Sciatic nerve fascicle differentiation on high-resolution ultrasound with histological verification: An ex vivo study.

INTRODUCTION/AIMS: The development of high-resolution ultrasound (HRUS) has enabled the depiction of peripheral nerve microanatomy in vivo. This study compared HRUS fascicle differentiation to the structural depiction in histological cross-sections (HCS). METHODS: A human cadaveric sciatic nerve was marked with 10 surgical sutures, and HRUS image acquisition was performed with a 22-MHz probe. The nerve was excised and cut into five segments for HCS preparation. Selected HCS were cross-referenced to HRUS, with sutures to improve orientation. Sciatic nerve and fascicle contouring were performed to assess nerve and fascicular cross-sectional area (CSA), fascicle count, and interfascicular distances. Three groups were defined based on HRUS fascicle differentiation in comparison to HCS, namely single fascicle (SF), fascicular cluster (FC), and no depiction (ND) group. RESULTS: On cross-referenced HRUS to HCS images, 58% of fascicles were differentiated. On HRUS, significantly larger fascicle CSA and smaller fascicle count were observed compared with HCS. Group analysis showed that 41% of fascicles were defined as SF, 47% as FC, and 12% as ND. The mean fascicle CSA in the ND group was 0.05 mm2. Compared with the SF, the FC had significantly larger fascicle CSA (1.2 ± 0.7 vs. 0.6 ± 0.4 mm2; p < .001) and shorter interfascicular distances (0.1 ± 0.04 vs. 0.5 ± 0.3 µm; p < .001). DISCUSSION: While HRUS can depict fascicular anatomy, only half of the fascicles visualized on HRUS directly correspond to single fascicles observed on HCS. The amount of interfascicular epineurium appears to influence the ability of HRUS to differentiate individual fascicles.

Endovascular revascularization of critical limb ischemia: the role of ultrasound-guided popliteal sciatic nerve block for the procedural pain management.

OBJECTIVES: To evaluate the impact of the ultrasound-guided popliteal sciatic nerve block (PSNB) for pain management during endovascular treatment of chronic limb-threatening ischemia (CLTI). MATERIAL AND METHODS: From November 2020 to January 2022, 111 CLTI patients that underwent endovascular procedures were prospectively enrolled in this prospective single-arm interventional study. Ultrasound-guided PSNB was used for procedural pain control. Pain intensity was evaluated throughout the procedure (baseline, 10 min after the block, pain peak, and at the end of the procedure) with the visual analog scale (VAS). RESULTS: Forty-six patients underwent above-the-knee revascularization (ATK), 20/111 below-the-knee (BTK) revascularization, 20/111 to both ATK and BTK revascularization. In 25 cases, no endovascular option was feasible at diagnostic angiography. The PSNB was effective in 96% of patients, with no need for further pain management with a statistically significant reduction (p < 0.0001) in the mean value of the VAS from 7.86 ± 1.81 (pre-procedural) to 2.04 ± 2.20 after 10 min from the block and up to 0.74 ± 1.43 at the end of the procedure (mean time 43 min). Only 1 complication related to the popliteal sciatic nerve block was registered (a temporary foot drop, completely resolved within 48 h). The time necessary to perform the block ranged between 4 and 10 min. CONCLUSION: Ultrasound-guided PSNB is a feasible and effective method to manage patients with rest pain and increase comfort and compliance during endovascular procedures. CLINICAL RELEVANCE STATEMENT: An ultrasound-guided popliteal sciatic nerve block is a safe, feasible, and effective technique to manage pain during endovascular treatment of chronic limb-threatening ischemia, especially in frail patients with multiple comorbidities who are poor candidates for deep sedoanalgesia or general anesthesia. KEY POINTS: Endovascular treatment of CTLI may require long revascularization sessions in patients with high levels of pain at rest, which could be exacerbated during the revascularization procedure. The PSNB is routinely used for anesthesia and analgesia during foot and ankle surgery, but the experience with lower limb revascularization procedures is very limited and not included in any international guideline. Ultrasound-guided PSNB is a feasible and effective regional anesthesia technique to relieve procedural and resting pain. Because of its safety and availability, every interventional radiologist should know how to perform this type of loco-regional anesthesia.

Nerve block, nerve damage, and fluid injection pressure: overturning the myth.

