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.

Radial Nerve Palsy in the Setting of Humeral Shaft Fracture

The upper limb has a complex anatomy comprised of many nerve and vascular structures, making humeral shaft fractures extremely important. Injury to the humeral shaft commonly occurs due to trauma and affects younger male or older female patients. The radial nerve travels along the spiral groove of the humerus, placing it at an increased risk of damage in humeral shaft fractures. If injured, there are a variety of classifications of radial nerve injury, different indications for exploration, and treatment methods that orthopedic surgeons have available in treating these injuries. This review aims to discuss the etiology of humeral shaft fracture-associated radial nerve palsy, tools for diagnosis, and treatment.

Natural history of neonatal radial nerve palsy

LEVEL OF EVIDENCE

IV.

A Fresh Cadaver Study on the Innervation of Brachioradialis and Extensor Carpi Radialis Longus Muscles

PURPOSE

Distal nerve transfers have revolutionized peripheral nerve surgery by allowing the transfer of healthy motor nerves to paralyzed ones without causing additional morbidity. Radial nerve branches to the brachialis (Ba), brachioradialis (Br), and extensor carpi radialis longus (ECRL) muscles have not been investigated in fresh cadavers.

METHODS

The radial nerve and its branches were dissected in 34 upper limbs from 17 fresh cadavers. Measurements were taken to determine the number, origin, length, and diameter of the branches. Myelinated fiber counts were obtained through histological analysis.

RESULTS

The first branch of the radial nerve at the elbow was to the Ba muscle, followed by the branches to the Br and ECRL muscles. The Ba and Br muscles consistently received single innervation. The ECRL muscle showed varying innervation patterns, with one, two, or three branches. The branches to the Br muscles originated from the anterior side of the radial nerve, whereas the branches to the Ba and ECRL muscles originated from the posterior side. The average myelinated fiber counts favored the nerve to Br muscle over that to the ECRL muscle, with counts of 542 versus 350 and 568 versus 302 observed in hematoxylin and eosin and neurofilament staining, respectively.

CONCLUSIONS

This study provides detailed anatomical insights into the motor branches of the radial nerve to the Ba, Br, and ECRL muscles.

CLINICAL RELEVANCE

Understanding the anatomy of the radial nerve branches at the elbow is of utmost importance when devising a reconstructive strategy for upper limb paralysis. These findings can guide surgeons in selecting appropriate donor or recipient nerves for nerve transfer in cases of high tetraplegia and lower-type brachial plexus injuries.

Anatomy of Profunda Brachial Artery in the Axilla and Its Relationship With the Radial Nerve: Fresh-Cadaver Anatomical Study and Clinical Observations

PURPOSE

Dissection of the radial nerve in the axilla and upper portion of and posterior aspect of arm may be necessary for brachial plexus reconstruction, in axillary nerve paralysis, and in radial nerve injuries. The radial nerve is in intimate contact with the profunda brachial artery (PBA). The authors sought to describe the relationship of the PBA with the radial nerve.

METHODS

We dissected the PBA and the radial nerve bilaterally in 20 upper limbs from 10 fresh cadavers after subclavian artery injection with green latex. We studied the relationship of the PBA with the radial nerve, its branching patterns, and its diameters. In addition, we performed surgery on 5 patients with brachial plexus, radial, or axillary nerve injury in whom we dissected the PBA.

RESULTS

The PBA was present in all dissections, originating from the brachial artery (n = 19 specimens) close to the latissimus dorsi tendon or from the subscapular artery (n = 1 specimen). In 15 dissections, the PBA bifurcated into an anterior (AB) and a posterior (PB) branch. In one dissection, the AB was absent. The AB traveled toward the triceps medial head. The PB flanked the radial nerve posteriorly and traveled around the humerus, with the radial nerve passing between the medial and the lateral head of the triceps. The AB and PB were longer than the PBA and measured on average 53 mm (SD ± 33 mm) and 39 mm (SD ± 26 mm), respectively. Intraoperatively, the radial nerve could be exposed in the upper arm by pulling the triceps medial head anteriorly together with the AB. The PB was lateral to the radial nerve in the posterior arm approach.

CONCLUSIONS

In the upper arm, the radial nerve was not flanked by a single branch as postulated in anatomical textbooks but by 2 branches resulting from the bifurcation of the PBA.

CLINICAL RELEVANCE

Awareness of PBA anatomy is essential during radial nerve dissection from the anterior or posterior arm approach.

Posterior Interosseous Nerve Compression in the Forearm, AKA Radial Tunnel Syndrome: A Clinical Diagnosis

BACKGROUND

Posterior interosseous nerve (PIN) compression in the forearm without motor paralysis is a challenging clinical diagnosis. This retrospective study evaluated the clinical assessment, diagnostic studies, and outcomes following surgical decompression of the PIN in the forearm.

METHODS

This study reviewed 182 patients' medical charts following PIN decompression between 2000 and 2020 by a single surgeon. After exclusion of combined nerve entrapments, polyneuropathy, motor palsy, or lateral epicondylitis, the study included 14 patients. Data collected included: clinical presentation and pain drawings, provocative testing, functional outcomes, and Disabilities of the Arm, Shoulder, and Hand (DASH) scores.

RESULTS

There were 15 PIN decompressions (14 patients, mean follow-up = 11.9 months). Clinical presentation included pain (n = 14) (proximal dorsal forearm, n = 14; distal forearm over radial sensory nerve, n = 3) and positive clinical tests (sensory collapse test over the radial tunnel, n = 8; pain with forearm pronation and compression over the radial tunnel, n = 10; Tinel sign, n = 5). Postoperatively, there were significant improvements in Visual Analog Scale pain scores (6.7 to 3.3, P = .0006), quality-of-life scores (74.7 to 32.7, P = .0001), and DASH scores (46.3 to 33.6, P = .02).

CONCLUSIONS

The PIN compression in the forearm without motor paralysis is a clinical diagnosis supported by pain drawings, pain quality, and provocative tests. Patients with persistent, therapy-resistant dorsal forearm pain should be evaluated for PIN compression. Surgical decompression provides statistically significant quantifiable improvement in pain and quality of life.

Immediate effects of percutaneous electrical nerve stimulation in patients with lateral elbow pain

INTRODUCTION

Ultrasound guided-percutaneous electrical nerve stimulation appears to be effective in the treatment of chronic musculoskeletal pain.

OBJECTIVE

To investigate the immediate effects of one session of percutaneous electrical nerve stimulation on the radial nerve in patients with lateral elbow pain.

METHODS

A randomized clinical trial was conducted. Sixty patients with chronic lateral elbow pain were allocated into real-percutaneous electrical nerve stimulation (n = 30) or sham-percutaneous electrical nerve stimulation (n = 30) where the patients received one-single session of the real or sham percutaneous stimulation on the radial nerve, respectively. Pressure pain thresholds, pain intensity, pain-free grip strength, and the self-perceived improvement were evaluated after the intervention.

RESULTS

Significant differences between groups for pain intensity (-11.55, 95% CI -21.79 to -1.30, p < .028), but not for pressure pain threshold or pain-free grip strength, were found. Patients receiving real-percutaneous stimulation had significant improvement in pain-free grip strength on the treated side. The proportion of individuals reporting moderate to large self-perceived improvement (≥4) was significantly higher (p = .026) after real-percutaneous stimulation than after sham-percutaneous stimulation.

