Nerve Section Research Articles

High-quality, large-scale, semi-thin, & ultra-thin sections of the optic nerve in large animals: An optimized procedure

Large animal model of optic nerve (ON) injury is an essential tool for translational medicine. Perfusion fixation with paraformaldehyde is mainly used for preparing the semi-thin (1–2 μm thick) and ultra-thin (<0.5 μm thick) sections of the ON tissues. However, this conventional fixation technique in large animals needs a large volume of fixatives, which increases the risk of toxic exposure and is environmentally unfriendly. Additionally, fixed residual ON cannot be used for other tests that require fresh tissue samples. Although conventional immersion fixation is feasible for preparing a semi-thin section of the ON in small animals (0.2–0.6 mm in diameter), it faces technical challenges when fixing the ON of large animals (3 mm in diameters), as increased diameter limits the permeability of the fixatives into deeper tissue. Therefore, we optimized the immersion-fixation method to obtain high-quality, large-scale, semi-thin, and ultra-thin sections for the ON of goat and rhesus macaques. Using this optimized technique, the ON microstructure was well preserved throughout the entire area of 1.5*1.5 square millimeters, allowing confident quantification of axon density/diameter on semi-thin section and identification of specific organelles and glial cells on ultra-thin sections.Furthermore, the optimized technique is a quick, simple, and environmentally friendly fixation method. Notably, the ON regions of large animals with or without an intact neurovascular system can be prepared for light and electron microscopy. In contrast, the residual unfixed ON from the same animal can be further utilized for experiments such as tissue culture and biomolecular tests.

Effects of Sigma-1 Receptor Ligands on Peripheral Nerve Regeneration

Peripheral nerve injuries lead to the loss of motor, sensory and autonomic functions in the territories supplied by the injured nerve. Currently, nerve injuries are managed by surgical repair procedures, and there are no effective drugs in the clinic for improving the capacity of axonal regeneration. Sigma-1 receptor (Sig-1R) is an endoplasmic reticulum chaperon protein involved in many functions, including neuroprotection and neuroplasticity. A few previous studies using Sig-1R ligands reported results that suggest this receptor as a putative target to enhance regeneration. The aim of this study was to evaluate the possible effects of Sig-1R ligands on axonal regeneration in a sciatic nerve section and repair model in mice. To this end, mice were treated either with the Sig-1R agonist PRE-084 or the antagonist BD1063, and a Sig-1R knock-out (KO) mice group was also studied. The electrophysiological and histological data showed that treatment with Sig-1R ligands, or the lack of this protein, did not markedly modify the process of axonal regeneration and target reinnervation after sciatic nerve injury. Nevertheless, the nociceptive tests provided results indicating a role of Sig-1R in sensory perception after nerve injury, and immunohistochemical labeling indicated a regulatory role in inflammatory cell infiltration in the injured nerve.

Clinical updates on phantom limb pain : German version

Most patients with amputation (up to 80 %) suffer from phantom limb pain postsurgery. These are often multimorbid patients who also have multiple risk factors for the development of chronic pain from a pain medicine perspective. Surgical removal of the body part and sectioning of peripheral nerves result in a lack of afferent feedback, followed by neuroplastic changes in the sensorimotor cortex. The experience of severe pain, peripheral, spinal, and cortical sensitization mechanisms, and changes in the body scheme contribute to chronic phantom limb pain. Psychosocial factors may also affect the course and the severity of the pain. Modern amputation medicine is an interdisciplinary responsibility. This review aims to provide an interdisciplinary overview of recent evidence-based and clinical knowledge. The scientific evidence for best practice is weak and contrasted by various clinical reports describing the polypragmatic use of drugs and interventional techniques. Approaches to restore the body scheme and integration of sensorimotor input are of importance. Modern techniques, including apps and virtual reality, offer an exciting supplement to already established approaches based on mirror therapy. Targeted prosthesis care helps to obtain or restore limb function and at the same time plays an important role reshaping the body scheme. Consequent prevention and treatment of severe postoperative pain and early integration of pharmacological and nonpharmacological interventions are required to reduce severe phantom limb pain. To obtain or restore body function, foresighted surgical planning and technique as well as an appropriate interdisciplinary management is needed.

