Local Nerve Research Articles

MRI genicular nerve mapping: a novel approach to sagittal genicular nerve localization

Background and objectivesChronic knee pain, including postarthroplasty knee pain, is a major cause of morbidity. Radiofrequency ablation of genicular nerve branches is a treatment option. The literature to date has...

Intraneural and Extraneural Ganglion Cysts at the Greater Sciatic Notch Involving the Sciatic Nerve Causing Sciatica: Two Case Reports

Intraneural ganglion cysts (IGCs) are benign mucinous cysts within the epineurium of peripheral nerves. Hip joint-related IGCs are much rarer than those that arise from peripheral nerves around the joints of limbs. The unifying articular synovial theory has been accepted as explaining the pathogenesis of IGCs. Herein, we present two cases of hip joint-related ganglion cysts—one case of an IGC and one case of an extraneural ganglion cyst—that involved the sciatic nerve through the articular branch of the hip joint and caused sciatica. Preoperative and postoperative magnetic resonance imaging (MRI) findings of the articular branch derived from a paralabral cyst of the hip are presented, as well as photographic findings of a ganglion cyst with the articular branch addressed through a transgluteal approach. Despite improvement in postoperative sciatica due to cyst decompression and treatment aimed at addressing the articular branch, the articular branch remained present on postoperative MRI. Unlike IGCs arising from peripheral nerves associated with limb joints, involvement of the sciatic nerve might make it challenging to treat articular branches due to the location of the sciatic nerve over the greater sciatic notch of the deep gluteal region.

Anatomic Study and Clinical Application of C7 Nerve Transfer Surgery via the Anterior Vertebral Approach for Central Upper Limb Spastic Paralysis

Objective: To explore the anatomic characteristics of C7 nerve localization, course, and length during cross-transfer surgery of the C7 nerve through the anterior vertebral approach and investigate the feasibility, safety, and clinical efficacy of C7 nerve transfer surgery through the anterior vertebral approach for the treatment of central upper limb spastic paralysis. Methods: Four fresh-frozen adult head and neck samples were selected. C7 nerve transfer surgery was simulated through the anterior vertebral approach. The vertical distance between the C7 nerve and the medial edge of the clavicle, the length of the C7 nerve, and the shortest distance of C7 nerve transfer required through the anterior vertebral approach were measured. This was a retrospective analysis of the clinical data of 2 patients with central upper limb spastic paralysis after C7 nerve transfer surgery at Northern Jiangsu People’s Hospital affiliated with Yangzhou University. The patients were all female, aged 50 to 51 years, with upper limb paralysis on the affected side. The muscle strength was grade 0 or grade 1, and the muscle tension was relatively high. Both patients underwent C7 nerve transfer surgery through the anterior vertebral approach. Upper limb sensation and motor function were observed. Results: Bilateral C7 nerves can be fully exposed and located through the anterior vertebral approach. The C7 nerve runs between the anterior and middle scalene muscles, with a vertical distance of 1.7 to 2.5 (2.1±0.3) cm from the inner edge of the clavicle. The length of the C7 nerve is 5.6 to 6.8 (6.4±0.5) cm, and the shortest distance of C7 nerve transfer through the anterior vertebral approach is 4.8 to 5.7 (5.3±0.4 cm). Two patients with central upper limb paralysis successfully underwent C7 nerve transfer surgery using the anterior vertebral approach. Two patients had normal motor function in the healthy upper limb after surgery but experienced pain and numbness in the healthy upper limb. Both patients recovered within 1 month. Two patients experienced significant relief of spasticity symptoms in the affected upper limb. One patient was followed up for 15 months, and, at the last follow-up, sensation in the affected upper limb was normal, with proximal muscle strength at level 3 and distal muscle strength at level 2. Another patient was followed up for 11 months, and at the last follow-up, sensation in the affected upper limb was normal, with proximal muscle strength at level 1+ and distal muscle strength at level 1. Conclusion: For central upper limb spastic paralysis, C7 nerve transfer surgery through the anterior vertebral approach is safe and feasible and is a good treatment option. Related anatomic research can effectively guide clinical surgery and assist in locating the C7 nerve, and incising the musculus longus colli can shorten the distance of C7 nerve transfer.

