Terminal Branches Research Articles

The Enigma of the Motor Nerve Conduction Study.

In motor nerve conduction studies (MNCS), proximal stimulation should give a longer duration and lower amplitude compound muscle action potential (CMAP) due to higher temporal dispersion. Yet the CMAP waveforms at the distal and proximal stimulation sites appear remarkably similar. The objective of this study was to confirm this anomaly and investigate its possible cause by studying the median and ulnar nerves. Recordings from 50 subjects with normal electrodiagnostic studies were reviewed. The conduction velocity (CV) was measured using different points on the negative phase of the CMAP including its peak and baseline crossing. Collision studies were performed in three healthy subjects to measure the dispersion when nerve action potentials (APs) propagated from elbow to wrist. CV was relatively unaffected by the measurement point on the CMAP. The CMAP duration with elbow stimulation increased minimally compared to wrist stimulation. This was inconsistent with the dispersion of the AP from wrist to elbow measured in collision studies. The insignificant change in the CMAP in spite of axon AP dispersion is an enigma. We hypothesize that the terminal conduction time (TCT) (i.e., conduction in terminal axon branches, neuromuscular transmission, etc.) is independent of axon CV, represents a significant portion of the latency, masks AP dispersion, and reduces CMAP dispersion. This yields similar CMAPs with distal and proximal stimulation. The onset latency at the distal stimulation site does not depend on CV. Thus, onset latency and CV may not reflect the conduction properties of the fastest conducting axons.

Post-procedural Brachial Neuritis: Clinical, Electrodiagnostic and Neuroimaging features.

Brachial neuritis is a monophasic condition affecting the brachial plexus and its branches, manifesting as acute shoulder and upper arm pain, followed by weakness and paresthesias. It can be triggered by antecedent events, including procedures such as surgery. Misdiagnosis and delay in diagnosis is common. Imaging is important to confirm the diagnosis of post-procedural brachial neuritis and exclude other etiologies. Clinical, electrodiagnostic, and neuroimaging features of patients with post-procedural brachial neuritis from a single quaternary care institution were identified and analyzed. Six (2 female) patients were identified with median age 62 (range 49-70) years. Antecedent procedures included 4 cervical spine surgeries, 1 rotator cuff repair, and 1 central venous catheter placement. Time to symptom onset ranged from 1-day to 2-weeks. The initial symptom for 5/6 patients was severe upper extremity pain followed by weakness. All patients had electrodiagnostic tests and MR neurography consistent with brachial neuritis. MR neurogram showed plexus and/or terminal branch abnormalities with associated muscular denervation edema. The C5 or C6 root, and/or upper trunk were always involved. The most common branches affected were the suprascapular, long thoracic, and axillary nerves. Hourglass constrictions of these nerves were seen in 3/6 patients. The average time to diagnosis was 3.4 (range 1.5-5) months. Post-procedural brachial neuritis is an underrecognized cause of acute upper extremity pain and weakness. MR neurography can exclude iatrogenic causes and document the presence of hourglass constrictions in affected nerves. Diagnostic neuroradiologists should be aware of this clinical entity and associated neuroimaging findings. HGC = hourglass constriction; EDX = electrodiagnostic; IRB = Institutional Review Board; ACDF = anterior cervical discectomy and fusion; NRS = Numerical Rating Scale; MUAP = motor unit action potential.

Evaluation of split flexor carpi ulnaris tendon transfer for fingers and thumb extension, pronator teres transfer for wrist extension in high radial nerve palsy

Background: The radial nerve is the largest terminal branch of the brachial plexus. Loss of radial nerve function creates a significant disability in the hand. The grip is severely impaired following loss of radial nerve function as a result of loss of extension of wrist, metacarpophalangeal joints of fingers and interphalangeal joints of the thumb. Methods: Prospective, quasi experimental study carried out for 3 years at National Institute of Traumatology and Orthopaedic Rehabilitation (NITOR). Forty-eight patients of high radial nerve palsy were selected for tendon transfer (split FCU tendon to EDC and EPL) and PT transferred to ECRB. Results: Mean age of the patients was 28.92 years (range 15-45 years), significantly higher in 26-35 years age group. There was preponderance of injury to the dominant right side (58.33%) than the none-dominant left side (41.67%). Motor vehicle accident (66.67%) was the common cause of injury followed by assault (33.33%). Out of 48 patients, 28 patients score 8-9 (excellent), 16 patients score 7 (good), 4 patients scores 5 (fair). So that, total 44 patients achieved satisfactory outcome (91.67%) and 4 patients achieved unsatisfactory outcome (8.33%). All patients can extend their wrist, fingers and thumb. Beyond this, all patients can flex their fingers up to mid palmar crease and thumb can be extended separately-independent of EDC function. Conclusions: Transfer of split FCU tendon to EDC and EPL for fingers and thumb extension in irreparable and neglected long standing high radial nerve palsy results significant functional outcome.

