Mixed Nerve Research Articles

Variability and clinical anatomy of the superior gluteal nerve-A systematic review and meta-analysis.

The superior gluteal nerve (SGN) is a mixed nerve of the sacral plexus that arises from the posterior divisions of the L4, L5, and S1 nerve roots. Its motor branch plays a crucial role in innervation of hip muscles, which allows for physiological gait or walk-pattern. As for its sensory branch, it provides innervation for the hip joint capsule, especially its superior part. The understanding of this nerve is crucial as it may be injured during many operations involving mostly pelvic surgery, both arthroscopic and open procedures. The risk of injury is especially high during total hip arthroplasty (THA). These lesions often result in the presentation of major walk-pattern abnormalities. The most classical and commonly known would be the Trendelenburg sign, which presents with pelvic instability characterized by having the patient standing on one leg whereby the pelvis on the contralateral side will be dropping, resulting in a positive sign. The aim of this meta-analysis was to obtain all relevant data on SGN and its variations, in order to emphasize its anatomical, physiological, as well as clinical implications. A large-scale search was conducted in all major databases (PubMed, Embase, Science Direct, Google Scholar, and Web of Science) in order to determine and pool all available and relevant SGN data. No restrictions were applied to date or language. The data collection was categorized by prevalence, branching, patterns, course, origin, and distance from anatomical landmarks. A total of 41 studies (n = 869 hemipelves) were included in our analysis. The most common branching pattern of SGN was a spray pattern, 70.4% (95% CI: 54.4-96.8; p < 0.001) of the general population. We found that the closest branch to the greater trochanter of the femur and concurrently the most at risk during surgery was a muscular branch to gluteus minimus muscle. As the trend of pelvic surgeries, especially THA continues to rise, SGN lesions are now more than ever at risk. Yet to the authors' knowledge, this does not seem to be reflected in the current literature thereby making this the first meta-analysis concerning this important anatomical structure. The authors believe it is paramount for surgeons, especially in the orthopedic specialty, to thoroughly understand the SGN with its anatomical variability and clinical tie-ins.

Preferential motor reinnervation is modulated by both repair site and distal nerve environments

To restore function after nerve injury, axons must regenerate from the injury site to the periphery, then reinnervate appropriate end organs when they arrive. Only 10 % of adults who suffer nerve injury will regain normal function, often because axons regenerate to functionally inappropriate targets (Brushart, 2011). The peripheral destination of these axons is largely determined by the pathways they enter at the site of nerve repair. To improve clinical outcomes, it is thus critical to improve the accuracy of axon pathfinding. In rodents, motor axons regenerating in mixed nerve preferentially reinnervate pathways leading to muscle, a process termed preferential motor reinnervation (PMR). Previous experiments have shown that PMR can be enhanced by predegenerating nerve grafts to enhance growth factor production and remove inhibitory factors (Abdullah et al., 2013). The current experiments explore the relative contributions of motor pathways, sensory pathways, and the repair environment to this enhancement. Sensory and/or motor pathways within rat femoral nerve grafts were predegenerated for 3 weeks to optimize growth factor production (Brushart et al., 2013) or for 12 weeks to deplete it. Optimizing the environment within previously motor Schwann cell tubes promoted PMR, regardless of whether adjacent sensory pathways were optimized or chronically denervated. However, this positive effect was abolished when sensory pathways were undergoing acute Wallerian degeneration immediately after nerve repair. The repair environment thus precluded motor axon pathfinding in spite of an optimized distal motor pathway. When sensory pathways were optimized and motor pathways were chronically denervated, not only was PMR abolished, but motoneurons failed to respond to the greater volume of growth factors in the sensory nerve. Small sensory neurons, however, selectively reinnervated cutaneous nerve under these conditions. These experiments thus strengthen the concept that, in adult rats, sensory and motor pathways have unique identities capable of influencing both sensory and motor axon regeneration. Furthermore, they demonstrate that, in the rat, delaying nerve repair for 3 weeks to enhance growth factor production and clear the products of acute Wallerian degeneration can enhance regeneration specificity without the need for exogenous treatments.

