Peripheral Nerve Field Stimulation for Intractable Post‐Thoracotomy Scar Pain not Relieved by Conventional Treatment

Peripheral nerve field stimulation (PNFS) is being applied in individual cases where conventional treatments have failed to control pain localized to limited dermatomal distribution. We applied PNFS for unrelieved post‐thoracotomy scar pain. Although spinal cord stimulation may have resulted in good coverage in the same dermatomal distribution, we chose the more peripheral approach to minimize the risk of complications, avoiding the potential neurologic sequelae associated with stimulation of the spinal cord. In summary, PNFS was effective in relieving post‐thoractomy pain refractory to conventional pain management suggesting great potential of PNFS as a treatment option for chronic surgical‐scar pain.     

Epidural Steroid and Clonidine for Chronic Intractable Post‐thoracotomy Pain: A Pilot Study

Background: Chronic post‐thoracotomy pain is relatively common after major thoracic surgery. The primary results of a pilot study using thoracic epidural steroid and clonidine injection to treat chronic intractable post‐thoracotomy pain are presented. Methods: Twenty‐one patients with intractable post‐thoracotomy pain participated in the study. Thirteen patients received thoracic epidural injection of a mixture of 150 μg clonidine and 80 mg of methylprednisolone acetate diluted in 8 mL 0.5% lidocaine. Eight patients continued with comprehensive medical management and served as a control group. A visual analog scale (VAS) for pain was recorded before treatment, 30 minutes after the epidural injection and before discharge, at 3 weeks and 6 months. Pain, sleep disturbances, appetite changes and daily activity, as well as the incidence of complications were recorded. The need for opioid rescue medications was recorded. Results: Twelve of 13 patients in the injection group reported improvement (> 50% reduction of pain) at 3 weeks and 6 months following the injection. Allodynia improved in all injection group patients compared to four of eight in the control group. Sleep disturbance, appetite changes and daily activity were improved in the injection group. The number of patients requiring opioid rescue medications was reduced from 61.5% to 15.3% during the 6‐month duration of study. Injection caused transient hypotension in 46.2% of patients. Mild sedation was noted in 30.7% of patients receiving injection; 15.3% of the patients had localized back pain at the site of injection. Discussion: Our preliminary data suggest possible efficacy of thoracic epidural steroid and clonidine mixture in the treatment of chronic post‐thoracotomy pain. No serious adverse effects were noted in this pilot study. ?     

Evidence for the Use of Botulinum Toxin in the Chronic Pain Setting—A Review of the Literature

▪ Abstract:   A significant proportion of chronic pain is of musculoskeletal origin. Botulinum toxin (BTX) has been successfully used in the treatment of spasmodic torticollis, limb dystonia, and spasticity. Investigators have, thus, become interested in its potential use in treating many chronic pain conditions. Practitioners have used BTX, outside the product license, in the treatment of refractory myofascial pain syndrome and neck and low back pain (LBP). This article reviews the current evidence relating to chronic pain practice. There is evidence supporting the use of both BTX type A and type B in the treatment of cervical dystonias. The weight of evidence is in favor of BTX type A as a treatment in: pelvic pain, plantar fasciitis, temporomandibular joint dysfunction associated facial pain, chronic LBP, carpal tunnel syndrome, joint pain, and in complex regional pain syndrome and selected neuropathic pain syndromes. The weight of evidence is also in favor of BTX type A and type B in piriformis syndrome. There is conflicting evidence relating to the use of BTX in the treatment whiplash, myofascial pain, and myogenous jaw pain. It does appear that BTX is useful in selected patients, and its duration of action may exceed that of conventional treatments. This seems a promising treatment that must be further evaluated. ▪     

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.     

Headache and Facial Pain Responsive to Botulinum Toxin: An Unusual Presentation of Blepharospasm

The diagnosis of blepharospasm is rarely considered in patients complaining of face pain or headache. This patient illustrates the importance of looking for blepharospasm in patients who present with headache or face pain, as her pain and blepharospasm were successfully treated with botulinum toxin type A injections.     

