Ultra high-frequency ultrasound of fascicles in the ulnar and radial nerves.

INTRODUCTION/AIMS: Ultra high-frequency ultrasound (UHFUS) has been demonstrated to allow easy visualization and quantification of median and digital nerve fascicles; however, there is a lack of normative data for other upper limb nerves. The purpose of this study was to use UHFUS to establish normative reference values and ranges for fascicle count and density within selected upper extremity nerves. METHODS: Twenty-one healthy volunteers underwent sonographic examination of the ulnar, superficial branch of the radial, and radial nerves on one upper limb using UHFUS with a 48 MHz linear transducer. The number of fascicles in each peripheral nerve and fascicle density were assessed. RESULTS: The mean fascicle number and fascicle density for each of the measured nerves was ulnar nerve at the wrist 11.7 and 2.0, ulnar nerve at the elbow 9.2 and 1.1, superficial branch of the radial nerve 7.3 and 2.5, and radial nerve at the spiral groove 4.2 and 0.8. A single significant association was observed between CSA and fascicle number in the ulnar nerve at the wrist (p = .023, r = 0.66). Neither fascicle number nor density could be predicted by age, sex, height, weight, or body mass index. DISCUSSION: UHFUS may help to establish a baseline of normative data on upper limb nerves that are not frequently biopsied due to their mixed motor and sensory functions and has the potential for increased understanding of nerve fascicular anatomy to improve diagnostic accuracy of focal nerve lesions, particularly those with selective fascicular involvement.

Unveiling the spiral groove: a journey through clinical anatomy, pathology, and imaging.

AIM: To review the anatomy of the spiral groove, its clinical significance, and the imaging characteristics of common pathologies affecting this area, highlighting the strengths of different imaging modalities. MATERIALS AND METHODS: A comprehensive review of the spiral groove anatomy and its clinical implications and an evaluation of various imaging techniques, including radiography, ultrasound, MRI, and CT, was conducted. The review covers pathologic conditions such as Saturday night palsy, humeral fractures, tumours, and infections, with an emphasis on their imaging findings and clinical implications. RESULTS: The spiral groove provides a pathway for the radial nerve and the deep brachial artery, both crucial for upper limb function. Each imaging modality offers unique advantages: radiography is useful for initial assessment, ultrasound provides dynamic visualisation, MRI offers high-resolution soft tissue imaging, and CT is ideal for detailed bone anatomy. Understanding these imaging characteristics is essential for diagnosing fractures, assessing humeral alignment, and detecting nerve entrapment or injury. CONCLUSION: Accurate imaging of the spiral groove is essential for diagnosing and treating pathologies related to this anatomical feature. The integrative approach of using appropriate imaging modalities enhances diagnostic precision and informs therapeutic strategies, ultimately improving patient outcomes.

Ancient Schawanoma of radial nerve: a rare case report.

Soft tissue swellings on the forearm can present with a range of clinical and histopathological diagnosis. Ancient Schawanoma is a rare benign condition that can develop over the flexor surface of the forearm as a cystic swelling and can involve the median or the ulnar nerve. However, the presentation of this condition on the extensor surface with involvement of the radial nerve is an extremely uncommon diagnosis. A 69 year old female presented at the outpatient department with a swelling on the extensor aspect of her right forearm for the past 2 years. Ultrasound examination showed a mixed cystic solid mass and MRI report revealed a complex predominantly cystic mass in the extensor compartment of the forearm, measuring 4.3 x 5.3 x 7.2 cm size. After obtaining informed consent, the patient was operated under tourniquet control and the mass was removed sparing the radial nerve that was adherent to its capsule. The final histopathological report confirmed the diagnosis as Ancient Schawanoma.

Ultrasound evaluation of radial nerve injuries by cortex overlapping screw tips after internal fixation of humeral fractures: a cadaveric study.

