Computational modeling of dorsal root ganglion stimulation using an Injectrode.

Minimally invasive neuromodulation therapies like the Injectrode, which is composed of a tightly wound polymer-coated Platinum/Iridium microcoil, offer a low-risk approach for administering electrical stimulation to the dorsal root ganglion (DRG). This flexible electrode is aimed to conform to the DRG. The stimulation occurs through a transcutaneous electrical stimulation (TES) patch, which subsequently transmits the stimulation to the Injectrode via a subcutaneous metal collector.

Multiformity of extracellular microelectrode recordings from Aδ neurons in the dorsal root ganglia: a computational modeling study.

Microelectrodes serve as a fundamental tool in electrophysiology research throughout the nervous system, providing a means of exploring neural function with a high resolution of neural firing information. We constructed a hybrid computational model using the finite element method and multicompartment cable models to explore factors that contribute to extracellular voltage waveforms that are produced by sensory pseudounipolar neurons, specifically smaller A-type neurons, and that are recorded by microelectrodes in dorsal root ganglia. The finite element method model included a dorsal root ganglion, surrounding tissues, and a planar microelectrode array.

An automaton for preclinical pain testing.

In this issue of Cell Reports Methods, Dedek et al. present RAMalgo-an AI-powered, automated platform for quantifying nociceptive behaviors in mice. With integrated video tracking and mechanical, thermal, and optogenetic stimulation, RAMalgo has the potential to increase standardization and throughput of pain behavior measurement in rodents.

Computational modeling of dorsal root ganglion stimulation using an Injectrode.

Objective: Minimally invasive neuromodulation therapies like the Injectrode, which is composed of a tightly wound polymer-coated platinum/iridium microcoil, offer a low-risk approach for administering electrical stimulation to the dorsal root ganglion (DRG). This flexible electrode is aimed to conform to the DRG. The stimulation occurs through a transcutaneous electrical stimulation (TES) patch, which subsequently transmits the stimulation to the Injectrode via a subcutaneous metal collector.

The role of endogenous opioid neuropeptides in neurostimulation-driven analgesia.

Due to the prevalence of chronic pain worldwide, there is an urgent need to improve pain management strategies. While opioid drugs have long been used to treat chronic pain, their use is severely limited by adverse effects and abuse liability. Neurostimulation techniques have emerged as a promising option for chronic pain that is refractory to other treatments.

Dorsal root ganglion stimulation produces differential effects on action potential propagation across a population of biophysically distinct C-neurons.

Dorsal root ganglion stimulation (DRGS) is a neurostimulation therapy used to manage chronic pain that does not respond to conventional therapies. Unfortunately, not all patients receive sufficient pain relief from DRGS, leaving them with few other treatment options. Presently, our understanding of the mechanisms of action of DRGS is incomplete, preventing us from determining why some patients do not receive analgesia from the therapy.

Molecular Determinants of Mechanical Itch Sensitization in Chronic Itch.

Chronic itch is associated with sensitization of the somatosensory nervous system. Recent studies have identified the neural circuits transmitting acute itch; however, the mechanisms by which itch transforms into a pathological state remain largely unknown. We have previously shown that Aβ low-threshold mechanoreceptors, together with spinal urocortin 3-positive (Ucn3) excitatory interneurons and neuropeptide Y-positive (NPY) inhibitory interneurons, form a microcircuit that transmits and gates acute mechanical itch.

Augmented Transcutaneous Stimulation Using an Injectable Electrode: A Computational Study.

Minimally invasive neuromodulation technologies seek to marry the neural selectivity of implantable devices with the low-cost and non-invasive nature of transcutaneous electrical stimulation (TES). The Injectrode is a needle-delivered electrode that is injected onto neural structures under image guidance. Power is then transcutaneously delivered to the Injectrode using surface electrodes.

The effect of axon trajectory on retinal ganglion cell activation with epiretinal stimulation.

For epiretinal prostheses, disc electrodes stimulate retinal ganglion cells (RGCs) with electric current to create visual percepts. Prior studies have determined that the sodium channel band (SOCB), located on the RGC axon (30-50 μm from the soma) is the most sensitive site to extracellular stimulation because of its high sodium channel density. Biophysical cable models used to study RGC activation often rely on simplified axon trajectories, disregarding the non-uniform paths that axons follow to the optic disc.

Dorsal Root Ganglion Stimulation for Chronic Pain: Hypothesized Mechanisms of Action.

Dorsal root ganglion stimulation (DRGS) is a neuromodulation therapy for chronic pain that is refractory to conventional medical management. Currently, the mechanisms of action of DRGS-induced pain relief are unknown, precluding both our understanding of why DRGS fails to provide pain relief to some patients and the design of neurostimulation technologies that directly target these mechanisms to maximize pain relief in all patients. Due to the heterogeneity of sensory neurons in the dorsal root ganglion (DRG), the analgesic mechanisms could be attributed to the modulation of one or many cell types within the DRG and the numerous brain regions that process sensory information.

The Effect of Clinically Controllable Factors on Neural Activation During Dorsal Root Ganglion Stimulation.