CONCLUSION

A single session of real-percutaneous electrical nerve stimulation targeting the radial nerve in subjects with lateral elbow pain decreased pain intensity between groups and increased pain-free grip strength on the treated side but not between groups.

Skin type and nerve effects on cortical tactile processing: a somatosensory evoked potentials study

Somatosensory evoked potential (SEP) studies typically characterize short-latency components following median nerve stimulations of the wrist. However, these studies rarely considered 1) skin type (glabrous/hairy) at the stimulation site, 2) nerve being stimulated, and 3) middle-latency (>30 ms) components. Our aim was to investigate middle-latency SEPs following simple mechanical stimulation of two skin types innervated by two different nerves. Eighteen adults received 400 mechanical stimulations over four territories of the right hand (two nerves: radial/median; two skin types: hairy/glabrous skin) while their EEG was recorded. Four middle-latency components were identified: P50, N80, N130, and P200. As expected, significantly shorter latencies and larger amplitudes were found over the contralateral hemisphere for all components. A skin type effect was found for the N80; glabrous skin stimulations induced larger amplitude than hairy skin stimulations. Regarding nerve effects, median stimulations induced larger P50 and N80. Latency of the N80 was longer after median nerve stimulation compared with radial nerve stimulation. This study showed that skin type and stimulated nerve influence middle-latency SEPs, highlighting the importance of considering these parameters in future studies. These modulations could reflect differences in cutaneous receptors and somatotopy. Middle-latency SEPs can be used to evaluate the different steps of tactile information cortical processing. Modulation of SEP components before 100 ms possibly reflects somatotopy and differential processing in primary somatosensory cortex.NEW & NOTEWORTHY The current paper highlights the influences of stimulated skin type (glabrous/hairy) and nerve (median/radial) on cortical somatosensory evoked potentials. Mechanical stimulations were applied over four territories of the right hand in 18 adults. Four middle-latency components were identified: P50, N80, N130, and P200. A larger N80 was found after glabrous skin stimulations than after hairy skin ones, regardless of the nerve being stimulated. P50 and N80 were larger after median than radial nerve stimulations.

Ancient Schwannoma of the Radial Nerve: A Case Report

Ancient schwannoma is a very rare subtype of schwannoma. In this report, a case of ancient schwannoma in the upper extremity is reported. A 40-year-old man presented with a slowly growing tumor in the right forearm. He underwent surgery to remove the tumor. Investigation revealed an ancient schwannoma originated from the right radius. Careful preoperative imaging evaluation is important for correct preoperative diagnosis and surgical strategy.

Pressure Pain Hypersensitivity and Ultrasound Changes in the Radial Nerve in Patients with Unilateral Lateral Epicondylalgia: A Case-Control Study

Some authors have proposed the potential role of the radial nerve in lateral epicondylalgia. The aims of this study were to investigate the presence of pressure pain hyperalgesia and nerve swelling (increased cross-sectional area) assessed with ultrasound imaging on the radial nerve in people with lateral epicondylalgia, and to investigate if an association exists between pressure pain sensitivity and cross-sectional area. A total of 37 patients with lateral epicondylalgia (43% women, age: 45.5 ± 9.5 years) and 37 age- and sex-matched pain-free controls were recruited for participation. Pressure pain thresholds (PPTs) were assessed bilaterally on the radial nerve at the spiral groove, the arcade of Frohse, and the anatomic snuffbox in a blinded design. Further, the cross-sectional area of the radial nerve at the spiral groove and antecubital fossa was also assessed. The results demonstrated lower PPTs on the radial nerve of the affected side in individuals with lateral epicondylalgia as compared with the unaffected side (p < 0.01) and with both sides in healthy controls (p < 0.001). Additionally, the cross-sectional area of the radial nerve on the affected side in patients was higher compared with the unaffected side (p < 0.01) and both sides in healthy controls (p < 0.001). The cross-sectional area of the radial nerve at the spiral groove was negatively associated with PPTs over the radial nerve at the spiral groove (r = -0.496, p = 0.002) and positively associated with function (r = 0.325, p = 0.045). Our findings revealed generalized pressure pain hyperalgesia and also nerve swelling of the radial nerve in people with lateral epicondylalgia, suggesting the presence of a widespread sensitization of nerve tissues in this population. The radial nerve could represent a potential peripheral drive to initial and maintain altered pain processing in lateral epicondylalgia.

Ultrasonographic Evaluation of the Optimal Needle Position in the Supinator Muscle

BACKGROUND AND PURPOSE

Investigating the supinator muscle (SUP) is important for diagnosing radial neuropathy or cervical radiculopathy in needle electromyography (EMG). However, different authors have proposed several locations for needle EMG placement in the SUP. This study aimed to determine the optimal needle insertion position for examining the SUP via needle EMG under ultrasonographic guidance.

METHODS

This study included 16 male (32 upper limbs) and 15 females (30 upper limbs). In the supine position, the line connecting the midpoint of the dorsal wrist to the upper margin of the radial head (RH) (RH_WRIST line) was measured while the forearm was pronated. Under ultrasonographic guidance, the thickness of the SUP was measured at 1-cm intervals from the RH to 4 cm along the RH_WRIST line. Moreover, the horizontal distance (HD) from the RH_WRIST line to the posterior interosseous nerve (PIN) and the distance from the RH to the point where the RH_WRIST line and the PIN intersected (VD_PIN_CROSS) were measured.

RESULTS

VD_PIN_CROSS was 51.25±7.0 mm (mean±SD). The muscle was the thickest at 3 cm (5.6±0.8 mm) and 4 cm (5.4±1.0 mm) from the RH. The distances from the PIN to these points were 14.1±3.9 mm and 9.0±4.3 mm, respectively.

CONCLUSIONS

Our findings suggest that the optimal needle placement is at 3 cm from the RH.

Primary non-Hodgkin's lymphoma of the superficial branch of the radial nerve: illustrative case

BACKGROUND

Lesions of the peripheral nervous system are many and varied. They range from benign to malignant, and determining risk can be challenging. Primary lymphoma of the peripheral nerve (PLPN) is a rare and malignant pathology. When recognized early, appropriate therapy can be delivered. The authors performed a systematic review of PLPNs and present the first case of a PLPN involving the superficial branch of the radial nerve.

OBSERVATIONS

The authors present the clinical presentation and radiological features of a rare case of primary non-Hodgkin's lymphoma of the superficial branch of the radial nerve. Following gross-total resection, the patient received adjuvant chemotherapy and was free of disease at the last follow-up.

LESSONS

With astute observation, less common and sinister peripheral nerve lesions can be recognized at an early stage and tend to be associated with a relatively short history of peripheral sensorimotor deficits and subtle radiographic changes. In such a setting, consideration should be given to performing a biopsy rather than gross-total resection, indeed sparing the parent nerve and facilitating diagnosis. Definitive treatment for PLPN is chemotherapy with the addition of radiotherapy in some circumstances.

Optimal timing of needle electromyography to diagnose lesion severity in traumatic radial nerve injury

INTRODUCTION/AIMS

In patients with traumatic radial nerve injury (RNI), the chance of spontaneous recovery must be balanced against the benefits of early surgical reconstruction. We aimed to explore the time-specific value of needle electromyography (NEMG) to diagnose nerve lesion severity.

