Medial Cord Research Articles

Right Hand Dominant Musician With Right Hand Weakness

HPI: EM is a RHD 19yF musician presenting with insidious onset, progressive RH weakness worsening over the last 1-2 years. No trauma. She has difficulty with pincer grasping. Weakness is constant but exacerbated when playing guitar or flute for long periods of time. No numbness, pain, tingling or swelling of the RUE. Denies any fevers, chills, recent URI, polyarthralgia. No family history of neurologic or autoimmune disease. PE: No notable muscle atrophy or TTP in the RUE. Full ROM in neck, shoulder, elbow and wrist. 4/5 strength in pincer grip on right, 5/5 strength in right rotator cuff muscles, tricep, bicep, wrist flexion/extension. +Median nerve weakness, radial and ulnar nerve intact. Normal sensation and RUE reflexes. Positive Adson’s. Negative Spurling, Roos tests., Hoffman, Negative Tinel’s and Phalen’s at the wrist. DDX: Radial neuropathy, Carpal tunnel syndrome, Paget Schroetter Syndrome, Thoracic outlet syndrome, Parsonage-Turner syndrome TEST AND RESULTS: Labs: Within normal limits EMG: Results consistent with a significant True Neurogenic Thoracic Outlet Syndrome on the right. There is also electrodiagnostic evidence of a mild right ulnar mononeuropathy at the ulnar groove. Xray cervical spine: Enlarged transverse processes bilaterally at C7, larger on the right. Partial fusion at C3-4 with 2 mm retrolisthesis of C4 on C5 in extension that reduces with flexion. MRI Brachial plexus: Right cervical rib (at C7), with a hyperintense C8 spinal nerve coursing through this area, as are the medial cord, and visualized proximal ulnar nerve and possibly of the median nerve, likely attributable to mass effect from the cervical rib and/or an accompanying fibrous band. RUE vascular study: negative FINAL WORKING DIAGNOSIS: Neurogenic Thoracic Outlet Syndrome TREATMENT AND OUTCOMES: Initial EMG pointed to neurogenic TOS. Subsequently, patient completed cervical spine xrays and MRI of the brachial plexus, revealing cervical ribs with likely brachial plexus compression. Patient attended physical therapy to focus on posture while playing instruments, stretching of scalene muscles and strengthening scapular stabilizers. Unfortunately, she did not improve with conservative management. She has been seen by orthopedics and vascular surgery and is currently awaiting cervical rib resection surgery.

Spinal Nerve Modeling Within The Spinal Canal

The objective of this work is to develop a high‐resolution model of the brachial plexus with detail including individual spinal nerve rootlets. Medical illustrations may include this level of detail with artistic enhancement of structures of interest and suppression of background visual noise. Careful cadaver dissection of an open spinal canal and separated dural sheath will reveal the detail we seek for our digital model, but such dissection usually demonstrates them in positions unlike that of the living and intact nervous system. Our goal is to segment the nerves forming the brachial plexus, retaining their positions in‐vivo. We use a high resolution Visible Human Project type block face image dataset. The image database is from whole‐body imaging of an elderly, female donor with visible pathology. The focus of this work was on modeling the spinal nerves from C3 to T1. The brachial plexus and some peripheral nerves were included for orientation. This image database is made up of voxels spaced orthogonally 63μ apart, compared to the Visible Human Male image database with voxels spaced 1000μ apart. This voxel size yields a spatial resolution on the order of 300μ for this new dataset compared to the 5mm resolution of the VH Male. We can now see individual rootlets exiting the spinal cord to form the anterior and posterior spinal nerve roots but it is still challenging to follow each rootlet from beginning to end. We concentrated on nerves C3 to T1 which are the most visible as they diverge from the spinal cord soon after exiting the spinal columns. We were able to identify an average of five rootlets for each anterior and posterior root for nerves C3 through T1. Splines were constructed with control points to fit the path of the nervous structures. Each control point was assigned a radius to approximate the size of the structure at that point. We identified an anatomic anomaly demonstrating a conjoined posterior rootlet, which emerged from the posterior gray horn as one rootlet but split to contribute to the roots of C6 and C7. Within the brachial plexus we were able to identify the posterior rami for spinal nerves C3 to C5, which we were unable to find in VH Male data. For nerves C5 through C8 we followed anterior rami into the trunks, divisions, and cords of the brachial plexus. Following divisions and cords proved difficult because the cadaver was oriented with arms at her side such that the brachial plexus was compact as it is in the anatomical position. Freezing artifacts occasionally obscured the tissue, making it hard to confidently follow specific nerve components in a cluster of multiple trunks or divisions. We were still able to identify the superior, middle, and inferior trunks of the brachial plexus, the posterior and anterior divisions of each trunk, the lateral, posterior, and medial cords, the terminal nerves, and branching peripheral nerves. This modeling of the cervical spinal nerves and the brachial plexus is not only unique because of the extraordinary detail of the nervous structures, but also advantageous because it allows anatomy students to visualize these nerves in the same spatial configuration as in the living human.Figure shows 3D splines of brachial plexus and spinal nerve rami, roots, and and rootlets of C3 through T1.Figure 1Figure shows anatomical anomaly found where two nerve rootlets coming out from the root of C6 and C7 conjoin into a single rootlet before entering the posterior gray horn.Figure 2