Multiscale X-ray phase-contrast CT uncovers adaptive changes and compensatory mechanisms of circulatory pathways during acute liver injury

Intrahepatic circulation is essential for the repair of acute liver injury (ALI); however, very limited information is available concerning changes in the circulatory pathways during ALI. Therefore, multi-scale X-ray phase-contrast CT combined with three-dimensional (3D) visualization is used to quantitatively analyze the intrahepatic circulation pathway (including the hepatic vein, portal vein and hepatic sinusoid) in the mouse model via the intraperitoneal injection of carbon tetrachloride (CCl4) from acute injury to recovery. The results demonstrate that the liver still preserves some vessel-like channels accessed to the central vein when the injury causes the severe collapse of the hepatic sinusoids that cannot be observed in two-dimensional pathologic slices. Moreover, angiogenesis is observed in the terminal branches of the hepatic vein and portal vein. Additionally, we extend the two-dimensional primary lobule to a 3D model and find that the sinusoids in zone III have the most severe injury. The sinusoids in different zones also show changes in parameters such as density and mean diameter during the ALI. In conclusion, phase-contrast CT can reveal the intact vascular system within the liver lobes, thus providing critical information for studying the mechanisms involved in the evolution of circulatory structures from damage to repair.

Anatomical Variation of the Recurrent Motor Branch of the Median Nerve.

The recurrent motor branch (RMB) of the median nerve has commonly thought to originate proximal to the terminal digital branches, although its anatomical course and number may vary. We report a rare variation of the RMB that arose from the second common palmar digital nerve. The median nerve bifurcated into the first and second common palmar digital nerves distal to the transverse carpal ligament, with the RMB dividing from the second common palmar digital nerve and traveling retrograde to enter the abductor pollicis brevis muscle. This high origin variation may be at increased risk of injury during procedures of the hand.

A Retrospective Study of Lateral Antebrachial Cutaneous Nerve Neuropathy: Electrodiagnostic Findings and Etiologies in 49 Cases.

The lateral antebrachial cutaneous nerve (LACN) is the terminal sensory branch of the musculocutaneous nerve and is rarely entrapped or injured. This study describes the electrodiagnostic (EDX) findings and etiologies of LACN neuropathy. This is a review of 49 patients with pain and/or paresthesia of the forearm who underwent EDX studies. The diagnosis of LACN neuropathy was based on clinical and sensory conduction abnormalities. The most common etiology of LACN neuropathy was iatrogenic injury in 30 (61.2%) patients, primarily due to biceps tendon repair at the elbow (11 [36.7%]) and phlebotomy (5 [16.7%]). Fifteen (30.6%) patients sustained a non-iatrogenic injury at the proximal forearm/elbow, consisting of six (60%) laceration injuries and five (33.3%) stretch injuries. Four (8.2%) patients comprised the "other" etiology category, including two mass lesions causing LACN compression. Pain, paresthesia, and/or numbness in the LACN distribution were reported in 33 (67.3%), 27 (55.1%), and 23 (46.9%) patients, respectively. Hypoesthesia was detected in 45 (91.8%) patients, and dysesthesia in 7 (14.3%). The sensory nerve action potentials (SNAPs) of the LACN on the symptomatic side were absent in 44 (89.8%) patients. Of the five patients whose SNAPs of the LACN were detected, all had a decreased amplitude, and two had increased sensory latency. The most common etiology for LACN neuropathy in this series was iatrogenic injury; repair of biceps tendon at the elbow was the most frequent provoking cause. Protection of the LACN during surgical procedures at the elbow and forearm is vital to prevent iatrogenic injury.

