Ultrasound guided costoclavicular block in pediatric population: A prospective observational study.

BACKGROUND: The costoclavicular space serves as an alternative approach to the infraclavicular brachial plexus block, and numerous studies in adults have demonstrated promising outcomes for distal upper limb surgery. Blocking the brachial plexus at this level is potentially advantageous because the cords are relatively superficial, located in close proximity to each other and easily identified using ultrasound. AIMS: This study aimed to assess the success rate and feasibility of costoclavicular block in children undergoing unilateral below elbow upper limb surgery. METHODS: Thirty children aged 2-12 years scheduled for unilateral below elbow surgery under general anesthesia were included. Costoclavicular block was performed under ultrasound and nerve stimulator guidance with 0.5% ropivacaine, 0.5 mL/kg. Success was evaluated based on the absence of significant hemodynamic response to skin incision made 20 min after the block. The sono-anatomy of costoclavicular space, ease of needling, complications, and the post-operative pain scores were assessed. RESULTS: The mean age and weight of the children were 6.5 ± 3.8 years and 19.7 ± 9.1 kg, respectively. The success rate of costoclavicular block in our cohort is 100%. Sonographic visualization was graded as excellent (Likert Scale 2) in 90% of cases. The plexus was located at a depth of 1.4 ± 0.3 cm from the skin, the lateral extent of cords from the artery was 0.8 ± 0.4 cm and they were observed inferior and lateral to the artery. The mean needling time was 3.6 ± 1.1 min. None of the children experienced complications such as vascular or pleural puncture, hematoma, Horner's syndrome or diaphragmatic palsy. Postoperative pain scores were low, and no rescue analgesia was required. CONCLUSIONS: In conclusion, the costoclavicular block exhibited a notably high success rate in pediatric population. This study substantiates that the three cords of the brachial plexus are consistently visible and superficial during ultrasound examination using this approach, confirming their separation from vascular structures and the reliable achievement of blockade without observed complications.

Convolutional neural network for brachial plexus segmentation at the interscalene level.

BACKGROUND: Regional anesthesia with ultrasound-guided brachial plexus block is widely used for patients undergoing shoulder and upper limb surgery, but needle misplacement can result in complications. The purpose of this study was to develop and validate a convolutional neural network (CNN) model for segmentation of the brachial plexus at the interscalene level. METHODS: This prospective study included patients who underwent ultrasound-guided brachial plexus block in the Anesthesiology Department of Beijing Jishuitan Hospital between October 2019 and June 2022. A Unet semantic segmentation model was developed to train the CNN to identify the brachial plexus features in the ultrasound images. The degree of overlap between the predicted segmentation and ground truth segmentation (manually drawn by experienced clinicians) was evaluated by calculation of the Dice index and Jaccard index. RESULTS: The final analysis included 502 images from 127 patients aged 41 ± 14 years-old (72 men, 56.7%). The mean Dice index was 0.748 ± 0.190, which was extremely close to the threshold level of 0.75 for good overlap between the predicted and ground truth segregations. The Jaccard index was 0.630 ± 0.213, which exceeded the threshold value of 0.5 for a good overlap. CONCLUSION: The CNN performed well at segregating the brachial plexus at the interscalene level. Further development could allow the CNN to be used to facilitate real-time identification of the brachial plexus during interscalene block administration. CLINICAL TRIAL REGISTRATION: The trial was registered prior to patient enrollment at the Chinese Clinical Trial Registry (ChiCTR2200055591), the site url is https://www.chictr.org.cn/ . The date of trial registration and patient enrollment is 14/01/2022.

Fascial plane approach to anesthetizing the radial, median, and ulnar nerves: an educational review.

Brachial plexus block provides effective anesthesia and analgesia for upper extremity surgery but requires injection of large anesthetic volumes near major vascular structures. Moreover, the extensive motor and sensory loss produced by plexus block often exceeds the neural distribution needed for corresponding surgical procedures.High-resolution ultrasound facilitates selective nerve blocks at nearly every level of the upper extremity. We present fascial plane injection techniques for selective radial, median, and ulnar nerve blocks. These techniques can be used to match sensory distribution with specific surgical procedures. They are performed using low anesthetic volumes and without proximity to nerves or vascular structures. In this article, fresh cadaver dissections with corresponding ultrasound images are used to demonstrate stepwise fascial plane techniques for the radial, median, and ulnar nerves. These techniques are performed using familiar anatomic landmarks.Practical applications of these techniques are demonstrated for commonly performed procedures of the upper extremity. Corresponding injection volumes with duration of postoperative analgesia are presented. Selected injections are described for both surgical anesthesia and postoperative analgesia.Selective fascial plane injections can provide surgical anesthesia and postoperative analgesia in settings that might otherwise require much larger volumes of local anesthetic. These selective nerve blocks can match sensory loss with the anatomic pain distribution in each patient. Reliable techniques for selective nerve blocks of the upper extremity can expand the capabilities for ultrasound-guided regional anesthesia.