METHODS

In this retrospective diagnostic accuracy study at Leiden Nerve Center, patients at least 12 years of age with RNI caused by fractures or fracture treatment were included. The sensitivity and specificity of the patients' first NEMG examination were assessed, stratified by the timing after the nerve injury. The absence of motor unit potentials (MUPs) in muscles distal to the nerve lesion was considered a positive test result. Lesion severity was dichotomized to moderate injury (spontaneous Medical Research Council grade ≥3 recovery) or severe injury (poor spontaneous recovery or surgical confirmation of a mainly neurotmetic lesion).

RESULTS

Ninety-five patients were included in our study. The sensitivity of NEMG to detect severe RNI was 75.0% (3 of 4) in the fourth, 66.7% (2 of 3) in the fifth, and 66.7% (2 of 3) in the sixth month after the nerve injury. The specificity in the first to the sixth month was 0.0% (0 of 1), 50.0% (2 of 4), 77.3% (17 of 22), 95.5% (21 of 22), 95.8% (23 of 24), and 100.0% (12 of 12), respectively.

DISCUSSION

The specificity of NEMG is higher than 95% and therefore clinically relevant from the fourth month after the nerve injury onward. Absence of MUPs at this time can be considered an indication to plan nerve exploration. Moreover, the presence of MUPs on NEMG does not completely exclude the necessity for surgical reconstruction.

Muscle responses during radial nerve-biased upper limb neurodynamic test in asymptomatic individuals: a cross-sectional study

This laboratory cross-sectional study aimed at explore the muscle response (MR) of the upper trapezius, infraspinatus, biceps brachii and extensor carpi radialis brevis (ECRB) during the radial nerve-biased upper limb neurodynamic test (RN-ULNT) in healthy participants. Myoelectric activity was stage-by-stage recorded during two sequencing variants of the RN-ULNT: S1, in which elbow extension was the last movement; and S2, in which wrist flexion was the last movement. Final elbow and wrist joint angle and sensory response (SR) in five zones (Z1-Z5) were also registered. MR was qualitatively categorized as 'absent' (No-MR), 'true' (TMR) or 'uneven' (UMR). In both sequences, significant increases in muscle activity occurred mostly during shoulder abduction and elbow extension (p ≤ 0.009). Also, elbow extension but not wrist flexion increased the activity of the ECRB muscle (p ≤ 0.009). S2 showed significantly higher upper trapezius (p = 0.04) and biceps brachii (p = 0.036) muscle activity during wrist flexion, and higher report of SR in Z1 and Z4 (p < 0.001) compared to S1. Only the ECRB muscle showed significant differences in the MR type between S1 and S2 (TMR, p = 0.016; UMR, = 0,012). Our results may be useful in the assessment of upper limb musculoskeletal disorders.

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.

Multiple tendon transfer for a case of radial nerve palsy in hereditary neuropathy with liability to pressure palsy

Hereditary neuropathy with liability to pressure palsy (HNPP) is a rare autosomal dominant disease characterized by focal, recurrent, demyelinating peripheral neuropathies. It is caused by deletions of the gene encoding for peripheral myelin protein 22 (PMP22) on chromosome 17. While it may range widely, the most common clinical presentation is an acute, focal mononeuropathy with numbness or muscle weakness after trauma or compression. Diagnostic tools include electrophysiological studies, genetic tests and nerve biopsies. There is no standard surgical or pharmacological treatment. The course of the disease is usually benign, with spontaneous improvement after most episodes of peripheral nerve palsy. HNPP is best managed by early detection, preventative measures, and subsequent treatment of symptoms. According to the medical literature, operative treatment was undertaken in few cases and limited to decompression of the nerve at the classic entrapment sites of the carpal or cubital tunnels. We present a case of multiple tendon transfer (pronator teres to extensor carpi radialis brevis and flexor carpi radialis to extensor digitorum communis) with a two-year follow-up in a 24-year-old woman with HNPP who was affected by irreversible radial nerve palsy, and conclude with a review of the medical literature related to the disease.

Transfer of extensor carpi radialis brevis branch of radial nerve to anterior interosseous nerve for lower trunk brachial plexopathy after motor vehicle accident

The patient is a 15-year-old male who sustained injury to his right lower brachial plexus (C8-T1) in a motor vehicle accident. Six months after the injury, the patient still had persistent hand weakness and wished to regain function in his first and second digits. Transfer of the extensor carpi radialis brevis (ECRB) branch of the radial nerve to the anterior interosseous nerve (AIN) was performed to restore motor function. The patient did well after the surgery, although it may take 12-24 months for benefits to fully manifest. Pertinent surgical anatomy and techniques are highlighted in this video demonstration. The video can be found here: https://stream.cadmore.media/rr10.3171/2022.10.FOCVID2287.

Traumatic injury to the axillary nerve associated with paralysis of triceps brachii: A case report

Although many textbooks reported the innervation of three heads of the triceps muscle with the radial nerve, some studies showed the axillary nerve supply to this muscle. Herein, we report a 21-year-old male patients with a traumatic injury to the axillary nerve associated with paralysis of his triceps muscle. Based on the electrophysiological findings, it could be reasonable to conclude that the main branch innervating all heads of the triceps muscle originated from the axillary nerve. It is vital to look for concomitant paralysis of the triceps in patients with an axillary nerve injury in terms of surgical management, prognosis, and nerve repair.

Schwannoma of the radial nerve: a case report

Schwannomas are the most common benign tumors of the peripheral nerves, but represents only 5%-8% of all soft tissue tumors. Their diagnosis is usually delayed due to their slow growth and the nervous adaptation to their increased volume. Ultrasound sonography and magnetic resonance imaging (MRI) images usually ease the diagnosis. Correct enucleation offers very good postoperative outcomes and avoids recurrences. We report an unusual case of schwannoma of the radial nerve (RN) that remained asymptomatic for one year and a half, and treated well, had good outcomes.

The Anatomy of Nerve Transfers Used in Tetraplegic Hand Reconstruction

PURPOSE

To evaluate the anatomy of nerve transfers used to reconstruct wrist extension, hand opening, and hand closing in tetraplegic patients.

METHODS

Nerve transfers were completed on 18 paired cadaveric upper limbs. The overlap of donor and recipient nerves was measured, as well as the distance to the target muscle. Axons were counted in each nerve and branch, with the axon percentage calculated by dividing the donor nerve count by that of the recipient.

RESULTS

Transfers with overlap of the donor and recipient nerve were from the radial nerve branch to extensor carpi radialis brevis to anterior interosseous nerve (AIN) and from the branch(es) to supinator to posterior interosseous nerve. The extensor carpi radialis brevis to AIN had the shortest distance to the target, with the branch to brachialis to AIN being the longest. The nerve transfers for wrist extension had the highest axon percentage. Of the transfers for hand closing, the brachialis to AIN had the highest axon percentage, and the branch to brachioradialis to AIN had the lowest.

CONCLUSIONS

The anatomical features of nerve transfers used in tetraplegic hand reconstruction are variable. Differences may help explain clinical outcomes.

CLINICAL RELEVANCE

This study demonstrates which nerve transfers may be anatomically favorable for restoring hand function in tetraplegic patients.

Nerve transfers in a patient with asymmetrical neurological deficit following traumatic cervical spinal cord injury: simultaneous bilateral restoration of pinch grip and elbow extension. Illustrative case

BACKGROUND

Cervical spinal cord injury (CSCI) causes severe motor deficit in upper extremities. The mixed segmental CSCI pattern is reflected in the combination of time-sensitive (TS) and non-TS myotomes in the upper extremities. Nerve transfers (NTs) restore upper extremity function yet remain TS procedures. A combination of neurological, magnetic resonance imaging (MRI), and electromyography (EMG) studies allows the identification of TS and non-TS myotomes in the upper extremities.