Objective: Dorsal root ganglion stimulation (DRGS) is an effective therapy for chronic pain, though its mechanisms of action are unknown. Currently, we do not understand how clinically controllable parameters (e.g.

A Patient-Specific Computational Framework for the Argus II Implant.

Goal: Retinal prosthesis performance is limited by the variability of elicited phosphenes. The stimulating electrode's position with respect to retinal ganglion cells (RGCs) affects both perceptual threshold and phosphene shape. We created a modeling framework incorporating patient-specific anatomy and electrode location to investigate RGC activation and predict inter-electrode differences for one Argus II user.

Spatial models of cell distribution in human lumbar dorsal root ganglia.

Dorsal root ganglia (DRG), which contain the somata of primary sensory neurons, have increasingly been considered as novel targets for clinical neural interfaces, both for neuroprosthetic and pain applications. Effective use of either neural recording or stimulation technologies requires an appropriate spatial position relative to the target neural element, whether axon or cell body. However, the internal three-dimensional spatial organization of human DRG neural fibers and somata has not been quantitatively described.

Evoked Potentials Recorded From the Spinal Cord During Neurostimulation for Pain: A Computational Modeling Study.

Objectives: Spinal cord stimulation (SCS) for pain is typically implemented in an open-loop manner using parameters that remain largely unchanged. To improve the overall efficacy and consistency of SCS, one closed-loop approach proposes to use evoked compound action potentials (ECAPs) recorded from the SCS lead(s) as a feedback control signal to guide parameter selection. The goal of this study was to use a computational modeling approach to investigate the source of these ECAP recordings and technical and physiological factors that affect their composition.

Dorsal root ganglion stimulation for chronic pain modulates Aβ-fiber activity but not C-fiber activity: A computational modeling study.

Objective: The goal of this project was to use computational models to investigate which types of primary sensory neurons are modulated by dorsal root ganglion stimulation (DRGS) to provide pain relief.

Methods: We modeled DRGS by coupling an anatomical finite element model of a human L5 dorsal root ganglion to biophysical models of primary sensory neurons. We calculated the stimulation amplitude needed to elicit an action potential in each neuron, and examined how DRGS affected sensory neuron activity.

Editorial Commentary: When the Shoulder Joint Has Lost Stoichiometry-Does Arthroscopic-Assisted Latissimus Dorsi Transfer Stack Up?

Non-arthroplasty treatment options for pseudoparalysis of the shoulder are preferable in the younger patient population. Although there are differing philosophies among shoulder surgeons, many prefer to avoid reversed total shoulder arthroplasty for patients under age 60 years. Arthroscopically assisted latissimus dorsi transfer may be a good alternative for these patients, but how the results compare with arthroscopic superior capsular reconstruction is the question.

Synaptic depression depends on charge delivered to network.

In vitro neuronal networks cultured on microelectrode arrays enable the study of network electrophysiology on a fundamental level. Neuronal response to electrical stimulation is an area of interest at the laboratory bench and in the clinic, given its wide application for remedying neurological disorders. Here we investigated the change in cortical network response over time to varied amounts of charge used for stimulation, which may lead to a phenomenon known as selective adaptation.

Ultrasound characterization of interface oscillation as a proxy for ventriculoperitoneal shunt function.

Hydrocephalus, where cerebrospinal fluid (CSF) production rate is greater than reabsorption rate, leads to impaired neurological function if left untreated. Ventriculoperitoneal shunts (VPS) are implanted in the brain ventricles to route CSF. VPS systems have a high failure rate, and failure symptoms resemble symptoms of common maladies.

The superior-medial shoulder arthroscopy portal is safe.

Purpose: The superior-medial (SM) shoulder arthroscopic portal (Neviaser portal) is the portal anatomically closest to the suprascapular nerve, and any potential benefits of this portal would be mitigated if risk of suprascapular nerve injury were significant. The purpose of this study is to determine the safety of the SM arthroscopic shoulder portal. We hypothesize that the SM shoulder arthroscopic portal is safe.

Arthroscopic rotator cuff repair: the learning curve.

Purpose: The purpose of this study was to answer the question: How many cases are required for a surgeon to become proficient in performing arthroscopic rotator cuff repair? We hypothesize that as surgical experienced is gained, learning can be quantitatively shown by a significant decrease in operative time.

Type Of Study: Prospective case series.

Methods: Rotator cuff repair time (RCRT) in minutes (as well as other time components comprising total surgical time) was recorded for 100 consecutive patients having arthroscopic rotator cuff repair performed by a single surgeon beginning with his first case in private practice.

An anatomic study of the effects on the suprascapular nerve due to retraction of the supraspinatus muscle after a rotator cuff tear.

The purpose of this anatomic study was to assess the risk to the suprascapular nerve by measuring the tension on the nerve and the angle between the nerve and its motor branch at the scapular notch with medial supraspinatus tendon retraction. Twelve shoulders in six cadavers were dissected to evaluate the branching point of the first motor branch of the suprascapular nerve, the change in angle between the nerve and its first motor branch at the scapular notch with retraction of the supraspinatus tendon, and the resulting tension on the nerve. The first motor branch originated at the notch in 9 cadavers, just proximal in 1, and just distal in 2.