Diagnosis of obstetric brachial plexus injury in a 2-year-old girl using high­frequency ultrasonography.

We describe an unusual case of infant obstetric brachial plexus injury located in the cervical (C)5-C6 brachial plexus nerve, which was preoperatively diagnosed using high-frequency ultrasonography (US) at 2 years of age. The girl was diagnosed with a right clavicular fracture because of shoulder dystocia. She had been showing movement limitations of her entire right upper limb after fracture healing and was then referred to our hospital at 2 years of age. High-frequency US showed that the roots of the right brachial plexus ran continuously, but the diameter of C6 was thinner on the affected side than on the contralateral side (right 0.12 cm vs. left 0.20 cm). A traumatic neuroma had formed at the upper trunk, which was thicker (diameter: right 0.35 cm vs. left 0.23 cm; cross-sectional area: right 0.65 cm2 vs. left 0.31 cm2) at the level of the supraclavicular fossa. Intraoperative findings were consistent with ultrasound findings. Postoperative pathology confirmed brachial plexus traumatic neuroma.

Thoracic Outlet Syndrome Caused by a Primary Tumour in the Brachial Plexus.

Thoracic outlet syndrome (TOS) caused by a primary brachial plexus tumour is very rare. A male politician in his 40s presented with numbness, left limb pain and positive Wright and Roos test results. Magnetic resonance imaging (MRI) revealed a tumour located just below the clavicle, compressing the subclavian artery during left arm elevation. Despite concerns regarding postoperative nerve deficits, surgery was performed because of worsening symptoms during the election campaigns. The pathology report revealed a schwannoma. Few reports have described TOS caused by primary tumours of the brachial plexus. While the decision to perform surgery for primary tumours of the brachial plexus requires careful consideration, surgery may be indicated in cases where the tumour location causes such symptoms. Level of Evidence: Level V (Therapeutic).

The value of the cinematic volume rendering technique: magnetic resonance imaging in diagnosing tumors associated with the brachial plexus.

PURPOSE: To examine the diagnostic advantages and clinical application value of the cinematic volume rendering technique (cVRT) when evaluating the relationship between the brachial plexus, peripheral tumor lesions, and blood vessels. MATERIALS AND METHODS: Seventy-nine patients with brachial plexus tumors between November 2012 and July 2022 were enrolled in our study. All patients underwent T1WI, T2WI, three-dimensional short recovery time reversal recovery fast spin-echo imaging (3D-STIR-SPACE), and the T1WI enhancement sequence. In addition, cVRT was used to render and obtain a three-dimensional model that clearly showed the location and tissue structure of the brachial plexus nerves and the tumor in all directions. RESULTS: Seventy-one patients (mean age, 47.1 years; 33 males, 38 females) with tumors around the brachial plexus were included in the study. The brachial plexus nerve, surrounding tumor lesions, and vascular anatomy of all patients were well displayed with cVRT. The tumors of 37 patients manifested as unilateral or bilateral growths along the brachial plexus nerve and were fusiform, spherical, or multiple beaded; seven patients' tumors pushed against the brachial plexus nerve and were circular, lobular, or irregular; sixteen patients' tumors encircled the brachial plexus nerve and were spherical; and eleven patients' tumors infiltrated the brachial plexus nerve and had irregular morphology. The mass has a moderately uniform or uneven signal on T1WI and a high or mixed signal on T2WI. After enhancement, the signal was evenly or unevenly strengthened. CONCLUSIONS: cVRT clearly showed the origin of tumors associated with the brachial plexus and their relationship with the nerves and peripheral blood vessels, providing reliable information for clinical diagnosis and treatment.

Myxofibrosarcoma involving brachial plexus diagnoses by contrast-enhanced ultrasound: A case report.