Relationship between Family Support and Quality of Life in Stroke Patients

Stroke is a disease of the brain in the form of impaired local nerve function that appears suddenly, progressively, and quickly. Family support is very influential on stroke patients, because family support is very instrumental in a form of assistance provided by family members to provide physical and psychological comfort when someone experiences illness and provides social support. This article review aims to determine the relationship between family support and quality of life in stroke patients. This study used the literature review method with the Preferred Reporting Items for Systematic Reviews & Meta-Analyses (PRISMA) protocol. Scientific articles or journals were downloaded from PubMed, Garuda Portal, and Google Scholar with SINTA IV and V standards within 2020-2024. In this literature, it was found that family support is an aspect that plays an important role in the quality of life of stroke patients. Family support itself includes emotional support, appreciation support, instrumental support and information support. The family is the closest person who always interacts with post-stroke patients, so the role of the family is very important in an effort to provide various supports that create a sense of security for patients.

Pharmacologic or genetic targeting of peripheral nerves prevents peri-articular traumatic heterotopic ossification

Heterotopic ossification (HO) is a pathological process that commonly arises following severe polytrauma, characterized by the anomalous differentiation of mesenchymal progenitor cells and resulting in the formation of ectopic bone in non-skeletal tissues. This abnormal bone growth contributes to pain and reduced mobility, especially when adjacent to a joint. Our prior observations suggested an essential role of NGF (Nerve Growth Factor)-responsive TrkA (Tropomyosin Receptor Kinase A)-expressing peripheral nerves in regulating abnormal osteochondral differentiation following tendon injury. Here, we utilized a recently developed mouse model of hip arthroplasty-induced HO to further validate the role of peripheral nerve regulation of traumatic HO. Nerve ingrowth was either modulated using a knockin transgenic animals with point mutation in TrkA, or local treatment with an FDA-approved formulation of long acting Bupivacaine which prevents peripheral nerve growth. Results demonstrate exuberant sensory and sympathetic nerve growth within the peri-articular HO site, and that both methods to reduce local innervation significantly reduced heterotopic bone formation. TrkA inhibition led to a 34% reduction in bone volume, while bupivacaine treatment resulted in a 50% decrease. Mechanistically, alterations in TGFβ and FGF signaling activation accompanied both methods of local denervation, and a shift in macrophages from M1 to M2 phenotypes was observed. In sum, these studies reinforce the observations that peripheral nerves play a role in the etiopathogenesis of HO, and that targeting local nerves represents a potential therapeutic approach for disease prevention.

Identification of potential biomarkers of cuproptosis in cerebral ischemia.

Cerebral ischemia can cause mild damage to local brain nerves due to hypoxia and even lead to irreversible damage due to neuronal cell death. However, the underlying pathogenesis of this phenomenon remains unclear. This study utilized bioinformatics to explore the role of cuproptosis in cerebral ischemic disease and its associated biomarkers. R software identified the overlap of cerebral ischemia and cuproptosis genes, analyzed Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), and explored hub genes. Expressions and localizations of hub genes in brain tissue, cells, and immune cells were analyzed, along with predictions of protein structures, miRNAs, and transcription factors. A network was constructed depicting hub gene co-expression with miRNAs and interactions with transcription factors. Ferredoxin 1 (FDX1) expression was determined using qRT-PCR. Ten cuproptosis-related genes in cerebral ischemia were identified, with GO analysis revealing involvement in acetyl-CoA synthesis, metabolism, mitochondrial function, and iron-sulfur cluster binding. KEGG highlighted processes like the tricarboxylic acid cycle, pyruvate metabolism, and glycolysis/gluconeogenesis. Using the Human Protein Atlas, eight hub genes associated with cuproptosis were verified in brain tissues, hippocampus, and AF22 cells. Lipoyl(octanoyl) transferase 1 (LIPT1), was undetected, while others were found in mitochondria or both nucleus and mitochondria. These genes were differentially expressed in immune cells. FDX1, lipoic acid synthetase (LIAS), dihydrolipoamide S-acetyltransferase (DLAT), pyruvate dehydrogenase E1 component subunit alpha 1 (PDHA1), PDHB, and glutaminase (GLS) were predicted to target 111 miRNAs. PDHA1, FDX1, LIPT1, PDHB, LIAS, DLAT, GLS, and dihydrolipoamide dehydrogenase (DLD) were predicted to interact with 11, 10, 10, 9, 8, 7, 5, and 4 transcription factors, respectively. Finally, FDX1 expression was significantly upregulated in the hippocampus of ovariectomized rats with ischemia. This study revealed an association between cerebral ischemic disease and cuproptosis, identifying eight potential target genes. These findings offer new insights into potential biomarkers for the diagnosis, treatment, and prognosis of cerebral ischemia, and provide avenues for the exploration of new medical intervention targets.

