Occipital Nerve Stimulation for Migraine: A Systematic Review

Patients who suffer from migraines often report impaired quality of life. Occipital nerve stimulation (ONS) is a novel treatment modality for migraines, although few systematic reviews have evaluated whether this therapy is efficacious. The objective of this study was to evaluate the clinical efficacy and safety of ONS for treating migraine through a literature review. We performed a literature search to identify studies that investigated ONS for migraine treatment. Evidence levels of these studies were assessed by recommendations set by the University of Oxford Centre for Evidence‐Based Medicine. Five randomized controlled trials, 4 retrospective studies, and one prospective study met the inclusion criteria. Results from the retrospective studies and case series indicated that ONS significantly reduced the pain intensity and the number of days with headache in patients with migraine. However, the evidence of ONS efficacy established by randomized controlled trials was limited. Improvement in the migraine disability assessment (MIDAS) score was more dramatic than improvement in the SF‐36 score at follow‐up. The mean complication incidence of ONS was 66% for the reviewed studies. Future clinical studies should optimize and standardize the ONS intervention process and identify the relationship among the surgical process, efficacy, and complications resulting from the procedure.     

Percutaneous Peripheral Nerve Stimulation for the Treatment of Chronic Low Back Pain: Two Clinical Case Reports of Sustained Pain Relief

As the leading cause of disability among U.S. adults, chronic low back pain (LBP) is one of the most prevalent and challenging musculoskeletal conditions. Neuromodulation provides an opportunity to reduce or eliminate the use of opioids to treat chronic LBP, but the cost and invasiveness of existing methods have limited its broad adoption, especially earlier in the treatment continuum. The present case report details the results of a novel method of short‐term percutaneous peripheral nerve stimulation (PNS) in 2 subjects with chronic LBP. At the end of the 1‐month therapy, stimulation was discontinued and the leads were withdrawn. PNS produced clinically significant improvements in pain (62% average reduction in Brief Pain Inventory Question #5, average pain), and functional outcomes (73% reduction in disability, Oswestry Disability Index; 83% reduction in pain interference, Brief Pain Inventory). Both subjects reduced nonopioid analgesic use by 83%, on average, and the one subject taking opioids ceased using all opioids. The only adverse event was minor skin irritation caused by a topical dressing. The clinically significant improvements were sustained at least 4 months after start of therapy (79% average reduction in pain; both reported minimal disability; 100% reduction in opioids; 74% reduction nonopioids). The results reveal the utility of this novel, short‐term approach and its potential as a minimally invasive neuromodulation therapy for use earlier in the treatment continuum to produce sustained pain relief and reduce or eliminate the need for analgesic medications, including opioids, as well as more expensive and invasive surgical or therapeutic alternatives.     

Peripheral Nerve Stimulation for the Treatment of Postamputation Pain—A Case Report

Many amputees suffer from postamputation pain, which can be extremely debilitating, decrease quality of life, increase the risk of depression, and negatively affect interpersonal relationships and the ability to work. Present methods of treatment, including medications, are often unsatisfactory in reducing postamputation pain. Electrical stimulation of the nerve innervating the painful area could reduce the pain, but peripheral nerve stimulation is rarely used to treat postamputation pain because present methods require invasive surgical access and precise placement of the leads in close proximity (≤ 2 mm) with the nerve. The present study investigated a novel approach to peripheral nerve stimulation in which a lead was placed percutaneously a remote distance (> 1 cm) away from the femoral nerve in a patient with severe residual limb pain (RLP) 33 years following a below‐knee amputation. Electrical stimulation generated ≥ 75% paresthesia coverage, reduced RLP by > 60%, and improved quality of life outcomes as measured by the pain interference scale of the Brief Pain Inventory‐Short Form (100% reduction in pain interference), Pain Disability Index (74% reduction in disability), and the Patient Global Impression of Change (very much improved) during a 2‐week home trial. There were no adverse events. The ability to generate significant paresthesia coverage and pain relief with a single lead inserted percutaneously and remotely from the target nerve holds promise for providing relief of postamputation pain.     

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.     

Transcutaneous Electrical Nerve Stimulation for Phantom Pain and Stump Pain in Adult Amputees

