Sanjeet Narang

Urine toxicology screening among chronic pain patients on opioid therapy: frequency and predictability of abnormal findings.

ObjectiveTo examine the incidence of abnormal urine toxicology screening among chronic pain patients prescribed opioids for their pain and to relate these results to patient descriptors and type, number, and dose of prescribed opioids. MethodsA retrospective analysis of data from 470 patients who had urine screening at a pain management program in an urban teaching hospital was performed. Urine samples were analyzed using gas chromatography-mass spectrometry. Patients were categorized as having urine screens that were “normal” (expected findings based on their prescribed drugs) or abnormal. Abnormal findings were those of (1) absence of a prescribed opioid, (2) presence of an additional nonprescribed controlled substance, (3) detection of an illicit substance, and (4) an adulterated urine sample. ResultsForty-five percent of the patients were found to have abnormal urine screens. Twenty percent were categorized as having an illicit substance in their urine. Illicit substances and additional drugs were found more frequently in younger patients than in older patients (P<0.001). No other variables were found to predict abnormal urine screen results. DiscussionThese results confirm past findings that random urine toxicology screens among patients prescribed opioids for pain reveal a high incidence of abnormal findings. Common patient descriptors, and number, type, and dose of prescribed opioids were found to be poor predictors of abnormal results.

Topical amitriptyline in healthy volunteers

Background and Objectives The antidepressant amitriptyline is used as an adjuvant in the treatment of a variety of chronic pain conditions. This drug interacts with many receptors and ion channels, such as Na+ channels. In a randomized, double-blinded, and placebo-controlled trial, we investigated whether amitriptyline also is capable of providing cutaneous analgesia when applied topically in 14 healthy volunteers. Methods Amitriptyline hydrochloride was prepared as a 45% water/45% isopropanol/10% glycerin solution and titrated to pH 8.5 with sodium hydroxide. Four areas, 2 on each arm, of approximately 1 cm2 each were marked on the ventral aspect of the upper arm. A piece of gauze, placed on each of the marked areas and affixed to the arm with an occlusive plastic dressing, was saturated via syringe with placebo and amitriptyline solutions (10 mmol/L, 50 mmol/L, and 100 mmol/L). After 1 hour, the dressings and gauze were removed. A 16-G blunt needle was used to grade the pain at the marked area once per hour (1 = complete analgesia, 10 = normal pain sensation). Results The analgesic effects of 50 mmol/L and 100 mmol/L solutions of amitriptyline were significantly higher than those of the placebo or the 10 mmol/L solution. However, no significant difference was found between the analgesia provided by the placebo solution versus the 10 mmol/L solution or between the 50 mmol/L versus the 100 mmol/L solution. The only side effect observed was a concentration-dependent redness of the skin. Conclusions Topically applied amitriptyline is effective as an analgesic in humans. Different vehicles may improve its efficacy and decrease the skin redness observed.

Alteration in Pain Modulation in Women With Persistent Pain After Lumpectomy: Influence of Catastrophizing

CONTEXT Persistent pain is common after surgical treatment of breast cancer, but fairly little is known about the changes in sensory processing that accompany such pain syndromes. OBJECTIVES This study used quantitative sensory testing to compare psychophysical responses to standardized noxious stimulation in two groups of women who had previously undergone breast cancer surgery: women with (n=37) and without (n=34) persistent postoperative pain. METHODS Participants underwent a single testing session in which responses to a variety of noxious stimuli were assessed. RESULTS Findings suggested that women with chronic pain after breast cancer surgery display enhanced temporal summation of mechanical pain, deficits in endogenous pain inhibition, and more intense painful aftersensations compared with those without long-term pain. Some of these group differences were mediated by higher levels of pain catastrophizing in the group of women with persistent pain. CONCLUSION These findings suggest that persistent postoperative pain is associated with alterations in central nervous system pain-modulatory processes. Future treatment studies might benefit from targeting these pain-modulatory systems, and additional studies using functional neuroimaging methods might provide further valuable information about the pathophysiology of long-term postsurgical pain in women treated for breast cancer.