Game-Based Assessment of Peripheral Neuropathy Combining Sensor-Equipped Insoles, Video Games, and AI: Proof-of-Concept Study.

Detecting peripheral neuropathy (PNP) is crucial in preventing complications such as foot ulceration. Clinical examinations for PNP are infrequently provided to patients at high risk due to restrictions on facilities, care providers, or time. A gamified health assessment approach combining wearable sensors holds the potential to address these challenges and provide individuals with instantaneous feedback on their health status. We aimed to develop and evaluate an application that assesses PNP through video games controlled by pressure sensor-equipped insoles. In the proof-of-concept exploratory cohort study, a complete game-based framework that allowed the study participant to play 4 video games solely by modulating plantar pressure values was established in an outpatient clinic setting. Foot plantar pressures were measured by the sensor-equipped insole and transferred via Bluetooth to an Android tablet for game control in real time. Game results and sensor data were delivered to the study server for visualization and analysis. Each session lasted about 15 minutes. In total, 299 patients with diabetes mellitus and 30 with metabolic syndrome were tested using the game application. Patients' game performance was initially assessed by hypothesis-driven key capabilities that consisted of reaction time, sensation, skillfulness, balance, endurance, and muscle strength. Subsequently, specific game features were extracted from gaming data sets and compared with nerve conduction study findings, neuropathy symptoms, or disability scores. Multiple machine learning algorithms were applied to 70% (n=122) of acquired data to train predictive models for PNP, while the remaining data were held out for final model evaluation. Overall, clinically evident PNP was present in 247 of 329 (75.1%) participants, with 88 (26.7%) individuals showing asymmetric nerve deficits. In a subcohort (n=37) undergoing nerve conduction study as the gold standard, sensory and motor nerve conduction velocities and nerve amplitudes in lower extremities significantly correlated with 79 game features (|R|>0.4, highest R value +0.65; P<.001; adjusted R2=0.36). Within another subcohort (n=173) with normal cognition and matched covariates (age, sex, BMI, etc), hypothesis-driven key capabilities and specific game features were significantly correlated with the presence of PNP. Predictive models using selected game features achieved 76.1% (left) and 81.7% (right foot) accuracy for PNP detection. Multiclass models yielded an area under the receiver operating characteristic curve of 0.76 (left foot) and 0.72 (right foot) for assessing nerve damage patterns (small, large, or mixed nerve fiber damage). The game-based application presents a promising avenue for PNP screening and classification. Evaluation in expanded cohorts may iteratively optimize artificial intelligence model efficacy. The integration of engaging motivational elements and automated data interpretation will support acceptance as a telemedical application.

Neuroma-to-Nerve Ratio: Does Size Matter?

Anatomic features of neuromas have been explored in imaging studies. However, there has been limited research into these features using resected, ex vivo human neuroma specimens. The aim of this study was to investigate the influence that time may have on neuroma growth and size, and the clinical significance of these parameters. Patients who underwent neuroma excision between 2022 through 2023 were prospectively included in this study. Neuroma specimens were obtained after operative resection. Standardized neuroma size measurements, expressed as a neuroma-to-nerve ratio (NNR), were conducted with ImageJ software. Pain data (numeric rating scale, 0-10) were prospectively recorded during preoperative evaluation, and patient factors were collected from chart reviews. Fifty terminal neuroma specimens from 31 patients were included, with 94.0% of the neuromas obtained from individuals with amputations. Most neuromas were excised from the lower extremities (n = 44, 88.0%). The neuromas had a median NNR of 2.45, and the median injury to neuroma excision interval was 6.3 years. Larger NNRs were associated with a longer injury to neuroma excision interval and with a smaller native nerve diameter. In addition, sensory nerves were associated with a larger NNR compared with mixed nerves. NNR was not associated with preoperative pain or with anatomical nerve distribution. This study suggests that neuromas seem to continue to grow over time and that smaller nerves may form relatively larger neuromas. In addition, sensory nerves develop relatively larger neuromas compared with mixed nerves. Neuroma size does not appear to correlate with pain severity. These findings may stimulate future research efforts and contribute to a better understanding of symptomatic neuroma development.