RATIONALE: Myxofibrosarcoma most commonly arises as a slowly enlarging, painless mass. We describe an unusual case of low-grade myxofibrosarcoma in the axillary fossa, which infiltrated the brachial plexus, axillary artery, and axillary vein, causing severe pain. The low incidence and complex anatomical structure make imaging examination and surgery face great challenges. To the best of our knowledge, such presentation of a low-grade myxofibrosarcoma that showed an extreme infiltrative growth pattern and presented severe pain has not been reported before. PATIENT CONCERNS: We reported a case of low-grade myxofibrosarcoma developed around the axillary neurovascular bundle, with multiple peripheral metastases in an 87-year-old male. Physical examination revealed a mass on the right axillary fossa measuring 5 × 4 cm. The patient underwent computed tomography but no definite diagnosis was obtained. Because he had claustrophobia and could not perform MRI examination. Thus, he underwent conventional ultrasound and contrast-enhanced ultrasound. Ultrasonic examination not only accurately determines the invasion scope of the tumor, but also clearly shows that the nerve has suffered from the invasion of the exogenous tumor and multiple metastatic foci around it. The contrast enhancement mode of the tumor showed centripetal high-enhancement, uneven internal enhancement, visible enhanced bridge, and non-enhancing central area. DIAGNOSES: Combined with the results of conventional ultrasound and contrast-enhanced ultrasound, we highly suspected it to be soft tissue sarcoma, giving strong clinical assistance. INTERVENTIONS: Given the risk of sarcoma implantation along the needle track and the underestimation of tumor malignancy, an excisional biopsy was considered the most practical choice to avoid unnecessary pain and potential implantation. OUTCOMES: The patient underwent surgery and a histopathological examination of the lesion confirmed it as low-grade myxofibrosarcoma. LESSONS SUBSECTIONS: This report describes a rare case of myxofibrosarcoma of the axillary fossa. High-resolution ultrasound is increasingly used for the initial assessment of soft-tissue masses. However, there are few reports about the ultrasound and contrast-enhanced ultrasound examinations of myxofibrosarcoma. Accurate preoperative diagnosis and proper treatment strategies are critical in managing patients with myxofibrosarcoma. Our case may provide diagnosis experiences and will help better understand and treat this disease.

The 90% minimum effective volume of 0.5 ropivacaine for ultrasound-guided supraclavicular brachial plexus block : A biased coin up-and-down design.

BACKGROUND: Ultrasound-guided supraclavicular brachial plexus block is widely used in upper limb surgery; however, it requires a higher dose (20-30 mL) of local anesthetic. In this study, we aimed to determine the 90% minimum effective volume for ultrasound-guided supraclavicular brachial plexus block. METHODS: All patients received an ultrasound-guided two-point injection of 0.5% ropivacaine at a starting volume of 0.18 mL/mm2 cross-sectional nerve area. In cases of a successful block, the next patient had the same volume with a probability of 0.89, and the volume was reduced by 0.04 mL/mm2 cross-sectional nerve area with a probability of 0.11. When the block failed, the dose was increased by 0.04 mL/mm2 cross-sectional nerve area. After 45 cases of successful blocks, the 90% minimum effective volume of local anesthetic was calculated using the centered isotonic regression function. RESULTS: Centered isotonic regression analysis resulted in a 90% minimum effective volume and a 95% confidence interval of 0.189 mL/mm2 and 0.176-0.225 mL/mm2 for the supraclavicular brachial plexus block. CONCLUSION: A good blocking effect can be achieved with 0.189 mL/mm2 of 0.5% ropivacaine with more precise dosing, thereby reducing the risk of local anesthetic poisoning.

Evaluation of brachial plexus stiffness in different arm and head positions by sonoelastography.