Histological and micro-ultrasound evidence rebuffs deep-rooted views on the nature of nerve block, nerve damage, and injection pressure monitoring. We propose that the ideal position of the needle tip for nerve block is between the innermost circumneural fascial layer and outer epineurium, with local anaesthetic passing circumferentially through adipose tissue. Thin, circumferential, subepineural expansion that is invisible to the naked eye was identified using micro-ultrasound, and could account for variability of outcomes in clinical practice. Pressure monitoring cannot differentiate between intrafascicular and extrafascicular injection. High injection pressure only indicates intraneural extrafascicular spread, not intrafascicular spread, because it is not possible to inject into the stiff endoneurium in most human nerves.

Consecutive assessment of recovery after peripheral nerve injury of the sciatic nerve within the same rat using PET/MRI.

BACKGROUND: Positron emission tomography (PET) has been reported as effective in diagnosing peripheral nerve injury (PNI). However, there is a lack of studies evaluating different degrees of PNI using PET within the same individual to reduce errors due to interindividual differences. PURPOSE: To evaluate the recovery process in the same rat after sciatic nerve injury using PET/magnetic resonance imaging (MRI). MATERIAL AND METHODS: Crushing nerve injuries were induced in the left sciatic nerves of six male rats, preserving the right ones. The degree of nerve damage was measured at one, two, three, four, and five weeks postoperatively using three assessment methods: paw withdrawal threshold test (RevWT); PET (SUVR); and MRI (MRSIR). All the representing values of each method are presented as ratio values of the right and left sides in each rat. RESULTS: Significant gradual recovery of all rats was observed over time in all the methods. No significant differences in RevWT and MRSIR were observed between before and more than four weeks after injury, whereas a significant difference in SUVR was still observed between before and five weeks after injury (P = 0.0007). The parameters of all methods decreased significantly over time (P = 0.000, all), and the explanatory power was significant in RevWT, SUVR, and MRSIR. CONCLUSION: PET and MRI could be valuable non-invasive techniques for diagnosing neuropathic pain resulting from PNI. PET/MRI would be expected to be a more accurate and informative diagnostic tool for PNI than MRI alone.

A near-infrared AIE fluorescent probe for myelin imaging: From sciatic nerve to the optically cleared brain tissue in 3D.

Myelin, the structure that surrounds and insulates neuronal axons, is an important component of the central nervous system. The visualization of the myelinated fibers in brain tissues can largely facilitate the diagnosis of myelin-related diseases and understand how the brain functions. However, the most widely used fluorescent probes for myelin visualization, such as Vybrant DiD and FluoroMyelin, have strong background staining, low-staining contrast, and low brightness. These drawbacks may originate from their self-quenching properties and greatly limit their applications in three-dimensional (3D) imaging and myelin tracing. Chemical probes for the fluorescence imaging of myelin in 3D, especially in optically cleared tissue, are highly desirable but rarely reported. We herein developed a near-infrared aggregation-induced emission (AIE)-active probe, PM-ML, for high-performance myelin imaging. PM-ML is plasma membrane targeting with good photostability. It could specifically label myelinated fibers in teased sciatic nerves and mouse brain tissues with a high-signal-to-background ratio. PM-ML could be used for 3D visualization of myelin sheaths, myelinated fibers, and fascicles with high-penetration depth. The staining is compatible with different brain tissue-clearing methods, such as ClearT and ClearT2 The utility of PM-ML staining in demyelinating disease studies was demonstrated using the mouse model of multiple sclerosis. Together, this work provides an important tool for high-quality myelin visualization across scales, which may greatly contribute to the study of myelin-related diseases.

In-Vivo MRI in Rodents: A Protocol for Optimal Animal Positioning.

