Mechanism of Action of Peripheral Nerve Stimulation for Chronic Pain: A Narrative Review.

The use of stimulation of peripheral nerves to test or treat various medical disorders has been prevalent for a long time. Over the last few years, there has been growing evidence for the use of peripheral nerve stimulation (PNS) for treating a myriad of chronic pain conditions such as limb mononeuropathies, nerve entrapments, peripheral nerve injuries, phantom limb pain, complex regional pain syndrome, back pain, and even fibromyalgia. The ease of placement of a minimally invasive electrode via percutaneous approach in the close vicinity of the nerve and the ability to target various nerves have led to its widespread use and compliance. While most of the mechanism behind its role in neuromodulation is largely unknown, the gate control theory proposed by Melzack and Wall in the 1960s has been the mainstay for understanding its mechanism of action. In this review article, the authors performed a literature review to discuss the mechanism of action of PNS and discuss its safety and usefulness in treating chronic pain. The authors also discuss current PNS devices available in the market today.

Consensus practice guidelines on interventions for lumbar facet joint pain from a multispecialty, international working group.

BACKGROUND: The past two decades have witnessed a surge in the use of lumbar facet blocks and radiofrequency ablation (RFA) to treat low back pain (LBP), yet nearly all aspects of the procedures remain controversial. METHODS: After approval by the Board of Directors of the American Society of Regional Anesthesia and Pain Medicine, letters were sent to a dozen pain societies, as well as representatives from the US Departments of Veterans Affairs and Defense. A steering committee was convened to select preliminary questions, which were revised by the full committee. Questions were assigned to 4-5 person modules, who worked with the Subcommittee Lead and Committee Chair on preliminary versions, which were sent to the full committee. We used a modified Delphi method, whereby the questions were sent to the committee en bloc and comments were returned in a non-blinded fashion to the Chair, who incorporated the comments and sent out revised versions until consensus was reached. RESULTS: 17 questions were selected for guideline development, with 100% consensus achieved by committee members on all topics. All societies except for one approved every recommendation, with one society dissenting on two questions (number of blocks and cut-off for a positive block before RFA), but approving the document. Specific questions that were addressed included the value of history and physical examination in selecting patients for blocks, the value of imaging in patient selection, whether conservative treatment should be used before injections, whether imaging is necessary for block performance, the diagnostic and prognostic value of medial branch blocks (MBB) and intra-articular (IA) injections, the effects of sedation and injectate volume on validity, whether facet blocks have therapeutic value, what the ideal cut-off value is for a prognostic block, how many blocks should be performed before RFA, how electrodes should be oriented, the evidence for larger lesions, whether stimulation should be used before RFA, ways to mitigate complications, if different standards should be applied to clinical practice and clinical trials and the evidence for repeating RFA (see table 12 for summary). CONCLUSIONS: Lumbar medial branch RFA may provide benefit to well-selected individuals, with MBB being more predictive than IA injections. More stringent selection criteria are likely to improve denervation outcomes, but at the expense of more false-negatives. Clinical trials should be tailored based on objectives, and selection criteria for some may be more stringent than what is ideal in clinical practice.

Erenumab: A novel calcitonin gene-related peptide receptor antagonist developed specifically for migraine prevention.

Headaches and migraines continue to be a leading cause of suffering and disability. As per the Global Burden of Disease Survey conducted in 2010, the exact magnitude of the disease still is underestimated. Migraine alone continues to rank seventh as a cause of disability. Various therapeutic modalities exist and newer classes of medications are currently being trialed to provide effective treatment to this population of patients. Erenumab, a calcitonin gene-related peptide receptor inhibitor, is a recent addition to this armamentarium and has been approved by the FDA for use in 2018. It has shown modestly improved outcomes according to the current trials. However, long-term outcomes and adverse effects still are under research. The following article elaborates on the current literature and evidence on this novel drug.

Value of Targeted Epidural Blood Patch and Management of Subdural Hematoma in Spontaneous Intracranial Hypotension: Case Report and Review of the Literature.

BACKGROUND: Spontaneous intracranial hypotension (SIH) is a more common than previously noted condition (1-2.5 per 50,000 persons) typically caused by cerebrospinal fluid (CSF) leakage. Initial treatment involves conservative therapies, but the mainstay of treatment for patients who fail conservative management is the epidural blood patch (EBP). Subdural hematoma (SDH) is a common complication occurring with SIH, but its management remains controversial. METHODS: In this report, we discuss a 62-year-old woman who presented with a 5-week history of orthostatic headaches associated with nausea, emesis, and neck pain. Despite initial imaging being negative, the patient later developed classic imaging evidence characteristic of SIH. Magnetic resonance imaging was unrevealing for the source of the CSF leak. Radionuclide cisternography showed possible CSF leak at the right-sided C7-T1 nerve root exit site. After failing a blind lumbar EBP, subsequent targeted EBP at C7-T1 improved the patient's symptoms. Two days later she developed a new headache with imaging evidence of worsening SDH with midline shift requiring burr hole drainage. This yielded sustained symptomatic relief and resolution of previously abnormal imaging findings at 2-month follow-up. RESULTS: A literature review revealed 174 cases of SIH complicated by SDH. This revealed conflicting opinions concerning the management of this condition. CONCLUSIONS: Although blind lumbar EBP is often successful, targeted EBP has a lower rate of patients requiring a second EBP or other further treatment. On the other hand, targeted EBP has a larger risk profile. Depending on the clinic situation, treatment of the SDH via surgical evacuation may be necessary.