Intraoperative positioning-related nerve injuries, particularly those affecting the brachial plexus, are concerning complications believed to arise from stretching and/or compression of peripheral nerves. Although sonoelastography, a new ultrasound technology, is emerging as a valuable tool in the musculoskeletal system, its utility in evaluating peripheral nerves remains unclear. This study aimed to utilize sonoelastography to assess the brachial plexus during surgery, specifically investigating changes in its stiffness values in relation to different head and arm positions. In this prospective cohort study, bilateral brachial plexuses of 8 volunteers in 3 different positions were enrolled. Using a high-frequency linear probe, the stiffness of the brachial plexus was quantitatively measured in kilopascals (kPa) under 3 different positions: neutral, head rotated, and head rotated with arm hyperabducted. Intra-class agreement was evaluated. The stiffness of the brachial plexus was 7.39 kPa in the neutral position (NP), 10.28 kPa with head rotation, and 17.24 kPa when the head was turned, and the ipsilateral arm was hyperabducted. Significant increases were observed in stiffness values when the head was turned, whether ipsilaterally or contralaterally, and during hyperabduction of the arm while the head was turned (for all P < .001). Strong intra-class correlations were found for the measurements of stiffness values (ICC = 0.988-0.989; P < .001; Cronbach Alpha = 0.987-0.989). Sonoelastography revealed significant increases in the stiffness of the brachial plexus with various head rotations and arm positions compared to the neutral state. These findings suggest that sonoelastography could potentially serve as a valuable tool for assessing the risk of brachial plexus injury during surgery and for guiding optimal patient positioning. Further research with larger sample sizes is needed to establish definitive clinical applications.

Will preoperative combined MRI and high-resolution ultrasonography redefine brachial plexus imaging? A comparative study of preoperative MRI versus combined MRI and high-resolution ultrasonography in assessing usable C5, C6 root-stumps for intra-plexal nerve grafting.

AIM: To compare the intraoperative findings with the preoperative imaging in detecting usable root stumps using magnetic resonance imaging (MRI) alone versus MRI combined with high-resolution ultrasonography (HRUS) in adults undergoing post-traumatic brachial plexus (BP) surgery. Further, when root stumps were present, the reliability of their measurements using both imaging methods was compared to their intraoperative length. MATERIALS AND METHODS: A consecutive group of adults who were planned for post-traumatic BP surgery between July 2015 and April 2016 were evaluated prospectively. They underwent preoperative MRI and HRUS and the agreement (kappa value) between these imaging methods and their intraoperative findings in categorising roots were then compared. When stumps were present, the reliability of the extraforaminal measurements by each method were compared to their corresponding intraoperative stump length using intraclass correlation coefficients (ICC), and Bland-Altman plots. RESULTS: Of the initial 60 patients, 48 patients with 82 roots were included in the study. Greater agreement was observed between HRUS and intraoperative findings in categorising BP root stumps (kappa value 0.70, SE 0.07) versus MRI and intraoperative findings (kappa value 0.42, SE 0.07). Similarly, there was a higher correlation between HRUS and intraoperative findings (ICC: 0.94, p<0.001) than that of MRI and intraoperative findings (ICC: 0.53, p<0.001) regarding stump length measurements. CONCLUSION: Combining HRUS with MRI in the preoperative imaging of the adult BP injury can better predict the presence of usable nerve root stumps for intra-plexal nerve grafting. HRUS also gave reliable preoperative stump length measurements, and it was determined that a stump should be at least 1.3 cm to be deemed usable for nerve grafting.

Diagnosis of thoracic outlet syndrome with the lower trunk compression of brachial plexus by high-frequency ultrasonography.

BACKGROUND: Thoracic outlet syndrome (TOS) with the lower trunk compression of brachial plexus (BP) is difficult to diagnosis. This study aimed to summarize the features of thoracic outlet syndrome (TOS) with the lower trunk compression of brachial plexus observed on high-frequency ultrasonography (HFUS). METHODS: The ultrasound data of 27 patients who had TOS with the lower trunk compression of brachial plexus were collected and eventually confirmed by surgery. The imaging data were compared, and the pathogenesis of TOS was analyzed on the basis of surgical data. RESULTS: TOS occurred predominantly in females (70.4%). Most cases had unilateral involvement (92.6%), mainly on the right side (66.7%). The HFUS features of TOS can be summarized as follows: (1) Lower trunk compression. HFUS revealed focal thinning that reflected compression at the level of the lower trunk; furthermore, the distal part of the nerve was thickened for edema (Affected side: 0.49 ± 0.12 cm vs. Healthy side: 0.38 ± 0.06, P = 0.009), and the cross-sectional area of brachial plexus cords was markedly greater on the injured side than on the healthy side (0.95 ± 0.08 cm² vs. 0.65 ± 0.11 cm², P = 0.004). (2) Hyperechoic fibromuscular bands behind the compressed nerve (mostly the scalenus minimus muscle). (3) Abnormal bony structures: cervical ribs or elongated transverse processes of the 7th cervical vertebra (C7). Surgical results showed that the etiological factors contributing to TOS were (1) muscle hypertrophy and/or fibrosis (100%) and (2) cervical ribs/elongated C7 transverse processes (20.7%). CONCLUSION: TOS with the lower trunk compression of brachial plexus can be diagnosed accurately and reliably by high-frequency ultrasound.