The human vestibulo-ocular reflex and compensatory saccades in schwannoma patients before and after vestibular nerve section

ObjectiveTo examine the vestibulo-ocular reflex (VOR) and compensatory-saccades before and after complete unilateral vestibular deafferentation (UVD). MethodsForty patients were studied before and after surgery for vestibular or facial schwannoma using the video head-impulse test (vHIT) and multivariable regression. ResultsPrior to UVD (median(IQR), 14(58.4) days), the average VOR-gain towards the lesioned-ear was lower than in normal for all semicircular canals (lateral, anterior, posterior: 0.69, 0.72, 0.49). One-week after UVD (5(3.0) days) VOR gains were further reduced (0.22, 0.37, 0.27), however, within one-year after UVD (171(125.0) days) the lesioned-ear VOR gains had slightly increased (+0.08, +0.11, +0.03), maximally for the anterior-canal. After UVD, the VOR gain asymmetry (gain towards minus away from intact-ear) was lower for the intact posterior-canal plane (0.56, 0.56, 0.22). For the lesioned canals, the frequency and amplitude of the first compensatory-saccade increased from 61–93% and 1.9–3.6° pre-surgery, to 98–99% and to 3.1–5.9° one-week post-surgery and remained unchanged over one-year; second saccade frequency and amplitude decreased over the same timespan. ConclusionsAfter UVD the high-acceleration VOR for the intact posterior-canal plane is more symmetrical than the other canals. First compensatory-saccades adapt within one week and subsequently change only marginally. SignificanceSaccade compensation from surgical UVD is near complete by one-week.

Vestibular Nerve Section via Middle Cranial Fossa Approach.

Vestibular nerve section (VNS) is a surgical intervention with hearing preservation used for the treatment of Menière's disease after conservative medical therapy has failed (1,2). With the recent rise in less invasive treatments such as intratympanic gentamicin, VNS has been performed less frequently (3). The middle cranial fossa (MCF) approach for VNS is an uncommon approach due to its technical difficulty. However, it can provide the best distinction of internal auditory canal contents compared with retrosigmoid and retrolabyrinthine approaches. Several advancements in the MCF approach have been described, including the use of intraoperative facial nerve monitoring with electromyography, early removal of the temporal lobe retractor, and the use of an ultrasonic bone aspirator for internal auditory canal decompression (4-6). We demonstrate a case study with a step-by-step approach to successfully sectioning the superior and inferior vestibular nerves while utilizing these advancements and avoiding facial and cochlear nerve injury via the MCF (7). SDC video link: http://links.lww.com/MAO/B409.

Brachial plexus injury following blunt trauma; an anatomical variation in electrodiagnostic findings

Damage to the brachial plexus branches is one of the most important events during traumatic events, which may cause various disabilities. Electrodiagnostic testing is the preferred method to evaluate the extent of damage to the brachial plexus following trauma. The case presented in this paper, is a 26-year-old man who had near normal function of pronator teres and flexor carpi radialis muscles on electrodiagnostic testing following a right upper limb severe blunt injury at the level of his arm. After surgical investigation, we found a rare variation in the proximal part of the median nerve. In this case, branches to the pronator teres muscle and flexor carpi radialis had emerged from the proximal section of the median nerve in the arm region. This new variation holds important clinical implications especially in trauma patients presenting with weakness in forearm flexion.

Epidemiological, Lesional, Therapeutic and Evolutionary Aspects of Olecranon Fractures

Introduction: Olecranon fractures are the most frequent articular fractures of the elbow. Objective: The aim of our work is to study the epidemiological, lesional, therapeutic and evolutionary aspects of olecranon fractures in the Orthopaedic-Traumatology Department of Aristide Le Dantec Hospital in Dakar. Patients and methods: This was a retrospective study over a period of 4 years, from January 1, 2014 to December 31, 2017, including 32 patients operated for a recent olecranon fracture using the pinning-hooking technique. Results: The series included 21 patients, 18 males and 3 females with an average age of 34 years (extremes 21 and 62 years). Road and traffic accidents were the leading cause with 09cases ie 43 percent. According to the Mayo Clinic classification, we observed 04 type I fractures (03 type IA and 01 type IB), 17 type II fractures (13 type IIA and 4 type IIB). The associated lesions were: skin openings with 03 cases (type I of Cauchoix and Duparc); section of the ulnar nerve; osteochondral and tendon fractures and lesions involving the elbow, forearm, radius and humerus. The average delay to consultation surgery was 13 days. Evaluation according to the modified Mayo Clinic criteria showed 80% good and excellent results and 20% fair results. The average follow-up was 3 years. Complications included 1 case of infection, 3 cases of secondary displacement, 2 cases of stiffness and 1 case of mal union. Conclusion: The treatment of olecranon fractures remains surgical and the technique of tension band wiring is the gold standard.