The 2-Dimensional and 3-Dimensional Anatomy of the Adult Brachial Plexus Divisions and Cords.

Background: The objective of this work was to perform a critical review of the 2-dimensional and 3-dimensional anatomy of the adult brachial plexus divisions and cords. Methods: Twelve adult brachial plexuses from fresh cadavers were dissected. All were male and aged between 30 and 50 years. Only corpses without brachial plexus injuries were selected. The purpose of the dissections was to identify the origin of the anterior and posterior divisions of the adult brachial plexus in their respective trunks, as well as the positioning of the posterior, lateral, and medial cords. Results: The posterior division of all trunks had a cranial and dorsal origin, while the anterior division of all trunks had a caudal and ventral origin. The posterior cord was the most cranial of all, the lateral cord was central, and the medial cord was the most caudal of all cords. The posterior division of the superior trunk was always between the suprascapular nerve and the anterior division. Conclusions: Brachial plexus diagrams in most textbooks and papers are different from what was found in our dissections. Contrary to the known diagram, the posterior divisions always had a cranial origin in the superior, middle, and inferior trunks.

Single- versus double-injection costoclavicular block: a randomized comparison

BackgroundThe costoclavicular approach targets the brachial plexus in the proximal infraclavicular fossa, where the lateral, medial, and posterior cords are tightly bundled together. This randomized trial compared single- and double-injection...

Cadaveric Study of Anatomical Variations in the Musculocutaneous Nerve and in the Median Nerve

Introduction The musculocutaneous nerve and the median nerve are branches from the lateral cord of the brachial plexus with a root value of C5, C6, and C7. The medial root of the median nerve is a branch of the medial cord. The present study aims at observing any variations in these peripheral nerves, so that this knowledge can be utilized by surgeons, anesthesiologists, and orthopedicians during surgical procedures and nerve block. Materials and Methods The present study was carried on 30 adult embalmed cadavers (60 upper limbs) in the department of anatomy of the Kasturba Medical College , Manipal, India. The infraclavicular part of the brachial plexus was dissected, and any anatomical variations in the formation and in the branching pattern of the musculocutaneous nerve and of the median nerve were noted and photographs were taken. Results The median nerve was noted to be formed from 3 roots in 8 out of 60 dissected upper limbs (13.33%). The musculocutaneous nerve was absent in 5% of the dissected limbs, and communications between these 2 nerves were noted in 13.33% of the dissected limbs. Conclusions Noted variations of the nerves may be of help to surgeons operating in the axillas and in the arms.

Ultrasound Visualization of Torsional Anatomic Changes From External Rotation of the Anterior Shoulder.

