographs and scored the treatment efficacy according to a standardized system.
                In the HS group, 61.9% (13 of 21) patients rated their pain as none or mild, whereas 90.5% (19 of 21) of patients in the LIDO group had no or mild discomfort. This difference is significant, with a P value of.034. There was no difference in the overall efficacy of treatment between the two groups. The groups had similar rates of vein thrombosis and skin necrosis.
                Although lidocaine is often used with sclerosing agents, there are no previous reports in the literature to evaluate its effectiveness in reducing the pain experienced by the patient. In this study, patients receiving LIDO experienced significantly less discomfort at the time of injection than patients who received HS alone. There were no differences in the effectiveness of treatment or in the incidence of complications between the two groups. Postherpetic neuralgia (PHN) following herpes zoster is a common and disabling neuropathic pain syndrome. In a double-blind, three-session study, 5% lidocaine gel or vehicle was applied simultaneously to both the area of pain and to the contralateral mirror-image unaffected skin. In the local session, lidocaine gel was applied to the painful skin area. In the remote session, lidocaine gel was applied to mirror-image skin. In the placebo session, vehicle was applied bilaterally. For cranial PHN, gel was applied without occlusion for 8 hours. For limb or torso PHN, gel was applied under occlusion for 24 hours. The 16 subjects with cranial PHN reported pain relief significantly favoring local drug application at 30 minutes, 2, 4, and 8 hours. The 23 subjects with torso or limb PHN reported significantly lower pain intensity with local drug application at 8 hours and both pain relief and reduced pain intensity at 24 hours. Remote lidocaine application to mirror-image skin was no different from placebo. No systemic adverse effects were reported and blood levels did not exceed 0.6 microgram/ml. Topical application of 5% lidocaine gel relieves PHN pain by a direct drug action on painful skin. Phantom and stump pains, common sequelae of limb amputations, are significant impediments to rehabilitation of amputees. The pathophysiology and optimal treatment of postamputation pain states are unclear. While stump pain may result from neuromas in the stump, phantom pain is thought to be related to cortical reorganization. The authors hypothesized that morphine and lidocaine may have differential effectiveness on stump and phantom pains.
                The authors conducted a randomized double-blind, active-placebo-controlled, crossover trial to compare the analgesic effects of intravenous morphine and lidocaine on postamputation stump and phantom pains. An intravenous bolus followed by an intravenous infusion of morphine (0.05 mg/kg bolus + 0.2 mg/kg infusion over 40 min), lidocaine (1 mg/kg bolus + 4 mg/kg infusion) and the active placebo, diphenhydramine (10 mg bolus + 40 mg infusion), were performed on three consecutive days. Phantom and stump pain ratings and sedation scores were recorded at 5-min intervals using a 0-100 visual analog scale. Pain measures were initiated 30 min before drug infusion and continued until 30 min after the end of infusion. Subjects' self-reported pain relief and satisfaction were assessed at the end of each infusion.
                Thirty-one of 32 subjects enrolled completed the study. Eleven subjects had both stump and phantom pains, 11 and 9 subjects had stump and phantom pain alone, respectively. Baseline pain scores were similar in the three drug groups. Compared with placebo, morphine reduced both stump and phantom pains significantly (P < 0.01). In contrast, lidocaine decreased stump (P < 0.01), but not phantom pain. The changes in sedation scores for morphine and lidocaine were not significantly different from placebo. Compared with placebo, self-reported stump pain relief was significantly greater for lidocaine (P < 0.05) and morphine (P < 0.01), while phantom pain relief was greater only for morphine (P < 0.01). Satisfaction scores were significantly higher for lidocaine (mean +/- SD: 39.3 +/- 37.8, P < 0.01) and morphine (45.9 +/- 35.5, P < 0.01) when compared with placebo (9.6 +/- 21.0).
                Stump pain was diminished both by morphine and lidocaine, while phantom pain was diminished only by morphine, suggesting that the mechanisms and pharmacological sensitivity of stump and phantom pains are different. There is a need for new clinical models to investigate effectively the development of pain after surgery and the effect, if any, of pre-emptive treatment. Bilateral models are of special interest, since the patient serves as his/her own control. The objective of this preliminary study was to test a clinical model for the study of acute and chronic pain after bilateral reduction mammoplasty.
                Eight patients participated in the study where the breasts were randomized to test and control groups. In each patient, one breast was preoperatively infiltrated with lidocaine and adrenaline and the other breast infiltrated with saline and adrenaline. Assessment included visual analogue scale (VAS) pain intensity, thermal thresholds, mapping for punctate hyperalgesia and tactile sensation. Assessments were made preoperatively, postoperatively and at 6 months after surgery.
                With regard to acute postoperative pain intensity, the model demonstrated a clear difference between lidocaine and placebo treated breasts. There was no difference between lidocaine and placebo treated breasts with regard to chronic pain, but these results are inconclusive due to small number of patients.
                The model is sensitive and may be useful in studies of mechanisms of development and prevention of chronic pain after surgery. Pain following spinal cord injury (SCI) is a therapeutic challenge. Only a few treatments have been assessed in randomized, controlled trials. The primary objective of the present study was to examine the analgesic effect of ketamine and lidocaine in a group of patients with neuropathic pain below the level of spinal cord injury. We also wanted to assess sensory abnormalities to see if this could help us to identify responders and if treatments resulted in changes of sensibility.