Ultrasound-Guided Blockade of the Lateral Cutaneous Branch of the Iliohypogastric Nerve to Differentiate Neuropathy From Greater Trochanteric Pain Syndrome: Cadaver Study and Initial Case Series

ObjectiveNeuropathy of the lateral cutaneous branch of the iliohypogastric nerve (LCBIN) may represent a differential diagnosis for greater trochanteric pain syndrome (GTPS). Ultrasound-guided neural blockade of the LCBIN may lead to diagnosis of this neuropathy. The aim of this study was to evaluate the accuracy of ultrasound-guided nerve block in cadavers and to present a first clinical case series of patients with neuropathy of the LCBIN where the workup for GTPS remained unremarkable. Ultrasound-guided nerve block led to pain relief in these patients, indicating LCBIN neuropathy. MethodsFirst, ultrasound-guided injections at the LCBIN were performed bilaterally in 24 fresh, non-frozen, non-embalmed body donors. Accuracy and nerve localization were validated by anatomic dissection. Second, a clinical case series of nine patients with suspected GTPS who underwent ultrasound-guided diagnostic LCBIN blockade was retrospectively analyzed. ResultsUltrasound-guided injections at the LCBIN yielded 91.7% accuracy (95% confidence interval: 0.80–0.98). On the right side the nerve was found within a range of 3–14 cm from the anterior superior iliac spine, and within a range of 7–15 cm on the left side. This clinical case series indicates that ultrasound-guided blockade at the LCBIN provides temporary pain relief and indicates the presence of LCBIN neuropathy. ConclusionUltrasound has demonstrated high accuracy for localization and injection guidance in the examination of LCBIN. Ultrasound-guided injection of local anesthetics may help to identify LCBIN neuropathy as a differential diagnosis in patients with suspected GTPS.

The anatomical course of the sciatic nerve in relation to different approaches in total hip arthroplasty.

Although sciatic nerve (SN) injury is relatively rare, it is a devastating complication after primary and revision total hip arthroplasty (THA). Therefore, precise localization of the SN is essential for arthroplasty surgeons. We dissected 50 hemipelves from formalin-fixed cadavers. The course and location of the sciatic nerve were investigated in relation to different approaches for THA with the help of anatomical landmarks like the greater trochanter (GT), the iliac tubercle, the ischial tuberosity (IschT), the infrapiriform foramen, and the suprapiriform foramen. We found and exposed the sciatic nerve in all 50 specimens with no sex-specific differences. No SN was encountered up to 22mm posterior from the GT. The zone affording the highest probability of finding the nerve was posterior to the GT between 32 and 55mm in 39 (78%) cases, thus defining a danger zone for different approaches for the THA. Special care should be taken with posterior and deep instrument placement between the GT and IschT during THA. Moreover, manipulations in the proximal third of the posterior approach reaching deep and posteriorly should be performed with the utmost care.

Local Infiltration Analgesia Is Superior to Regional Nerve Blocks for Total Hip Arthroplasty: Less Falls, Better Mobility, and Same-Day Discharge.

Background: Multimodal analgesia in total hip arthroplasty (THA) provides better pain control, mobility, and reduced side effects compared to monotherapies. Local infiltration analgesia (LIA) and regional nerve blocks (RNBs) are commonly used throughout these protocols. This study aimed to compare these procedures as part of a multimodal analgesia protocol for patients undergoing THA. Materials and Methods: A retrospective review of 1100 consecutive elective primary THAs was performed in 996 patients between June 2018 and December 2021. The RNB consisted of a preoperative continuous femoral nerve catheter and single-shot obturator nerve block, and LIA consisted of the intraoperative infiltration of weight-based bupivacaine. Results: A total of 579 (52.6%) patients received RNB, and 521 (47.4%) received LIA. Mean oral morphine equivalents (OMEs) during the first four hours postoperatively were significantly lower for LIA group (p < 0.001). However, the numeric pain rating scale in the post-anesthesia care unit (PACU) was similar between groups. Patients with LIA had significantly greater first ambulation distance in the PACU (p < 0.001), higher successful same-day discharge rate (p = 0.029), fewer falls (p = 0.041), and less refill OMEs post-discharge (p < 0.001) than RNB. Conclusions: In the setting of similar pain management between groups and better functional outcomes for LIA, the use of minimally invasive procedures like LIA for pain control following THA is favorable.