PURPOSE: The radial nerve may be painfully irritated or damaged by open reduction and internal fixation (ORIF) of humeral fractures. Secondary radial nerve lesions after ORIF of humeral shaft fractures are described in up to 16%. Not only peripheral nerves but also orthopaedic instruments and osteosynthesis material are well visible by ultrasound. The aim of this study was to evaluate the accuracy of ultrasound in assessing the relation between the bone overlapping screw tips and the radial nerve close to the humeral bone. METHODS: Ultrasound-guided drilling was used to place screws as close as possible to the radial nerve in 8 humeral bones of four cadavers. The relation between the radial nerve and the screw tips was assessed by high-resolution ultrasound, and the overlap of all screw tips over the bone was measured by ultrasound and fluoroscopy. Thereafter, the findings were validated by anatomical dissection. RESULTS: We could correctly identify all screw tips and their relation to the radial nerve by ultrasound. In 7 of 8 cases, the screw tip had direct contact with the radial nerve. The overlaying length of the screw tip was accurately measured by using ultrasound in all cases. In contrast fluoroscopy underestimated this length in 50% of cases. CONCLUSION: With this study, we show that ultrasound can reliable visualize the screw tips and its relation to the radial nerve. Ultrasound is a promising diagnostic tool to evaluate patients with radial nerve irritations or lesions after ORIF of humeral fractures. Furthermore, ultrasound could be an adequate tool to guide drilling.

Sonographic peripheral nerve cross-sectional area in adults, excluding median and ulnar nerves: A systematic review and meta-analysis.

INTRODUCTION/AIMS: Although electromyography remains the "gold standard" for assessing and diagnosing peripheral nerve disorders, ultrasound has emerged as a useful adjunct, providing valuable anatomic information. The objective of this study was to conduct a systematic review and meta-analysis evaluating the normative sonographic values for adult peripheral nerve cross-sectional area (CSA). METHODS: Medline and Cochrane Library databases were systematically searched for healthy adult peripheral nerve CSA, excluding the median and ulnar nerves. Data were meta-analyzed, using a random-effects model, to calculate the mean nerve CSA and its 95% confidence interval (CI) for each nerve at a specific anatomical location (= group). RESULTS: Thirty groups were identified and meta-analyzed, which comprised 16 from the upper extremity and 15 from the lower extremity. The tibial nerve (n = 2916 nerves) was reported most commonly, followed by the common fibular nerve (n = 2580 nerves) and the radial nerve (n = 2326 nerves). Means and 95% confidence interval (CIs) of nerve CSA for the largest number of combined nerves were: radial nerve assessed at the spiral groove (n = 1810; mean, 5.14 mm2 ; 95% CI, 4.33 to 5.96); common fibular nerve assessed at the fibular head (n = 1460; mean, 10.18 mm2 ; 95% CI, 8.91 to 11.45); and common fibular nerve assessed at the popliteal fossa (n = 1120; mean, 12.90 mm2 ; 95% CI, 9.12 to 16.68). Publication bias was suspected, but its influence on the results was minimal. DISCUSSION: Two hundred thirty mean CSAs from 15 857 adult nerves are included in the meta-analysis. These are further categorized into 30 groups, based on anatomical location, providing a comprehensive reference for the clinician and researcher investigating adult peripheral nerve anatomy.

Compare the clinical value of two minimally invasive approaches to locating radial nerve in the posterior humeral approach.

PURPOSE: To compare the clinical value between locating radial nerve (RN) guided by Color Doppler ultrasonography and posterior antebrachial cutaneous nerve (PACN) in the posterior humeral approach. METHODS: The five fresh adult cadavers (ten upper arms) were selected to compare the two methods of locating the RN in the posterior humeral approach (guided by ultrasound and PACN) by measuring the operation time, the length of incision, and the area of subcutaneous free. And the comparison between the two groups was statistically analyzed by paired t-test. RESULTS: The results of this study demonstrated that the length of incision and the area of subcutaneous free in the ultrasound group were smaller than that in the PACN group (P < 0.05), while the operation time was just the opposite (P < 0.05). However, after excluding the time of ultrasound location, the operation time in the ultrasound group was shorter than that in the PANC group, and the difference was statistically significant (P < 0.05). CONCLUSION: The RN can be quickly and safely exposed by both methods. The ultrasound approach requires a long learning curve, but is more minimally invasive and can help determine whether the intraoperative nerve is compressed by the plate. And the PACN method requires a longer incision and a wider area of subcutaneous free, while specialized equipment and professional training for surgeons are not required. In a word, these two methods have advantages and disadvantages, so they should be selected based on the exact situation.

Anatomic consideration of the radial nerve in relation to humeral length for unilateral external fixation: a retrospective study using magnetic resonance imaging findings in korean.