Development of a convolutional neural network for the identification and the measurement of the median nerve on ultrasound images acquired at carpal tunnel level

BackgroundDeep learning applied to ultrasound (US) can provide a feedback to the sonographer about the correct identification of scanned tissues and allows for faster and standardized measurements. The most frequently adopted parameter for US diagnosis of carpal tunnel syndrome is the increasing of the cross-sectional area (CSA) of the median nerve. Our aim was to develop a deep learning algorithm, relying on convolutional neural networks (CNNs), for the localization and segmentation of the median nerve and the automatic measurement of its CSA on US images acquired at the proximal inlet of the carpal tunnel.MethodsConsecutive patients with rheumatic and musculoskeletal disorders were recruited. Transverse US images were acquired at the carpal tunnel inlet, and the CSA was manually measured. Anatomical variants were registered. The dataset consisted of 246 images (157 for training, 40 for validation, and 49 for testing) from 103 patients each associated with manual annotations of the nerve boundary. A Mask R-CNN, state-of-the-art CNN for image semantic segmentation, was trained on this dataset to accurately localize and segment the median nerve section. To evaluate the performances on the testing set, precision (Prec), recall (Rec), mean average precision (mAP), and Dice similarity coefficient (DSC) were computed. A sub-analysis excluding anatomical variants was performed. The CSA was automatically measured by the algorithm.ResultsThe algorithm correctly identified the median nerve in 41/49 images (83.7%) and in 41/43 images (95.3%) excluding anatomical variants. The following metrics were obtained (with and without anatomical variants, respectively): Prec 0.86 ± 0.33 and 0.96 ± 0.18, Rec 0.88 ± 0.33 and 0.98 ± 0.15, mAP 0.88 ± 0.33 and 0.98 ± 0.15, and DSC 0.86 ± 0.19 and 0.88 ± 0.19. The agreement between the algorithm and the sonographer CSA measurements was excellent [ICC 0.97 (0.94–0.98)].ConclusionsThe developed algorithm has shown excellent performances, especially if excluding anatomical variants. Future research should aim at expanding the US image dataset including a wider spectrum of normal anatomy and pathology. This deep learning approach has shown very high potentiality for a fully automatic support for US assessment of carpal tunnel syndrome.

Histopathology and high-resolution ultrasound imaging for peripheral nerve (injuries).

Neuropathies are commonplace in clinical practice and ultrasound assessment of the peripheral nerves is increasingly becoming a valuable diagnostic tool to support the physical and electrophysiological examinations. In the pertinent literature, several sonographic approaches have been proposed to evaluate the peripheral nerve tissue-mainly based on (semi)-quantitative measures. To define a standardized sonographic approach aiming to evaluate the different sono-histological sections of the peripheral nerve also in a qualitative way. Using high-frequency ultrasound probes and high-level ultrasound machines, we matched the histopathological features of the peripheral nerve (in acute and chronic phase) and the different sonographic patterns. Moreover, high-sensitive power Doppler assessments have been performed to assess the microcirculation of the peripheral nerve in physiological and pathological conditions. Modern ultrasound equipment allows a "real-time dissection" of the peripheral nerve evaluating the sonographic patterns of its different histological compartments in physiological and pathological conditions. Moreover, high-sensitive power Doppler allows clear visualization of the microcirculation of the peripheral nerve both in the acute and chronic phases of the neuropathy. In clinical practice, using adequate technological equipment, (semi)-quantitative measurements of the peripheral nerve can be coupled with different sonographic patterns of its histological components-both in the acute and chronic phase of the peripheral neuropathy. This way, better/prompt diagnosis and optimal management of the patients would be possible.

Electrophysiological characterization of ectopic spontaneous discharge in axotomized and intact fibers upon nerve transection: a role in spontaneous pain?