A prospective observational study on the anatomical variations of recurrent laryngeal nerve and its application in the prevention of injury during thyroid surgery in a tertiary care centre

BackgroundThyroid gland is the largest and most vascular structure among the endocrine glands. The recurrent laryngeal nerve and the superior laryngeal nerve are closely related to the thyroid gland; these nerves control voice and are vital in breathing. Anatomical preservation of the recurrent laryngeal nerve (RLN) is the gold standard in thyroid surgery. Visual identification of RLN has decreased the rates of permanent RLN palsy during thyroid and parathyroid operations. Prior knowledge about the branching patterns will help in predicting and preventing injury to the nerve during thyroid surgery.Aim and objectivesThe aim of the study is to observe the terminal branching pattern of recurrent laryngeal nerve before its entry into the larynx.MethodsAn observational study with 50 participants who fulfilled the inclusion and exclusion criteria were enrolled in the study. After a complete evaluation and pre-anaesthetic checkup, the patients were operated and intraoperative findings of RLN branching were recorded and compared for the study.ResultsIn our study, out of the 50 patients who underwent thyroid surgery during the course of the study, right-sided RLN branching was demonstrated in 25 patients (21 right hemithyroidectomy and 4 total thyroidectomy). Ten patients had RLN bifurcation, 7 had trifurcation, 5 had numerous branches, and 3 with no branching pattern were noted. Similarly, out of 29 patients (25 left hemithyroidectomy and 4 total thyroidectomy) in whom left-sided RLN branching was studied, bifurcation was seen in 10 patients, trifurcation in 12 patients, and multiple branching was observed in 7.ConclusionThe anatomical variations seen in RLN may increase the risk of vocal cord palsy due to its injury. Anatomical variations are categorized according to the original direction of the RLN and the number of terminal branches in the larynx. This classification aids in the identification and preservation of its branches, hence facilitating a safer thyroidectomy.

Assessment of trochanteric vascularity using quantitative magnetic resonance imaging in a cadaveric model

AbstractPurposeFew studies have assessed trochanteric vascularity despite its implications for bone healing and surgical approaches. This study aimed to assess the regional arterial contributions of the medial femoral circumflex artery (MFCA) versus the lateral femoral circumflex artery (LFCA) to trochanteric vascularity.MethodsTen adult human cadaveric pelvises to mid‐femur specimens were obtained. One hip was randomly assigned experimental (either MFCA or LFCA MRI‐contrast infusion) and contralateral as control (MFCA and LFCA magnetic resonance imaging [MRI]‐contrast infusion). Vascular dissection was performed for MFCA and LFCA cannulation. Pre‐ and post‐contrast 3T MRI was completed, and intra‐osseous contributions were quantified by region: greater trochanter (GT), intertrochanteric (IT), lesser trochanter (LT) and subtrochanteric (ST). A polyurethane compound mixed with barium sulfate was injected into the LFCA cannula, and into the MFCA cannula for the contralateral hip. Computed tomography (CT) imaging was completed to assess terminal branch locations.ResultsMFCA provided the majority of arterial contributions to the full trochanteric region (68.5% MFCA, 31.5% LFCA; standard deviation [SD]: 10.7%, p < 0.001). Over 70% of arterial contributions to ST, LT and IT regions are derived from MFCA. GT contributions were more balanced (52.5% MFCA, 47.5% LFCA; SD: 33.7%; p = 0.853). Significant differences were found between MFCA and LFCA contributions in all regions except for the GT. CT revealed multiple consistent MFCA and LFCA trochanteric terminal branches.ConclusionsMFCA provided the dominant trochanteric arterial supply, which highlights MFCA's importance to overall hip vascularity. LFCA's trochanteric contribution was smaller but still provided trochanteric contributions, especially the GT region. Knowledge of trochanteric arterial contributions can be beneficial for optimizing surgical approaches and fixation to protect terminal branches during trochanteric fracture, nonunion treatment and trochanteric osteotomies.Level of EvidenceNot applicable.