ABSTRACT: Magnetic resonance imaging (MRI) is a potentially powerful novel peripheral nerve diagnosis technique. To determine its validity, in-vivo preclinical studies are necessary. However, when using a rodent model, positioning rats and achieving high-resolution images can be challenging. We present a short report that outlines an optimal protocol for positioning rats for in-vivo MRI acquisition. Female Sprague-Dawley rats with sciatic nerve injury were induced into anesthesia using 4% isoflurane in oxygen and maintained at 1.5%. Rats were placed into a plexiglass cradle in a right lateral recumbent position, and a surface coil was placed over the left leg. Respiration rate and body temperature were monitored throughout the scan. Our protocol was successful as rats were able to undergo MRI scanning safely and efficiently. There were no adverse reactions, and clear images of the left sciatic nerve were obtained. Animal positioning took 30 minutes, and 5 different acquisitions were obtained in 2 hours. The total time from anesthesia induction to recovery was under 3 hours. Given the increasing interest in MRI diagnostic techniques, we hope this report aids other researchers studying peripheral nerve injury imaging in rat models.

Myxofibrosarcoma involving the sciatic nerve: From ultrasonography to histopathology.

Myxofibrosarcoma (MFS) is a unique soft tissue (fibroblastic) sarcoma, characterized by malignant with a locally infiltrative behavior. In this case image, we aimed to report an uncommon/challenging scenario of MFS involving the scatic nerve in which the potential contribution of ultrasound examination has been touched upon.

Ultrasound-Guided Popliteal Sciatic Nerve Block: A Minimally Invasive Method for Pain Control During Endovascular Treatment of Critical Limb Ischemia.

PURPOSE: To evaluate the safety and effectiveness of ultrasound-guided popliteal sciatic nerve block (PSNB) for pain control in endovascular treatment of critical limb ischemia (CLI). MATERIALS AND METHODS: This retrospective study included 252 patients who underwent endovascular treatment for CLI between January 2020 and August 2022. Of these, 69 patients underwent PSNB, whereas moderate procedural sedation and analgesia was delivered in 183 patients. Pain scores were assessed using the visual analog scale (VAS) before and during the intervention. Technical and clinical success of PSNB, duration of the procedure, time to onset of nerve block, time for block resolution, and adverse events were recorded. Patient and operator satisfaction were assessed using the Likert scale. RESULTS: All PSNB procedures were technically and clinically successful, and the mean procedural duration of PSNB was 5.0 minutes ± 0.8 (range, 4-7 minutes). Prolonged effect of PSNB was observed in 3 patients, which resolved within 24 hours. No adverse events were encountered. Median VAS score was significantly lower in the PSNB group than in the moderate procedural sedation and analgesia group during endovascular treatment (0 [range, 0-2] vs 3 [range, 0-7]; P < .001). Patient satisfaction was comparable ("very satisfied" in 66 [95.7%] vs 161 [88.0%]; P = .069). However, operator satisfaction was significantly higher in the PSNB group ("very satisfied" in 69 [100%] vs 161 [88.0%]; P = .003). CONCLUSIONS: PSNB is safe and effective for pain control during endovascular treatment of CLI. Low adverse event rates with high patient and operator satisfaction make PSNB a reasonable alternative for high-risk patients.

Ultrasound guided transgluteal sciatic nerve hydrodissection for the treatment of acute sciatica in the emergency department.

Radicular pain due to sciatica is a common occurrence with a lifetime incidence of up to 40%. Typical approaches to treatment vary and may include topical and oral analgesics, such as opioids, acetaminophen, and non-steroidal anti-inflammatory drugs (NSAIDs); however, these medications may be contraindicated in some or result in untoward effects in others. The use of ultrasound-guided regional anesthesia is an important component of multimodal analgesia in the emergency department. Transgluteal sciatic nerve block has been described as an effective method to treat patients with sciatica but carries risk of injury and falls due to its resultant loss of motor function and potential for systemic toxicity when higher volumes are used. Ultrasound-guided peripheral nerve hydrodissection with D5W has been shown to be an effective treatment of various compressive neuropathies in the outpatient setting. Here we present 4 cases of patients who presented to the emergency department with severe acute sciatica and were treated successfully using an ultrasound guided transgluteal sciatic nerve hydrodissection (TSNH). This technique may offer a safe and effective approach to treating patients with sciatica, but more studies are needed to assess its utility on a larger scale.

Novel use of ultrasound-guided transgluteal sciatic nerve block to treat severe herpes zoster pain along the S1 dermatome.