Many patients experience positive symptoms after traumatic nerve injury. Despite the increasing number of experimental studies in models of peripheral neuropathy and the knowledge acquired, most of these patients lack an effective treatment for their chronic pain. One possible explanation might be that most of the preclinical studies focused on the development of mechanical or thermal allodynia/hyperalgesia, neglecting that most of the patients with peripheral neuropathies complain mostly about spontaneous forms of pains. Here, we summarize the aberrant electrophysiological behavior of peripheral nerve fibers recorded in experimental models, the underlying pathophysiological mechanisms, and their relationship with the symptoms reported by patients. Upon nerve section, axotomized but also intact fibers develop ectopic spontaneous activity. Most interestingly, a proportion of axotomized fibers might present receptive fields in the skin far beyond the site of damage, indicative of a functional cross talk between neuromatose and intact fibers. All these features can be linked with some of the symptoms that neuropathic patients experience. Furthermore, we spotlight the consequence of primary afferents with different patterns of spontaneous discharge on the neural code and its relationship with chronic pain states. With this article, readers will be able to understand the pathophysiological mechanisms that might underlie some of the symptoms that experience neuropathic patients, with a special focus on spontaneous pain.

The effect of charge-balanced transcutaneous electrical nerve stimulation on rodent facial nerve regeneration

This study aimed to investigate the effect of charge-balanced transcutaneous electrical nerve stimulation (cb-TENS) in accelerating recovery of the facial function and nerve regeneration after facial nerve (FN) section in a rat model. The main trunk of the left FN was divided and immediately sutured just distal to the stylomastoid foramen in 66 Sprague–Dawley rats. The control group had no electrical stimulus. The other two groups received cb-TENS at 20 Hz (20 Hz group) or 40 Hz (40 Hz group). Cb-TENS was administered daily for seven days and then twice a week for three weeks thereafter. To assess the recovery of facial function, whisker movement was monitored for four weeks. Histopathological evaluation of nerve regeneration was performed using transmission electron microscopy (TEM) and confocal microscopy with immunofluorescence (IF) staining. In addition, the levels of various molecular biological markers that affect nerve regeneration were analyzed. Whisker movement in the cb-TENS groups showed faster and better recovery than the control group. The 40 Hz group showed significantly better movement at the first week after injury (p < 0.0125). In histopathological analyses using TEM, nerve axons and Schwann cells, which were destroyed immediately after the injury, recovered in all groups over time. However, the regeneration of the myelin sheath was remarkably rapid and thicker in the 20 Hz and 40 Hz groups than in the control group. Image analysis using IF staining showed that the expression levels of S100B and NF200 increased over time in all groups. Specifically, the expression of NF200 in the 20 Hz and 40 Hz groups increased markedly compared to the control group. The real-time polymerase chain reaction was performed on ten representative neurotrophic factors, and the levels of IL-1β and IL-6 were significantly higher in the 20 and 40 Hz groups than in the control group (p < 0.015). Cb-TENS facilitated and accelerated FN recovery in the rat model, as it significantly reduced the recovery time for the whisker movement. The histopathological study and analysis of neurotrophic factors supported the role of cb-TENS in the enhanced regeneration of the FN.

Nervus Intermedius Neuralgia With Vestibular Paroxysmia -A Rare Combination of Nerve Compression Syndromes

Introduction: Posterior cranial fossa nerve compressions in a rare combination are discussed here. Case Reports: 51 year old male with intractable vertigo, vomiting and left ear ache, had left spontaneous nystagmus. Another 25 year old female had recurrent ear ache and vertigo.Both MRI Brain showed compression of VII/VIII nerve complex in the cistern. They were given Ox carbamazepine with supportive therapy tapered with no recurrence in past 1 year. Discussion: The combination of the 7th and 8th cranial neuralgias presents with common symptomatology. The investigation of choice is HR T2 weighted MRI brain (CISS/FIESTA SPACE sequence), treated medically. Surgically, decompression or nerve sectioning are done. Conclusion: Though rare due to different positions of the nerve entry/exit zones of these nerves, this combination of posterior cranial fossa nerve compression syndromes can coexist. Diagnosis can help in the proper management of such patients and even open the hori-zon for surgical options in recalcitrant cases.