                Ten patients with spinal cord injury and neuropathic pain below the level of injury were included. The analgesic effect of ketamine 0.4 mg kg(-1) and lidocaine 2.5 mg kg(-1) was investigated. Saline was used as placebo. The drugs were infused over 40 min. A randomized, double-blind, three-period, three-treatment, cross-over design was used. Systemic plasma concentrations of ketamine and lidocaine were assessed. Pain rating was performed using a visual analogue scale (VAS). Sensory function was assessed with a combination of traditional sensory tests and quantitative measurement of temperature thresholds.
                Response to treatment, defined as 50% reduction in VAS-score during infusion, was recorded in 5/10 in the ketamine, 1/10 in the lidocaine and 0/10 in the placebo groups. Neither ketamine nor lidocaine changed temperature thresholds or assessments of mechanical; dynamic and static sensibility. Nor could these sensory assessments predict response to treatment in this setting. Lidocaine and particularly ketamine were associated with frequent side-effects.
                Ketamine but not lidocaine showed a significant analgesic effect in patients with neuropathic pain after spinal cord injury. The pain relief was not associated with altered temperature thresholds or other changes of sensory function. To determine whether intraoperative unpreserved lidocaine further decrease discomfort or pain during sutureless small incision cataract surgery and intraocular lens (IOL) implantation under topical anesthesia.
                Outpatient ambulatory surgical center.
                In this prospective controlled study, comparable eligible patients were randomized to receive 0.1 cc unpreserved lidocaine 1% or 0.1 cc balanced salt solution (BSS) (control group) in double-masked fashion. Study drugs were injected intracamerally 1 minute before phacoemulsification. A predefined uniform pain/discomfort scale was used for assessment during phacoemulsification and IOL insertion. A secondary study using a 0.5 cc dose was also performed.
                Twenty-six percent in the control group and 9% in the lidocaine group had discomfort pain scores of 2 or more; 10% in the BSS group felt increased pressure or pain during phacoemulsification. In the lidocaine group, discomfort was felt mainly during IOL insertion, possibly as a result of wound manipulation. During phacoemulsification, no patient in the lidocaine group reported pain; 2% felt increased pressure during phacoemulsification. A dose increase to 0.5 cc reduced any intraocular sensation to 3% in the lidocaine group. No patient in either group had significant cell loss or adverse events.
                Intraoperative lidocaine is safe and effective in controlling intraoperative discomfort. Post-herpetic neuralgia (PHN) is a common and often intractable neuropathic pain syndrome predominantly affecting the elderly. Topical local anesthetics have shown promise in both uncontrolled and controlled studies. Thirty-five subjects with established PHN affecting the torso or extremities completed a four-session, random order, double-blind, vehicle-controlled study of the analgesic effects of topically applied 5% lidocaine in the form of a non-woven polyethylene adhesive patch. All subjects had allodynia on examination. Up to 3 patches, covering a maximum of 420 cm2, were applied to cover the area of greatest pain as fully as possible. Lidocaine containing patches were applied in two of the four 12-h-long sessions, in one session vehicle patches were applied, and one session was a no-treatment observation session. Lidocaine containing patches significantly reduced pain intensity at all time points 30 min to 12 h compared to no-treatment observation, and at all time points 4--12 h compared to vehicle patches. Lidocaine patches were superior to both no-treatment observation and vehicle patches in averaged category pain relief scores. The highest blood lidocaine level measured was 0.1 micrograms/ml, indicating minimal systemic absorption of lidocaine. Patch application was without systemic side effect and well tolerated when applied on allodynic skin for 12 h. This study demonstrates that topical 5% lidocaine in patch form is easy to use and relieves post-herpetic neuralgia. To compare pain on injection and the efficacy of anesthesia of three modified lidocaine solutions for use in eyelid surgery: 1) 2% lidocaine with 1:100,000 epinephrine, 2) 2% lidocaine with 1:100,000 epinephrine buffered 9:1 with 8.4% sodium bicarbonate, and 3) 2% lidocaine with 1:100,000 epinephrine diluted 1:9 with 0.9% bacteriostatic saline solution (with benzyl alcohol).
                In this prospective, randomized, double-masked, controlled clinical trial, 30 consecutive patients undergoing bilateral identical eyelid surgery were randomized to one of three treatment groups. Group 1 received buffered solution on one side and stock solution on the other, group 2 received bacteriostatic saline diluted solution on one side and stock solution on the other, and group 3 received buffered solution on one side and bacteriostatic saline diluted solution on the other. Patients used a 5-point scale to rate the perceived pain on injection and the pain felt during the operative procedure.
                Comparison of mean injection pain scores showed that buffered solution was significantly less painful than unmodified solution (2.2 versus 3.1, p < 0.05), bacteriostatic saline modified solution was significantly less painful than unmodified solution (0.9 versus 3.3, p < 0.05), bacteriostatic saline modified solution was significantly less painful than buffered solution (1.2 versus 2.3, p < 0.05). Comparison of mean intraoperative pain scores demonstrated no significant difference between the solutions in any of the treatment groups.
                For local anesthesia in eyelid surgery, bacteriostatic saline modified solution provides more comfort on injection than either buffered or unmodified lidocaine-epinephrine solution and provides an adequate level of anesthesia that does not differ significantly from either the buffered or unmodified solutions.
Lidocaine and oral analogs were safe drugs in controlled clinical trials for neuropathic pain, were better than placebo, and were as effective as other analgesics. Future trials should enroll specific diseases and test novel lidocaine analogs with better toxicity profiles. More emphasis is necessary on outcomes measuring patient satisfaction to assess if statistically significant pain relief is clinically meaningful.