Assessment of differential blockade by amitriptyline and its N-methyl derivative in different species by different routes

Background Increasing the duration of local anesthesia and/or creating greater differential blockade (i.e., selective block of pain-transmitting nerve fibers) has been attempted by modifying currently available agents. Most drugs show a different profile depending on the model or species studied. This study was designed to investigate the differential nerve-blocking properties of amitriptyline and its quaternary ammonium derivative in rats and sheep. Methods The Na+ channel–blocking properties of N-methyl amitriptyline were determined with the patch clamp technique in cultured GH3 cells. Various functions (motor, nociception, proprioception–ataxia) were compared in rats (spinal and sciatic nerve blockade) and sheep (spinal blockade) with amitriptyline, N-methyl amitriptyline, lidocaine, and bupivacaine (partially from historical data). Results In vitro testing revealed N-methyl amitriptyline to be a potent Na+ channel blocker similar to amitriptyline but with a much longer duration of action. All drug concentrations tested in both the sciatic nerve model and the spinal block model produced no significant differential blockade in rats. Three of six rats in the 20-mm N-methyl amitriptyline group showed residual blockade 4 days after sciatic nerve injection. However, in the sheep spinal model, amitriptyline and in particular N-methyl amitriptyline displayed significant differential blockade at most time points. Sheep data for lidocaine and bupivacaine seemed to be more comparable to the clinical experience in humans than did rat data. Conclusions Amitriptyline and N-methyl amitriptyline are potent Na+ channel blockers and show greater differential blockade in sheep than in rats. This differential blockade in sheep is greater than that produced by lidocaine or bupivacaine.

ANESTHESIA FOR PATIENTS WITH A MEDIASTINAL MASS

Anesthesia for patients with mediastinal masses carries a significant risk for fatal or near-fatal cardiorespiratory events. Careful history taking and thorough preoperative investigation, including CT, identify most susceptible patients. Preoperative fiberoptic bronchoscopy performed by or involving the anesthesiologist is invaluable for determining the plan for intubation and ventilation. A coordinated approach involving anesthesiologists and surgeons is essential.

Local Anesthetic Blockade of Peripheral Nerves for Treatment of Neuralgias: Systematic Analysis

BACKGROUND: Nerve blocks with local anesthetics have been used in the diagnosis and treatment of neuralgias. Usually these blocks were administered in combination with corticosteroids and other drugs that can be effective by themselves. Although lasting benefits from nerve blocks in neuralgias have long been described, definitive evidence is lacking. We had the following objectives in this systematic review: to analyze the evidence behind the practice of peripheral nerve blockade with local anesthetics in patients with neuralgias and radicular pain syndromes; to assess the duration of pain relief after conduction block resolution; and to evaluate the effectiveness of the treatment of these syndromes with a series of blocks. METHODS: We searched Medline, Embase, narrative reviews, and book chapters. Only articles published in English were collected. The list of 3347 identified articles was reduced to 39 articles that were read entirely, 12 of which met inclusion criteria. RESULTS: Twelve included articles were analyzed. Each can be classified as a single case report or case series; there were no controlled studies among them. Nine reports assessed a single block outcome; all recorded pain relief beyond the duration of conduction blockade. Those 9 reports represented a total of 69 patients, 30 of whom had complete pain relief and 10 had relief ≥50%. Seven reports with the assessment of continuous pain ≥1 week after a single block reported complete or profound pain relief in 11 of 17 patients. All 3 reports with the assessment of a series of blocks in a large number of patients (total of 270) reported overall positive results. CONCLUSION: Because all reviewed articles were only single case reports or case series, no reliable conclusion could be drawn concerning the effectiveness of nerve blocks with local anesthetics in neuralgia. However, 2 features of the analyzed reports—the large magnitude of the effect and the high consistency of the reported outcome—indicate that future research efforts are warranted.