Relation of Transversus Abdominis to Rectus Abdominis Muscle in Various Anatomical Landmark Levels: A Cadaveric Study

Abstract Background Posterior Component Separation (PCS) is a surgical technique used in abdominal wall reconstruction. Understanding the relationship between the rectus abdominis and transversus abdominis muscles and the location of intercostal nerves is crucial for minimizing nerve injury during PCS. This cadaveric study aimed to investigate these anatomical relationships and propose practical guidelines for safer PCS procedures. Methods Eighteen fresh cadavers were dissected to assess the overlap or separation of the rectus abdominis and transversus abdominis muscles at seven abdominal levels. The distance of intercostal nerves from the lateral border of the rectus abdominis was measured. Results The study found that the muscles overlapped at the xiphoid and upper abdominal levels but began to separate below the 2/4 upper to umbilicus level. Intercostal nerves entered at varying distances from the lateral edge of the rectus abdominis, suggesting that levels above the 3/4 upper to umbilicus level are relatively safe for dissection. Conclusion The study recommends initiating the first incision for PCS between the subxiphoid and 2/4 upper to the umbilicus, based on observed muscle relationships and nerve distances. This practical approach enhances safety and simplifies decision-making during surgery.

Nerve entry points in the mimic musculature of the horse head.

Facial expressions are important in pain recognition in horses, but current observation-based pain scales remain subjective. A promising technique to quantitatively measure subtle changes in expression patterns, including changes invisible to the human eye, is surface electromyography (sEMG). To achieve high-quality and reliable sEMG signals, unilateral placement of bipolar electrodes is required in relation to the motor endplates (MEP). We aimed to localize the nerve entry points (NEPs; where the nerve branch first pierced the muscle belly) and the direction of the terminal nerve endings to estimate MEP locations of the innervating nerves in five equine facial muscles involved in pain expression. Three cadaveric Dutch Warmblood horse heads were dissected to identify the NEPs in the musculi caninus, levator anguli oculi medialis, nasolabialis, masseter and zygomaticus. These points were marked with pins and measured in relation to a reference line between two anatomical landmarks near the origin and insertion of the respective muscle. Relative distances were calculated from the most caudally situated landmark. NEPs were located at 33%-38% (caninus), 69%-86% (levator anguli oculi medialis) and 0%-18% (zygomaticus) from the caudal landmark. The nasolabialis showed two innervations zones. Its NEPs were located at 47%-72% (dorsal muscle branch) and 52%-91% (ventral branch). All terminal nerve endings were found to run in rostral direction. The masseter showed numerous NEPs diffusely spread within the muscle belly. Therefore, calculation of relative positions was not performed. These results could form the basis for feasibility studies and standardization of bipolar electrode positioning invivo to measure facial muscle activity patterns in horses.

MRI and Ultrasound Visualization of a Nerve Repair Implant Containing Nitinol.

Nerve Tape is a novel nerve repair device containing nitinol microhooks that provide sutureless attachment for nerve coaptation. This study evaluated visualization of Nerve Tape on magnetic resonance imaging (MRI) and ultrasound, with the objective of exploring its potential as an imaging marker for localizing nerve repair sites. Phantom imaging experiments were first conducted to assess the visibility of Nerve Tape on MRI and ultrasound. A cadaveric limb investigation was then performed to further characterize the magnetic susceptibility patterns of Nerve Tape and to confirm its localization at the repair site. Phantom imaging experiments demonstrated clear visualization of Nerve Tape on both MRI and ultrasound, with Nerve Tape microhooks appearing as signal voids on MRI and hyperechoic foci on ultrasound. Subsequent cadaveric limb investigation further characterized Nerve Tape's magnetic susceptibility patterns and confirmed localization of the device at the repair site. The physical dimensions of Nerve Tape and locations observed on both MRI and ultrasound matched design and measurements made during surgery. Measurement discrepancies could be attributed to magnetic susceptibility artifacts in MRI, and to comet tail and shadowing effects in ultrasound. Repairs performed with Nerve Tape can be reliably localized for imaging, potentially facilitating assessment of repair site integrity and further advancement toward image-based monitoring of nerve regeneration. Further research, including in vivo human studies, is warranted to confirm these preliminary findings.