Ultrasound-Guided Perineural Vitamin B12 Injection for Brachial Plexus Injury: A Preliminary Study.

Individuals with brachial plexus injury (BPI) require upper limb function restoration, but the treatment remains controversial. Vitamin B12 may aid in pain control and nerve regeneration. We present the technical aspects of ultrasound-guided perineural vitamin B12 injection for BPI. The demonstrative case is a 50-year-old man with BPI resulting from a traffic accident. Under ultrasound guidance, vitamin B12 was injected precisely into the brachial plexus compartment around the swollen neuroma of the C6 root. Motor and sensory functions of the left upper extremity improved over 6 months. Ultrasound-guided perineural vitamin B12 injection may be an efficient and personalized intervention in cases of post-ganglionic BPI that failed to improve in the first 3 months.

Ultrasound-guided brachial plexus nerve block in a patient with a left palmar schwannoma: A case report.

RATIONALE: Ultrasound-guided brachial plexus block is a common anesthetic procedure used in upper extremity surgery. However, it may not be a suitable option for some patients. PATIENT CONCERNS: A 17-year-old woman with the left palmar schwannoma scheduled for surgical treatment received ultrasound-guided brachial plexus block. The anesthesia modalities of the disease were discussed. DIAGNOSES: Based on the patient's complaints and clinical appearance, provisional diagnosis of neurofibroma was considered. INTERVENTIONS: In this case, we present a case of ultrasound-guided axillary brachial plexus block used for upper extremity surgery in this patient. It was not easily and painlessly reduced in the surgery, although the visual analogue scale score was 0 and no motor movements of the left arm and palm were observed. The pain was relieved by intravenous injection of 50 mcg remifentanil. OUTCOMES: Immunohistochemically labeled pathological examination confirmed the mass to be a schwannoma. There was no need to apply additional analgesia after surgery, although the patient felt numbness in the left thumb for 3 days follow up. LESSONS: Even if there is painless when skin-cutting after implementation of brachial plexus block, the patient is painful when pulls the nerve around the tumor during excision. It is necessary to give an analgesic drug or anesthetize a single terminal nerve as a supplement for brachial plexus block in patients with schwannoma.

The role of computed tomography and magnetic resonance imaging in surgical planning for thoracic outlet syndrome: the experience of a single third level reference center for peripheral nerve surgery.

OBJECTIVE: Anatomical abnormalities in the thoracic outlet syndrome are very frequent, but radiological images are not always reliable. Therefore, the different features and abilities of CT angiogram and brachial plexus MRI to detect anatomical abnormalities have been investigated. METHODS: All radiological and surgical records of patients operated for thoracic outlet syndrome between January 2011 and December 2018 were retrospectively analyzed. Considering the CT angiogram and/or brachial plexus MRI reports of the preoperative period, the performance of these investigations was evaluated by calculating the precision (P), sensitivity (Recall) and Hamming loss (L). RESULTS: From a total of 107 patients screened, 84 were eligible for study inclusion. Out of these, 46 had surgical abnormalities (group 1), while 38 did not (group 2). Among them, 30 patients have performed CT angiogram (subgroup A), 32 brachial plexus MRI (subgroup B) and 22 both (subgroup C). The best result is obtained when both diagnostic examinations are performed (subgroup C: P = 0.62; recall = 0.52; L = 0.038). CONCLUSIONS: Prescribing both investigations in selected patients increases the probability of finding anatomic anomalies and facilitates preoperative planning. However, as the radiological images are not completely exhaustive, the surgeon should always actively search and remove any potential source of compression on the nervous vascular bundle along the thoracic outlet.

Comparison of the anesthesia effect of ultrasound-guided middle and low interscalene brachial plexus block: a randomized, controlled, non-inferiority trial.