Ultrasonographic Evaluation of Morphological Changes in Peripheral Nerves after Traumatic Injury and Nerve Repair - A Prospective Study.

Purpose Ultrasound (US) has gained in importance for the visualization of morphological changes of injured nerves. After surgical repair, changes in neural structures are seen over time. The correlation of morphologic changes in US with the corresponding nerve function is uncertain. The aim of this study is to determine a correlation of post-traumatic morphological nerve changes with US and with nerve function after surgery. Materials and Methods This dual-center, prospective cohort study was conducted between 2017 and 2022 and included 20 mixed sensory motor nerve lesions. Patients were followed up clinically (sensitivity, pain, and motor function) with US and electroneuromyography. We determined the US changes of the nerves including the interaction of the tissue after nerve repair and any correlation with nerve function. With US nerve cross-sectional area (CSA), the number of traversing fascicles, hypo-echogenicity, and presence of perineural scar were analyzed. Results 20 lesions (12 median and 8 ulnar nerves) of 18 patients with intraoperatively confirmed nerve injury of at least 50% in the forearm were included. The average CSA was over 20 mm 2 throughout the follow-up period, corresponding to a neuroma in continuity compared to the opposite side (10.75 mm 2 ). Sensibility and motor function at 12 months were 6xS3/4 and 10xM3-5. There was a statistically significant correlation between continuous fascicles on US at 6 months and sensitivity at 12 months. Conclusion This study supports the presence of post-traumatic morphological changes in nerve fibers with US after traumatic injury. Morphological changes in nerve structure after trauma can be detected with US indicating a correlation between continuity of nerve fascicles and development of sensitivity and motor function.

Variations of musculocutaneous nerve – A cadaveric study

Background: Musculocutaneous nerve (MCN) is a mixed nerve arising from the lateral cord of brachial plexus having root values C5, 6, and 7. It supplies the muscles of the flexor compartment of the arm namely; coracobrachialis, most part of brachialis and both heads of biceps brachii. It is cutaneous to the lower lateral part of forearm. Variations in the origin, course, branching pattern, termination, and connections of MCN are very common. Knowledge about these variations is important while evaluating unusual presentations of peripheral nerve injuries, during surgical procedures such as arthroscopy of shoulder joint, corrections of fracture humerus, brachial plexus block, and so on. Aims and Objectives: The study was conducted to find out any variations in the origin, course, branching pattern of the MCN. The secondary objective was to understand about the communication of the MCN with any other nerve. Materials and Methods: A descriptive study was conducted in 60 upper limb specimens dissected from 10% formalin embalmed 30 cadavers (adult) in the Department of Anatomy, Government Medical College, Kottayam. All limbs were carefully dissected and studied about the origin, course, termination, and variations of MCN. Results: Out of 60 specimens studied, in 46 specimens MCN Originate from lateral cord, eight from medial cord, and in six from the lateral root of the median nerve (MN). In 52 specimens, MCN supplies coracobrachialis but only in 34 it pierces this muscle. In four specimens, there is a communication between MCN and MN was seen. Conclusion: The MCN has significant variations and knowledge of these variations is clinically important in diagnosis and management of peripheral nerve injuries as well as surgical interventions in the arm.

SCOPING: A Pilot Study Exploring the Role of A Series of Clinical Observational Parameters as Indicators of Nerve Regeneration.