OBSERVATIONS

Nineteen months after NTs, flexor pollicis longus (FPL) and deep flexor of the index finger (FDP2) recovered to M4 (right UE), FPL recovered to M3 and FDP2 to M2 (left EU). The long head of the triceps brachii muscle recovered to M4 bilaterally. The Capabilities of Upper Extremity Questionnaire (CUE-Q) score for unilateral arm functionality increased by 44% (right) and 112.5% (left) and for bilateral arm functionality by 400%; the CUE-Q score for unilateral hand and finger function increased by 283% (right) and 166% (left).

LESSONS

The combination of neurological, MRI, and EMG studies before surgery and data obtained during surgery provides reliable information on the CSCI pattern, specifically the availability of motor donor nerves. Simultaneous bilateral restoration is required in the event of CSCI and significantly improves the unilateral and bilateral function of the UEs.

Duplicated superficial branch of the radial nerve and brachioradialis muscle belly: prevalence and significance

BACKGROUND

The superficial branch of the radial nerve (SBRN) is a sensory nerve innervating the dorsoradial part of the hand. It originates in the cubital fossa, runs under the belly of the brachioradialis muscle (BM), emerges from underneath in the distal third of the forearm and continues in the subcutaneous tissue towards the hand. There exist several anatomical variations of its branching and course, including a rare variation of its duplication combined with a duplication of the brachioradialis muscle belly. The aim of this study was to find out the prevalence of this variation on a sample of cadaveric human bodies which has not been reported yet.

MATERIALS AND METHODS

We have carefully dissected 208 cadaveric upper limbs (Central European population). All cases of limbs containing the variation of a double SBRN and/or a double BM belly were measured and documented.

RESULTS

We have identified 2 cases of a double SBRN combined with a double BM belly (0.96%). Both were present in the right forearm of a male donor and in both cases the nerve was impinged by muscle bundles connecting the 2 muscle bellies together. Moreover, we have encountered 1 case of a double SBRN without a double BM belly (0.48%), i.e. the total prevalence of a double SBRN was 1.44%.

CONCLUSIONS

The duplicated SBRN with the duplicated BM is a relatively rare anatomical variation that might cause complications while performing various surgical procedures in the forearm, moreover it might be a rare cause of Wartenberg's syndrome.

A meta-analysis on the anatomical variability of the brachial plexus: Part III - Branching of the infraclavicular part

INTRODUCTION

The anatomy of the brachial plexus has been a subject of interest to many researchers over time resulting in an inconsistent amount of data. Previously, our team had published two evidence-based studies on the anatomical variations involving the brachial plexus, therefore the aim of this study was to analyze the findings regarding the infraclavicular part of the brachial plexus with the use of meta-analytic techniques to complete the comprehensive series.

MATERIAL AND METHODS

Major scientific databases were extensively searched to compile anatomical studies investigating the morphology of the infraclavicular part of the brachial plexus. Extracted data were classified based on our proposed classification system and subsequently analyzed with the use of random effects meta-analysis to state the pooled prevalence estimates of the distinct variation patterns.

RESULTS

A total of 75 studies (4772 upper limbs) were selected for the meta-analysis. The branches of the lateral cord, including the lateral pectoral nerve and musculocutaneous nerve, resembled their usual origin in 76.8% (95% CI 50-96%) and 98.8% (95% CI 98-100%), respectively. The medial pectoral nerve, medial brachial cutaneous nerves, medial antebrachial cutaneous nerve and ulnar nerve emerging from the medial cord were observed originating from their usual origins in 90.9% (95% CI 68-100%), 90.7% (95% CI 73-100%), 87.9% (95% CI 67-99%) and 97.7% (95% CI 94-100%), respectively. Lastly, nerves branching from the posterior cord, including the superior and inferior subscapular nerves, thoracodorsal nerve, axillary nerve and radial nerve, originated as per textbook description in 90.7% (95% CI 80-98%), 76.1% (95% CI 61-89%), 90.1% (95% CI 84-95%), 79.8% (95% CI 68-90%) and 99.0% (95% CI 96-100%), respectively. Moreover, the usual origin of the median nerve from the lateral and medial cord via the corresponding roots was encountered in 89.7% (95% CI 84-95%) of cases.

CONCLUSIONS

The nerves originating from the infraclavicular part of the brachial plexus exhibit a wide spectrum of possible origins. However, the usual patterns were significantly the most common types present in more than three quarters of cases. Especially clinicians might profit from the enhanced understanding of the brachial plexus anatomy presented herein, since we offer a strong guide for handling the anatomically challenging pathologies in this specific area.

A novel method to measure sensory nerve conduction of the posterior antebrachial cutaneous nerve

INTRODUCTION/AIMS

Posterior antebrachial cutaneous (PABC) nerve conduction studies could be useful for distinguishing PABC neuropathy from C7 radiculopathy. In the conventional method using an antidromic method, the sensory nerve action potential (SNAP) is sometimes followed by a large volume-conducted motor potential. In this report we describe a reliable nerve conduction study using an orthodromic method for recording SNAPs of the PABC nerve.

METHODS

Thirty-six healthy volunteers participated in this study. PABC SNAPs were recorded by placing a surface-active electrode 2 cm anterior to the lateral epicondyle. The PABC nerve was stimulated 10 cm distal to the active recording electrode along a line from the recording point to the mid-dorsum of the wrist, midway between the radial and ulnar styloid processes. We also performed PABC nerve conduction studies using an antidromic method and compared the findings.

RESULTS

PABC SNAPs were recorded bilaterally from all subjects. The mean peak-to-peak amplitude for SNAPs was 13.4 ± 4.8 μV. Mean maximum conduction velocity was 62.7 ± 3.9 m/s and mean negative peak conduction velocity was 51.2 ± 2.6 m/s. The mean side-to-side difference in amplitude was 22.1 ± 16.0%. The mean amplitude of SNAPs obtained by our method was 48.9% higher than that of SNAPs obtained by the conventional method (13.4 vs 9.0 μV; P < .001). In contrast to the conventional method, our method enabled SNAPs to be recorded without a volume-conducted motor potential.

DISCUSSION

The higher mean amplitude of SNAPs with our method enables them to be obtained easily.

Radial nerve palsy: If in doubt, use ultrasound

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

The anatomy of the anconeus nerve redefined

The anconeus nerve is the longest branch of the radial nerve and suitable as a donor for the neurotization of the axillary nerve. The aim of this study was to map its topographical course with reference to palpable, anatomical landmarks. The anconeus nerve was followed in 15 cadaveric specimens from its origin to its entry to the anconeus. It runs between the lateral and the medial head of the triceps before entering the medial head and running intramuscularly further distal. Exiting the muscle, it lies on the periosteum and the articular capsule of the elbow, before entering the anconeus muscle. Two types of anconeus nerve in relation to branches innervating triceps were found: nine nerves also innervated the lateral triceps head, while the other six only contributed two branches to its innervation. The course of the anconeus nerve is important for harvesting as a donor nerve and to protect the nerve in surgical elbow approaches.