Evaluation of Brachial Plexus Nerve Variations in Axilla by Ultrasonography

The use of ultrasound in peripheral blocks has now become the gold standard. Ultrasound is a method that is easy to apply and most importantly does not carry any risk, and its only disadvantage is based on the skill and knowledge of the practitioner. Injury to vascular structures, which is the most common occurrence in peripheral block applications, has been significantly reduced by the use of ultrasound. The aim of this study is to determine the location of nerve branches and to determine the most common anthropometric parameters in the axillary fossa. In this way, the common anatomy of the axillary BP will be determined and will guide the practitioners while performing the axillary plexus block. Observational Clinical Study. The patients were positioned with forearm abducted 90 degrees and elbow flexed 90 degrees. A high-frequency linear ultrasound probe was placed on the lateral border of the pectoralis major muscle in the transverse plane. Pulsation of the axillary artery was visualized and shifted slowly to view the nerves around the artery. The axillary vein was also visualized to facilitate the movement of the transducer and to find the nerve localization more easily. The regions on the prepared wheel were marked. At the same time, demographic information such as gender, age, weight, and height of the patients were also recorded. The sample was 248 patients, 61.3% female and 38.7% male. Our results showed that only 59% were compatible with the most common nerve locations in cadaveric dissections and the locations described in anatomy textbooks. Since there are many anatomical variations, validation of nerves with a nerve stimulator as well as simultaneous visual application under ultrasound guidance will increase the success chance of axillary brachial plexus block and protect it from unwanted complications.

Efficacy and Safety of Obturator Nerve Block in Transurethral Resection of Bladder Tumors: A Comprehensive Review.

Transurethral resection of bladder tumors (TURBT) is a pivotal procedure in the management of bladder cancer, essential for both diagnosis and treatment. Effective anesthesia is crucial in TURBT to ensure a stable and pain-free operative field, facilitate precise tumor resection, and minimize complications such as the obturator reflex, which can lead to involuntary leg movement and bladder injury. The obturator nerve block (ONB) is a regional anesthesia technique designed to prevent the obturator reflex by blocking the obturator nerve, which innervates the adductor muscles of the thigh. This comprehensive review evaluates the efficacy and safety of ONB in TURBT. It begins by discussing the anatomical and physiological aspects of the obturator nerve, followed by a detailed examination of various ONB techniques, including ultrasound-guided and landmark-based methods. The review assesses the impact of ONB on pain management, reduction of adductor muscle spasms, and overall improvement in surgical conditions and patient satisfaction. Additionally, it explores the incidence and types of complications associated with ONB, such as hematoma, nerve injury, and local anesthetic systemic toxicity (LAST). It compares ONB with other anesthesia techniques used in TURBT, such as general, spinal, and epidural anesthesia. A critical analysis of key clinical studies and meta-analyses is presented to provide a comprehensive understanding of the current evidence on ONB efficacy and safety. Future directions and innovations in ONB techniques, including advances in imaging and nerve localization, are also discussed. Practical recommendations for implementing ONB in clinical practice, including guidelines for clinician training and patient selection criteria, are provided. This review aims to inform clinicians about the benefits and risks of ONB in TURBT, guide clinical practice, and identify areas for future research to optimize anesthesia management in bladder cancer surgery.

Central activation of catecholamine-independent lipolysis drives the end-stage catabolism of all adipose tissues.

Several adipose depots, including constitutive bone marrow adipose tissue (cBMAT), resist conventional lipolytic cues, making them metabolically non-responsive. However, under starvation, wasting, or cachexia, the body can eventually catabolize these stable adipocytes through unknown mechanisms. To study this, we developed a mouse model of brain-evoked depletion of all fat, including cBMAT, independent of food intake. Genetic, surgical, and chemical approaches demonstrated that depletion of stable fat required adipose triglyceride lipase-dependent lipolysis but was independent of local nerves, the sympathetic nervous system, and catecholamines. Instead, concurrent hypoglycemia and hypoinsulinemia activated a potent catabolic state by suppressing lipid storage and increasing catecholamine-independent lipolysis via downregulation of cell-autonomous lipolytic inhibitors Acvr1c, G0s2, and Npr3. This was also sufficient to delipidate classical adipose depots. Overall, this work defines unique adaptations of stable adipocytes to resist lipolysis in healthy states while isolating a potent in vivo neurosystemic pathway by which the body can rapidly catabolize all adipose tissues.