Abstract Following amputation, 50% to 90% of individuals experience phantom and/or stump pain. Transcutaneous electrical nerve stimulation (TENS) may prove to be a useful adjunct analgesic intervention, although a recent systematic review was unable to judge effectiveness owing to lack of quality evidence. The aim of this pilot study was to gather data on the effect of TENS on phantom pain and stump pain at rest and on movement. Ten individuals with a transtibial amputation and persistent moderate‐to‐severe phantom and/or stump pain were recruited. Inclusion criteria was a baseline pain score of ≥3 using 0 to 10 numerical rating scale (NRS). TENS was applied for 60 minutes to generate a strong but comfortable TENS sensation at the site of stump pain or projected into the site of phantom pain. Outcomes at rest and on movement before and during TENS at 30 minutes and 60 minutes were changes in the intensities of pain, nonpainful phantom sensation, and prosthesis embodiment. Mean (SD) pain intensity scores were reduced by 1.8 (1.6) at rest (P < 0.05) and 3.9 (1.9) on movement (P < 0.05) after 60 minutes of TENS. For five participants, it was possible to project TENS sensation into the phantom limb by placing the electrodes over transected afferent nerves. Nonpainful phantom sensations and prosthesis embodiment remained unchanged. This study has demonstrated that TENS has potential for reducing phantom pain and stump pain at rest and on movement. Projecting TENS sensation into the phantom limb might facilitate perceptual embodiment of prosthetic limbs. The findings support the delivery of a feasibility trial.     

Vagus Nerve and Vagus Nerve Stimulation,a Comprehensive Review: Part II

The development of vagus nerve stimulation (VNS) began in the 19th century. Although it did not work well initially, it introduced the idea that led to many VNS‐related animal studies for seizure control. In the 1990s, with the success of several early clinical trials, VNS was approved for the treatment of refractory epilepsy, and later for the refractory depression. To date, several novel electrical stimulating devices are being developed. New invasive devices are designed to automate the seizure control and for use in heart failure. Non‐invasive transcutaneous devices, which stimulate auricular VN or carotid VN, are also undergoing clinical trials for treatment of epilepsy, pain, headache, and others. Noninvasive VNS (nVNS) exhibits greater safety profiles and seems similarly effective to their invasive counterpart. In this review, we discuss the history and development of VNS, as well as recent progress in invasive and nVNS.     

Vagus Nerve and Vagus Nerve Stimulation,a Comprehensive Review: Part III

Vagus nerve stimulation (VNS) is currently undergoing multiple trials to explore its potential for various clinical disorders. To date, VNS has been approved for the treatment of refractory epilepsy and depression. It exerts antiepileptic or antiepileptogenic effect possibly through neuromodulation of certain monoamine pathways. Beyond epilepsy, VNS is also under investigation for the treatment of inflammation, asthma, and pain. VNS influences the production of inflammatory cytokines to dampen the inflammatory response. It triggers the systemic release of catecholamines that alleviates the asthma attack. VNS induces antinociception by modulating multiple pain‐associated structures in the brain and spinal cord affecting peripheral/central nociception, opioid response, inflammation process, autonomic activity, and pain‐related behavior. Progression in VNS clinical efficacy over time suggests an underlying disease‐modifying neuromodulation, which is an emerging field in neurology. With multiple potential clinical applications, further development of VNS is encouraging.     

Vagus Nerve and Vagus Nerve Stimulation,a Comprehensive Review: Part I

The vagus nerve (VN), the “great wondering protector” of the body, comprises an intricate neuro‐endocrine‐immune network that maintains homeostasis. With reciprocal neural connections to multiple brain regions, the VN serves as a control center that integrates interoceptive information and responds with appropriate adaptive modulatory feedbacks. While most VN fibers are unmyelinated C‐fibers from the visceral organs, myelinated A‐ and B‐fiber play an important role in somatic sensory, motor, and parasympathetic innervation. VN fibers are primarily cholinergic but other noncholinergic nonadrenergic neurotransmitters are also involved. VN has four vagal nuclei that provide critical controls to the cardiovascular, respiratory, and alimentary systems. Latest studies revealed that VN is also involved in inflammation, mood, and pain regulation, all of which can be potentially modulated by vagus nerve stimulation (VNS). With a broad vagal neural network, VNS may exert a neuromodulatory effect to activate certain innate “protective” pathways for restoring health.     

Large and Small Fiber Dysfunction in Peripheral Nerve Injuries With or Without Spontaneous Pain

Few data have been available on the functional role of small fiber damage in patients with peripheral nerve injuries with and without spontaneous pain. The aim of the present study was to investigate the function of large myelinated nerve fibers as well as small nerve fibers in a material of 60 patients with peripheral nerve injuries in upper or lower extremities, 30 patients with spontaneous pain, and 30 patients without pain. Patients were questioned about the characteristics of pain and investigated clinically with EMG/neurography and assessment of thermal thresholds in the innervation territory of the lesioned nerve as well as in the contralateral area. Sensation of touch and warmth and cold detection was significantly reduced in the injured side in both groups. There was a tendency, not significant, for heat pain thresholds to be more elevated in the affected side compared with the healthy side in the pain group only (47.8°C versus 45.1°C). There were no significant differences in thermal thresholds between the 2 groups of patients. The main finding was a high percentage of hyperphenomena (allodynia to light touch and reduced mechanical pain thresholds) in the pain group only.