Patients presenting with herpes zoster (HZ) to emergency departments (EDs) across the United States represent a significant number of visits and have pain that is difficult to manage, sometimes even requiring opioid medications for adequate analgesia. Ultrasound-guided nerve blocks (UGNBs) are becoming more integrated into the ED physician's tool box for a multimodal approach to analgesia in various indications. Here we describe a novel use of the transgluteal sciatic UGNB for treatment of HZ pain along the S1 dermatome. A 48-year-old woman presented to the ED with right-sided leg pain associated with a HZ rash. After initially failing non-opioid pain management, the ED physician performed a transgluteal sciatic UGNB for our patient, leading to successful complete resolution of her pain, with no adverse effects reported. Our case highlights the potential role of using the transgluteal sciatic UGNB for analgesia related to HZ-related pain, as well as its potential opioid-sparing benefits. Although UGNBs require a baseline understanding of ultrasound technique for procedural guidance, this skillset has recently been incorporated as core competency within emergency medicine training in the United States. UGNBs should therefore be considered in the multimodal analgesic armamentarium for the ED treatment of HZ pain.

The effect of warming ropivacaine on ultrasound-guided subgluteal sciatic nerve block: a randomized controlled trial.

BACKGROUND: There is a long latent period for the sciatic nerve block before a satisfactory block is attained. Changes in the temperature of local anesthetics may influence the characters of the peripheral nerve block. This study was designed to evaluate the effect of warming ropivacaine on the ultrasound-guided subgluteal sciatic nerve block. METHODS: Fifty-four patients for distal lower limbs surgery were randomly allocated into warming group (group W, n = 27) or room tempeture group (group R, n = 27) with the ultrasound-guided subgluteal sciatic nerve block. The group W received 30 ml of ropivacaine 0.5% at 30℃ and the group R received 30 ml of ropivacaine 0.5% at 23℃. The sensory and motor blockade were assessed every 2 min for 30 min after injection. The primary outcome was the onset time of limb sensory blockade. RESULTS: The onset time of sensory blockade was shorter in group W than in group R (16 (16,18) min vs 22 (20,23) min, p < 0.001), and the onset time of motor blockade was also shorter in group W than in group R (22 (20,24) min vs 26 (24,28) min, p < 0.001). The onset time of sensory blockade for each nerve was shorter in group W than in group R (p < 0.001). No obvious differences for the duration of sensory and motor blockade and the patient satisfaction were discovered between both groups. No complications associated with nerve block were observed 2 days after surgery. CONCLUSIONS: Warming ropivacaine 0.5% to 30℃ accelerates the onset time of sensory and motor blockade in the ultrasound-guided subgluteal sciatic nerve block and it has no influence on the duration of sensory and motor blockade. TRIAL REGISTRATION: The trial was registered on October 3, 2022 in the Chinese Clinical Trial Registry ( https://www.chictr.org.cn/bin/project/edit?pid=181104 ), registration number ChiCTR2200064350 (03/10/2022).

yippee like 3 (ypel3) is a novel gene required for myelinating and perineurial glia development.

Hypomyelination, a neurological condition characterized by decreased production of myelin sheets by glial cells, often has no known etiology. Elucidating the genetic causes of hypomyelination provides a better understanding of myelination, as well as means to diagnose, council, and treat patients. Here, we present evidence that YIPPEE LIKE 3 (YPEL3), a gene whose developmental role was previously unknown, is required for central and peripheral glial cell development. We identified a child with a constellation of clinical features including cerebral hypomyelination, abnormal peripheral nerve conduction, hypotonia, areflexia, and hypertrophic peripheral nerves. Exome and genome sequencing revealed a de novo mutation that creates a frameshift in the open reading frame of YPEL3, leading to an early stop codon. We used zebrafish as a model system to validate that YPEL3 mutations are causative of neuropathy. We found that ypel3 is expressed in the zebrafish central and peripheral nervous system. Using CRISPR/Cas9 technology, we created zebrafish mutants carrying a genomic lesion similar to that of the patient. Our analysis revealed that Ypel3 is required for development of oligodendrocyte precursor cells, timely exit of the perineurial glial precursors from the central nervous system (CNS), formation of the perineurium, and Schwann cell maturation. Consistent with these observations, zebrafish ypel3 mutants have metabolomic signatures characteristic of oligodendrocyte and Schwann cell differentiation defects, show decreased levels of Myelin basic protein in the central and peripheral nervous system, and develop defasciculated peripheral nerves. Locomotion defects were observed in adult zebrafish ypel3 mutants. These studies demonstrate that Ypel3 is a novel gene required for perineurial cell development and glial myelination.