Cadaveric and Ultrasound Validation of Percutaneous Electrolysis Approaches at the Arcade of Frohse: A Potential Treatment for Radial Tunnel Syndrome

Entrapment of the radial nerve at the arcade of Frohse could contribute to symptoms in patients with lateral epicondylalgia or radial tunnel syndrome. Our aim was to determine the validity of applying percutaneous electrolysis, targeting the supinator muscle at the Frohse’s arcade with ultrasound imaging and in a Thiel-embalmed cadaver model (not ultrasound-guiding). Percutaneous electrolysis targeting the supinator muscle was conducted in five healthy volunteers (ultrasound study) and three Thiel-embalmed cadaver forearms. Two approaches, one with the forearm supinated and other with the forearm pronated were conducted. The needle was inserted until the tip reached the interphase of both bellies of the supinator muscle. Accurate needle penetration of the supinator muscle was observed in 100% in both US-imaging and cadaveric studies. No neurovascular bundle of the radial-nerve deep branch was pierced in any insertion. The distance from the tip of the needle to the neurovascular bundle was 15.3 ± 0.6 mm with the forearm supinated, and 11.2 ± 0.6 mm with the forearm pronated. The results of the current study support that percutaneous electrolysis can properly target the supinator muscle with either the forearm in supination or in pronation. In fact, penetration of the neurovascular bundle was not observed in any approach when percutaneous needling electrolysis was performed by an experienced clinician.

[Diagnosis and treatment of paralysis following intrafascicular peripheral nerve torsion: two clinical observations and a literature review]

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%.

Measurement of the Radial Nerve Danger Zone in Filipino Adults: A Cadaveric Study

Introduction

The radial nerve danger zone (RNDZ) is an important anatomic consideration to anticipate or prevent injury in trauma assessment or surgical fixation. No published estimate currently exists for Filipinos. In this study, we sought to provide a local estimate and explore potential predictors of this anatomic region in Filipino adult cadavers.

Materials and methods

Posterior dissection to expose and measure the radial nerve, from the lateral epicondyle to the lateral intermuscular septum, was performed in 60 upper limbs from 30 formalin-preserved cadavers in the laboratory of the Department of Anatomy, College of Medicine, University of the Philippines Manila. Univariate and multivariate linear regression modelling was performed with RNDZ as the dependent variable and age, sex, height and humeral length as potential independent variables individually and in combinations.

Results

The mean radial nerve length from the lateral epicondyle to the lateral intermuscular septum was estimated at 10.6 cm (95% confidence interval: 10.3 cm, 10.9cm). Height and humeral length were statistically significant univariate predictors in female cadavers, while only height was significant in male cadavers. In addition, all multivariate regression models were statistically significant and accounted for more than 57% of the variability in female RNDZ estimates. In comparison, only models that included height and age were statistically significant predictors of RNDZ and accounted for at most 22% of the variability of the estimate in males.

Conclusion

The estimated length of the radial nerve danger zone generated in this study should be strongly considered over other published estimates in surgical fixation procedures performed in adult Filipinos.

Radial motor nerve conduction studies recorded from triceps brachii and extensor carpi radialis longus: Techniques and reference values

INTRODUCTION/AIMS

Optimal timing of nerve transfer surgery in cervical spinal cord injury (SCI) depends upon the integrity of lower motor neurons (LMNs) in recipient nerves, which is best predicted by compound muscle action potential (CMAP) amplitude. There are no established techniques for obtaining the CMAP in two recipient muscles: triceps brachii and extensor carpi radialis longus (ECRL). This study aimed to develop recording techniques for radial motor studies to triceps and ECRL, and to determine reference values for CMAP amplitudes in healthy volunteers.

METHODS

This was a prospective observational study of healthy adults aged 18 years and older. Motor nerve conduction studies were performed, stimulating the radial nerve in the axilla, over the axillary pulse at the pectoralis major insertion. Recording was from triceps (long head) and ECRL. CMAP amplitude, area, latency, and stimulus intensity were recorded. Reference values (RV) were calculated for CMAP amplitudes using a value 2 standard deviations below the mean. Cube root or logarithmic transformations were used to correct for non-normal distributions.

RESULTS

Twenty-five healthy subjects participated. Triceps mean CMAP amplitude was 15.5 mV (SD 4.19), with an RV of 8.1 mV. ECRL mean CMAP amplitude was 11.5 mV (SD 3.54), with an RV of 6.2 mV. CMAP amplitude at ECRL was 75% (95% confidence interval 50%-100%) of that at triceps.

DISCUSSION

We describe a technique for recording radial motor NCS from triceps and ECRL. Knowledge of normal CMAP amplitudes will help identify LMN injury in patients with cervical SCI being considered for nerve transfers.

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.

Unusual sensory innervation of the dorsal hand and why we should bear this variation in mind

Detailed knowledge of the anatomy and different variations of the superficial branch of the radial nerve could be of great importance not only to anatomists but also to clinicians. A predominant radial nerve supply to the dorsum of the hand is rare. Herein, we present an unusual case of unilateral sensory innervation of the dorsal hand found during routine anatomical dissection of a 72-year-old at death male Caucasian cadaver. We also present a brief discussion of the reported variation and emphasize its potential clinical implications.

Posterior Interosseous Fascicular Constriction Within the Radial Nerve in a Diabetic Patient With Bilateral Neuralgic Amyotrophy: A Case Report

Background: Neuralgic amyotrophy (NA) is an acute, monophasic, painful inflammatory dysimmune focal, or multifocal mononeuropathy. The lesion in NA is not always restricted to the brachial plexus but also involves individual nerves or branches. The prognosis of NA is less favorable than previously assumed, but the reasons for poor recovery remain unknown. Nerve constriction may be one of the causes of poor prognosis in NA.

Case Presentation: Herein, we described a 54-year-old male with a history of type 2 diabetes in whom bilateral neuralgic amyotrophy developed with constriction of the posterior interosseous fascicle within the radial nerve. The patient experienced sudden-onset severe pain in both shoulders followed, 2 days later, by weakness in bilateral shoulders and the left forearm extensors over the subsequent month. The left forearm extensors were more severely affected than both shoulder girdle muscles. He noted a 7-kg weight loss for 1 month before pain onset. After diagnosing diabetic NA based on the clinical symptoms, imaging, and electrophysiological studies, treatment with systemic steroids improved pain and weakness in both shoulder muscles. Weakness in the left forearm extensors persisted after 1 month of steroid treatment. Follow-up ultrasound revealed constriction of the posterior interosseous fascicle within the main trunk of the left radial nerve at the elbow. Surgical exploration at 6 months after onset identified fascicle constriction, for which neurolysis was performed. Weakness in the extensors of the wrist and fingers did not improve during the 16-month follow-up.

Conclusion: A single constriction of the fascicle within a peripheral nerve may often be under-recognized if NA presents with variable degrees of weakness in bilateral upper limbs. Furthermore, fascicular constriction without edema of the parent nerve may be easily missed on the initial ultrasound. A lack of early recognition of nerve constriction and delay in surgical intervention can result in unfavorable outcomes. The physician should consider the possibility of the fascicular constriction when evaluating patients suspected of brachial NA with significant weakness in the distal upper limb compared to the proximal weakness or weakness of the distal upper limb that does not improve over time.

