Sukdeb Datta

Behavioral and anatomical characterization of the bilateral sciatic nerve chronic constriction (bCCI) injury: correlation of anatomic changes and responses to cold stimuli

BackgroundUnilateral constrictive sciatic nerve injury (uCCI) is a common neuropathic pain model. However, the bilateral constrictive injury (bCCI) model is less well studied, and shows unique characteristics. In the present study, we sought to correlate effects of bCCI on nocifensive responses to cold and mechanical stimuli with selected dorsal horn anatomic markers. bCCI or sham ligation of both rat sciatic nerves were followed up to 90 days of behavioural testing. Additional rats sacrificed at 15, 30 and 90 days were used for anatomic analyses. Behavioural tests included hindpaw withdrawal responses to topical acetone, cold plate testing, an operant thermal preference task and hindpaw withdrawal thresholds to mechanical probing.ResultsAll nocifensive responses to cold increased and remained enhanced for >45 days. Mechanical withdrawal thresholds decreased for 25 days only. Densitometric analyses of immunoperoxidase staining in the superficial dorsal horn at L4-5 revealed decreased cholecystokinin (CCK) staining at all times after bCCI, decreased mu opiate receptor (MOR) staining, maximal at 15 days, increased neuropeptide Y (NPY) staining only at days 15 and 30, and increased neurokinin-1 receptor (NK-1R) staining at all time points, maximal at 15 days. Correlation analyses at 45 days post-bCCI, were significant for individual rat nocifensive responses in each cold test and CCK and NK-1R, but not for MOR or NPY.ConclusionsThese results confirm the usefulness of cold testing in bCCI rats, a new approach using CCI to model neuropathic pain, and suggest a potential value of studying the roles of dorsal horn CCK and substance P in chronic neuropathic pain. Compared to human subjects with neuropathic pain, responses to cold stimuli in rats with bCCI may be a useful model of neuropathic pain.

Incidence and root cause analysis of wrong-site pain management procedures: a multicenter study.

Background:Medical errors exact an inordinate toll on healthcare costs. One of the most publicized and analyzed type of medical error is wrong-site surgery. Yet, despite the burgeoning number of procedures performed, no literature exists on wrong-site pain management injections. The purpose of this study was to estimate the relative incidence and determine the causes of wrong-site pain management procedures. Methods:Quality improvement records were examined during a 2-yr period from four civilian academic teaching hospitals, three military treatment facilities, and three private practices, for “sentinel” events involving wrong-site pain management procedures. A total of 13 cases (incidence 0.027%; 95% CI 0.01–0.05%) were identified from approximately 48,941 collective procedures of which 52.4% were deemed to be “at risk” for the occurrence. Root cause analyses were then conducted to determine the origin of each error. Results:The 13 cases included five wrong-side transforaminal epidural steroid injections, six other wrong-side injections, and two wrong-level minimally invasive surgical procedures. In only one case was the “universal protocol” completely followed, and in nine procedures, multiple lapses occurred in protocol. Three patients had bilateral pathology, and in seven cases, the patient knew at the time that the wrong side was being injected. In no instance did any technical, legal, or professional consequences ensue from the error. Conclusions:Wrong-site nerve blocks occur more frequently in pain management centers than has previously been acknowledged. Adaptation of the universal protocol to nerve blocks and strict adherence to widely accepted guidelines may prevent wrong-site interventional pain procedures.

Re: A Systematic Review to Assess Comparative Effectiveness Studies in Epidural Steroid Injections for Lumbar Spinal Stenosis and to Estimate Reimbursement Amounts

To the Editor, We read with great interest the systematic review by Bresnahan et al [1] in which they assessed comparative effectiveness studies in epidural steroid injections for lumbar spinal stenosis and also estimated reimbursement amounts. They concluded that there was no evidence for epidural injections and that they were not cost effective. It appears that the authors have missed the purpose of a systematic review, which is to highlight the findings and provide clinicians and other stakeholders a coherent recommendation that uses clear-cut methodologies that are transparent and reproducible and to provide a clinical utility of the therapy in question. Although the authors claim that they evaluated the articles for the presence of bias, the final recommendations reek of personal bias. Bresnahan et al [1] seemingly used appropriate search criteria but failed to find all the manuscripts that were included by some of the authors of this letter in the past. In the search criteria through August 2012, the authors missed 3 systematic reviews [2-4] and 2 randomized, double-blind controlled trials [5,6] in which investigators assessed the effectiveness of caudal and lumbar interlaminar approaches with 1-year follow-up with comparative effectiveness of a local anesthetic with or without steroids. Both of the studies are of high quality and report positive results on a long-term basis. In addition, the authors also have missed another randomized trial by Wilson-MacDonald et al [7], who found that the use of either an epidural steroid injection or an intramuscular injection of local anesthetic and steroids showed positive results in the short-term. However, the authors did include multiple poor-quality studies with small sample sizes and short-term follow-ups. Assessment bias appears to be extremely confusing. The authors state that using the standard evidence-based criteria, 5 of the 6 randomized controlled trials were judged to have low risk of bias from insufficient blinding or loss of followup. However, it is confusing that they have quoted 3 references, 12, 15, 17, from the manuscript. In addition, the authors have not shown the table of bias assessment and the resultant scores. In multiple systematic reviews, all of the studies included in this manuscript were judged with less than high quality or low risk of bias except the manuscript