BACKGROUND: This study aimed to present a safe zone for distal pin insertion for external fixation using magnetic resonance imaging (MRI) images. METHODS: All patients who took at least one upper arm MRI from June 2003 to July 2021 were searched via a clinical data warehouse. For measuring the humerus length, proximal and distal landmarks were set as the highest protruding point of the humeral head and lowermost margin of ossified bone of the lateral condyle, respectively. For children or adolescents with incomplete ossification, the uppermost and lowermost ossified margin of the ossification centers were set as proximal and distal landmarks respectively. The anterior exit point (AEP) was defined as the location of the radial nerve exiting the lateral intermuscular septum to the anterior humerus and distance between the distal margin of the humerus and AEP was measured. The proportions between the AEP and full humeral length were calculated. RESULTS: A total of 132 patients were enrolled for final analysis. The mean humerus length was 29.4 cm (range 12.9-34.6 cm). The mean distance between the ossified lateral condyle and AEP was 6.6 cm (range 3.0-10.6 cm). The mean ratio of the anterior exit point and humeral length was 22.5% (range 15.1-30.8%). The minimum ratio was 15.1%. CONCLUSION: A percutaneous distal pin insertion for humeral lengthening with an external fixator may be safely done within 15% length of the distal humerus. If pin insertion is required more proximal than distal 15% of the humeral shaft, an open procedure or preoperative radiographic assessment is advised to prevent iatrogenic radial nerve injury.

Deep branch of the radial nerve: effect of pronation/supination on longitudinal nerve alignment.

OBJECTIVE: To evaluate the effect of maximal pronation and supination of the forearm on the alignment and anatomic relationship of the deep branch of the radial nerve (DBRN) at the superior arcade of the supinator muscle (SASM) by using high-resolution ultrasound (HRUS). MATERIALS AND METHODS: In this cross-sectional study, HRUS in the long axis of the DBRN was performed in asymptomatic participants enrolled from March to August 2021. DBRN alignment was evaluated by measuring angles of the nerve in maximal pronation and maximal supination of the forearm independently by two musculoskeletal radiologists. Forearm range of motion and biometric measurements were recorded. Student t, Shapiro-Wilk, Pearson correlation, reliability analyses, and Kruskal-Wallis test were used. RESULTS: The study population included 110 nerves from 55 asymptomatic participants (median age, 37.0 years; age range, 16-63 years; 29 [52.7%] women). There was a statistically significant difference between the DBRN angle in maximal supination and maximal pronation (Reader 1: 95% CI: 5.74, 8.21, p < 0.001, and Reader 2: 95% CI: 5.82, 8.37, p < 0.001). The mean difference between the angles in maximal supination and maximal pronation was approximately 7° for both readers. ICC was very good for intraobserver agreement (Reader1: r ≥ 0.92, p < 0.001; Reader 2: r ≥ 0.93, p < 0.001), as well as for interobserver agreement (phase 1: r ≥ 0.87, p < 0.001; phase 2: r ≥ 0.90, p < 0.001). CONCLUSION: The extremes of the rotational movement of the forearm affect the longitudinal morphology and anatomic relationships of the DBRN, primarily demonstrating the convergence of the nerve towards the SASM in maximal pronation and divergence in maximal supination.

Risk of nerve injury during elbow arthroscopy: ultrasonographic evaluation of preoperative patients.

BACKGROUND: To clarify the real risk of nerve injury during elbow arthroscopy, the distances of the radial and median nerves to the elbow joint were investigated using ultrasonography in patients who underwent surgery. METHODS: A total of 35 patients who underwent arthroscopic surgery of the elbow were investigated. The distances of the nerves to the capsule and bony landmarks were measured using ultrasonography. The radial nerve distances were measured at the capitellum, joint space, radial head, and radial neck levels. The median nerve distances were measured at the trochlear, joint space, and coronoid process levels. The patients were divided into 2 groups: nine patients in the hydrarthrosis (HA) group and 26 patients in the non-hydrarthrosis (non-HA) group. HA was defined as the intra-articular effusion on magnetic resonance imaging scans. RESULTS: The radial nerve ran closer to the capsule at the radial neck level in the HA group than in the non-HA group (2.0 mm vs. 5.9 mm, P < .01). In the non-HA group, the radial nerve ran closer to the radial head than in the HA group (6.3 mm vs. 8.5 mm, P = .01). The median nerve ran closer to the capsule at the trochlear level in the HA group than in the non-HA group (5.2 mm vs. 8.8 mm, P < .01). Nerves at a distance of ≤2 mm from the capsule were found in 7 patients at the radial neck of the radial nerve and in 2 patients at the trochlear region of the median nerve in the HA group. In the non-HA group, they were found in 3 patients at the radial head and in 1 patient at the joint space of the radial nerve. CONCLUSIONS: The dangerous locations for nerve injury during elbow arthroscopy vary according to hydrarthrosis, and this risk should be recognized during arthroscopic surgery.