Ultrasound images were obtained in a healthy human subject. Conventional imaging locations were selected that are typically utilized to assess musculoskeletal and peripheral nerve anatomy as well as perform therapeutic injections. The transducer was centered over each region to obtain both short- and long-axis views. A pair of sonographic images was recorded for both imaging planes at each site: the first in anatomic neutral and second in full external rotation. In addition, a video recording was made at each site to track the movement of the muscles and nerves during external rotation. The rotator interval including the intertubercular groove and biceps brachii long head moves far laterally when viewed in short axis, and it becomes out of plane when viewed in long axis. The subscapularis is relatively poorly visualized with the shoulder in neutral position, but the tendon and more distal aspect of the muscle are well visualized in full external rotation. The pectoralis major tendon insertion is well visualized in long axis with the shoulder in both neutral position and full external rotation. Movement of the humerus and the pectoralis major insertion are seen with shoulder rotation. The muscle appears to tighten and lengthen. The pectoralis major muscle is also seen in greater detail in external rotation. The cord level of the brachial plexus is also visualized at the infraclavicular portion of the anterior shoulder. The medial, posterior, and lateral cords are visualized in relation to the axillary artery. The relative position of the cords is only minimally altered with external rotation; however, the overlying pectoralis minor is tightened, and its influence can be visualized. External rotation has a considerable effect on the sonographic appearance of the anterior shoulder. Targets used for therapeutic injections, such as the bicipital groove, rotate out of clear view. Some chemodenervation targets, such as the muscle of the subscapularis, can only be accessed with the shoulder in full external rotation. Full external rotation of the shoulder also places torsional stress on some of the anterior shoulder structures, such as the pectorals, which can provide diagnostic clues in certain pathologic conditions. Movement into external rotation changes the sonographic appearance of the anatomic relationships of the anterior shoulder. Knowledge of these torsional changes can have both diagnostic and therapeutic implications.

A prospective study of high resolution ultrasound in brachial plexopathies – Correlation with electrophysiological measurements

ObjectivesTo evaluate the diagnostic role of ultrasound in brachial plexopathies. MethodsWe included 59 healthy subjects (HS) and 42 patients consecutively referred with clinical suspicion of brachial plexopathy from October 2015 to May 2016. Patients underwent routine electrodiagnostic testing (EDx) as reference standard and a blinded standardised ultrasound examination of the brachial plexus as index test with cross-sectional area (CSA) as the ultrasound parameter of choice. ResultsSeventeen patients were diagnosed by EDx with brachial plexopathy, ten with mononeuropathies, and ten had normal EDx. Five had a cervical radiculopathy. In 11 (64%) out of the 17 patients with EDx diagnosed plexopathy, we found at least one abnormal level on ultrasound. Six (60%) out of ten normal EDx patients had a normal ultrasound examination at all levels. Ultrasound identified the same abnormal level(s) as EDx in eight (73%) of the 11 patients who had both abnormal EDx and ultrasound results. Mean CSA was higher in the plexopathy group compared to HS at the level of the C6 root (p = .022), the middle trunk (p = .027), and the medial cord (p = .003). ConclusionUltrasound examination showed abnormalities in patients with brachial plexopathies in good agreement with EDx. SignificanceUltrasound may be an important supplement to electrodiagnostics in evaluating brachial plexopathies.

Patterns of injury to the infraclavicular brachial plexus following dislocation of the glenohumeral joint

Objectives: Brachial plexus injury (BPI) often results in devastating loss of upper limb function and debilitating neuropathic pain. The medial cord is often damaged following low-energy falls and glenohumeral dislocation. Medial cord injury (MCI) is associated with poor functional hand outcome due to paralysis of intrinsic muscles innervated by median and ulnar nerves, yet management options are limited. Nerve injury severity, demographic factors and concomitant injuries are poorly defined in this group. This study aims to understand patterns of infraclavicular BPI to guide management. Methods: All consecutive cases of infraclavicular BPI presenting to a regional peripheral nerve injury service over a 3-year period were retrospectively analysed. Medical records and neurophysiology reports were reviewed, and demographics and injury details were recorded on a database. Results: Ninety-nine infraclavicular BPI cases were identified. Of these, 34 (34%) were attributed to glenohumeral dislocations sustained in low-energy falls. There were 21 females and 13 males with mean age 62 years and mean body mass index 31. Five (13%) and 11 (29%) patients sustained vascular injuries and rotator cuff tears, respectively. Twelve (35%) patients sustained 13 fractures, of the proximal humerus or greater tuberosity. Review of injury patterns identified MCI in 24 cases (71%), 12 (50%) of which were amenable to nerve transfers. Conclusion: Low-energy falls are often accompanied by glenohumeral dislocation, whereby the medial cord is commonly damaged, resulting in an intrinsic minus hand. This injury subgroup has not been previously described, yet early recognition and referral for novel nerve transfer surgery can improve outcomes for these life-changing injuries.