Following the repair of a mixed peripheral nerve, functional recovery requires successful nerve regeneration across the repair site and, eventually, reinnervation of distal targets. Reliably determining a failing nerve repair so that revision may be performed before irreversible muscle atrophy remains a challenge in peripheral nerve surgery. This study aimed to ascertain whether any commonly used clinical examination tests during surveillance after nerve repair can detect a failing repair and prompt earlier salvage intervention. A prospective observational cohort study was performed to evaluate commonly used clinical determinants of neuron regeneration that may provide early surrogate recovery measures. Sequential cutaneous thermography was used to identify temperature differences between denervated and normal skin in the hand operated on, with the contralateral hand as a control. Six out of nine patients completed between 6 and 18 months of follow-up. Tinel sign progression was observed in all subjects. Tinel progression rate was associated with motor and sensory Medical Research Council grade. The delta temperature was calculated to document the size and direction of any temperature differentials in the hand detected by thermography, but we did not have sufficient data to calculate any correlations with motor and sensory Medical Research Council grade. Specifically, the progression of Tinel sign is associated with recovery measured by progression of the British Medical Research Council motor and sensory grades. The use of thermographic imaging demonstrates that there is a difference in temperature between an injured and noninjured nerve. Future studies could investigate to what extent thermographic imaging predicts final nerve repair outcomes.

Creation of a biological sensorimotor interface for bionic reconstruction

Neuromuscular control of bionic arms has constantly improved over the past years, however, restoration of sensation remains elusive. Previous approaches to reestablish sensory feedback include tactile, electrical, and peripheral nerve stimulation, however, they cannot recreate natural, intuitive sensations. Here, we establish an experimental biological sensorimotor interface and demonstrate its potential use in neuroprosthetics. We transfer a mixed nerve to a skeletal muscle combined with glabrous dermal skin transplantation, thus forming a bi-directional communication unit in a rat model. Morphological analyses indicate reinnervation of the skin, mechanoreceptors, NMJs, and muscle spindles. Furthermore, sequential retrograde labeling reveals specific sensory reinnervation at the level of the dorsal root ganglia. Electrophysiological recordings show reproducible afferent signals upon tactile stimulation and tendon manipulation. The results demonstrate the possibility of surgically creating an interface for both decoding efferent motor control, as well as encoding afferent tactile and proprioceptive feedback, and may indicate the way forward regarding clinical translation of biological communication pathways for neuroprosthetic applications.

Polyethylene-Glycol Assisted Neurorrhaphy Promotes Superior Functional Recovery Following Injury of Mixed Nerves in the Upper Extremities

Polyethylene-Glycol Assisted Neurorrhaphy Promotes Superior Functional Recovery Following Injury of Mixed Nerves in the Upper Extremities

A transmuscular path of the medial branch of the high division of the median nerve: an anatomical variation of clinical and surgical importance

The median nerve (MN) is a mixed nerve formed in the brachial plexus, which innervates a large part of the upper limb. It presents several variations in its trajectory, resulting in many pathologies and iatrogenic surgical compromises. This report highlights a transmuscular route of the medial branch of the upper division of the MN, which to date does not fit into the classifications described in the literature on MN variations. Knowledge of this high division of the MN, as well as its transfixation by the flexor digitorum superficialis muscle, is of fundamental importance in neuropathy syndromes due to entrapment of the MN, as well as in surgical guidance to prevent injuries. Late diagnosis of traumatic peripheral nerve injuries results in greater functional impairment and greater socioeconomic loss, especially in young patients. Therefore, timely identification is essential to minimize long-term consequences and improve the patient's quality of life.

Overview of Brown-Sequard Syndrome.

A neurologic syndrome called Brown-Séquard syndrome is brought on by spinal cord hemisection. On the side of the body, ipsilateral to the lesion, it presents as weakness or paralysis, proprioceptive abnormalities, and loss of pain and temperature perception. Brown-Séquard syndrome is an incomplete spinal cord syndrome with a range of severity in its clinical presentation.&#x0D; One of the most intricate and fascinating areas of the nervous system to study is the spinal cord. Its overwhelming clinical presentation, development problems, lesions, and intricate connections call for a deeper comprehension of its anatomical and physiological makeup.&#x0D; Like the brain, the extremely fragile and sensitive spinal cord is well-protected by the robust bony cage comprising the vertebral arch and vertebral bodies. Together, they create the spinal hollow, or long spinal column, which houses the spinal cord. Millions of neurons reside in the spinal cord, and their bundled fibers run as ascending or descending tracts. Thirty-one pairs of spinal nerves, primarily supplying the trunk and limbs, emerge from the spinal cord. These are mixed spinal nerves with a motor component that assists in controlling the trunk and voluntary muscles in all limbs. Additionally, they have a sensory component that aids in taking in the sensory data from these regions. Therefore, for a better understanding of the clinical presentation and its pathology in any spinal cord lesion, it is imperative to grasp the fundamentals of anatomy.&#x0D; In this short review, we have discussed the symptoms, management, and prevention of brown syndrome.