A Critical Appraisal of the Evidence for Botulinum Toxin Type A in the Treatment for Cervico‐Thoracic Myofascial Pain Syndrome

Myofascial pain syndrome (MPS) is a musculoskeletal condition characterized by regional pain and muscle tenderness associated with the presence of myofascial trigger points (MTrPs). The last decade has seen an exponential increase in the use of botulinum toxin (BTX) to treat MPS. To understand the medical evidence substantiating the role of therapeutic BTX injections and to provide useful information for the medical practitioner, we applied the principles of evidence‐based medicine to the treatment for cervico‐thoracic MPS. A search was conducted through MEDLINE (PubMed, OVID, MDConsult), EMBASE, SCOPUS and the Cochrane database for the period 1966 to 2012 using the following keywords: myofascial pain, muscle pain, botulinum toxin, trigger points, and injections. A total of 7 trials satisfied our inclusion criteria and were evaluated in this review. Although the majority of studies found negative results, our analysis identified Gobel et al.'s as the highest quality study among these prospectively randomized investigations. This was due to appropriate identification of diagnostic criteria, excellent study design and objective endpoints. The 6 other identified studies had significant failings due to deficiencies in 1 or more major criteria. We conclude that higher quality, rigorously standardized studies are needed to more appropriately investigate this promising treatment modality.     

Evidence for Antinociceptive Activity of Botulinum Toxin Type A in Pain Management

The neurotoxin, botulinum toxin type A, has been used successfully, in some patients, as an analgesic for myofascial pain syndromes, migraine, and other headache types. The toxin inhibits the release of the neurotransmitter, acetylcholine, at the neuromuscular junction thereby inhibiting striated muscle contractions. In the majority of pain syndromes where botulinum toxin type A is effective, inhibiting muscle spasms is an important component of its activity. Even so, the reduction of pain often occurs before the decrease in muscle contractions suggesting that botulinum toxin type A has a more complex mechanism of action than initially hypothesized. Current data points to an antinociceptive effect of botulinum toxin type A that is separate from its neuromuscular activity. The common biochemical mechanism, however, remains the same between botulinum toxin type A's effect on the motor nerve or the sensory nerve: enzymatic blockade of neurotransmitter release. The antinociceptive effect of the toxin was reported to block substance P release using in vitro culture systems. ¹
The current investigation evaluated the in vivo mechanism of action for the antinociceptive action of botulinum toxin type A. In these studies, botulinum toxin type A was found to block the release of glutamate. Furthermore, Fos, a product of the immediate early gene, c- fos , expressed with neuronal stimuli was prevented upon peripheral exposure to the toxin.
These findings suggest that botulinum toxin type A blocks peripheral sensitization and, indirectly, reduces central sensitization. The recent hypothesis that migraine involves both peripheral and central sensitization may help explain how botulinum toxin type A inhibits migraine pain by acting on these two pathways. Further research is needed to determine whether the antinociceptive mechanism mediated by botulinum toxin type A affects the neuronal signaling pathways that are activated during migraine.     

A Review of Duloxetine 60 mg Once‐Daily Dosing for the Management of Diabetic Peripheral Neuropathic Pain,Fibromyalgia, and Chronic Musculoskeletal Pain Due to Chronic Osteoarthritis Pain and Low Back Pain

Background: Duloxetine is a selective dual neuronal serotonin (5‐Hydroxytryptamine, 5‐HT) and norepinephrine reuptake inhibitor (SSNRI). It is indicated in the United States for treatment of major depressive disorder (MDD), generalized anxiety disorder (GAD), and several chronic pain conditions, including management of diabetic peripheral neuropathic pain, fibromyalgia, and chronic musculoskeletal pain due to chronic osteoarthritis (OA) pain and chronic low back pain (LBP). Its use for antidepressant and anxiolytic actions has been extensively reviewed previously. We here review the evidence for the efficacy of 60 mg once‐daily dosing of duloxetine for chronic pain conditions. Method: The literature was searched for clinical trials in humans conducted in the past 10 years involving duloxetine. Results: There were 199 results in the initial search. Studies not in the English language were excluded. We then included only studies of diabetic peripheral neuropathic pain, fibromyalgia, and chronic musculoskeletal pain (OA and LBP). Studies of painful symptoms reported in mental health studies were excluded. This resulted in 32 studies. Articles that did not include a 60 mg/day daily dose as a study arm were excluded. This resulted in 30 studies, broken down as follows: 12 for diabetic peripheral neuropathy, 9 for fibromyalgia, 6 for LBP, and 3 for OA pain. Conclusions: The studies reviewed report that duloxetine 60 mg once‐daily dosing is an effective option for the management of diabetic peripheral neuropathic pain, fibromyalgia, and chronic musculoskeletal pain due to chronic OA pain and chronic LBP. As these pains are often comorbid with MDD or GAD, duloxetine might possess the pharmacologic properties to be a versatile agent able to address several symptoms in these patients. With adequate attention to FDA prescribing guidance regarding safety and drug–drug interactions, duloxetine 60 mg once‐daily dosing appears to be an effective option in the appropriate pain patient population.     