Is Dry Needling of the Supinator a Safe Procedure? A Potential Treatment for Lateral Epicondylalgia or Radial Tunnel Syndrome. A Cadaveric Study

The supinator muscle is involved in two pain conditions of the forearm and wrist: lateral epicondylalgia and radial tunnel syndrome. Its close anatomical relationship with the radial nerve at the arcade of Frohse encourages research on dry needling approaches. Our aim was to determine if a solid filiform needle safely penetrates the supinator muscle during the clinical application of dry needling. Needle insertion of the supinator muscle was conducted in ten cryopreserved forearm specimens with a 30 × 0.32 mm filiform needle. With the forearm pronated, the needle was inserted perpendicular into the skin at the dorsal aspect of the forearm at a point located 4cm distal to the lateral epicondyle. The needle was advanced to a depth judged to be in the supinator muscle. Safety was assessed by measuring the distance from the needle to the surrounding neurovascular bundles of the radial nerve. Accurate needle penetration of the supinator muscle was observed in 100% of the forearms (needle penetration:16.4 ± 2.7 mm 95% CI 14.5 mm to 18.3 mm). No neurovascular bundle of the radial nerve was pierced in any of the specimen’s forearms. The distances from the tip of the needle were 7.8 ± 2.9 mm (95% CI 5.7 mm to 9.8 mm) to the deep branch of the radial nerve and 8.6 ± 4.3 mm (95% CI 5.5 mm to 11.7 mm) to the superficial branch of the radial nerve. The results from this cadaveric study support the assumption that needling of the supinator muscle can be accurately and safely conducted by an experienced clinician.

Morphological basis of radial nerve dysfunction in newborns differs from that of no radial nerve dysfunction in adults in C5-C6-C7 injuries to the brachial plexus: a cadaveric study

OBJECTIVE

Injuries to the upper and middle trunks of brachial plexus result in dysfunction of radial nerves in newborns but do not in adults. We hypothesized that the radial nerve had a lower proportion of myelinated nerve fibers (MNFs) from the lower trunk in newborns than in adults, and in newborns those MNFs were less developed than MNFs in the radial nerve from the middle and upper trunks.

METHODS

We dissected bilateral brachial plexus of six newborn and six adult cadavers. The radial nerve and its fascicles were separated proximally to posterior divisions of the upper, middle and lower trunks, and fascicles of the radial nerve were harvested from three trunks to calculate respective percentage of MNFs accounting for the total number of MNFs in the radial nerve. We determined diameters of axons and g-ratios of MNFs in the radial nerve from three trunks.

RESULTS

Compared with adults, the percentage of MNFs in the radial nerve from the lower trunk was lower (p < 0.05), from the middle trunk higher (p < 0.05) and from the upper trunk similar (p > 0.05) in newborns, though MNF counts from three trunks were higher in newborns, respectively (p < 0.01, all). In newborns, MNFs in the radial nerve from the lower trunk had smaller axonal diameters and higher g-ratios than those from the middle and upper trunks (p < 0.017, all), while in adults there were no such differences.

CONCLUSIONS

Lower proportion of MNFs in the radial nerve from the lower trunk in newborns than in adults, and in newborns immaturity of MNFs from the lower trunk relative to MNFs from the middle and upper trunks may be the major morphological basis of difference in clinical appearances of radial nerve palsy caused by injuries to C5-C6-C7 between newborns and adults.

Reference values for the cross-sectional area of normal radial nerve at two levels using high-resolution ultrasonography

Aim of the study

High-resolution ultrasound is less often used to evaluate the radial nerves. The radial nerve is often involved in entrapment syndromes. The aim of the study is to establish the reference values for the cross-sectional area of the normal radial nerve on high-resolution ultrasonography, and to identify relationships between the cross-sectional area and the subject’s age, gender, height, weight, body mass index, and hand dominance.

Material and methods

The study was conducted on 200 subjects of both sexes, between 18 and 75 years of age, who did not have history of peripheral neuropathy or trauma to the upper limb. High-resolution real-time sonographic examination of the radial nerves was performed in both arms at two different levels. Level 1 was taken just proximal to the nerve bifurcation, and level 2 just after the nerve exits the spiral grove.

Results

The mean cross-sectional area measured at level 2 (4.3 ± 0.4 mm²) was greater than that measured at level 1 (2.3 ± 0.3 mm²). No significant relationship was seen with age and hand dominance (p >0.05), but the cross-sectional area values at above mentioned levels were larger in males than in females (p <0.05). In addition, the cross-sectional areas of the radial nerves showed a positive correlation with height, weight, and body mass index (p <0.05).

Conclusion

The established ultrasonographic reference values along with basic clinical data will aid in the diagnosis, response to treatment, and prognostic evaluation of peripheral neuropathies.

Ultrasound-Guided Percutaneous Neuromodulation in Patients with Chronic Lateral Epicondylalgia: A Pilot Randomized Clinical Trial

OBJECTIVE

The aim was to analyze effects of a percutaneous neuromodulation (PNM) treatment on the radial nerve, regarding pain, functionality, electrophysiologic excitability, and morphology, in patients with chronic lateral epicondylalgia (LE).

METHODS

Twenty-four patients with chronic unilateral elbow pain were recruited for this preliminary study and were divided into two groups: control (n = 12) and PNM group (n = 12). The subjects in the PNM group received percutaneous peripheral neurostimulation with an acupuncture needle that was located next to the nerve with ultrasound guidance. Pain using a numerical rating scale (NRS), functional ability using patient-rated tennis elbow evaluation (PRTEE), radial nerve cross-sectional area measured by ultrasound, and chronaxie and accommodation index (AI) measured by the strength-duration curve were evaluated.

RESULTS

Both groups showed no differences in the baseline measurements (all p = 0.001). However, at the end of the treatment, there were significant differences between groups since only the PNM group significantly improved their values compared to their baseline values: level of pain and cross-sectional area (CSA) values showed a significant decrease while the PRTEE scores showed a significant improvement. Then, regarding AI, the PNM group showed significant improvement for the electrophysiologic nerve excitability pattern, reporting normal function in all radial nerves after treatment (p = 0.001). However, chronaxie values always reported similar values with no differences between groups (p >0.05); Conclusion: Ultrasound-PNM technique may be an interesting therapeutic tool for the treatment of chronic LE due to the improvement in the level of pain, functionality, nerve morphology, and excitability in this population.

Current concepts in diagnosis and management of common upper limb nerve injuries in children

Peripheral nerve injuries (PNI) of the upper limb are a common event in the paediatric population, following both fractures and soft tissues injuries. Open injuries should in theory be easier to identify and the repair of injured structures performed as soon as possible in order to obtain a satisfying outcome. Conversely, due to the reduced compliance of younger children during clinical assessment, the diagnosis of a closed nerve injury may sometimes be delayed. As the compliance of patients is influenced by pain, anxiety and stress, the execution of the clinical manoeuvres intended to identify a loss of motor function or sensibility, can be impaired. Although the majority of PNI are neuroapraxias resulting in spontaneous recovery, there are open questions regarding certain aspects of closed PNI, e.g. when to ask for electrophysiological exams, when and how long to wait for a spontaneous recovery and when a surgical approach becomes mandatory. The aim of the article is therefore to analyse the main aspects of the different closed PNI of the upper limb in order to provide recommendations for timely and correct management, and to determine differences in the PNI treatment between children and adults.

