{'fraction_non_alphanumeric': 0.031096059113300493, 'fraction_numerical': 0.012007389162561576, 'mean_word_length': 5.383104125736739, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Emerging concepts in the closed-loop spinal cord stimulation system: preliminary results of the Avalon study.

Ann Palliat Med 2020;9(3):1272-1274 | http://dx.doi.org/10.21037/apm-20-642 Invasive nonsurgical techniques have a central role in the management of patients suffering from acute and chronic pain. Common percutaneous pain procedures include trigger point injections, intra-articular injections, spinal injections, nerve blocks, radiofrequency lesioning, epidural adhesiolysis, intradiscal procedures, and minimally invasive surgical spine procedures (1). Historically, neuromodulation and continuous intrathecal analgesia were offered when conventional therapies fail (2,3). Neurost imulators de l iver e lectr ica l energy to neuronal and glial structures. The goal is to improve pain and function. The administration of low-intensity electrical currents avoids pharmacological side effects. Neurostimulation has been used for a variety of chronic pain indications including failed back surgery syndrome, complex regional pain syndrome, diabetic neuropathy, intractable angina pectoris, and chronic migraine (2,3). In the United States, the most common clinical role of spinal cord stimulation is for failed back surgery syndrome. In most European countries, the most common role of spinal cord stimulation is for peripheral ischemia. Technological advances have been seen in recent years in neurostimulation. These build on the science of interrupting pain impulses mediated by C fibers and A-delta fibers, stimulating larger A-beta fibers, and activating glial tissue. These upgrades have improved a number of important aspects with regard to patient satisfaction. Russo et al., published the preliminary six-month results of a prospective trial of a novel spinal cord spinal stimulation system (1). This study antecedes a more recent study of the same group of patients at the twelve-month mark (4). The study is sponsored by the manufacturer, Saluda Medical and many of the authors disclose their relationships to this manufacturer. These clinical studies follow earlier proof of concept studies in animal and human volunteers (5,6). Although the exact mechanism of action of pain relief with spinal cord stimulation systems is not fully elucidated, neurophysiology suggests that delivered current can activate sensory fibers in the spinal cord (6). If this current crosses a threshold, a single fiber action potential is created, best measured in the dorsal columns (5). The sum of these single fiber action potentials is known as an evoked compound action potential. The evoked compound action potential has several measurable parameters, of which the amplitude is the most important clinically. As the current increases, more single fibers are recruited and the evoked compound action potential amplitude increases. The evoked compound action potential and single fiber action potentials are thought to emanate from a few low threshold A-beta fibers in the dorsal columns, whereas unpleasant sensations occur with recruitment of the higher threshold A-beta fibers and A-delta fibers (5,6). Conversely, a drop-in fiber recruitment leads to loss of effect. In traditional tonic spinal cord systems, the patient Editorial Commentary