Increased Postoperative Deltoid Signal seen after Suprapectoral Biceps Tenodesis: Potential Risk to the Anterior Branch of the Axillary Nerve

BackgroundArthroscopic suprapectoral biceps tenodesis is a common procedure for lesions of the long head of the biceps in the setting of anterior shoulder pain. However, the distal portal poses a theoretical risk to the terminal branches of the axillary nerve as the nerve travels from posterior to anterior to innervate the anterior deltoid. The purpose of this retrospective cohort study was to assess for axillary nerve branch injury, identified by deltoid signal change in postoperative magnetic resonance imaging (MRI) in patients who underwent an arthroscopic suprapectoral biceps tenodesis. MethodsPatients who underwent rotator cuff repair with a concomitant arthroscopic suprapectoral biceps tenodesis, had a postoperative MRI, and at least 1 year of follow-up were included. The incidence of increased deltoid signal consistent with injury to an anterior branch of the axillary nerve on proton density fat saturated sequences was collected. Age, sex, body mass index (BMI), and patient reported outcome measures (PROMs) including the American Shoulder and Elbow Surgeons Shoulder Score (ASES) score, Patient-Reported Outcomes Measurement Information System (PROMIS) pain, physical function (PF), and upper extremity (UE) scores, and Single Assessment Numeric Evaluation (SANE) score were compared in patients with and without increased deltoid signal on postoperative MRI. P<0.05 was used for significance. ResultsTwenty-four patients were eligible for inclusion (9 female, average age 59.0±10.1, BMI 27.6±6.7). Edema-like signal within the anterior deltoid musculature was observed in 9 patients on postoperative MRI. Two patients had a second follow-up MRI performed which demonstrated resolution of signal, and one patient required a second surgery for release of adhesions. Patients with increased deltoid signal had higher BMI (p=0.03). There was no difference in any other demographic or postoperative PROM between patients with increased signal and those without at any follow-up time point. No patient demonstrated persistent weakness or numbness in the axillary nerve distribution at final follow-up. DiscussionOver one third of patients in our cohort had MRI evidence of axillary nerve branch injury as seen on proton density fat saturated MRI sequences postoperatively. The distal arthroscopic portal for a suprapectoral biceps tenodesis may place anterior terminal branches of the axillary nerve at risk for injury. Additional investigation and strategies for avoidance of nerve injury in this area should be pursued.

Anterior transfer of the long head of triceps nerve to the terminal part of the anterior division of the axillary nerve through two incisions: A cadaveric feasibility study

PurposeRestoring shoulder function after axillary nerve injury is always a challenge. Transferring a branch of the radial nerve destined to the triceps onto the anterior division of the axillary nerve has become the preferred technique. However, this is not always possible, especially when the axillary nerve is severely injured around the posterior part of the humeral neck. The purpose of this cadaver study was to assess the feasibility of transferring the nerve of the long head of the triceps through an anterior and lateral humeral neck tunnel, directly onto the branch of the anterior division of the distal axillary nerve where it enters the deltoid fibers, by two surgical approaches. Materials and MethodsThis anatomical study was performed using 6 fresh cadavers (12 shoulders). A medial brachial approach was used to locate the radial nerve and its first branch, innervating the long head of the triceps. Then a second, transdeltoid approach was made to locate the end of the anterior branch near where it enters the deltoid fibers. The long head of the triceps nerve was transected as close as possible to the muscle, to provide the longest length possible. Then an anterior and lateral subdeltoid tunnel was made to retrieve this branch through the transdeltoid approach. ResultsThe long head of the triceps nerve could always be sutured to the anterior branch of the axillary nerve. Given the 7−12 mm surplus length (mean, 8.8 mm), tensionless suturing was possible in an anatomical region amenable to easier microsurgery. DiscussionTransfer of the long head of the triceps to the anterior branch of the axillary nerve through an axillary or posterior approach remains the preferred method for reinnervating the deltoid. However, in some patients, the axillary nerve is injured at or beyond the typical microsurgical suturing zone, which means that transfer cannot be accomplished under optimal conditions. For this reason, we suggest making the transfer more distally, using a dual approach that allows direct suturing of the long head of the triceps nerve onto the anterior terminal branch, which shortens the distance between the sutured nerve and the deltoid, and should improve outcome.

Origin of ventricular fibrillation triggers in a model of localized repolarization heterogeneity