Porphyric neuropathy

Acute hepatic porphyrias are inherited metabolic disorders that may present with polyneuropathy, which if not diagnosed early can lead to quadriparesis, respiratory weakness, and death. Porphyric neuropathy is an acute to subacute motor predominant axonal neuropathy with a predilection for the upper extremities and usually preceded by a predominantly parasympathetic autonomic neuropathy. The rapid progression and associated dysautonomia mimic Guillain-Barré syndrome but are distinguished by the absence of cerebrospinal fluid albuminocytologic dissociation, progression beyond 4 wk, and associated abdominal pain. Spot urine test to assess the porphyrin precursors delta-aminolevulinic acid and porphobilinogen can provide a timely diagnosis during an acute attack. Timely treatment with intravenous heme, carbohydrate loading, and avoidance of porphyrinogenic medications can prevent further neurological morbidity and mortality.

Optimal recording electrode placement for radial motor nerve conduction study using extensor indicis muscle: Cadaver and electrophysiological studies

INTRODUCTION/AIMS

The aim of this study was to determine the optimal combination of active (E1) and reference (E2) recording electrode placements for the radial motor nerve conduction study recording over the extensor indicis muscle using surface electrodes.

METHODS

Thirty-six upper limbs from 18 fresh frozen cadavers were dissected to determine the midpoint of the extensor indicis muscle. Radial nerve conduction study was performed in 112 arms of 56 healthy subjects. Six combinations of three E1 and two E2 sites were studied. The stimulation site was 8 cm proximal to the E1 electrode.

RESULTS

The optimal combination of placement sites for the E1 and E2 electrodes to provide the largest amplitude is E1 electrode at the distal 1/4 point of the forearm length and E2 electrode at the extensor indicis tendon point in the wrist.

DISCUSSION

Optimal recording electrode placement may increase the accuracy and reproducibility of radial motor nerve conduction studies.

Cross-sectional area reference values for peripheral nerve ultrasound in adults: a systematic review and meta-analysis-Part I: Upper extremity nerves

BACKGROUND AND PURPOSE

Measurement of the cross-sectional area (CSA) of peripheral nerves using ultrasound is useful in the evaluation of focal lesions like entrapment syndromes and inflammatory polyneuropathies. Here, a systematic review and meta-analysis of published CSA reference values for upper extremity nerves was performed.

METHODS

Available to date nerve ultrasound studies on healthy adults were included and a meta-analysis for CSA was provided of the following nerves: median nerve at the wrist, forearm, upper arm; ulnar nerve at the Guyon's canal, forearm, elbow, upper arm; radial nerve at the upper arm. Regression and correlation analyses for age, gender, height, weight, geographic continents and publication year are reported.

RESULTS

Seventy-four studies with 4186 healthy volunteers (mean age 42.7 years) and 18,226 examined nerve sites were included. The calculated mean pooled CSA of the median nerve at the wrist was 8.3 mm² (95% confidence interval [95% CI] 7.9-8.7, n = 4071), at the forearm 6.4 mm² (95% CI 5.9-6.9, n = 3021), at the upper arm 8.3 mm² (95% CI 7.5-9.0, n = 1388), of the ulnar nerve at the Guyon's canal 4.1 mm² (95% CI 3.6-4.6, n = 1688), at the forearm 5.2 mm² (95% CI 4.8-5.7, n = 1983), at the elbow 5.9 mm² (95% CI 5.4-6.5, n = 2551), at the upper arm 6.6 mm² (95% CI 5.1-6.1, n = 1737) and of the radial nerve 5.1 mm² (95% CI 4.0-6.2, n = 1787). Substantial heterogeneity across studies (I² > 50%) was found only for the radial nerve. Subgroup analysis revealed a positive effect of age for the median nerve at the wrist and for height and weight for different sites of the ulnar nerve.

CONCLUSION

The first meta-analysis on CSA reference values for the upper extremities with no or only low heterogeneity of reported CSA values in most nerve sites is provided. Our data facilitate the goal of an international standardized evaluation protocol.

Three-dimensional measurement of the course of the radial nerve at the posterior humeral shaft: An in vivo anatomical study

PURPOSE

Iatrogenic radial nerve injury caused by surgical exposure of the humerus is a serious complication. We aimed to describe the course of the radial nerve at the posterior humeral shaft using a three-dimensional (3D) reconstruction technique by utilizing computed tomography (CT) images of living subjects. We hypothesized that the course of the radial nerve in the posterior aspect of the humeral shaft would be reliably established using this technique and the measurements would have satisfactory intraobserver/interobserver reliabilities.

METHODS

This in vivo anatomical study utilized 652 upper extremity CT angiography images from 326 patients. A 3D modeling of the humerus and radial nerve was performed. We evaluated the segment of the radial nerve that lays directly on the posterior aspect of the humeral shaft and measured its proximal point, mid, and distal points. The shortest distances from the olecranon fossa to these points were defined as R1, R2, and R3, respectively. The relationships between these parameters and humeral length (HL) and transcondylar length (TL) were evaluated, and the intraobserver/interobserver reliabilities of these parameters were measured.

RESULTS

The HL was 293.6 mm, and TL was 58.64 mm on average. The R1 measured 159.2 (range 127.1-198.2) mm, R2 was 136.6 (105.7-182.5), and R3 was 112.8 (76.8-150.0) mm on average (p < .001). The intraobserver/interobserver reliabilities ranged from 0.90 to 0.98.

CONCLUSION

The course of the radial nerve at the posterior aspect of the humeral shaft can be reliably established using the 3D reconstruction technique, and all measurements had excellent intraobserver/interobserver reliability.

Ultrasound guidance may have advantages over landmark-based guidance for some nerve conduction studies

BACKGROUND

Precise placement of stimulating and recording electrodes is vital when performing nerve conduction studies (NCSs). In this study, we aimed to determine whether ultrasonography (US) was more precise in localizing the superficial radial nerve (SRN), dorsal ulnar cutaneous nerve (DUCN), ulnar nerve (UN) crossing the cubital tunnel, and radial nerve (RN) crossing the spiral groove (SG) compared to conventional techniques.

METHODS

Thirty healthy young subjects (15 male) were recruited. Each subject underwent both landmark-based and US-guided NCS. Onset latencies and amplitudes of compound motor action potentials (CMAPs) and sensory nerve action potentials (SNAPs), and stimulation levels (ie, intensity × duration) required to obtain maximal CMAP amplitudes were compared between the two techniques.

RESULTS

The mean CMAP amplitudes of the UN above the cubital tunnel (9.55 ± 1.96 vs 8.96 ± 1.94 mV, P = .030), UN below the cubital tunnel (10.11 ± 2.07 vs 9.37 ± 1.95 mV, P < .001), and RN below the SG (5.21 ± 1.56 vs 4.34 ± 1.03 mV, P < .001) were significantly greater using US-guided NCSs compared to landmark-based NCSs. The mean onset latency of the DUCN was significantly shorter using US-guided NCSs (1.49 ± 0.15 vs 1.57 ± 0.14 ms, P = .020). The required stimulation level in the UN and RN was significantly lower using US-guided NCSs.

CONCLUSIONS

When performing NCSs, US guidance provides a more precise localization of the stimulator and electrodes for the DUCN, UN, and RN, while providing comparable localization for the SRN, compared to landmark-based techniques.

Anatomy of the nerves to the teres minor and the long head of the triceps brachii for electromyography

BACKGROUND

We investigated the branching pattern and topographic anatomy of the nerves to the teres minor (Tm) and the long head of the triceps brachii (LHT) in relation to reference lines extending between surface landmarks, to identify the innervation patterns of, and the optimal needle placement points within, the Tm and the LHT.

METHODS

The anatomical courses of the nerves to the Tm and the LHT were investigated in 37 upper limbs of fresh-frozen cadavers. Distances from the acromion to nerve penetration points, and crossing points of reference lines with the Tm and LHT were measured in 27 cadaveric upper limbs.