Ultrasound-guided preoperative localization of radial nerve in the treatment of extra-articular distal humeral shaft fractures.

BACKGROUND: The aim of this study was to discuss the treatment of extra-articular distal humeral shaft fractures using ultrasound-guided preoperative localization of radial nerve. METHODS: Between May 2010 and December 2019, 56 patients with extra-articular distal humeral shaft fractures were retrospectively reviewed. Twenty eight patients were received examination by using preoperative localization of radial nerve guided by ultrasound-guided preoperative localization (group A) and 28 control patients without ultrasound-guided (group B). All patients were treated surgically for distal humeral shaft fractures by posterior approach techniques. Operative time, radial nerve exposure time, intraoperative bleeding volume, union time and iatrogenic radial nerve palsy rate were compared between the two groups. Elbow function was also evaluated using the Mayo Elbow Performance Score (MEPS). RESULTS: A significant difference was observed between the two groups, Operative time (113.25 min vs 135.86 min) (P < 0.001), radial nerve exposure time (20.82 min vs 32.53 min) (P < 0.001), intraoperative bleeding volume (246.80 ml vs 335.52 ml) (P < 0.001). However, iatrogenic radial nerve palsy rate (3.6% vs 7.1%) (P = 0.129), the fracture union time (13.52 months vs 12.96 months) (P = 0.796) and the MEPS score (87.56 vs 86.38) (P = 0.594) were no significantly different in both groups. CONCLUSIONS: The study demonstrates that ultrasound-guided preoperative localization is an effective approach in the treatment of extra-articular distal humeral shaft fracture by revealing radial nerve, which may help reduce the operative time, radial nerve exposure time and the intraoperative bleeding volume.

Application of ultrasound in avoiding radial nerve injury during elbow arthroscopy: a retrospective follow-up study.

BACKGROUND: A safe and effective technique for anterolateral portal placement in elbow arthroscopy is significant. We compared the outcomes of patients who underwent elbow arthroscopy using different ultrasound-assisted techniques. METHODS: From May 2016 to June 2021 a retrospective analysis on all patients who underwent elbow arthroscopy in our department was performed. Patients were separated into three groups: non-ultrasound; preoperative ultrasound; and intraoperative ultrasound. The minimum follow-up period was 1 year. Nerve injuries, visual analog scale (VAS), Mayo elbow-performance score (MEPS), Disabilities of the Arm, Shoulder, and Hand Questionnaire (DASH), and range of motion (ROM) of the elbow were evaluated for comparison among the three groups pre- and post-operatively. RESULTS: All 55 patients completed a 1-year follow-up: non-ultrasound (n = 20); preoperative ultrasound (n = 17); and intraoperative ultrasound (n = 18). There were 3 cases (15.0%) of transient radial nerve palsy in the non-ultrasound group. No nerve complications occurred in preoperative ultrasound and intraoperative ultrasound groups. The probability of postoperative radial nerve injury in the three groups was statistically different (P < 0.05). There was no significant difference in the VAS score, MEPS, DASH score, and ROM among the three groups at the follow-up evaluation (P > 0.05). CONCLUSION: Performing anterolateral portal placement during elbow arthroscopy with ultrasound-assisted techniques successfully avoided radial nerve injury.

Radial nerve palsy: If in doubt, use ultrasound.

Sonographic demonstration of radial nerve compression by a strict permanent suture, with intra-operative correlation.

Ultrasound-Guided Hydrodissection Provides Complete Symptom Resolution in Radial Tunnel Syndrome: A Case Series and Scoping Review on Hydrodissection for Radial Nerve Pathology.