A cadaveric feasibility study for a staged musculocutaneous to medial cord nerve transfer for restoration of hand function following infraclavicular brachial plexus injury

A cadaveric feasibility study for a staged musculocutaneous to medial cord nerve transfer for restoration of hand function following infraclavicular brachial plexus injury

OBLIGATORY ALTERATIONS IN THE MORPHOLOGY OF MEDIAN NERVE: A SONOGRAPHIC STUDY IN ASYMPTOMATIC INDIVIDUALS

Introduction: Median nerve is formed in axilla by contributions from medial and lateral cords of brachial plexus. It descends in the arm, forearm and then through carpal tunnel in close conjunction with flexor tendons of forearm. Carpal tunnel syndrome (CTS) is a common entrapment neuropathy. Median nerve cross sectional area (CSA) and ratio of nerve major axis to minor axis (flattening ratio) serve as potential diagnostic criteria for carpal tunnel syndrome. Median nerve cross sectional area and flattening ratio (FR) can be assessed by ultrasonography (US). Aim of the study was to assess median nerve by US and tabulate mean values for CSA and FR in asymptomatic population. This would serve to limit the cut-off values that differentiate asymptomatic nerves from neuropathic nerves. Material & Methods: Study was conducted in the Department of Anatomy, KGMU, Lucknow. Fifty randomly selected asymptomatic volunteers (undergraduate students: 30 males, 20 females) participated in the study. Sonography was performed to evaluate certain morphological dimensions of median nerve. Height, weight and wrist circumference of participants were also noted. Ultrasonography was performed using high frequency linear probe and observations were made at two pre-determined sites. Observations were recorded, tabulated and analyzed. Results: Median nerve was easily observable at both sites. It was round in shape in forearm (Fo), and flattened as it reached the carpal tunnel (Ct). Among all 50 study subjects, at both sites, flattening was more on right side (FRFoRt-1.71; FRCtRt-3.08) than on left side (FRFoLt-1.66; FRCtLt-2.78). In right forearm, nerve was flatter in females (FRFoRt-1.77) as compared to males (FRFoRt-1.68). In left forearm, median nerve was slightly rounder in females (FRFoLt-1.65) as compared to males (FRFoLt-1.67). At the distal wrist crease on right side, increased flattening was observed in females (FRCtRt-3.30) as compared to males (FRCtRt-2.94), whereas on left side, at same site flattening was more in females (males FRCtLt-2.74; females FRCtLt-2.83). Conclusion: Altered FR has both diagnostic as well as prognostic values in carpal tunnel syndrome. The database generated from the study will help in facilitating comparisons between normal, asymptomatic and pathological, asymptomatic individuals.

RETRACTED: Medial cord block after pectoral nerves block

RETRACTED: Medial cord block after pectoral nerves block

All-Endoscopic Resection of an Infraclavicular Brachial Plexus Schwannoma: Surgical Technique

Due to recent progress in shoulder arthroscopy, all-endoscopic brachial plexus (BP) dissection has progressively become a standardized procedure. Based on previously described techniques, we present an additional neurological procedure that may be performed all-endoscopically, that is, the excision of an infraclavicular BP schwannoma. Starting from a standard shoulder arthroscopy with posterior and lateral portals, additional anterior and medial portals are progressively opened outside the joint under endoscopic control to access the BP. At first, dissection of the subcoracoid space allows the identification of the posterior and lateral cords, along with the axillary artery. Then, by performing a pectoralis minor tenotomy, the medial cord and axillary vein are exposed, giving access to the whole infraclavicular plexus. Intraneural dissection is performed using arthroscopic tools such as a long beaver blade, a grasper, and a smooth dissector to progressively extract the encapsulated tumor from the nerve without any damage. Using a standardized technique, endoscopy may be an advantageous tool in selected cases of BP benign peripheral nerve sheath tumors.