Close relationship with the glandular capsule：a highly sensitive diagnostic indicator of major salivary gland metastatic malignancies in ultrasound.

To investigate the ultrasound (US) characteristics of metastatic malignancies (MM) in the major salivary glands and to assess the diagnostic value of the close relationship with the glandular capsule in identifying MM. From January 2016 and April 2022, 122 patients with major salivary gland malignancies, including 20 patients with MM and 102 patients with primary malignancies (PM) confirmed by histopathological examination, were enrolled in this study. Their clinicopathologic and US data were recorded and analyzed. The diagnostic performance of the close relationship with the glandular capsule for differentiating MM from PM was analyzed. The mean age of MM were older than that of PM (59.50 ± 14.57 vs. 49.96 ± 15.73, p = 0.013). Compared with PM patients, MM were associated with a higher prevalence of local pain symptoms (p = 0.007) and abnormal facial nerve function (p < 0.001). MM were also more frequently characterized by unclear borders, rough margins, irregular shapes, heterogeneous internal echos, absence of cystic areas, presence of calcifications, close relationship with the glandular capsule, and US-reported positive cervical lymph nodes (all p < 0.05). The close relationship with the glandular capsule showed to be a good indicator in distinguishing between MM and PM, with an area under the receiver operating characteristic curve of 0.863, a sensitivity of 100%, a specificity of 72.5%, and an accuracy of 92.2%. Positive and negative predictive were calculated at 41.7% and 100%, respectively. The US finding of a close relationship with the glandular capsule is a highly sensitive diagnostic indicator for MM. Following this finding, US-guided needle biopsy should be recommended to further confirm the diagnosis.

Transvesical blockade of the obturator nerve to prevent adductor contraction in transurethral resection of urinary bladder tumor.

Urinary bladder tumors are one of the most common urological malignancies. Traditionally, it has been managed with trans-urethral resection of urinary bladder tumor (TURBT) for both diagnostic and therapeutic purposes. During TURBT of lateral wall tumors, there is risk of obturator nerve reflex (ONR), which can lead to serious complications such as inadvertent bleeding and urinary bladder perforation. To prevent this, obturator nerve block is given after spinal anesthesia. In this study, we have used the transvesical approach to block the obturator nerve. In total, 60 patients were included in the study. In 30 of them, TURBT was performed under only SA and transvesical obturator nerve block (ONB). In the other 30 patients, TURBT was performed under SA and peripheral nerve stimulator (PNS) guided obturator nerve block (performed by anesthetists) was given. The patients underwent TURBT using conventional monopolar cautery. The procedure time and peri-operative complications were studied. In all patients, informed consent was taken. In this study, 30 ONBs (all bilateral) were performed transvesically. After confirming the location of the obturator nerve, transvesical ONB was given using local anesthetic. Two patients (6.67%) experienced adductor jerk during the operation. In the 30 patients who underwent peripheral nerve stimulator (PNS) guided ONB, 6 of the patients (20%) experienced adductor jerk during the operation and 1 of those (3.33%) suffered from urinary bladder perforation which was managed conservatively. Transvesical ONB is an easy method to prevent adductor jerk during TURBT of lateral wall tumors. The learning curve is less and it has a high success rate.

Initial findings using high-resolution magnetic resonance imaging for visualisation of the sural nerve and surrounding anatomy in healthy volunteers at 7 Tesla.