BackgroundHeterogeneities in ventricular repolarization contribute significantly to the genesis of ventricular fibrillation (VF). Although clinical arrhythmias are spontaneously triggered by premature ventricular complexes, these triggers are difficult to document and little is known about their site of origin. ObjectiveTo characterize spontaneous VF initiation in an experimental model of repolarization heterogeneity and to identify the origin of triggers in relation to the spatial dispersion of repolarization. MethodsSpatially limited repolarization heterogeneity was created in isolated perfused porcine right ventricles (N =16) by local administration of pinacidil (20 μM) into a terminal branch of the right coronary artery. High-resolution optical mapping and pseudo-ECG were performed in control conditions and after pinacidil perfusion. ResultsNo arrhythmia occurred at baseline, but 74 VF episodes were observed in 13 hearts (82%) after pinacidil perfusion and were most often initiated by a ventricular trigger with short coupling interval (297±66ms). Sixteen VF initiations were optically mapped in four hearts. Mapping showed triggers originating in all cases from the border zone between altered and normal repolarization areas where local action potential duration and repolarization time gradients were steep (15.9 and 15.8 ms/mm versus 1.5 and 3.0 ms/mm in non-trigger sites). Optical action potential traces were compatible with a phase-two reexcitation mechanism. The subsequent VF cycles were driven by activities located in the same region. ConclusionsThis model of localized repolarization heterogeneity is able to produce spontaneous VF initiation. Our study demonstrates that VF triggers originate consistently from the border zone of repolarization dispersion.

Trans-arterial chemo-emobilization (TACE) combined with laparoscopic portal vein ligation and terminal branches portal vein embolization for hepatocellular carcinoma: a novel conversion strategy

Trans-arterial chemo-emobilization (TACE) combined with laparoscopic portal vein ligation and terminal branches portal vein embolization for hepatocellular carcinoma: a novel conversion strategy

Vascular supply of the radial nerve and its terminal branches: an anatomical study.

The aim of this cadaveric study was to further describe the vascular supply of the radial, posterior interosseous and superficial radial nerves. 11 cadaveric upper limbs, injected with colored latex, were dissected. Vascular afferents to the radial nerve, superficial radial nerve (SRN) and posterior interosseous nerve (PIN) were described and located. Their origin was identified and its distance to interepicondylar line was measured. The radial nerve had an average of 3 vascular afferents (1-5), of septomuscular origin in 54% of cases. 46% came from adjacent arteries. The PIN had an average of 8 vascular afferents (6-14), arising from septomuscular branches in 82% of cases. The PIN was vascularized in 100% of cases by a large arterial plexus originating from the supinator muscle between its two heads. The SRN had an average of 4 vascular afferents (3-7). Before crossing the septum of the brachioradialis, vascularization was predominantly septomuscular; after crossing the septum, the nerve was exclusively vascularized by septocutaneous arteries. This is the first study to describe the vascularization of the radial nerve and its terminal branches along their entire length. Our results are in line with the data available in the literature. An arterial plexus between the two heads of the supinator was surrounding the PIN in all cases. This vascular plexus might be involved in dynamic compression of the posterior interosseous nerve.

Stress heterogeneity in the eastern Tibetan Plateau and implications for the present-day plateau expansion

The eastward expansion of the Tibetan Plateau has resulted in different earthquake types in the eastern Tibetan Plateau, but the mechanism remains unclear. Here, we construct a three-dimensional visco-elastoplastic finite element model considering the topography to investigate the influence of fault geometry and rheological heterogeneity on stress fields. In our best-fitting model, the minimum principal stress is nearly vertical around the southern Huya fault zone, which is adjacent to the Longmen Shan fault zone, due to the significant mid-lower crust lateral rheological heterogeneity, and the thrust stress regime accounts for the reverse fault and thrust-dominated earthquakes. In this scenario, the eastward horizontal motion of the mid-lower crust is obstructed and facilitates thrust faulting, suggesting the limited eastward expansion of the Tibetan Plateau. In contrast, the northern Huya fault zone, one of the terminal branches of the East Kunlun fault, accommodates the continuous eastward extrusion of the East Kunlun fault, where the stress regime under a more homogenized crust favors the strike-slip faulting process, along with the dominant strike-slip earthquakes. Moreover, the best-fitting of stress regime explains the thrust-dominated 2008 Ms. 8.0 Wenchuan and 2013 Ms. 7.0 Lushan earthquakes on the Longmen Shan fault zone. Combining geophysical and geodetic observations and model analyses, we propose that the hybrid deformation mode in the eastern Tibetan Plateau is accommodated by upper crustal shear and thrusting deformation and mid-lower crustal thickening driven by the gravitational potential energy gradient. Our results elucidate the mechanism for differences in strong historical earthquakes and, more importantly, isolate the effect of fault geometry from those of heterogeneous viscosity on crustal deformation and stress heterogeneity in the eastern Tibetan Plateau.

Progressive Ulnar Neuropathy Following a Presumed Catfish Sting.