Lead fracture of peripheral nerve stimulator for brachial plexopathy -a case report.

Peripheral nerve stimulation (PNS) is a useful treatment for chronic pain, but it can cause damage depending on its application site. Here, we describe the case of a 54-year-old man who underwent PNS for brachial plexopathy in 2015. One lead was implanted on the left medial cord to stimulate the medial antebrachial cutaneous nerve, and the other was implanted on the radial nerve to stimulate the posterior antebrachial cutaneous nerve. Both leads were inserted near the shoulder joint but did not cross it. Before PNS, the patient did not move his shoulder and elbow because of severe pain, but the treatment greatly alleviated this pain. Twenty months after the operation, both leads were fractured, and the severe pain returned. Repetitive motion near the joint was closely related to the lead fractures. In conclusion, large joints as the insertion sites of PNS leads should be avoided to prevent lead fractures.

T110. Visualization of nerve impulse traveling along the brachial plexus after ulnar nerve stimulation using magnetoneurography system

Introduction In somatosensory evoked potential (SEP) testing, an analysis of Erb’s potentials following median or ulnar nerve stimulation at the wrist may be useful to define a lesion of the lateral cord or the medial cord of the brachial plexus (BP) neuropathy. However, there have been few SEP studies on multiple site recording of Erb’s potentials so that traveling nature of the nerve impulse along BP has not been visualized yet. By analysis of magnetoneurogram with superconducting quantum interference device (SQUID) sensor system, we succeeded in visualizing the nerve impulse traveling along BP and then propagating into the C5–C8 intervertebral foramen after median nerve stimulation. Here we aimed to analyze the nerve impulse traveling along BP following ulnar nerve stimulation at the wrist. Methods Magnetoneurogram over BP of 5 healthy volunteers (Age range, 25–45 years; mean, 32.8 y.o) were measured after ulnar nerve stimulation (supramaximal stimulus; 5 Hz and averaging 2000 responses) using a newly developed 132 channel SQUID biomagnetometer with an X-ray imaging system (RICOH COMPANY, Ltd., Tokyo, Japan). At the same time, SEP was measured at Erb’s point using MEB-2300 (Nihon Kohden Corporation, Tokyo, Japan) for making sure to deliver supramaximal stimulation. After magnetoneurogram recording, evoked action currents were computationally reconstructed by a spatial filter method and the estimated electric currents map was superimposed over X-ray images. Results We were able to record the magnetic fields over the brachial plexus with good signal quality after ulnar nerve stimulation. Distribution of neural activity currents in the brachial plexus were estimated from the measured magnetic fields and visualized over X-ray images in all subjects. The currents distribution showed axonal activity pattern and passed medially to the coracoid process, crossed the clavicle, and reached the C7 - Th1 intervertebral foramen along the nerve path in the period between 8.0 ms and 13.0 ms after the stimulation. The conduction velocity calculated using the peak latency of the estimated current waveform on the nerve path was 67.13 ± 1.96 m/s. Conclusion By analysis of magnetoneurogram with participants’ X-ray image of the upper thorax,we succeeded in visualizing the nerve impulse traveling along (possibly) the medial cord of BP and then propagating into the C7 – Th1 intervertebral foramen after ulnar nerve stimulation at the wrist. Together with our previous study on magnetoneurogram after median nerve stimulation, we consider magnetoneurogram testing as superior to conventional SEP for analyzing the conductive function of BP because the former enables us to evaluate the conductive function of the nerve from the lateral or medial cord of BP to C5 – Th1 intervertebral foramen after median or ulnar nerve stimulation. We propose that the method of magnetoneurograph with the X-ray image can provide useful information for the non-invasive diagnosis of localization of conduction block in BP neuropathy.

Ultrasonography of Plantar Fibromatosis: Updated Case Series, Review of the Literature, and a Novel Descriptive Appearance Termed the "Comb Sign".