Histopathological diagnosis is the gold standard in many acquired inflammatory, infiltrative and amyloid based peripheral nerve diseases and a sensory nerve biopsy of sural or superficial peroneal nerve is favoured where a biopsy is deemed necessary. The ability to determine nerve pathology by high-resolution imaging techniques resolving anatomy and imaging characteristics might improve diagnosis and obviate the need for biopsy in some. The sural nerve is anatomically variable and occasionally adjacent vessels can be sent for analysis in error. Knowing the exact position and relationships of the nerve prior to surgery could be clinically useful and thus reliably resolving nerve position has some utility. 7T images of eight healthy volunteers' (HV) right ankle were acquired in a pilot study using a double-echo in steady-state sequence for high-resolution anatomy images. Magnetic Transfer Ratio images were acquired of the same area. Systematic scoring of the sural, tibial and deep peroneal nerve around the surgical landmark 7 cm from the lateral malleolus was performed (number of fascicles, area in voxels and mm2, diameter and location relative to nearby vessels and muscles). The sural and tibial nerves were visualised in the high-resolution double-echo in steady-state (DESS) image in all HV. The deep peroneal nerve was not always visualised at level of interest. The MTR values were tightly grouped except in the sural nerve where the nerve was not visualised in two HV. The sural nerve location was found to be variable (e.g., lateral or medial to, or crossing behind, or found positioned directly posterior to the saphenous vein). High-resolution high-field images have excellent visualisation of the sural nerve and would give surgeons prior knowledge of the position before surgery. Basic imaging characteristics of the sural nerve can be acquired, but more detailed imaging characteristics are not easily evaluable in the very small sural and further developments and specific studies are required for any diagnostic utility at 7T.

Ultrasound-guided localization of the radial nerve along the humerus: providing reference points for safer upper arm surgery.

The close proximity of the radial nerve to the humerus poses a risk during upper arm surgery. Although the general course of the radial nerve is well-known, its exact position in relation to anatomical reference points remains poorly investigated. This study aimed to develop a standardized protocol for the sonographic and clinical identification of the radial nerve in the upper arm. The ultimate goal is to assist surgeons in avoiding iatrogenic radial nerve palsy. A total of 76 measurements were performed in 38 volunteers (both sides). Ultrasound measurements were performed using a linear transducer (10MHz) to identify the radial nerve at two key points: RD (where the radial nerve crosses the dorsal surface of the humerus) and RL (where the radial nerve crosses the lateral aspect of the humerus). Distances from specific reference points (acromion, lateral epicondyle, medial epicondyle, olecranon fossa) to RD and RL were measured, and the angle between the course of the nerve and the humeral axis was recorded. Humeral length was defined as the distance between the posterodorsal corner of the acromion and the lateral epicondyle. The distance from the lateral epicondyle to RD was on average 15.5cm ± 1.3, corresponding to 50% of the humeral length. The distance from the lateral epicondyle to RL was on average 6.7cm ± 0.8, corresponding to 21% of the humeral length. The course of the nerve between RD and RL showed an average angulation of 37° to the anatomical axis of the humerus. Gender, BMI, dominant hand, and arm thickness did not correlate with the distances to RD or RL. Measurements were consistent between the left and right side. The radial nerve can typically be identified by employing a 1/2 and 1/5 ratio on the dorsal and lateral aspects of the humerus. Due to slight variations in individual anatomy, the utilization of ultrasound-assisted visualization presents a valuable and straightforward approach to mitigate the risk of iatrogenic radial nerve palsy during upper arm surgery. This study introduces an easy and fast protocol for this purpose.

A Wearable Dual-Mode Probe for Image-Guided Closed-Loop Ultrasound Neuromodulation.

Low-intensity focused ultrasound (FUS) is an emerging non-invasive and spatially/temporally precise method for modulating the firing rates and patterns of peripheral nerves. This paper describes an image-guided platform for chronic and patient-specific FUS neuromodulation. The system uses custom wearable probes containing separate ultrasound imaging and modulation transducer arrays realized using piezoelectric transducers assembled on a flexible printed circuit board (PCB). Dual-mode probes operating around 4 MHz (imaging) and 1.3 MHz (modulation) were fabricated and tested on tissue phantoms. The resulting B-mode images were analyzed using a template-matching algorithm to estimate the location of the target nerve and then direct the modulation beam toward the target. The ultrasound transmit voltage used to excite the modulation array was optimized in real-time by automatically regulating functional feedback signals (the average rates of emulated muscle twitches detected by an on-board motion sensor) through a proportional and integral (PI) controller, thus providing robustness to inter-subject variability and probe positioning errors. The proposed closed-loop neuromodulation paradigm was experimentally demonstrated in vitro using an active tissue phantom that integrates models of the posterior tibial nerve and nearby blood vessels together with embedded sensors and actuators.