Three Useful Tips and Tricks for Intraoperative Nerve Stimulation.

Disposable handheld nerve stimulators are widely used in peripheral nerve surgery. Such devices stimulate a motor nerve or the motor component of a mixed nerve by applying electrical current to the proximal region, targeting the main nerve trunk. This stimulation then travels along the motor nerve, reaching the distal end to control the corresponding muscle(s). In this study, the authors demonstrate three useful tips and tricks for handheld nerve stimulation during targeted muscle reinnervation and peripheral nerve surgery. The three tips are (1) identification of proximal muscle contraction by retrograde electrical stimulation of a distal sensory nerve; (2) graded stimulation for identifying motor nerves within fibrotic scarred tissue beds or parallel to the major motor/mixed nerve of interest; and (3) proximal stimulation for validation of adequate post-targeted muscle reinnervation coaptation(s).

Microsurgical anatomy of the glossopharyngeal nerve.

The glossopharyngeal nerve is a complicated and mixed nerve including sensory, motor, parasympathetic, and visceral fibers. It mediates taste, salivation, and swallowing. The low cranial nerves, including IXth, Xth, and XIth, are closely related, sharing some nuclei in the brainstem. The glossopharyngeal nerve arises from the spinal trigeminal nucleus and tract, solitary tract and nucleus, nucleus ambiguous, and inferior salivatory nucleus in the brainstem. There are communicating branches forming a neural anastomotic network between low cranial nerves. Comprehensive knowledge of the anatomy of the glossopharyngeal nerve is crucial for performing surgical procedures without significant complications. This review describes the microsurgical anatomy of the glossopharyngeal nerve and illustrates some pictures involving the glossopharyngeal nerve and its connective and neurovascular structures.

Tunable Hydrogel Electronics for Diagnosis of Peripheral Neuropathy.

Peripheral neuropathy characterized by rapidly increasing numbers of patients is commonly diagnosed via analyzing electromyography signals obtained from stimulation-recording devices. However, existing commercial electrodes have difficulty in implementing conformal contact with skin and gentle detachment, dramatically impairing stimulation/recording performances. Here, we develop on-skin patches with polyaspartic acid-modified dopamine/ethyl-based ionic liquid hydrogel (PDEH) as stimulation/recording devices to capture electromyography signals for the diagnosis of peripheral neuropathy. Triggered by a one-step electric field treatment, the hydrogel achieves rapid and wide-range regulation of adhesion and substantially strengthened mechanical performances. Moreover, hydrogel patches assembled with a silver-liquid metal (SLM) layer exhibit superior charge injection and low contact impedance, capable of capturing high-fidelity electromyography. We further verify the feasibility of hydrogel devices for accurate diagnoses of peripheral neuropathy in sensory, motor, and mixed nerves. For various body parts, such as fingers, the elderly's loose skin, hairy skin, and children's fragile skin, we regulate the adhesion of PDEH-SLM devices to establish intimate device/skin interfaces or ensure benign removal. Noticeably, hydrogel patches achieve precise diagnoses of nerve injuries in these clinical cases while providing extra advantages of more effective stimulation/recording performances. These patches offer a promising alternative for the diagnosis and rehabilitation of neuropathy in future. This article is protected by copyright. All rights reserved.

Segmental reflex, long-latency reflex, and mixed nerve silent period in dystonia.