Catfish are a highly diverse group of fish comprising more than 3500 species found in both freshwater and marine ecosystems. Upon handling, they can inflict a sting, with certain species capable of inducing significant pain and injury to the affected extremity. The prevalence of aquatic activities, such as fishing by line or manual capture ("noodling"), increases the likelihood of catfish stings, making prompt identification and treatment an important aspect of managing such encounters. A case of a presumed catfish spine injury during noodling in Tallahassee, Florida, is presented. The pectoral fin penetrated the volar aspect of the patient's right hand resulting in immediate pain and numbness. Over the course of 2 weeks, the patient developed distal ulnar neuropathy with conduction block at the wrist level. Surgical exploration revealed the ulnar nerve to be grossly intact, but the area surrounding the terminal division point of the ulnar nerve in the hand displayed infiltration by fibrous tissue that entrapped the nerve and its branches. Following surgical release of the ulnar nerve and its terminal branches from the fibrous tissue, complete resolution of distal ulnar neuropathy was achieved. In this patient's case, the absence of foreign bodies and the lack of visible nerve damage suggest that the injury to the patient's hand was largely attributable to toxin-mediated proinflammatory response and fibrosis.

Extratemporal Facial Nerve Interconnections and Trunk's Variability: A Systematic Review with Meta-Analysis.

The present systematic review with meta-analysis is a significant contribution to the understanding of the morphological variability of the facial nerve (FN) extratemporal segment, i.e., the facial trunk (FT) variability, its division, and terminal branching patterns. The study also provides a comprehensive overview of the clinical significance of the FN extracranial division. Four online databases were utilized to conduct the systematic review according to evidence-based anatomy guidelines. A meta-analysis of the studies included was carried out using R programming software. The combined prevalence of the FN variants was calculated, along with subgroup and cumulative analysis. From the systematic review, 29 studies were retrieved as eligible for our initial purpose. However, 19 studies followed the same classification system and were selected for the meta-analysis, with a total sample of 2453 nerves. The most common pattern of the FN morphology was the FT bifurcation (typical pattern), with a pooled prevalence of 94.1% and a single interconnection (IC) between the temporofacial and cervicofacial branches (23.1% pooled prevalence). Two ICs between these branches were the rarest pattern (8.9% pooled prevalence). Our findings underscore the extensive morphological variability of the FN extratemporal anatomy, which has led to confusion among researchers. While several classification systems have been developed, none accurately represent the typical and variant anatomy. Our meta-analysis provided a small range between 8.9-23.1% for the rarest and most common pattern; thus, diversity is the rule. Therefore, it is not safe to conclude the typical morphology of FN extratemporal anatomy for its whole distribution before the FT's division (proximally) and its terminal branches (distally). Nevertheless, the bifurcation of the FT can be considered the typical morphology, and it is far more constant than the distal branching pattern. These findings have significant implications for surgical procedures, particularly parotidectomy, where surgeons must exercise utmost caution due to the potential clinical implications of FN injury.

Phylodynamic and Epistatic Analysis of Coxsackievirus A24 and Its Variant.

Coxsackievirus A24 (CV-A24) is a human enterovirus that causes acute flaccid paralysis. However, a Coxsackievirus A24 variant (CV-A24v) is the most common cause of eye infections. The causes of these variable pathogenicity and tissue tropism remain unclear. To elucidate the phylodynamics of CV-A24 and CV-A24v, we analyzed a dataset of 66 strains using Bayesian phylodynamic approach, along with detailed sequence variation and epistatic analyses. Six CV-A24 strains available in GenBank and 60 CV-A24v strains, including 11 Taiwanese strains, were included in this study. The results revealed striking differences between CV-A24 and CV-A24v exhibiting long terminal branches in the phylogenetic tree, respectively. CV-A24v presented distinct ladder-like clustering, indicating immune escape mechanisms. Notably, 10 genetic recombination events in the 3D regions were identified. Furthermore, 11 missense mutation signatures were detected to differentiate CV-A24 and CV-A24v; among these mutations, the F810Y substitution may significantly affect the secondary structure of the GH loop of VP1 and subsequently affect the epitopes of the capsid proteins. In conclusion, this study provides critical insights into the evolutionary dynamics and epidemiological characteristics of CV-A24 and CV-A24v, and highlights the differences in viral evolution and tissue tropism.