Ultrasound Imaging of the Sciatic Nerve.

The sciatic nerve (SN) is the biggest nerve in the human body and innervates a large skin surface of the lower limb and several muscles of the thigh, leg, and foot. It originates from the ventral rami of spinal nerves L4 through S3 and contains fibers from both the posterior and anterior divisions of the lumbosacral plexus. After leaving the neural foramina, the nerve roots merge with each other forming a single peripheral nerve that travels within the pelvis and thigh. Non-discogenic pathologies of the SN are largely underdiagnosed entities due to nonspecific clinical tests and poorly described imaging findings. Likewise, to the best of our knowledge, a step-by-step ultrasound protocol to assess the SN is lacking in the pertinent literature. In this sense, the aim of the present manuscript is to describe the normal sono-anatomy of the SN from the greater sciatic foramen to the proximal thigh proposing a standardized and simple sonographic protocol. Then, based on the clinical experience of the authors, a few tips and tricks have been reported to avoid misinterpretation of confounding sonographic findings. Last but not least, we report some common pathological conditions encountered in daily practice with the main purpose of making physicians more confident regarding the sonographic "navigation" of a complex anatomical site and optimizing the diagnosis and management of non-discogenic neuropathies of the SN.

Schwannomatosis of the sciatic nerve: a case report.

Schwannomas are one of the most common peripheral nerve sheath neoplasms. These tumors, which are characteristically slow-growing and encapsulated, can occur in solitary or multiple forms. Although they usually occur sporadically, they can be seen with various genetic tumor predisposition syndromes such as neurofibromatosis type 2 (NF-2) or schwannomatosis. However, schwannomatosis is a relatively rare disease. We present a case of a 22-year-old patient with segmental schwannomatosis of the sciatic nerve and a comprehensive literature review.

Contrast-enhanced ultrasonography for evaluation of the blood perfusion of sciatic nerves in healthy dogs.

Blood supply to the peripheral nerves is essential for fulfilling their structural and functional requirements. This prospective, experimental, exploratory study aimed to assess the feasibility of contrast-enhanced ultrasonography (CEUS) for evaluating blood perfusion of the sciatic nerve in normal dogs. Contrast-enhanced ultrasonography examinations were performed on the bilateral sciatic nerves after bolus injection of Sonazoid™ (0.015 mL/kg) in 12 healthy Beagles for 150 s. Then, qualitative assessment of the wash-in timing, degree and enhancement patterns, and quantitative measurement of the peak intensity and time to peak intensity were performed from the sciatic nerve. The results were compared to those obtained from the adductor muscle around the nerve and caudal gluteal artery. After contrast agent injection, the sciatic nerve was enhanced at approximately 13-14 s, immediately after wash-in of the caudal gluteal artery. The peak intensity of the sciatic nerve was significantly lower than that of the caudal gluteal artery and higher than that of the adductor muscle. The time to peak intensity was significantly slower than that of the caudal gluteal artery; but was not significantly different from that of the adductor muscle. There were no significant differences in the peak intensity and time to peak intensity between the left and right sciatic nerves. These results demonstrate the feasibility of CEUS to assess blood perfusion of the sciatic nerve in healthy dogs qualitatively and quantitatively. This result from healthy dogs could serve as a reference for further studies that evaluate the sciatic nerve under pathological conditions.

Feasibility of simultaneous high-resolution anatomical and quantitative magnetic resonance imaging of sciatic nerves in patients with Charcot-Marie-Tooth type 1A (CMT1A) at 7T.