BACKGROUND: Ultrasound-guided low interscalene brachial plexus block (LISB) can provide satisfactory anesthesia for surgery at or below the elbow. However, the anesthesia effect of ultrasound-guided middle interscalene brachial plexus block (MISB) has not been fully investigated. We hypothesized that MISB provides a non-inferior anesthesia effect to LISB for surgery at or below the elbow. METHODS: A total of 82 patients with ASA I-III (18-65 years) scheduled for elective surgery at or below the elbow were randomized to the MISB group or the LISB group equally, located 1/2 or 2/3 of the caudal distance from C6 to the clavicle. Both groups were administered 15 mL 0.5% ropivacaine at the lower part of the brachial plexus with the first injection and equivalent volume at the upper part with the second injection. RESULTS: For the primary outcome, 92.3% in the MISB group experienced successful anesthesia compared to 94.6% in the LISB group [difference: -2.3%, 95% confidence interval (CI) -13.4% to 8.8%], exceeding the predefined non-inferiority margin -15%. For the secondary outcomes, the incidence of pleura suppression for the first injection (7.7% vs. 45.9%, P < 0.001) and the time to perform the block (9.9 ± 1.3 vs. 10.7 ± 1.3 min, P = 0.006) were significantly less in MISB compared to LISB. No significant differences were observed in the consumption of perioperative rescue analgesics, VAS score, and adverse events within the two groups. CONCLUSIONS: MISB provides a non-inferior anesthesia effect to LISB for surgery at or below the elbow. TRIAL REGISTRATION: Chinese Clinical Trial Register (identifier: ChiCTR2100054196).

Comparison of ultrasound-guided supraclavicular and costoclavicular brachial plexus blocks in pediatric patients: a randomized clinical trial.

PURPOSE: Costoclavicular brachial plexus block has been described recently as a new technique in adults and pediatric patients. In this study, we aimed to compare the supraclavicular and costoclavicular approaches, which are claimed to be effective and practical in pediatric patients. METHODS: Sixty children were randomized to receive supraclavicular (SC group) or costoclavicular (CC group) brachial plexus blocks prior to surgical incision. Block performance times were recorded as the primary outcome. Procedural features (ideal brachial plexus cord visualization/needle pathway planning time, needle tip/shaft visualization difficulty, number of needle maneuvers, requirement of extra needle maneuvers due to insufficient local anesthetic distribution) and postoperative pain-related data (sensorimotor block intensities, Wong-Baker and FLACC pain scores and analgesic requirements) were also evaluated. To observe the tendency toward respiratory complications, ultrasonographic diaphragm movement amplitude (with M-mode) and diaphragm thickness (with B-mode) were measured postoperatively. RESULTS: A total of 56 patients were included. Block performance times [70(7-97) vs. 115(75-180) s] were significantly lower in the CC group (p < 0.01). The block success rates did not differ (p > 0.05). The incidence of hemidiaphragm paralysis was 44% in the SC group (p < 0.001), and inspiratory diaphragm thickness was significantly lower (p < 0.01). None of CC group patients experienced hemidiaphragm paralysis. All other parameters were comparable (p > 0.05). CONCLUSIONS: Although costoclavicular block did not show superiority in pain management, the block performance was perceived as more practical than supraclavicular block. We believe that costoclavicular brachial plexus block stands as a good option in upper extremity surgeries with the advantages of shorter block performance time and reduced ipsilateral hemidiaphragm paralysis risk in pediatric patients.

Detailed magnetoelectric analysis of a nerve impulse propagation along the brachial plexus.

OBJECTIVE: To visualize impulse conduction along the brachial plexus through simultaneous electromagnetic measurements. METHODS: Neuromagnetic fields following median nerve stimulation were recorded above the clavicle with a superconducting quantum interference device biomagnetometer system in 7 healthy volunteers. Compound nerve action potentials (CNAPs) were obtained from 12 locations. Pseudocolor maps of equivalent currents reconstructed from magnetic fields and isopotential contour maps were superimposed onto X-ray images. Surface potentials and current waveforms at virtual electrodes along the brachial plexus were compared. RESULTS: In magnetic field analysis, the leading axonal current followed by a trailing backward current traveled rostrally along the brachial plexus. The spatial extent of the longitudinal intra-axonal currents corresponded to the extent of the positive-negative-positive potential field reflecting transmembrane volume currents. The peaks and troughs of the intra-axonal biphasic current waveforms coincided with the zero-crossings of triphasic CNAP waveforms. The amplitudes of CNAPs and current moments were linearly correlated. CONCLUSIONS: Reconstructed neural activity in magnetic field analysis visualizes not only intra-axonal currents, but also transmembrane volume currents, which are in good agreement with the surface potential field. SIGNIFICANCE: Magnetoneurography is a novel non-invasive functional imaging modality for the brachial plexus whose performance can surpass that of electric potential measurement.

Isolated Primary Neurolymphomatosis in the Right Brachial Plexus Proven by Partial Nerve Biopsy.