ABSTRACT We hypothesized that “long latency reflexes” (LLRs), associated segmental reflex (SR), and mixed nerve silent periods (MnSPs) recorded on the distal upper extremity muscles would behave differently in patients with cervical dystonia and focal hand dystonia. We enrolled patients with cervical dystonia, generalized dystonia, focal hand dystonia, and healthy individuals. We recorded SR, LLRs, and MnSPs. The mean amplitude of SR on the affected side of focal hand dystonia was significantly lower (p = 0.010). The parameters related to LLRs and MnSPs were not different between groups. We suggest, using SR, LLRs, and MnSPs, we could not show an electrophysiological signature specific to dystonia.

Selective recording of physiologically evoked neural activity in a mixed autonomic nerve using a minimally invasive array.

Real-time closed-loop control of neuromodulation devices requires long-term monitoring of neural activity in the peripheral nervous system. Although many signal extraction methods exist, few are both clinically viable and designed for extracting small signals from fragile peripheral visceral nerves. Here, we report that our minimally invasive recording and analysis technology extracts low to negative signal to noise ratio (SNR) neural activity from a visceral nerve with a high degree of specificity for fiber type and class. Complex activity was recorded from the rat pelvic nerve that was physiologically evoked during controlled bladder filling and voiding, in an extensively characterized in vivo model that provided an excellent test bed to validate our technology. Urethane-anesthetized male rats (n = 12) were implanted with a four-electrode planar array and the bladder instrumented for continuous-flow cystometry, which measures urodynamic function by recording bladder pressure changes during constant infusion of saline. We demonstrated that differential bipolar recordings and cross-correlation analyses extracts afferent and efferent activity, and discriminated between subpopulations of fibers based on conduction velocity. Integrated Aδ afferent fiber activity correlated with bladder pressure during voiding (r2: 0.66 ± 0.06) and was not affected by activating nociceptive afferents with intravesical capsaicin (r2: 0.59 ± 0.14, P = 0.54, and n = 3). Collectively, these results demonstrate our minimally invasive recording and analysis technology is selective in extracting mixed neural activity with low/negative SNR. Furthermore, integrated afferent activity reliably correlates with bladder pressure and is a promising first step in developing closed-loop technology for bladder control.

Dual Peripheral Stimulation of Musculocutaneous and Radial Nerves for Refractory Upper Extremity Pain: Case Report

BACKGROUND: Peripheral nerve stimulation has been available for many years, yet there is relatively little information available regarding stimulation of many of the large sensory and mixed nerves. CASE REPORT: A 42-year-old woman presented to the clinic for a 10-year history of intractable left upper extremity and forearm pain following a motor vehicle accident requiring skin grafting. Based on the patient’s failure of more conservative therapy, a shared decision was made to pursue opioid sparing interventional modalities. Implantable radial and musculocutaneous nerve stimulators were chosen for this patient for ease of use and high likelihood of favorable outcomes. CONCLUSIONS: Sequential radial and musculocutaneous stimulation provided a 45% and 50% reduction in pain respectively, with the summative reduction of pain from original presentation being greater than 72% relief in total. KEY WORDS: Peripheral nerve stimulation, neuromodulation, musculocutaneous nerve, radial nerve, regional anesthesia, upper extremity pain, pain medicine, implantable stimulation

Trigeminal or peripheral nerve stimulation improves functional outcomes of nerve recovery in a rodent forelimb gap repair model

The hypothesis of this study was that trigeminal nerve stimulation (TNS) or peripheral nerve stimulation (PNS) could improve functional outcomes of peripheral nerve injury in a rat forelimb model when compared to control rats not receiving electrical stimulation (ES). While PNS is known to improve outcomes after nerve surgery, the role of TNS has not been explored. Lewis rats were trained to perform a reach and grasp task before receiving a 2mm gap repair of the ulnar and median nerves and randomized into four treatment groups: (1) sham injury, (2) nerve injury with sham ES, (3) nerve injury with PNS, and (4) nerve injury with TNS. Functional motor (median pull force and percent success in motor task) and sensory metrics (forelimb paw withdrawal thresholds) were collected both pre-injury and throughout rehabilitation. Nerves stained using Gomori's trichrome were assessed quantitatively and qualitatively. The sham ES group did not recover their pre-injury baseline functional outcomes. In contrast, the TNS and PNS groups fully recovered following injury, with no difference in functional outcomes between the pre-injury baseline and the final week of rehabilitation (P>0.05, all). Histomorphology results demonstrated no quantitative difference, but qualitative differences in architecture were evident. Electrical stimulation of the trigeminal nerve or the injured nerve improved the functional outcomes of nerve regeneration in rodents. Histomorphology results of nerves from the TNS group support the proposed central mechanisms. This is an important step in translating this therapy as an adjunct, non-invasive treatment for high, mixed nerve injuries in humans.

