Naum Shaparin

Inhaled Cannabis for Chronic Neuropathic Pain: A Meta-analysis of Individual Patient Data

UNLABELLED Chronic neuropathic pain, the most frequent condition affecting the peripheral nervous system, remains underdiagnosed and difficult to treat. Inhaled cannabis may alleviate chronic neuropathic pain. Our objective was to synthesize the evidence on the use of inhaled cannabis for chronic neuropathic pain. We performed a systematic review and a meta-analysis of individual patient data. We registered our protocol with PROSPERO CRD42011001182. We searched in Cochrane Central, PubMed, EMBASE, and AMED. We considered all randomized controlled trials investigating chronic painful neuropathy and comparing inhaled cannabis with placebo. We pooled treatment effects following a hierarchical random-effects Bayesian responder model for the population-averaged subject-specific effect. Our evidence synthesis of individual patient data from 178 participants with 405 observed responses in 5 randomized controlled trials following patients for days to weeks provides evidence that inhaled cannabis results in short-term reductions in chronic neuropathic pain for 1 in every 5 to 6 patients treated (number needed to treat = 5.6 with a Bayesian 95% credible interval ranging between 3.4 and 14). Our inferences were insensitive to model assumptions, priors, and parameter choices. We caution that the small number of studies and participants, the short follow-up, shortcomings in allocation concealment, and considerable attrition limit the conclusions that can be drawn from the review. The Bayes factor is 332, corresponding to a posterior probability of effect of 99.7%. PERSPECTIVE This novel Bayesian meta-analysis of individual patient data from 5 randomized trials suggests that inhaled cannabis may provide short-term relief for 1 in 5 to 6 patients with neuropathic pain. Pragmatic trials are needed to evaluate the long-term benefits and risks of this treatment.

Neuraxial Anesthesia in Parturients with Low Platelet Counts.

The obstetric anesthesiologist must consider the risk of spinal–epidural hematoma in patients with thrombocytopenia when choosing to provide neuraxial anesthesia. There are little data exploring this complication in the parturient. In this single-center retrospective study of 20,244 obstetric patients, the incidence of peripartum thrombocytopenia (platelet count <100,000/mm3) was 1.8% (368 patients). Of these patients, 69% (256) received neuraxial anesthesia. No neuraxial hematoma occurred in any of our patients. The upper 95% confidence limit for spinal–epidural hematoma in patients who received neuraxial anesthesia with a platelet count of <100,000/mm3 was 1.2%.

A longitudinal linear model of patient characteristics to predict failure to attend an inner-city chronic pain clinic

UNLABELLED Patients often fail to attend appointments in chronic pain clinics for unknown reasons. We hypothesized that certain patient characteristics predict failure to attend scheduled appointments, pointing to systematic barriers to accessing chronic pain services for certain underserved populations. We collected retrospective data from a longitudinal observational cohort of patients at an academic pain clinic in Newark, New Jersey. To examine the effect of demographic factors on appointment status, we fit a marginal logistic regression using generalized estimating equations with exchangeable correlation. A total of 1,394 patients with 3,488 total encounters between January 1, 2006, and December 31, 2009, were included. Spanish spoken as a primary language (alternatively Hispanic or other race) and living between 5 and 10 miles from the clinic were associated with reduced odds of arriving for an appointment; making an appointment for a particular complaint such as cancer pain or back pain, an interventional pain procedure scheduled in connection with the appointment, unemployed status, and continuity of care (as measured by office visit number) were associated with increased odds of arriving. Spanish spoken as a primary language and distance to the pain clinic predicted failure to attend a scheduled appointment in our cohort. If these constitute systematic barriers to access, they may be amenable to targeted interventions. PERSPECTIVE We identified certain patient characteristics, specifically Spanish spoken as a primary language and geographic distance from the clinic, that predict failure to attend an inner-city chronic pain clinic. These identified barriers to accessing chronic pain services may be modifiable by simple cost-effective interventions.

Peripheral neuromodulation for the treatment of refractory trigeminal neuralgia

Trigeminal neuralgia is an extremely painful condition. Treatment options for trigeminal neuralgia include anticonvulsants, opioids and surgical methods; however, some cases may be refractory to these therapies. In this article, the authors report a case involving a patient for whom conventional treatments failed; she underwent a successful trial of peripheral nerve stimulation and subsequently opted for a permanent implantation of an internal pulse generator, leading to long-term relief of her pain.