In Response To: Are We Lemmings Going Off a Cliff? The Case Against the “Interventional” Pain Medicine Label

Dear Editor, We appreciate and agree with what seems to be the crux of Dr Richeimers editorial: “… we want pain medicine to be viewed as a legitimate medical specialty, with a broad knowledge base & a wide arsenal of treatments …”. However, we strongly disagree with his statement: “Hopefully, it is clear that the trend toward the use of the label ‘interventional pain medicine’ is very problematic for our specialty.” The valid points that the author makes are diminished by the derisive tone of this letter. The two anecdotes that he provides upon which he builds his arguments (there are no data or statistics presented) seem to be attestations to the superiority of his skills over those of the referring physicians: 1. The 23-year-old woman with complex regional pain syndrom (CRPS) who was “… referred to a community pain specialist who immediately started procedural treatment.” Following this, the patient was referred to the authors pain clinic and received two years of medications and psychological therapy without much relief before finally receiving a spinal cord stimulation (SCS) with 60% reduction in pain. The ASIPP guidelines indicate that this patient should have been offered not only psychological INTERVENTION but …

Lumbar Sympathetic Block and Neurolysis

Lumbar sympathetic block is a commonly utilized modality for the modulation of hyperactivity of the lumbar sympathetic chain. Indications include varied conditions such as occlusive vascular disease, cancer pain, chronic regional pain syndrome (CRPS) I and II, phantom limb pain, and early stages of postherpetic neuralgia. The lumbar sympathetic ganglia usually contain four interconnected ganglia and run in the extraperitoneal connective tissue anterior to the vertebral column and along the medial margin of the psoas major. Approaches to the lumbar sympathetic block include the paramedian (classic Mandl’s) approach, the lateral (Reid’s) approach, and transdiscal and the paradiscal extraforaminal (Datta’s and Pai’s) techniques. The lumbar artery is located in the middle of the vertebral artery, and the sympathetic ganglia are located in a paradiscal position, so techniques avoiding the middle of the vertebral body are advocated. Neurolysis can be performed by either chemical agents or radiofrequency. Complications include backache and genitofemoral neuralgia. The evidence for sympathectomy is somewhat effective. Evidence for neurolytic sympatholysis is limited.

Intradiscal electrothermal therapy treatment for back pain

The intradiscal electrothermal therapy (IDET) procedure is a minimally invasive technique designed to treat discogenic chronic low back pain. The debate surrounding IDET ranges from the concept of the procedure, the technique and patient selection, to its effectiveness. The procedure provides modest improvement; however, it is considered less invasive and destructive than other modalities of treatments available at the present time, and has lower cost. The effectiveness evidence is limited at the present time, but based on the results of six recently published positive single-arm studies, it appears that patients experienced a perceptible clinical benefit from the IDET procedure. Thus, IDET is recommended in patients with moderate functional impairment, relatively well-maintained disc heights and discogenic pain caused by annular tears or protrusions less than 3-4 mm after the failure of less invasive procedures.

Different Injectate Volumes in Cervical Medial Branch Blocks: Does Increased Diagnostic Accuracy with Smaller Injectate Volume Lead to Changes in Outcome?

To the Editor: We read with great interest the article by Cohen et al., and we complement the authors on such a well-designed randomized study. Cohen et al. highlight the importance of improving diagnostic efficacy of cervical medial branch blocks by injecting two different volumes (0.25 and 0.5 ml) of injectate. We note from the results that three nerves were missed in each treatment group, indicating a 93% accuracy rate. Thus, missing the nerve is more of a “technical challenge” rather than being due to the volume of local anesthetic injected (0.25 vs. 0.5 ml). As shown in table 1 of their article, the authors note that six (54.5%) of the medial branch blocks with 0.25 ml versus three (25%) of the medial branch blocks with 0.5 ml received greater than 50% pain relief. Decreasing the volume of local anesthetic by 50% led to doubling (from 25 to 54.5%) of pain relief. Cohen et al. then comment in the discussion section: “it is interesting to note that the higher incidence of inadvertent spread to untargeted nervous tissue did not translate to reduced pain scores in the 0.5 ml.” This leads us to conclude that if this is truly the case, that decreasing the volume of injectate to improve the diagnostic accuracy led to increased prevalence of pain relief, then the volume injected does not really matter in improved outcomes. That is to say, using volumes of 0.25 or 0.5 ml will produce similar outcomes in diagnostic cervical medial branch blocks with comparable true positive rates (93%).