Blood flow effects of percutaneous peripheral nerve stimulation. A blinded, randomized clinical trial.

The vasculature function is mainly regulated by the autonomic nervous system. Importantly, the sensory-motor nervous system also innervates peripheral vessels and has the capacity to modulate vascular tone. Here we investigated the effects of electrical stimulation of a mixed nerve trunk on blood flow in deep arteries and muscle perfusion. Our hypothesis is that stimulation of a mixed nerve can modify blood flow. Twenty-nine healthy participants were included into a randomized-crossover and blinded clinical trial. Each subject received a placebo and two percutaneous peripheral nerve stimulation (pPNS) protocols on the median nerve: Pain Threshold continuous Low Frequency (PT-cLF) and Sensory Threshold burst High Frequency (ST-bHF). Blood flow was then assessed bilaterally using Power Doppler Ultrasonography at the main arteries of the arm, and blood perfusion at the forearm muscles. Afterwards, blood flow was quantified using a semi-automatized software, freely shared here. Placebo, consisting in needle insertion, produced an immediate and generalized reduction on peak systolic velocity in all arteries. Although nerve stimulation produced mainly no effects, some significant differences were found: both protocols increased the relative perfusion area of the forearm muscles, the ST-bHF protocol prevented the reduction in peak systolic velocity and TAMEAN of the radial artery produced by the control protocol and PT-cLF produced a TAMEAN reduction of the ulnar artery. Therefore, the arterial blood flow in the arm is mainly impervious to the electrical stimulation of the median nerve, composed by autonomic and sensory-motor axons, although it produces mild modifications in the forearm muscles perfusion.

Effect of 2% Topical Lidocaine Gel on Discomfort from Electrical Stimulation During Nerve Conduction Studies- A Prospective Double-Blind Placebo-Controlled Study.

Procedure discomfort can limit electrodiagnostic studies. Reducing discomfort can maximize the benefits of these diagnostic tools. This study targeted the discomfort associated with nerve conduction studies (NCS). This was a prospective randomized double-blind placebo-controlled study comparing the effect of topical lidocaine gel (2%) versus analgesic-free lubricant gel (K-Y gel) on pain perception during NCS. Sequential patients (n=130) referred for routine NCS participated in the study. We applied 1 mL of lidocaine gel to one palm, and 1 mL of K-Y gel to the other as a control. After 20-45 min of application, graded increments of electrical stimulation intensity were delivered to record the median and ulnar mixed palmar nerve responses. Patients were then asked to score the degree of pain felt from electrical stimulation over each palm using the Wong-Baker Faces Pain Scale (WBFPS) and the Numeric Rating Scale (NRS), independent of baseline pain. Mean WBFPS and NRS scores for lidocaine-treated palms were significantly lower than those for controls using parametric paired t-test (3.79 vs 4.37 and 3.35 vs 3.78 respectively, all p-values<0.05). Subgroup analysis showed a significant decrease in mean scores in females, patients aged ≤50 years, patients without a history of previous NCS, and patients without comorbidities (all p-values<0.05). Median scores using nonparametric Wilcoxon ranked test also showed statistically significant differences (all p-values<0.05). The results indicate that topical lidocaine 2% gel reduces discomfort associated with NCS. However, despite the statistical significance, clear clinical significance may be lacking. Clinical implementation may be considered for the subgroups that showed the greatest benefit. Further studies that incorporate more efficient drug delivery methods may yield better results.