2-Acetylcyclopentanone, an Enolate-Forming 1,3-Dicarbonyl Compound, Is Cytoprotective in Warm Ischemia-Reperfusion Injury of Rat Liver

We have previously shown that 2-acetylcyclopentanone (2-ACP), an enolate-forming 1,3-dicarbonyl compound, provides protection in cell culture and animal models of oxidative stress. The pathophysiology of ischemia-reperfusion injury (IRI) involves oxidative stress, and, therefore, we determined the ability of 2-ACP to prevent this injury in a rat liver model. IRI was induced by clamping the portal vasculature for 45 minutes (ischemia phase), followed by recirculation for 180 minutes (reperfusion phase). This sequence was associated with substantial derangement of plasma liver enzyme activities, histopathological indices, and markers of oxidative stress. The 2-ACP (0.80–2.40 mmol/kg), administered by intraperitoneal injection 10 minutes prior to reperfusion, provided dose-dependent cytoprotection, as indicated by normalization of the IRI-altered liver histologic and biochemical parameters. The 2-ACP (2.40 mmol/kg) was also hepatoprotective when injected before clamping the circulation (ischemia phase). In contrast, an equimolar dose of N-acetylcysteine (2.40 mmol/kg) was not hepatoprotective when administered prior to reperfusion. Our studies to date suggest that during reperfusion the enolate nucleophile of 2-ACP limits the consequences of mitochondrial-based oxidative stress through scavenging unsaturated aldehyde electrophiles (e.g., acrolein) and chelation of metal ions that catalyze the free radical-generating Fenton reaction. The ability of 2-ACP to reduce IRI when injected prior to ischemia most likely reflects the short duration of this experimental phase (45 minutes) and favorable pharmacokinetics that maintain effective 2-ACP liver concentrations during subsequent reperfusion. These results provide evidence that 2-ACP or an analog might be useful in treating IRI and other conditions that have oxidative stress as a common molecular etiology.

Investigating the Efficacy of Dexmedetomidine as an Adjuvant to Local Anesthesia in Brachial Plexus Block: A Systematic Review and Meta-analysis of 18 Randomized Controlled Trials

Background and Objectives Dexmedetomidine has been thought to be an effective adjuvant to local anesthetics in brachial plexus blockade. We sought to clarify the uncertainty that still exists as to its true efficacy. Methods A meta-analysis of randomized controlled trials was conducted to assess the ability of dexmedetomidine to prolong the duration and hasten the onset of motor and sensory blockade when used as an adjuvant to local anesthesia for brachial plexus blockade versus using local anesthesia alone (control). A search strategy was created to identify eligible articles in MEDLINE, EMBASE, and The Cochrane Library. The methodological quality for each included study was evaluated using the Cochrane Tool for Risk of Bias. Results Eighteen randomized controlled trials were included in this meta-analysis (n = 1092 patients). The addition of dexmedetomidine significantly reduced sensory block time onset time by 3.19 minutes (95% confidence interval [CI], −4.60 to −1.78 minutes; I 2 = 95%; P < 0.00001), prolonged sensory block duration by 261.41 minutes (95% CI, 145.20–377.61 minutes; I 2 = 100%; P < 0.0001), reduced the onset of motor blockade by 2.92 minutes (95% CI, −4.37 to −1.46 minutes; I 2 = 96%, P < 0.0001), and prolonged motor block duration by 200.90 minutes (CI, 99.24–302.56 minutes; I 2 = 99%; P = 0.0001) as compared with control. Dexmedetomidine also significantly prolonged the duration of analgesia by 289.31 minutes (95% CI, 185.97–392.64 minutes; I 2 = 99%; P < 0.00001). Significantly more patients experienced intraoperative bradycardia with dexmedetomidine (risk difference [RD], 0.06; 95% CI, 0.00–0.11; I 2 = 72%; P = 0.03); however, there was no difference in the incidence of intraoperative hypotension (RD, 0.01; 95% CI, −0.02 to 0.04; I 2 = 3%; P = 0.45). It is important to note that all studies reported that intraoperative bradycardia was either transient in nature or reversible, when needed, with the administration of intravenous atropine. Conclusions Dexmedetomidine has the ability to hasten the onset and prolong the duration of blockade when used as an adjuvant to local anesthesia for brachial plexus blockade. Considering an analgesic effect to be either decreased pain, a longer duration of analgesic block, or decreased opioid consumption, the addition of dexmedetomidine to local anesthetics for brachial plexus blockade was found to significantly improve analgesia in all 18 included studies. However, patients receiving dexmedetomidine should be continuously monitored for the potentially harmful but reversible adverse effect of intraoperative bradycardia. Level of Evidence Therapeutic, level I.