The purpose of this series is to review the appearance of plantar fibromatosis with high-resolution ultrasonography (US) and highlight a new imaging sign termed the "comb sign." A retrospective study was performed for patients with a clinical diagnosis of plantar fibromatosis. Charts of 43 patients (age range, 26-77 years; mean age, 54 years) were reviewed to gather patient demographics and symptoms. Several US characteristics were evaluated with emphasis on any new imaging features. A total of 57 plantar fibromas in 43 patients were examined. Plantar fibromatosis was seen as a lobular marginated oval nodule along the superficial plantar fascia involving the central or medial cord, often at the middle third (84%) of the plantar fascia, showing posterior acoustic enhancement (65%), mixed echogenicity (82%), and intralesional vascularity (53%). Slightly more than half (51%) of the lesions showed a previously unrecognized appearance, designated the comb sign. This sign was more commonly seen in the setting of larger fibromas (P < .05). Plantar fibromatosis is usually a clinical diagnosis that can be aided by a typical US appearance. Although the imaging characteristics are largely similar to prior literature, this series suggests that most show mixed echogenicity and posterior acoustic enhancement, and approximately half show internal vascularity. A new US sign, termed the comb sign, shows alternating bands of hypoechogenicity and isoechogenicity, particularly in larger plantar fibromas, and can help in further characterization.

P3-6-03. Visualization of nerve impulse traveling along the brachial plexus after ulnar nerve stimulation using 132ch SQUID magnetoneurography system

Using 132ch superconducting quantum interference device (SQUID) magnetoneurography sensor system, we succeeded in visualizing nerve impulse traveling along the brachial plexus (BP) after median nerve stimulation and propagating into the C5–C8 intervertebral foramen with participant’s X-ray imaging. Here we analyzed the nerve impulse traveling along BP following ulnar nerve stimulation at the wrist. Magnetoneurogram following wrist stimulation were measured over BP from 5 healthy volunteers. Somatosensory evoked potential (SEP) was simultaneously measured at Erb’s point for making sure to deliver supramaximal stimulation. Evoked action currents were estimated offline and superimposed on participant’s X-ray images. Similar to median nerve stimulation, the estimated currents distribution for the ulnar nerve stimulation comprised leading and trailing dipoles which traveled along the BP. Then, the estimated currents propagated into the C7 - Th1 intervertebral foramen. Together with our previous study on magnetoneurogram after median nerve stimulation, we consider magnetoneurogram testing as superior to conventional SEP for analyzing the conductive function of BP because the former enables us to evaluate the conductive function of the nerve from the lateral or medial cord of BP to C5 – Th1 intervertebral foramen after median or ulnar nerve stimulation.

Preventing brachial plexus injury during shoulder surgery: a real-time cadaveric study

Brachial plexopathy is not uncommon after shoulder surgery. Although thought to be due to stretch neuropathy, its etiology is poorly understood. This study aimed to identify arm positions and maneuvers that may risk causing brachial plexopathy during shoulder arthroplasty. Tensions in the cords of the brachial plexuses of 6 human cadaveric upper limbs were measured using load cells while each limb was placed in different arm positions and while they underwent shoulder hemiarthroplasty and revision reverse arthroplasty. Arthroplasty procedures in 4 specimens were performed with standard limb positioning (unsupported), and 2 specimens were supported from under the elbow (supported). Each cord then underwent biomechanical testing to identify tension corresponding to 10% strain (the stretch neuropathy threshold in animal models). Tensions exceeding 15 N, 11 N, and 9 N in the lateral, medial, and posterior cords, respectively, produced 10% strain. Shoulder abduction >70° and combined external rotation >60° with extension >50° increased medial cord tension above the 10% strain threshold. Medial cord tensions (mean ± standard error of the mean) in unsupported specimens increased over baseline during hemiarthroplasty (sounder insertion [4.7 ± 0.6 N, P = .04], prosthesis impaction [6.1 ± 0.8 N, P = .04], and arthroplasty reduction [5.0 ± 0.7 N, P = .04]) and revision reverse arthroplasty (retractor positioning [7.2 ± 0.8 N, P = .02]). Supported specimens experienced lower tensions than unsupported specimens. Shoulder abduction >70°, combined external rotation >60° with extension >50°, and downward forces on the humeral shaft may risk causing brachial plexopathy. Retractor placement, sounder insertion, humeral prosthesis impaction, and arthroplasty reduction increase medial cord tensions during shoulder arthroplasty. Supporting the arm from under the elbow protected the brachial plexus in this cadaveric model.