INTRODUCTION: Isolated primary neurolymphomatosis is a rare manifestation of lymphoma, which is challenging to diagnose as there is only involvement of the nervous system, and nerve biopsy is not frequently pursued due to the high risk of irreversible complications. CASE REPORT: We present a case of isolated primary neurolymphomatosis of diffuse large B-cell lymphoma restricted to only the right brachial plexus and right axillary nerve. The clinical course has been indolent for several years. The initial examination, including MRI and the cerebrospinal fluid study, did not yield any evidence of malignancy. Eventually, due to the patient's symptom progression and the follow-up imaging findings, we conducted a partial nerve biopsy of the brachial plexus to confirm the malignancy. His neurological symptoms did not further deteriorate post-biopsy. CONCLUSION: Isolated primary neurolymphomatosis with an indolent course is rare and challenging to diagnose. Serial MRI and fluorodeoxyglucose-positron emission tomography reveal clues for tumor involvement. Partial nerve biopsy or targeted fascicular nerve biopsy could be an alternative for achieving a pathologic diagnosis.

Application of CUBE-STIR MRI and high-frequency ultrasound in contralateral cervical 7 nerve transfer surgery.

OBJECTIVE: The objective of the study was to investigate the feasibility of CUBE-SITR MRI and high-frequency ultrasound for the structural imaging of the brachial plexus to exclude neoplastic brachial plexopathy or structural variation and measure the lengths of anterior and posterior divisions of the C7 nerve, providing guidelines for surgeons before contralateral cervical 7 nerve transfer. METHODS: A total of 30 patients with CNS and 20 with brachial plexus injury were enrolled in this retrospective study. All patients underwent brachial plexus CUBE-STIR MRI and high-frequency ultrasound, and the lengths of the anterior and posterior divisions of C7 nerve were measured before surgery. Precise length of anterior and posterior divisions of contralateral C7 nerve was measured during surgery. RESULTS: MRI-measured lengths of anterior and posterior divisions of C7 nerves were positively correlated with that measured during surgery (anterior division, r = 0.94, p < .01; posterior division, r = 0.92, p < .01). High agreement was found between MRI-measured and intra-surgery measured length of anterior and posterior divisions of C7 nerve by BLAD-ALTMAN analysis. Ultrasonography could feasibly image supraclavicular C7 nerve and recognize small variant branches derived from middle trunk of C7 nerve root, which could be dissected intra-operatively and confirmed by electromyography during the procedure of contralateral C7 nerve transfer. CONCLUSION: CUBE-STIR MRI had advantages for the imaging of the brachial plexus and measurement of the length of root-trunk-anterior/posterior divisions of C7 nerve. The clinical role of ultrasonography may be a simple way of evaluating general condition of C7 nerve and provide guidelines for contralateral C7 nerve transfer surgery.

Single injection combined suprascapular and axillary nerve block: A randomised controlled non-inferiority trial in healthy volunteers.

BACKGROUND: A shoulder block without lung affection is desirable. In this study, we compared a low versus a high volume of a modified supraclavicular brachial plexus block. We hypothesised that a low volume of local anaesthetic would provide non-inferior block success rate with better preserved lung function. METHODS: Healthy volunteers were randomised to receive ultrasound guided 5 or 20 ml ropivacaine 0.5% at the departure of the suprascapular nerve from the brachial plexus. Primary outcome was successful shoulder block-defined as cutaneous sensory affection of the axillary nerve and motor affection of the suprascapular nerve (>50% reduction in external rotation force measured with dynamometry). We used a non-inferiority margin of 20%. Secondary outcome was change in lung function measured with spirometry. RESULTS: Thirteen of 16 (81.3%; 95% confidence interval [CI] 57.0% to 93.4%) in the 5 ml group and 15 of 16 (93.8%; 95% CI 71.7% to 98.9%) in the 20 ml group had successful shoulder block (p = .6). The ratio of the event rates of the 20 ml (standard) and 5 ml (intervention) groups was (15/16)/(13/16) = 0.937/0.813 = 1.15 (95% CI 0.88 to 1.51). All mean reductions in lung function parameters were non-significantly lower in the 5 ml group compared with the 20 ml group. CONCLUSION: For our primary outcome, the 95% CI of the difference of event ratio included the non-inferiority margin. We are therefore unable to conclude that 5 ml LA is non-inferior to 20 ml LA with respect to block success rate.