Posture‐dependent collapse of the optic nerve subarachnoid space: a combined MRI and modeling study

AbstractPurposeLarge trans‐lamina cribrosa pressure differences (TLCPD) have been suggested to play a role in the development of normal‐tension glaucoma. To avoid substantial increases in the TLCPD in upright postures, we hypothesize that a collapse of the optic nerve subarachnoid space (ONSAS) protects the eyes from large TLCPDs when we stand up, i.e., by preventing low cerebrospinal fluid pressures around the optic nerve. In this study, we combined magnetic resonance imaging (MRI) and mathematical modeling to investigate the suggested ONSAS collapse and its effects on the TLCPD.MethodsFirst, MRI was performed on six healthy volunteers in 6° head‐down tilt (HDT) and 13° head‐up tilt (HUT) to assess changes in ONSAS volume with changes in posture. The volume change represents optic nerve sheath distensibility. Second, we used the MRI data and mathematical modeling to simulate the ONSAS pressure and the potential ONSAS collapse in a fully upright posture (90°).ResultsThe MRI showed a decrease of 33% in the ONSAS volume when going from the HDT to the HUT position (p &lt; 0.001). In the upright posture, the simulations predicted an ONSAS collapse in the orbital section of the optic nerve, disrupting the pressure communication between the ONSAS and the intracranial subarachnoid space. The collapse reduced the simulated postural increase in TLCPD by roughly 1 mmHg, although this reduction was highly sensitive to the optic nerve sheath distensibility, varying between 0–4.8 mmHg when varying the distensibility by ±1 SD.ConclusionsThe ONSAS volume along the optic nerve is posture dependent during acute posture changes. The simulations supported the hypothesized ONSAS collapse in the upright posture and showed that even small changes in optic nerve sheath stiffness/distensibility may substantially affect the TLCPD, and thereby bear relevance for suggested TLCPD‐related disorders such as normal‐tension glaucoma.Ref‐erenceHolmlund, P. et al. Posture‐Dependent Collapse of the Optic Nerve Subarachnoid Space: A Combined MRI and Modeling Study. IOVS 62.4 (2021).

Berrettini Anastomosis Iatrogenic Injury Relating to Carpel Tunnel Syndrome Case Study

Some diseases require medical mitigation following the diagnosis, and sometimes the situation means that the patient has to undertake strong medication. However, this medicine is designed pharmacodynamically to interact with other organs before they reach the intended organ. Some mitigation imposes challenges on the involved organ. While the main organ will be healed, some drugs’ footprints will be left out to other organs. These are called iatrogenic injuries. In the case of anastomosis, it requires the alteration of surgical methods or the origin of iatrogenic injury in the arm; thus, the knowledge of anastomosis is very important to the field of medical practice. In addition, carpal tunnel release becomes vital in curing carpal tunnel syndrome. The paper focuses on a case of a 42-year-old woman found to have a complication to her middle finger. This case becomes important for studying Berrettini anastomosis iatrogenic injury, which relates to carpal tunnel syndrome. The Berrettini branch is a complication that facilitates communication between the superficial ulnar and median nerve. The analysis also provides the electro-diagnostic evidence of Berrettini anastomosis on how it can give a position three-finger and thus contribute to a force explanation of the median neuropraxia. Lastly, the paper provides information on the implication of the Berrettini branch for surgical use. The implication of pictures in the digital era can be used to analyze the varied connection and length between the median nerve and ulnar section. It’s easy to locate the position of high risk of iatrogenic injury in the palm due to the consistent location of Berrettini communication branches. The precaution is that operations have to be conducted moderately for a clear vision as the carefully mitigated practice ensures protection from the destruction and injury of the surrounding structures.

Neuroprotective Effects of Cordyceps cicadae (Ascomycetes) Mycelium Extract in the Rat Model of Optic Nerve Crush.

Cordyceps cicadae mycelium is an herbal medicine used to provide anti-inflammatory and antiapoptotic actions. However, little is known about the role of C. cicadae mycelium in neuroprotection. This study aimed to investigate the neuroprotective effects of C. cicadae mycelium extract (CCME) in the optic nerve crush (ONC) model. The optic nerves of adult male Wistar rats (aged 7-8 weeks) were crushed by a standardized method. Rats were divided equally into three groups: 1) a sham-operated group (sham), 2) a phosphate buffered saline-treated control group (crush), and 3) a CCME-treated group (CCME) that received CCME once daily for 7 consecutive days at doses of 100 mg/kg before ONC. Two weeks after ONC in rats, retinal ganglion cell (RGC) density and visual function were determined by using retrograde labeling with FluoroGold and flash visual evoked potentials. The terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and immunohistochemistry of ED1 (a marker of macrophage/microglia) were used to evaluate the antiapoptotic and anti-inflammatory effects of CCME in the optic nerve section. The P1-N2 amplitude and RGC density in the CCME-treated group were higher than those in the ONC control (crush) group by 5.15- and 3.13-fold, respectively. The numbers of TUNEL-positive cells and ED1-positive cells in the CCME-treated group were reduced by 4.38- and 6.63-fold, respectively, compared to those in the crush group. Oral administration of CCME provided neuroprotective effects in the ONC model via antiapoptotic and anti-inflammatory actions, which provides a potential treatment for patient with traumatic optic neuropathy.