RESULTS

The Tm was innervated by the axillary nerve in all specimens in three patterns, and the LHT was innervated exclusively by the radial nerve. Our dissection and measurements indicate that the midpoint of the reference line from the acromion to the inferior angle of the scapula is the optimal needle insertion point for the Tm. The target point for the LHT appears to be the one-third point of the reference line from the acromion to the medial epicondyle, or the two-thirds point of the reference line from the acromion to the axillary fold.

CONCLUSIONS

We investigated the branching pattern of the nerves to the Tm and the LHT and propose optimal needle placement points for electromyography of the Tm and LHT.

New Functional Evaluation Scheme - Modality of the Results of Forearm Tendon Transfers Evaluation in Cases of Irreparable Radial Nerve Injury

Introduction

There are several evaluation schemes for the results of tendon transfers in case of radial nerve paralysis, and the most logical and commonly used are evaluation schemes that use the range of active joint movements to evaluate the results.

Aim

Present an original evaluation scheme for tendon transfer results based on functional wrist and fingers joint movements. The aim of the article is to present the advantages of our own Functional scheme in comparison with other schemes, its simplicity and applicability in the evaluation of all clinical cases of different postoperative outcome of the variables being evaluated, and to present the ease of comparison of the achieved results with other authors who would possibly use our scheme because it minimizes the subjective error of the examiner. The secondary aim is to compare the results of flexor carpi radialis (FCR) vs. flexor carpi ulnaris (FCU) tendon transfers (TT).

Methods

The study was conducted as clinical and retrospective. The study included 60 patients with isolated radial nerve palsy operated by two tendon transfer surgical methods (FCR and FCU) over a 10-year period. The evaluation of the results was performed by using Zachary, Neimann-Pertecke, Tajima evaluation schemes, our own Functional Evaluation Scheme as well as subjective patient evaluation.

Results

The time elapsed from injury to surgery ranged from 105 to 956 days in case of FCR tendon transfer and from 109 to 712 days in cases of FCU tendon transfer. The overall average age of patients is 36.71 years. A statistically significant difference in values with t -test based on the Functional Evaluation Scheme was found in the variables of ulnar deviation (p=0.000731), extension of the MP fingers joints II-V (p=0.04610) and extension of the MP of the thumb joint (p=0.0475). Evaluation of the total results with t-test (p=0.007532) and with U-test (p=0,00433) showed statistically better FCR tendon transfer results. A statistically significant difference in value measured by the t-test was found in the evaluation of the overall results (p=0.022) with Zachary and Neumann-Pertecke schemes and by the Tajima evaluation Scheme (p=0.042) in favor of better FCR tendon transfer results. With a use of Functional Evaluation Scheme, it is possible to evaluate all the results unlike most available schemes.

Conclusion

The functional evaluation scheme is based on the functional joint movements evaluated and incorporating radial and ulnar deviation of the wrist (RD and UD), extension of the metacarpophalangeal (MCP) joint and flexion of the intephalangeal (IP)joint of the thumb in the final evaluation becomes completely original. A functional evaluation scheme is simply applicable for the evaluation of all clinical cases of different postoperative outcome of the variables being evaluated. FCR tendon transfer achieves better results than FCU TT.

Strategy for the treatment of lateral epicondylitis of the elbow using denervation surgery

Background

A number of treatments for lateral epicondylitis of the elbow have been described. We have developed a strategy for the treatment of this condition.

Methods

We diagnosed lateral epicondylitis of the elbow in 86 patients. Conservative treatment resulted in resolution in 71 patients. Surgery was required in the remaining 15 patients. If the posterior branch of the posterior cutaneous nerve of the forearm showed a positive response to local anesthesia (block test), we performed denervation surgery on the posterior branch of the posterior cutaneous nerve of the forearm. Patients were asked to rate the degree of pain and sensory disturbance using a visual analog scale; the 11-item version of the Disabilities of the Arm, Shoulder and Hand measure; and the Patient-Rated Elbow Evaluation.

Results

A positive response to the block test was seen in 10 elbows (67%). After denervation surgery, pain relief was seen in 9 of 10 elbows (90%). The mean follow-up period was 30.4 months. At final follow-up, the average scores on the visual analog scale, 11-item version of the Disabilities of the Arm, Shoulder and Hand, and Patient-Rated Elbow Evaluation were 4.3 mm, 10.45 points, and 5.9 points, respectively. In the early period after denervation surgery, sensory disturbance was observed in 9 cases (90%).

Conclusion

Our strategy of denervation surgery for lateral epicondylitis of the elbow was effective for pain relief among patients showing a positive response to the block test.

The Branching and Innervation Pattern of the Radial Nerve in the Forearm: Clarifying the Literature and Understanding Variations and Their Clinical Implications

BACKGROUND

This study attempted to clarify the innervation pattern of the muscles of the distal arm and posterior forearm through cadaveric dissection.

METHODS

Thirty-five cadavers were dissected to expose the radial nerve in the forearm. Each muscular branch of the nerve was identified and their length and distance along the nerve were recorded. These values were used to determine the typical branching and motor entry orders.

RESULTS

The typical branching order was brachialis, brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, supinator, extensor digitorum, extensor carpi ulnaris, abductor pollicis longus, extensor digiti minimi, extensor pollicis brevis, extensor pollicis longus and extensor indicis. Notably, the radial nerve often innervated brachialis (60%), and its superficial branch often innervated extensor carpi radialis brevis (25.7%).

CONCLUSIONS

The radial nerve exhibits significant variability in the posterior forearm. However, there is enough consistency to identify an archetypal pattern and order of innervation. These findings may also need to be considered when planning surgical approaches to the distal arm, elbow and proximal forearm to prevent an undue loss of motor function. The review of the literature yielded multiple studies employing inconsistent metrics and terminology to define order or innervation.

Shear Wave Elastography to Guide Perineural Hydrodissection: Two Case Reports

Radial nerve palsy is not uncommon after humeral shaft fractures. Ultrasound-guided hydrodissection is an emerging treatment for nerve entrapment. Two cases of radial nerve injury after humeral shaft fractures with plate fixation are presented. Shear wave elastography was used to identify hardened scars surrounding the nerve, causing entrapment. These areas were marked on the skin as targets for ultrasound-guided hydrodissection. Each patient experienced full recovery of their radial nerve function. Shear wave elastography may be used to precisely identify sites of neural entrapment by scar tissue and accurately guide perineural hydrodissection, particularly in complex postoperative cases.

Upper extremity regional anesthesia techniques: A comprehensive review for clinical anesthesiologists

Surgeries and chronic pain states of the upper extremity are quite common and pose unique challenges for the clinical anesthesiology and pain specialists. Most innervation of the upper extremity involves the brachial plexus. The four most common brachial plexus blocks performed in clinical setting include the interscalene, supraclavicular, infraclavicular, and axillary brachial plexus blocks. These blocks are most commonly performed with the use of ultrasound-guided techniques, whereby analgesia is achieved by anesthetizing the brachial plexus at different levels such as the roots, divisions, cords, and branches. Additional regional anesthetic techniques for upper extremity surgery include wrist, intercostobrachial, and digital nerve blocks, which are most frequently performed using landmark anatomical techniques. This review provides a comprehensive summary of each of these blocks including anatomy, best practice techniques, and potential complications.