Analgesic Effect of Botulinum Toxin A in Myofascial Pain Syndrome Patients Previously Treated with Local Infiltration of Anesthetic and Steroids

The purpose of this study was to evaluate the analgesic effect of botulinum toxin A (BoNTA) injections in patients with myofascial pain syndrome (MPS) who were previously treated with the local infiltration of anesthetic and steroids (LIAS). The study included a retrospective phase and a longitudinal open-label prospective phase, which were conducted on consecutive patients with MPS previously treated with the local infiltration of anesthetic (levobupivacaíne 0.25%) and steroids (triamcinolone 40 mg). Eligible patients were treated with a single intramuscular injection of BoNTA (Botox; Allergan, Inc., Irvine, CA). The treatment efficacy was determined according to the degree of pain relief obtained. Eighty-two patients met the inclusion/exclusion criteria and were included in the study. Successful results were obtained for 32 (39.0%) and 30 (36.6%) patients, during treatment with BoNTA and LIAS, respectively. The mean (standard deviation) length of the analgesic effect was significantly longer with BoNTA (29.6 [SD = 17.7] weeks) than with LIAS (8.5 [SD = 6.4] weeks), P <.0001. As regards the side effects, 19 (23.2%) patients reported transient soreness at the injection site for 2 to 3 days with BoNTA. The MPS patients previously treated with a local infiltration of anesthetic and steroids who then received a single injection of BoNTA experienced significantly reduced pain for a relatively long time.     

Botulinum Toxin Injection for Cervicogenic Headache

We report a 28-year-old woman with a 5-year history of cervicogenic headache following a whiplash injury, Her unilateral neck pain, if aggravated by exertion, would create a predictable sequence of events leading to a hemicephalgia. She proved medically refractory to usual therapies, but had a striking response to a single botulinum toxin injection in her symptomatic rapezius muscle. Repeated injections every 3 months have been required to maintain this benefit. The implications of this observation are discussed.     

Preoperative Gabapentin for Acute Post‐thoracotomy Analgesia: A Randomized,Double‐Blinded,Active Placebo‐Controlled Study

Background: The role of preoperative gabapentin in postoperative pain management is not clear, particularly in patients receiving regional blockade. Patients undergoing thoracotomy benefit from epidural analgesia but still may experience significant postoperative pain. We examined the effect of preoperative gabapentin in thoracotomy patients. Methods: Adults undergoing elective thoracotomy were enrolled in this prospective, randomized, double‐blinded, placebo‐controlled study, and randomly assigned to receive 600 mg gabapentin or active placebo (12.5 mg diphenhydramine) orally within 2 hours preoperatively. Standardized management included thoracic epidural infusion, intravenous patient‐controlled opioid analgesia, acetaminophen and ketorolac. Pain scores, opioid use and side effects were recorded for 48 hours. Pain was also assessed at 3 months. Results: One hundred twenty patients (63 placebo and 57 gabapentin) were studied. Pain scores did not significantly differ at any time point (P = 0.53). Parenteral and oral opioid consumption was not significantly different between groups on postoperative day 1 or 2 (P > 0.05 in both cases). The frequency of side effects such as nausea and vomiting or respiratory depression was not significantly different between groups, but gabapentin was associated with decreased frequency of pruritus requiring nalbuphine (14% gabapentin vs. 43% control group, P < 0.001). The frequency of patients experiencing pain at 3 months post‐thoracotomy was also comparable between groups (70% gabapentin vs. 66% placebo group, P = 0.72). Conclusions: A single preoperative oral dose of gabapentin (600 mg) did not reduce pain scores or opioid consumption following elective thoracotomy, and did not confer any analgesic benefit in the setting of effective multimodal analgesia that included thoracic epidural infusion.     