ABSTRACT: This study analyzes the effectiveness of ultrasound-guided hydrodissection (HD) perineural as a treatment for radial tunnel syndrome (RTS). A literature search was performed along with retrospective analysis of local cases to assess outcomes and safety of this procedure. In the case series, surgical candidates, defined as cases with over 80% but temporary relief after diagnostic injection, were treated with ultrasound-guided HD. Of 22 patients who received ultrasound-guided diagnostic injections, 11 proceeded to HD. All HD patients experienced complete and lasting symptom resolution for a minimum of 2 years, and none required surgery. Thorough literature review provided seven studies, which fulfilled inclusion criteria. Sixty-one patients are represented in the literature. All studies reported significant benefit to pain symptoms with HD of radial nerve, with five specifying over 90% improvement. No adverse effects from HD were noted in any study. Ultrasound-guided HD of the radial tunnel has potential to be a surgery sparing treatment for RTS.

[Diagnosis and treatment of paralysis following intrafascicular peripheral nerve torsion: two clinical observations and a literature review]. / Diagnostika i lechenie paralicha, vyzvannogo intrafastsikulyarnym perekrutom perifericheskogo nerva: dva klinicheskikh nablyudeniya i obzor literatury.

BACKGROUND: Intrafascicular nerve torsion is a rare and poorly studied type of nerve compression. This disease can be assigned to compression-induced neuropathies, but it has a distinctive feature. It is a spontaneous intrafascicular compression following internal local spiral deformation and compression of the nerve outside routine tunnels due to its torsion around its own axis. Understanding the pathogenesis of such spiral compression is essential in diagnosis, prognosis and treatment of these patients. OBJECTIVE: To assess the effectiveness of various diagnostic techniques, the possibility and effectiveness of surgical treatment of patients with spiral intrafascicular nerve deformation. MATERIAL AND METHODS: The authors report 2 patients (45-year-old man and 38-year-old woman) who were examined for progressive radial neuropathy of unknown etiology. Ultrasound of the radial nerve and electroneuromyography were performed. These data made it possible to diagnose nerve lesion in both cases. These findings justified external and internal radial nerve decompression. RESULTS: Ultrasound was valuable to establish localization and cause of radial nerve lesion (local hourglass-shaped deformation). Electroneuromyography confirmed conduction disturbances along the altered segment of radial nerve in both patients. Intraoperatively, intrafascicular nerve torsion as a cause of functional disorders was confirmed in both cases. Both patients required external and internal nerve decompression with restoration of linear orientation of the nerve and its fixation within the epineurium. Positive effect was noted immediately after surgery. Control survey after 3 and 6 months revealed significant regression of symptoms (increase in muscle strength and motion amplitude) and high satisfaction with treatment outcomes. CONCLUSION: Clinical manifestations of intrafascicular radial nerve torsion imitate typical compression-induced neuropathy. However, this lesion is characterized by another unclear pathogenesis, localization far from natural tunnels, typical ultrasound and intraoperative patterns. Surgical treatment has certain features, and its effectiveness depends on surgical technique and ranges from 60% to 90%.

Ultrasonographic anatomy of posterior antebrachial cutaneous nerve in healthy subjects.

INTRODUCTION/AIMS: The posterior antebrachial cutaneous nerve (PACN) is one of the cutaneous branches of the radial nerve, and receives sensory input from the posterior arm and forearm. The aim of this study is to describe the ultrasonographic anatomy of the PACN. METHODS: PACN and its branches were scanned using ultrasonography in 30 healthy volunteers. The distances between the epicondylar line and the bifurcation site of each branch of PACN (A) point of separation of the radial nerve and the PACN, (B) point of separation of the anterior and posterior divisions, (C) point of bifurcation of the posterior division into the epicondylar and anconeus branches), cross-sectional areas and depths from the skin surface to each nerve at positions A, B, and C were measured. RESULTS: The mean distance from the epicondylar line to A, B, and C was 10.01 ± 0.82 cm, 7.46 ± 0.98 cm, and 4.02 ± 1.16 cm, respectively. The mean depth from the skin surface at A, B, and C was 1.00 ± 0.19 cm, 0.72 ± 0.19 cm, and 0.51 ± 0.12 cm, respectively. DISCUSSION: Ultrasonographic visualization of the PACN and its major branches was feasible. The reference values in this study may be helpful for more accurate sonographic assessment and electrophysiologic study, and contribute to safer interventions around the elbow region.