Surgical Management of Intractable Meniere's Disease.

Meniere's Disease (MD) is an inner ear disorder characterized by spontaneous recurrent vertigo, fluctuating sensorineural hearing loss, aural fullness and low-pitch tinnitus. Therapeutic management of MD includes dietary restriction and medical therapy. A minority of cases is characterized by frequent vertigo attacks, progressive hearing loss and persistent tinnitus even through the continuous medical treatments; this condition is called intractable MD and requires a therapeutic escalation from non-invasive medical treatment to surgical intervention. Invasive procedures include endolymphatic sac surgery, vestibular nerve section and labyrinthectomy. These procedures have a very high success rate on symptom control but may have a severe impact on the hearing function. However, the simultaneous combined approach of demolitive surgery and cochlear implantation may be a valid approach to treat symptoms of intractable MD and preserve hearing function. In the present study, we review current literature focusing on intractable MD to describe and discuss advantages and disadvantages of established and newly proposed surgical treatments for intractable MD.

Surgical Correction of Breast Animation Deformity with Implant Pocket Conversion to a Prepectoral Plane.

We have read with interest the article by Holland et al.1 on prepectoral conversion as a treatment for animation deformity in patients with retropectoral breast implants. Animation deformity is a breast distortion caused during contraction of the pectoralis major in women with retropectoral implants, which can happen both in breast augmentation surgery and in reconstruction after mastectomy. The incidence of animation deformity varies according to the surgical technique used, reaching 75 percent to 100 percent in reconstructions after mastectomy.2–4 Various methods have been described for treating animation deformity, including selective nerve sectioning, replacing the implants by a muscle flap, conversion according to the split-muscle technique, and that described in the article by Holland et al.1 for prepectoral conversion. This last method is booming, given that it resolves the animation deformity in 100 percent of the cases.5 However, we believe that prepectoral conversion presents some limitations. First, this surgery theoretically restores the function of the pectoralis major by fixing its distal fibers to the chest wall. Nevertheless, the function of this muscle has already been supplied by other muscle groups; therefore, patients typically have no functional limitations. Second, this surgery is not without complications. In fact, Holland et al.1 reported an infection rate of 13.8 percent and a 6.3 percent rate of capsular contracture. Third, the cosmetic results can be suboptimal due to visibility of the implant, requiring revision surgery in 11.3 percent of patients.1 For this reason, Holland et al.1 in their series contraindicate the procedure for those women with a pinch test less than 1 cm who do not have donor fat. They used a biological mesh to cover the implant in 81 percent of patients, and in 52.5 percent, they performed lipofilling before the prepectoral conversion, thereby increasing the costs of the process. We recently treated a 26-year-old patient with retropectoral breast augmentation implants who presented with bilateral animation deformity and had undergone surgery on five occasions in various centers to correct this deformity without success. In our unit, we proposed sectioning the pectoralis major using a transcapsular approach. The surgery consisted of an incision in the inframammary fold, sectioning of the periprosthetic capsule, and withdrawal of the implant. Subsequently, we identified the muscle fibers responsible for the animation deformity using an electrical muscle stimulator (6 Hz; 400 μsec; 35 mA; 1 second of pause and 4 seconds of activity). Once we had performed the sectioning of the muscle fibers, we activated the electrical muscle stimulator to confirm elimination of the animation deformity. Many reasons motivate us to propose this procedure as an alternative for women with retropectoral implants and recurrent animation deformity. First, the technique has lower morbidity compared with prepectoral conversion due to not requiring capsulectomy and a new pocket for the implant. Second, the technique can be performed in patients with scarce subcutaneous tissue. Lastly, the procedure preserves the muscle coverage that provides an optimal cosmetic result because it reduces the implant’s visibility without needing a mesh or lipofilling, which increase the costs and complications of the surgical process. The technique of sectioning the pectoralis major guided by an electrical muscle stimulator should therefore be considered an alternative for resolving animation deformity. Its main advantages are its low morbidity, low cost, and good cosmetic results. However, prospective studies will be needed to assess the results of this technique. DISCLOSURE The authors have no disclosure or financial support to report. Benigno Acea-Nebril, M.D., Ph.D.Alejandra García-Novoa, M.D., Ph.D.Isabel Casal-Beloy, M.D., Ph.D.Breast UnitSurgery DepartmentHospital QuirosanludA Coruña, Spain