Co-Innervation of Triceps Brachii Muscle with Variant Branch of Ulnar Nerve.

To evaluate the existence of nerve innervation of the triceps brachii muscle via the ulnar nerve and its clinical importance in terms of nerve transfer or susceptibility to iatrogenic injuries during surgical procedures. Thirty-five skeletally mature upper extremities of adult cadavers were included in the present study. The ulnar nerve was revealed from the medial cord to the distal part of the cubital fossa. The existence of the branches of the ulnar nerve and communicant branch of the radial nerve was examined in the brachium. The diameter and length of the variant nerve branches were measured. A nerve branch from the ulnar nerve to the triceps brachii muscle was found in five of the dissected extremities (14.7%). The mean length and diameter of the variant nerve branch were 20.2 mm and 1.46 mm, respectively. The mean distance of the muscle entry point of the variant nerve branch from the bi-condylar line was 8.18 cm. A variant nerve branch via the ulnar nerve can innervate the medial head of the triceps brachii at the distal third of the brachium. This variant nerve branch will be under risk of iatrogenic injury during elbow surgery and it seems to be an option for nerve grafts.

Ulnar-Median Nerve Transposition: Embryology and Clinical Implications

Branches of the brachial plexus situated within the flexor compartment of the arm, the musculocutaneous, median and ulnar nerves maintain a predictive topography. The musculocutaneous nerve courses lateralward, the ulnar medial-ward, and the median between these. The present case features bilateral occurrence of ulnar and median transposition in a 74-year-old female cadaver. This transposition is related to dissimilar lengths of the lateral and medial roots of the median nerve. Both lateral roots of the median nerve were found to be unusually longer than usual. In addition, both medial roots coursed infero-medially instead of its usual superolateral coursing from their respective medial cords. These anomalies resulted in the median nerve being placed postero-inferior and medial to the ulnar nerve both lateral roots were observed crossing anterior to and impinging on their respective ulnar nerve. Clinical implications of the observed transposition include possible neurographic or MR ultrasonography misinterpretation of images. In addition such transposition may pose challenges to trauma surgeons engaged in nerve reconstruction following crush or mangled arm injuries. Anesthesiologists engaged in selective median or ulnar nerve blocks may witness increased procedural time and failures, as well as unexplained failure of analgesia in the skin areas normally supplied by their intended blocked nerve, a clinical situation that can be resolved by performing a neurostimulation.

Topographic Sonoanatomy of Infraclavicular Brachial Plexus: Variability and Correlation with Anthropometry.

Objective:The aim of the study was to assess the effectiveness of ultrasound in analyzing topographic relationship of nerve cords with axillary artery at lateral infraclavicular level, their variations, and the distance from the skin and to correlate findings with anthropometric parameters.Materials and Methods:Two hundred patients aged 18–75 years were enrolled for the study after informed written consent. A 7–12 MHz linear ultrasonic transducer was used for scanning of the brachial plexus at lateral infraclavicular fossa. The results of the cord positions were expressed on a 12-section pie chart, and the number of arteries and veins was reported. Measurements included the vertical distance from the upper part of the artery to the skin, diagonal distance to the apical corner of the ultrasound image, and distances from center of cords to the center of artery. Age, sex, weight, height, body mass index, and biceps girth were recorded. Data were expressed as mean with standard deviation or frequency and percentage for categorical variables, and statistical analysis was done using correlation analysis and two-sample t-test.Results:The most frequent positions of the cords were observed in 2–4 sections (92%) for the medial cord, 6–7 sections (92%) for the posterior cord, 10–11 sections (89%) for the lateral cord, and 4–5 sections (95%) for the axillary vein. More than one axillary vein was seen in 12.5% and two axillary arteries were seen in 1.5% of cases. Cord visibility and distance between artery and apical corner of the ultrasound image correlated with anthropometric parameters.Conclusions:A topographical study of brachial plexus at lateral infraclavicular fossa showed anatomical variations and abnormal vascular formations. This sonoanatomic knowledge can be helpful in improving safety and success of nerve blocks.