Botulinum Toxin A, Adjunctive Therapy for Refractory Headaches Associated With Pericranial Muscle Tension

Pericranial muscle tension may contribute to the development of facial discomfort, chronic daily headache, and migraine-type headache. Elimination of pericranial muscle tension may reduce associated myalgia and counteract influences that can trigger secondary headaches which fall within the migraine continuum. Four patients with chronic, predominantly tension-type headaches and associated pericranial muscles tension failed prolonged conventional treatment and, therefore, symptomatic areas were treated with botulinum toxin A. This alleviated myalgia and reduced the severity and frequency of migraine-type headaches with a concomitant reduction in subsequent medical and physical therapy interventions. Judicious use of botulinum toxin A into defined areas of pericranial muscle tension may be useful for reducing primary myalgia and secondary headache.     

Botulinum Toxin A in the Treatment of Chronic Tension-Type Headache With Cervical Myofascial Trigger Points: A Randomized, Double-Blind, Placebo-Controlled Pilot Study

Objective.— To evaluate the efficacy of botulinum toxin A (BT-A) as a prophylactic treatment for chronic tension-type headache (CTTH) with myofascial trigger points (MTPs) producing referred head pain. Background.— Although BT-A has received mixed support for the treatment of TTH, deliberate injection directly into the cervical MTPs very often found in this population has not been formally evaluated. Methods.— Patients with CTTH and specific MTPs producing referred head pain were assigned randomly to receive intramuscular injections of BT-A or isotonic saline (placebo) in a double-blind design. Daily headache diaries, pill counts, trigger point pressure algometry, range of motion assessment, and responses to standardized pain and psychological questionnaires were used as outcome measures; patients returned for follow-up assessment at 2 weeks, 1 month, 2 months, and 3 months post injection. After 3 months, all patients were offered participation in an open-label extension of the study. Effect sizes were calculated to index treatment effects among the intent-to-treat population; individual time series models were computed for average pain intensity. Results.— The 23 participants reported experiencing headache on a near-daily basis (average of 27 days/month). Compared with placebo, patients in the BT-A group reported greater reductions in headache frequency during the first part of the study (P = .013), but these effects dissipated by week 12. Reductions in headache intensity over time did not differ significantly between groups (P = .80; maximum d = 0.13), although a larger proportion of BT-A patients showed evidence of statistically significant improvements in headache intensity in the time series analyses (62.5% for BT-A vs 30% for placebo). There were no differences between the groups on any of the secondary outcome measures. Conclusions.— The evidence for BT-A in headache is mixed, and even more so in CTTH. However, the putative technique of injecting BT-A directly into the ubiquitous MTPs in CTTH is partially supported in this pilot study. Definitive trials with larger samples are needed to test this hypothesis further.     

A型肉毒毒素治疗三叉神经痛

目的:观察A型肉毒毒素治疗三叉神经痛(TN)的临床疗效。方法:选取57例TN患者,随机分为A、B 2组。A组28例患者口服卡马西平片治疗;B组29例在疼痛部位及板机点周围皮下注射肉毒素治疗。治疗后1,3及6个月时随访,行简式McGill疼痛问卷表(SF-MPQ)及生活质量评价量表(SF-36)评分,并观察不良反应。结果:治疗中脱失7例,A组3例,B组4例。与治疗前3个月SF-MPQ及SF-36平均分作为基础水平比较,治疗1,3及6个月后2组SF-MPQ评分明显下降,SF-36明显上升(P<0.01),B组表明更明显(P<0.05,P<0.01)。治疗过程中,A组出现不适患者多于B组。结论:A型肉毒毒素疼痛点皮下注射治疗TN发作作用高峰1～3个月,维持时间6个月,且临床疗效显著,不良反应轻微。