Hourglass-Like Constriction Neuropathy of the Upper Limb Nerve: Diffusion-Weighted Magnetic Resonance Neurography Imaging Findings.

OBJECTIVE: The purposes of this study were to determine reliable diffusion-weighted magnetic resonance neurography (DW-MRN) features of hourglass-like constriction of the upper limb nerve and to evaluate the application value of DW-MRN compared with ultrasonography (US). METHODS: We retrospectively reviewed MRN studies of 13 patients. Qualitative and quantitative image analyses were carried out. The number of constrictions based on DW-MRN and US findings was compared. RESULTS: Of the 13 cases, there were 7 cases with radial nerve abnormalities, 4 with median nerve abnormalities, and 2 with radial and median nerve abnormalities. Diffusion-weighted MRN showed a single-segmental constriction in 7 of 13 cases and multisegmental constrictions in 6 of 13 cases; the hourglass-like constriction appeared in all cases (13 of 13). Thirty-three nerve constrictions were found in DW-MRN, and 29 nerve constrictions were found in US. CONCLUSIONS: Diffusion-weighted MRN is a noninvasive and helpful diagnostic for hourglass-like constriction of the upper limb nerve.

Ultrasound of the Radial Nerve: A Pictorial Review.

This pictorial review focuses on the ultrasound (US) appearance of the normal and pathological radial nerve (RN) and its branches and provides tips with which to locate them and avoid misinterpretation of normal findings. A wide range of our pathological cases are reviewed and presented to help in familiarizing the reader with common and uncommon clinical scenarios that affect the RN and its main branches.

Cross-sectional area reference values for sonography of nerves in the upper extremities.

INTRODUCTION: Detailed morphological features of the peripheral nerves could improve the diagnostic sensitivity in some polyneuropathies. In this study we aimed to establish multiple-site, cross-sectional area (CSA) reference values for peripheral nerves of upper extremities in a healthy Chinese population. METHODS: One hundred eleven healthy subjects, 15 to 70 years of age, were prospectively recruited. CSA at predetermined sites of the median, ulnar, radial nerves, and brachial plexus was measured bilaterally. Ten consecutive sites were studied along the median/ulnar nerves. RESULTS: The CSA at ten sites of the median nerve ranged from 5.59 ± 0.89 to 8.43 ± 1.30 mm2 , and for the ulnar nerve from 2.94 ± 0.57 to 5.63 ± 1.08 mm2 . Both age and gender correlated with nerve CSA at most sites. DISCUSSION: CSA was not uniform along the length of the median and ulnar nerves. The multiple-site reference values could be helpful for investigating polyneuropathies in the Asian population.

Techniques for Peripheral Nerve Stimulator Implantation of the Upper Extremity.

OBJECTIVE: To present a technical note on how to perform upper extremity peripheral nerve stimulators for three major nerves: median, ulnar, and radial. DESIGN: Literature review and expert opinion. SETTING: Single academic center. RESULTS: Peripheral nerve stimulation has recently become popular with the development and availability of peripheral nerve stimulators with an external pulse generator. Here, we describe ultrasound anatomy and technical details for peripheral nerve stimulation in the upper extremity for three major nerves: median, ulnar, and radial. CONCLUSIONS: Upper extremity peripheral nerve stimulation can be considered as an option for refractory neuropathic upper extremity pain.

Ultrasound-Guided Hydraulic Release Associated With Corticosteroids in Radial Tunnel Syndrome: Description of Technique and Preliminary Clinical Results.

The aim of this study was to describe a perineural ultrasound-guided infiltration technique for management of radial tunnel syndrome and to report its preliminary results in 54 patients. A mixture of a saline solution, a local anesthetic, and a corticosteroid solution was infiltrated in the perineural region at the arcade of Frohse. Pain was reported in 100% of patients before the procedure versus 1.9% after the procedure. Scratch collapse and Cozen test results were positive in 98.1% and 66.7% of patients before infiltration, respectively, versus 5.6% and 9.2% after infiltration. All variables had statistically significant differences between preprocedure and postprocedure evaluations (P < .01).