Use of oral tramadol to prevent perianesthetic shivering in patients undergoing transurethral resection of prostate under subarachnoid blockade.

CONTEXT: Under regional anesthesia, geriatric patients are prone to shivering induced perioperative complications that Anesthesiologists should prevent rather than treat. AIM: We investigated the prophylactic efficacy of oral tramadol 50 mg to prevent the perioperative shivering after transurethral resection of prostate (TURP) surgery under subarachnoid blockade (SAB). Shivering is usually overlooked in patients undergoing urological surgery under spinal anesthesia and may result in morbidity, prolonged hospital stay and increased financial burden. Use of prophylactic measures to reduce shivering in geriatric patients who undergo urological procedures could circumvent this. Oral formulation of tramadol is a universally available cost-effective drug with the minimal side-effects. SETTINGS AND DESIGN: Prospective, randomized, double-blinded, placebo-controlled study. PATIENTS AND METHODS: A total of 80 patients who were scheduled for TURP surgery under subarachnoid block were randomly selected. Group I and II (n = 40 each) received oral tramadol 50 mg and placebo tablet respectively. After achieving subarachnoid block, the shivering, body temperature (tympanic membrane, axillary and forehead), hemodynamic parameters and arterial saturation were recorded at regular intervals. STATISTICAL ANALYSIS USED: T-test, analysis of variance test, Z-test and Fisher exact test were utilized while Statistical Product and Service Solutions, IBM, Chicago (SPSS statistics (version 16.0)), software was used for analysis. RESULTS: Incidence of shivering was significantly less in patients who received tramadol (7.5% vs. 40%; P < 0.01). The use of tramadol was associated with clinically inconsequential side-effects. CONCLUSION: We conclude that the use of oral tramadol 50 mg is effective as a prophylactic agent to reduce the incidence, severity and duration of perioperative shivering in patients undergoing TURP surgery under SAB.

Anesthetic considerations in pemphigus vulgaris: Case series and review of literature.

A case series of the anesthetic management of 4 patients with pemphigus vulgaris (PV) undergoing emergency/elective surgery is presented. PV presents serious concerns for anesthesiologist, when present, in a surgical patient but handling of these patients with care and taking all the due precautions can decrease morbidity and airway-related complications. Various clinical presentations and precautions, which should be ensured during anesthesia in patients suffering from PV, are discussed.

Does our sleep debt affect patients' safety?

The provision of anaesthesia requires a high level of knowledge, sound judgement, fast and accurate responses to clinical situations, and the capacity for extended periods of vigilance. With changing expectations and arising medico-legal issues, anaesthesiologists are working round the clock to provide efficient and timely health care services, but little is thought whether the "sleep provider" is having adequate sleep. Decreased performance of motor and cognitive functions in a fatigued anaesthesiologist may result in impaired judgement, late and inadequate responses to clinical changes, poor communication and inadequate record keeping, all of which affect the patient safety, showing without doubt the association of sleep debt to the adverse events and critical incidents. Perhaps it is time that these issues be promptly addressed to prevent the silent perpetuation of a problem that is pertinent to our health and our profession. We endeavour to focus on the evidence that links patient safety to fatigue and sleepiness of health care workers and specifically on anaesthesiologists. The implications of sleep debt are deep on patient safety and strategies to prevent this are the need of the hour.

Accidental carbon monoxide poisoning in our homes.

Carbon monoxide (CO) is a colorless, odorless, tasteless, nonirritating, but significantly toxic gas. It is a product of combustion of organic matter in presence of insufficient oxygen supply. Symptoms of mild poisoning include headaches, vertigo and flu like effects, whereas larger exposures can lead to significant toxicity of the central nervous system (CNS), heart, and even death. We are reporting two cases that presented to us in the winter months of December to January with history, sign, symptoms, and radiological evidence of suspected CO poisoning.

Anaesthetic consideration in macroglossia due to lymphangioma of tongue: a case report.

SUMMARY: Successful airway management of an infant or child with macroglossia prerequisites recognition of a potential airway problem. We describe our experience with a debilitated 13-year-old girl who presented with severe macroglossia, secondary to lymphangioma of the tongue. Along with the social discomfort she had inability to speak, eat or drink properly and exposure-induced dryness. Such patients are a challenge for the anaesthesiologists due to the anticipated difficult intubation associated with the oral mucosa occupying lesion. It also becomes pertinent to rule out any of the associated congenital anomalies. The importance of a thorough preoperative evaluation and attention to difficult intubation and maintenance of airway is emphasized. We endeavor to review the available literature regarding patient's perioperative management of such patients.