INTRODUCTION/AIMS: Magnetic resonance imaging (MRI) of peripheral nerves can provide image-based anatomical information and quantitative measurement. The aim of this pilot study was to investigate the feasibility of high-resolution anatomical and quantitative MRI assessment of sciatic nerve fascicles in patients with Charcot-Marie-Tooth (CMT) 1A using 7T field strength. METHODS: Six patients with CMT1A underwent imaging on a high-gradient 7T MRI scanner using a 28-channel knee coil. Two high-resolution axial images were simultaneously acquired using a quantitative double-echo in steady-state (DESS) sequence. By comparing the two DESS echoes, T2 and apparent diffusion coefficient (ADC) maps were calculated. The cross-sectional areas and mean T2 and ADC were measured in individual fascicles of the tibial and fibular (peroneal) portions of the sciatic nerve at its bifurcation and 10 mm distally. Disease severity was measured using Charcot-Marie-Tooth Examination Score (CMTES) version 2 and compared to imaging findings. RESULTS: We demonstrated the feasibility of 7T MRI of the proximal sciatic nerve in patients with CMT1A. Using the higher field, it was possible to measure individual bundles in the tibial and fibular divisions of the sciatic nerve. There was no apparent correlation between diffusion measures and disease severity in this small cohort. DISCUSSION: This pilot study indicated that high-resolution MRI that allows for combined anatomical and quantitative imaging in one scan is feasible at 7T field strengths and can be used to investigate the microstructure of individual nerve fascicles.

Proximal nerve MR neurography with diffusion tensor imaging in differentiating subtypes of Charcot-Marie-Tooth disease.

OBJECTIVES: To evaluate the feasibility of proximal nerve MR neurography with diffusion tensor imaging (DTI) for differentiating Charcot-Marie-Tooth (CMT) 1A, CMT2, and healthy controls. METHODS: The diameters, fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) of L4-L5 nerve roots, femoral nerve (FN), and sciatic nerve (SN) were compared. Receiver operating characteristic (ROC) curve analyses were conducted to evaluate the diagnostic performance. DeLong's tests were applied to compare multiple ROC curves. Intraclass correlation coefficients were calculated for interobserver agreement assessment. RESULTS: The diameters of the L4 nerve root, L5 nerve root, and SN of CMT1A patients were significantly larger than those of CMT2 patients and healthy controls. The FA values of all measured proximal nerves were significantly higher in controls (0.46 ± 0.09, 0.46 ± 0.08, 0.45 ± 0.07, and 0.48 ± 0.08) than in CMT1A patients (0.30 ± 0.09, 0.29 ± 0.06, 0.35 ± 0.08, and 0.29 ± 0.09). The FA values of the L5 nerve root, FN, and SN were significantly higher in controls (0.46 ± 0.08, 0.45 ± 0.07, and 0.48 ± 0.08) than in CMT2 patients (0.36 ± 0.06, 0.34 ± 0.07, and 0.34 ± 0.10). The MD and RD values of the L5 nerve root in CMT1A patients (1.59 ± 0.21 and 1.37 ± 0.21) were higher than those in CMT2 patients (1.31 ± 0.17 and 1.05 ± 0.14). The AUCs of the above parameters ranged from 0.780 to 1.000. For the measurements of nerve diameters, the ICC ranged from 0.91 to 0.97. For the measurements of DTI metrics, the ICC ranged from 0.87 to 0.97. CONCLUSIONS: MR neurography with DTI is able to differentiate CMT1A patients, CMT2 patients, and healthy controls. KEY POINTS: • MR neurography with diffusion tensor imaging of the L4-5 nerve roots, proximal femoral nerve, and proximal sciatic nerve is able to discriminate CMT1A, CMT2, and healthy controls. • This method provides an alternative for the diagnosis and discrimination of CMT1A and CMT2, which is crucial for clinical management.

Ultrasound-Guided Subgluteal Sciatic Nerve Block for Pain Management during Endovascular Treatment for Below-the-Knee Arterial Occlusions.

PURPOSE: To evaluate the ability of subgluteal sciatic nerve block (SSNB) to provide pain control during endovascular treatment of below-the-knee (BTK) occlusions. MATERIALS AND METHODS: This randomized prospective controlled study evaluated 60 consecutive adult patients who underwent endovascular treatment for BTK occlusions. The patients were randomized into 2 equal groups; the SSNB group underwent SSNB in the subgluteal space under ultrasound guidance, while the control group received fentanyl as an analgesic. The visual analog scale (VAS) and Face, Legs, Activity, Cry, Consolability (FLACC) scale scores were recorded. RESULTS: Compared with the control group, the SSNB group showed significantly lower median VAS (0 [range, 0-30] vs 70 [range, 20-100], P < .001) and median FLACC scale (0 [range, 0-2] vs 6 [range, 3-10], P < .001) scores. There was no statistically significant difference between the 2 groups regarding the remaining parameters. There was a very strong correlation between the VAS and FLACC scale scores in both the SSNB (r = 0.805, P < .001) and control (r = 0.950, P < .001) groups. The procedure time and total balloon inflation time correlated with the VAS (r = 0.411, P = .024, and r = 0.402, P = .031, respectively) and FLACC scale (r = 0.431, P = .017, and r = 0.414, P = .022, respectively) scores in the control group but not in the SSNB group (r = 0.364, P = .056, and r = 0.300, P =.085, respectively, for correlation with VAS score and r = 0.730, P = .068, and r = 0.704, P = .075, respectively, for correlation with the FLACC scale score). CONCLUSIONS: SSNB is a highly effective and safe pain management modality for the endovascular treatment of BTK occlusions.