Bevel direction of epidural needles reliably predicts direction of catheter placement and contrast spread in human cadavers: results of a pilot study

STUDY OBJECTIVE To confirm the relationship between bevel orientation, catheter direction, and radiopaque contrast spread in the lumbar region. DESIGN Pilot cadaver study. SETTING Anatomy laboratory of a university hospital. MEASUREMENTS Cadavers were randomized to two groups of 4 cadavers each. In Group 1, needle bevel direction at epidural entry was cephalad; in Group 2, it was caudad. After placement of each epidural catheter in L4-L5 interspace, 2 mL of radiopaque contrast was injected and a lumbar posterior-anterior radiograph was obtained. Catheter direction and direction of radiopaque contrast spread were collected. MAIN RESULTS Due to the inability to access the epidural space secondary to surgical changes in the lumbar spine, one cadaver in the cephalad group was excluded. In 7 of 7 (100%) cadavers, the catheter tip direction according to the radiograph corresponded directly with bevel direction. CONCLUSIONS A strong relationship exists between bevel orientation and catheter direction; however, catheter position does not reliably predict the direction in which the injected fluid spreads in all cadavers.

Trigger Point Injections

Myofascial pain syndrome, which is caused by myofascial trigger points, is a very common muscular disorder. Myofascial trigger points (MTrPs) are defined as the most tender (hyperirritable) foci in a palpable taut band of skeletal muscle fiber that can elicit pain, referred pain, a local twitch response (LTR), motor dysfunction, as well as autonomic phenomena, among other symptoms. MTrPs can develop secondary to overextension of a muscle, acute trauma, or repetitive microtrauma. The pathophysiology of the development of MTrPs can be explained using the integrated hypothesis. This hypothesis has three essential features that include excessive acetylcholine release, sarcomere shortening, and the release of sensitizing substances. The most common way in which trigger points are localized is through a proper history and physical exam. Trigger point injections are specific techniques aimed at the alleviation of pain located within the MTrP. Whether an agent is injected into the MTrP or dry needling is performed, both techniques disrupt the trigger point by causing the relaxation and lengthening of the involved muscle fibers. Trigger point injections are generally very safe, but like all procedures, certain precautions must be taken into consideration.

The Anatomic Relationship of the Tibial Nerve to the Common Peroneal Nerve in the Popliteal Fossa: Implications for Selective Tibial Nerve Block in Total Knee Arthroplasty.

Background. A recently described selective tibial nerve block at the popliteal crease presents a viable alternative to sciatic nerve block for patients undergoing total knee arthroplasty. In this two-part investigation, we describe the effects of a tibial nerve block at the popliteal crease. Methods. In embalmed cadavers, after the ultrasound-guided dye injection the dissection revealed proximal spread of dye within the paraneural sheath. Consequentially, in the clinical study twenty patients scheduled for total knee arthroplasty received the ultrasound-guided selective tibial nerve block at the popliteal crease, which also resulted in proximal spread of local anesthetic. A sensorimotor exam was performed to monitor the effect on the peroneal nerve. Results. In the cadaver study, dye was observed to spread proximal in the paraneural sheath to reach the sciatic nerve. In the clinical observational study, local anesthetic was observed to spread a mean of 4.7 + 1.9 (SD) cm proximal to popliteal crease. A negative correlation was found between the excess spread of local anesthetic and bifurcation distance. Conclusions. There is significant proximal spread of local anesthetic following tibial nerve block at the popliteal crease with possibility of the undesirable motor blocks of the peroneal nerve.

Intravenous Conscious Sedation for Routine Fluoroscopically Guided Lumbar Interventions

A healthy 43-year-old man with no significant medical history has been seen in a pain management clinic for radicular symptoms into his right leg that started a month prior to presentation. Pain starts in the right lower back with radiation into the right lateral thigh and posterolateral calf. He does not report any weakness. The patient has tried taking oral anti-inflammatory drugs and has completed 10 sessions of physical therapy without significant relief. He is neurologically intact with full strength and reflexes, and examination reveals a positive straight leg raise on the right. Magnetic resonance imaging shows a right paracentral disk protrusion at the L3/L4 level that is compressing the traversing right L4 nerve root. At this time, a decision is made to offer the patient a transforaminal lumbar epidural steroid injection. On the day of the procedure, the patient’s preprocedural pain score is 4/10 at rest. He mentions in the preprocedure holding area that a friend underwent a similar injection with conscious sedation, and he requests the same. Drs Neel Mehta and Jennifer Zocca will argue that conscious sedation should be offered to this patient. Drs Naum Shaparin and Max Snyder will argue against the use of conscious sedation.