Anatomical characteristics of mental foramen and canal: A cone-beam computed tomography analysis.

So far, different studies have endeavored to evaluate the position and dimensions of mental foramen and canal using cone-beam computed tomography (CBCT) images with various results. This study aimed to assess the anatomical variations of the mental foramen and canal utilizing CBCT images. In this retrospective observational study, we investigated CBCT scans of 355 patients (710 terminal branches of mental canal and foramen) who were referred to a private dental and maxillofacial radiology center in Babol, during 2020-2022. We recorded different anatomical variations of mental foramina and canals on left (n=355) and right (n=355) mandibles. Most of the mental canals had a distal opening (n=334, 47.0%). The distance between the mental foramen and the lower mandibular border was greater on left mandible (13.92±3.73 mm) than on the right mandible (12.25±3.94 mm) (p<0.001). On left mandible, the vertical diameter of the mental foramen, as well as the distance between the mental foramen and the lower mandibular border, were significantly greater in men than in women. On right mandible, the distance between the mental foramen and the upper alveolar crest edge, as well as the distance between the mental foramen and the lower mandibular border, were significantly greater in men versus women. Finally, on right mandible, the vertical diameter of the mental foramen was significantly greater in subjects aged >45 years compared with those aged ≤45 (p=0.024). There were notable variations in the morphological characteristics of the mental foramen and canal, which should be considered by clinicians. Key words:Mental foramen, mental canal, cone-beam computed tomography.

Structural changes shaping the Drosophila ellipsoid body ER-neurons during development and aging

The ellipsoid body (EB) of the insect brain performs pivotal functions in controlling navigation. Input and output of the EB is provided by multiple classes of R-neurons (now referred to as ER-neurons) and columnar neurons which interact with each other in a stereotypical and spatially highly ordered manner. The developmental mechanisms that control the connectivity and topography of EB neurons are largely unknown. One indispensable prerequisite to unravel these mechanisms is to document in detail the sequence of events that shape EB neurons during their development. In this study, we analyzed the development of the Drosophila EB. In addition to globally following the ER-neuron and columnar neuron (sub)classes in the spatial context of their changing environment we performed a single cell analysis using the multi-color flip out (MCFO) system to analyze the developmental trajectory of ER-neurons at different pupal stages, young adults (4d) and aged adults (∼60d). We show that the EB develops as a merger of two distinct elements, a posterior and anterior EB primordium (prEBp and prEBa, respectively. ER-neurons belonging to different subclasses form growth cones and filopodia that associate with the prEBp and prEBa in a pattern that, from early pupal stages onward, foreshadows their mature structure. Filopodia of all ER-subclasses are initially much longer than the dendritic and terminal axonal branches they give rise to, and are pruned back during late pupal stages. Interestingly, extraneous branches, particularly significant in the dendritic domain, are a hallmark of ER-neuron structure in aged brains. Aging is also associated with a decline in synaptic connectivity from columnar neurons, as well as upregulation of presynaptic protein (Brp) in ER-neurons. Our findings advance the EB (and ER-neurons) as a favorable system to visualize and quantify the development and age-related decline of a complex neuronal circuitry.

Anatomical analysis of the radial nerve and arcade of Frohse in the cubital fossa using human cadavers.

The radial nerve (RN) is a peripheral nerve that originates from the posterior bundle of the brachial plexus and carries C5-Th1 fibers. In the cubital fossa radial nerve divides into a superficial branch of the radial nerve (SBRN) and a deep branch of the radial nerve (DBRN). Next DBRN enters under the arcade of Frohse (AF) and changes its name to posterior interosseous nerve of antebrachii (PIN). The AF was first described in 1908 by Frohs and Frankel. It is the superior proximal part of the supinator muscle, which can be tendinous or membranous. Eight dissected upper limbs were examined to measure the distances and characteristics of the RN, DBRN, SBRN and AF, utilizing precise electronic caliper. The average distance from the point of branching of the RN into its terminal branches to the AF was 54.64 mm on average. In half of the cases DBRN divided before entering the AF. The average distance from the point of branching of the DBRN to the AF in these cases was 13.88 mm. The width of the AF averaged 8.60 mm. Five tendinous AF and three membranous AF were identified. A thorough understanding of the anatomy of the radial nerve and its branches in the cubital fossa, as well as the AF, is important for the development of anatomy and may also contribute to the reduction of surgical complications during procedures in this area.