Examining the impact perceptual learning artificial-intelligence-based on the incidence of paresthesia when performing the ultrasound-guided popliteal sciatic block: simulation-based randomized study.

OBJECTIVE: To explore the impact of artificial-intelligence perceptual learning when performing the ultrasound-guided popliteal sciatic block. METHODS: This simulation-based randomized study enrolled residents who underwent ultrasound-guided sciatic nerve block training at the Department of Anesthesiology of Beijing Jishuitan Hospital between January 2022 and February 2022. Residents were randomly divided into a traditional teaching group and an AI teaching group. All residents attended the same nerve block theory courses, while those in the AI teaching group participated in training course using an AI-assisted nerve identification system based on a convolutional neural network instead of traditional training. RESULTS: A total of 40 residents were included. The complication rates of paresthesia during puncture in the first month of clinical sciatic nerve block practice after training were significantly lower in the AI teaching group than in the traditional teaching group [11 (4.12%) vs. 36 (14.06%), P = 0.000093]. The rates of paresthesia/pain during injection were significantly lower in the AI teaching group than in the traditional teaching group [6 (2.25%) vs. 17 (6.64%), P = 0.025]. The Assessment Checklist for Ultrasound-Guided Regional Anesthesia (32 ± 3.8 vs. 29.4 ± 3.9, P = 0.001) and nerve block self-rating scores (7.53 ± 1.62 vs. 6.49 ± 1.85, P < 0.001) were significantly higher in the AI teaching group than in the traditional teaching group. There were no significant differences in the remaining indicators. CONCLUSION: The inclusion of an AI-assisted nerve identification system based on convolutional neural network as part of the training program for ultrasound-guided sciatic nerve block via the popliteal approach may reduce the incidence of nerve paresthesia and this might be related to improved perceptual learning. CLINICAL TRIAL: CHiCTR2200055115 , registered on 1/ January /2022.

Magnetic resonance imaging study of the sciatic nerve variation in the pediatric gluteal region: Implications for the posterior approach of the sciatic nerve blockade.

INTRODUCTION: In pediatric patients, the sciatic nerve is one of the most commonly blocked peripheral nerves during orthopedic procedures of the lower limb. Ultrasound guidance is the current standard for a successful localization of the sciatic nerve in the gluteal region. Relevant anatomical landmarks are also used to determine the nerve location when ultrasound is not available or inadequate. However, reports have demonstrated paucity of information regarding the sciatic nerve location and variation in the hip throughout pediatric development. This imaging study aimed to document and analyze the relative morphometric relationship of the sciatic nerve in the pediatric gluteal region throughout development. METHODS: The location of the sciatic nerve in relation to bony landmarks was measured in 84 pediatric magnetic resonance imaging of patients aged 0.7-15.8 years. RESULTS: The sciatic nerve was identified medial to the most lateral point of greater trochanter at the level of ischial spine and the tip of coccyx. The strong positive correlation between sciatic nerve to landmark distances and age and stature demonstrated linear variation between sciatic nerve location with age and growth of children. To predict the nerve location in the gluteal region, regression equations using patient age were created, having implications for the posterior approach of the sciatic nerve blockade in children. Clinically significant differences were found between sexes, specifically in the older age group. CONCLUSION: Despite the small sample size of younger age group, this study is the first to document the morphometric changes of the sciatic nerve in the gluteal region across pediatric development and may be useful for providing confirmatory guidelines for nerve location when ultrasound is not accessible or cannot be utilized for practice.