THE SUBJECTIVE PSYCHOACTIVE EFFECTS OF ORAL DRONABINOL STUDIED IN A RANDOMIZED, CONTROLLED CROSSOVER CLINICAL TRIAL FOR PAIN

Background:Many cannabinoid medications are approved in North America or in phase III trials, such as dronabinol, nabilone, or nabiximols. Little is known about their subjective psychoactive effects when used for pain management. We hypothesized that when used for pain, dronabinol has psychoactive effects in a dose-response relationship, whose peak effects are comparable with smoking marijuana. Methods:This was a randomized controlled trial of single dose placebo, 10 or 20 mg dronabinol in 30 chronic noncancer pain patients taking opioids and not using marijuana. Participants completed the Addiction Research Center Inventory (ARCI) hourly for 8 hours during 3 monitored sessions. Comparison sample was the ARCI ratings in participants with no pain (N=20), monitored every 30 minutes after smoking a 1.99% THC (low) and a 3.51% (high strength) marijuana cigarette. Results:The 10 and 20 mg dronabinol doses had significantly elevated scores over time on 4/5 subscales versus placebo (P<0.05). Average daily morphine use, total pain relief (TOTPAR), age, sex, and baseline pain level were not significant covariates. ARCI peak effects at 2 hours were similar to peak effects of smoked marijuana at 30 minutes (P=0.80, 10 mg=low strength, 20 mg=high strength). Conclusions:In pain patients, oral dronabinol has similar psychoactive effects to smoking marijuana. This risk must be considered in any decision to prescribe cannabinoid medications for pain.

Harlequin Syndrome Following Implantation of Intrathecal Pumps: A Case Series

Harlequin syndrome (HS) is a condition that has been associated with one‐sided sympathetic denervation of the face, characterized by contralateral hemifacial flushing and relative hyperhidrosis. Case series associate HS with conditions and procedures, including neuraxial anesthesia, that disrupt unilateral facial sympathetic innervation. However, to the best of our knowledge, this is the first series of HS following implantation of an intrathecal drug delivery system.

Fusiform aneurysms of the lenticulostriate artery

Lenticulostriate artery aneurysms are rare, can be difficult to diagnoze, and when they rupture they are often associated with deep intraparenchymal hemorrhages. In particular, fusiform, dissecting aneurysms of a distal lenticulostriate artery are extremely rare. Typically, they are usually associated with underlying systemic conditions such as systemic lupus erythematosus, moyamoya disease, and substance abuse. Given their usual small size and location, these aneurysms may be difficult to detect with angiography and can be challenging to treat with either endovascular or microsurgical techniques. We provide background information, review the existing treatment experiences reported in the literature, and present a discussion regarding the optimal management using an illustrative clinical vignette. Parent artery obliteration can be a safe and effective treatment in these rare aneurysms.

A report on the consequences of the first implanted device for long-term analgesia in refractory cancer pain.

BACKGROUND During the early 1970s, satisfactory long-term treatment of the severe pain associated with metastatic cancer was not available. Spinal cord stimulation introduced a few years earlier in 1967 had not proven to be effective in treating nociceptive pain. We describe our pioneering experience using an implanted device to infuse local anesthetics into the epidural space and provide pain relief to the patient. METHODS Increasing doses of systemic opioids were unsuccessful in treating the intractable pain of spinal metastases in our patient. We devised an analgesic delivery system by modifying equipment usually used for ventriculoperitoneal shunts. A lumbar epidural catheter was inserted in the patients spine, then tunneled subcutaneously across the flank to the anterior abdominal wall, and subsequently connected to a modified Ommaya reservoir with ventriculoperitoneal shunt tubing. This was filled with local anesthetic and injected into the patients epidural space by manual compression. RESULTS The system was used for several months with intermittent addition of local anesthetic to the reservoir with satisfactory control of the patients pain. CONCLUSIONS We describe the first use of an implanted epidural catheter system for long-term relief of pain due to terminal cancer that occurred at Peter Bent Brigham Hospital in Boston. We contend that this event played an important role in the cascade of devices that followed and connect it to the changes in the attitude of health care providers toward treatment of cancer pain.