Macro-Microscopic Features of the Leg Muscles Innervation

The purpose of the study was to disclose topographic anatomical features of the extra- and intramuscular innervation points of the leg. Materials and methods. 15 adult human subjects and one-month old baby legs at three levels were studied using such methods: cross-sections according to N.I. Pirogov technique, histotopographic sections, macro-microscopic method, histological staining with hematoxylin-eosin and Krutsay. Results. In our macro-microscopic study, the main attention was paid to the individual anatomical variability in the innervation of the lower leg muscles. Study of the nerves of the leg muscles allowed to clarify the course of the neurovascular bundle of the leg at its three levels, taking into account individual age characteristics, and also to show the myeloarchitectonics of both the main nerve trunks and their intramuscular branches. Such differences in the location of the leg muscles of an adult and of one month-old baby undoubtedly related to the fact that the child’s muscular belly is longer in relation to the tendon. The histotopography of intramuscular nerves on total transverse sections of antagonistic muscles was studied: flexor and extensor digitorum longus, longus flexor and extensor of the big toe, and also the spectrum of myelin fibers contained in these nerves in a one-month-old baby and an adult was investigated. On histotopographic sections of the extensor digitorum longus nerve in a one-month-old baby, thick-diameter myelin fibers are absent, whereas in the long finger flexor nerve, on average, they are 0.5%. The number of thin and medium is respectively 8%, 13% and 83.5%, 16%. However, we have determined individual anatomical variability in the location of the vessels in relation to the main nerve trunks, as well as differences in the topography of the nerve in the corresponding muscles. Conclusion. In the nerves of the leg muscles, features were found, both in quantitative and qualitative composition of the conductors forming them; in the nerves of the flexor muscles, the composition of the nerve fibers is more diverse (with a slight predominance of the number of medium, thick and very thick fibers), which is associated with the peculiarity of their functions; in adulthood, the % ratio in the spectrum of myelin fibers in the nerves of the lower leg changes significantly

A case of ulnar nerve section at the elbow alleviated by Martin-Gruber communicating branch. Diagnostic characterization

Martin-Gruber communicating branch may be a confounding factor in the diagnosis of ulnar neuropathy at the elbow. It may also lead to a surprising level of motor function conservation despite evident neuropathy. We present a patient with ulnar nerve section at the elbow who underwent early treatment by nerve suture. At 7 months, function was good, despite sonographic findings of neurotmesis at the elbow. Electroneurography revealed Martin-Gruber communicating branch. This type of communicating branch can be associated with functional conservation despite ulnar nerve section. Electrophysiological and ultrasound findings can be highly contributive in defining these conditions.

AxonDeep: Automated Optic Nerve Axon Segmentation in Mice With Deep Learning.

PurposeOptic nerve damage is the principal feature of glaucoma and contributes to vision loss in many diseases. In animal models, nerve health has traditionally been assessed by human experts that grade damage qualitatively or manually quantify axons from sampling limited areas from histologic cross sections of nerve. Both approaches are prone to variability and are time consuming. First-generation automated approaches have begun to emerge, but all have significant shortcomings. Here, we seek improvements through use of deep-learning approaches for segmenting and quantifying axons from cross-sections of mouse optic nerve.MethodsTwo deep-learning approaches were developed and evaluated: (1) a traditional supervised approach using a fully convolutional network trained with only labeled data and (2) a semisupervised approach trained with both labeled and unlabeled data using a generative-adversarial-network framework.ResultsFrom comparisons with an independent test set of images with manually marked axon centers and boundaries, both deep-learning approaches outperformed an existing baseline automated approach and similarly to two independent experts. Performance of the semisupervised approach was superior and implemented into AxonDeep.ConclusionsAxonDeep performs automated quantification and segmentation of axons from healthy-appearing nerves and those with mild to moderate degrees of damage, similar to that of experts without the variability and constraints associated with manual performance.Translational RelevanceUse of deep learning for axon quantification provides rapid, objective, and higher throughput analysis of optic nerve that would otherwise not be possible.