Nerve Bundles Research Articles

Myelin Basic Protein and Cardiac Sympathetic Neurodegeneration in Nonhuman Primates.

Minimal myelination is proposed to be a contributing factor to the preferential nigral neuronal loss in Parkinson's disease (PD). Similar to nigral dopaminergic neurons, sympathetic neurons innervating the heart have long, thin axons which are unmyelinated or minimally myelinated. Interestingly, cardiac sympathetic loss in PD is heterogeneous across the heart, yet the spatial relationship between myelination and neurodegeneration is unknown. Here, we report the mapping of myelin basic protein (MBP) expression across the left ventricle of normal rhesus macaques (n = 5) and animals intoxicated with systemic 6-OHDA (50 mg/kg iv) to model parkinsonian cardiac neurodegeneration (n = 10). A subset of 6-OHDA-treated rhesus received daily dosing of pioglitazone (5 mg/kg po; n = 5), a PPARγ agonist with neuroprotective properties. In normal animals, MBP-immunoreactivity (-ir) was identified surrounding approximately 14% of axonal fibers within nerve bundles of the left ventricle, with more myelinated nerve fibers at the base level of the left ventricle than the apex (p < 0.014). Greater MBP-ir at the base was related to a greater number of nerve bundles at that level relative to the apex (p < 0.05), as the percent of myelinated nerve fibers in bundles was not significantly different between levels of the heart. Cardiac sympathetic loss following 6-OHDA was associated with decreased MBP-ir in cardiac nerve bundles, with the percent decrease of MBP-ir greater in the apex (84.5%) than the base (52.0%). Interestingly, cardiac regions and levels with more MBP-ir in normal animals showed attenuated sympathetic loss relative to areas with less MBP-ir in 6-OHDA + placebo (r = −0.7, p < 0.014), but not in 6-OHDA + pioglitazone (r = −0.1) subjects. Our results demonstrate that myelination is present around a minority of left ventricle nerve bundle fibers, is heterogeneously distributed in the heart of rhesus macaques, and has a complex relationship with cardiac sympathetic neurodegeneration and neuroprotection.

The effect of adding Magnesium sulfate to Bupivcaine in Supraclavicular Brachial Plexus Block in Upper Limb Surgeries

Abstract Background Brachial plexus is a bundle of nerves that arises from the neck crossing through the axilla to supply the whole upper limb with motor and sensory supply. The aim in upper limb surgeries is to block this plexus using local anesthetics. Objective To study the effect of magnesium sulfate as an adjuvant to bupivacaine in supraclavicular brachial plexus block. Patients and Methods In our study 82 adult patients (age group 18-60, ASA I-II) were randomly and evenly divided into two equal groups (41 patients each), control group received only bupivacine 0.5 % and magnesium group received 2.5ml of 10% of magnesium in addition to bupivacine 0.5%. Patients were in semisitting position 45° the block was introduced US guided. Results Our study showed that addition of 250 mg of magnesium to bupivacine slightly delayed the onset time of both sensory and motor block (p value &amp;gt;0.05) which was non significant. Conclusion The addition of 250 mg magnesium sulfate to bupivacaine 0.5 % solution in supraclavicular brachial plexus block prolongs the duration of sensory and motor blockade, the duration of postoperative analgesia and reduces the requirement of rescue analgesic without any detected side effects.

The Role of Bcl-2 in Pediatric Functional Bowel Obstruction Cases with Ganglionated Specimens

Abstract Background Functional disturbances of the gastrointestinal tract is caused by a number of neurodysplastic conditions including other diseases, rarer than the Hirschsprung’s disease dysganglionosis, such as ganglion cells immaturity including Intestinal Neuronal Dysplasia (IND). Bcl-2 shows positive immunoreactivity in the degenerative and immature ganglion cells . Aim This work evaluates the role of immunohistochemical expression of Bcl-2 in pediatric functional bowel obstruction cases with ganglionated specimens. Material and Methods Twenty one cases of functional bowel obstruction were enrolled in our study including the Hirschsprung Allied Disorders (HAD) and operated cases of Hirschsprung’s Disease (HD) with adequate ganglionated resection margins and presented by obstructive symptoms following surgery. All cases underwent histologic examination of ganglion cells and nerve bundles as well as evaluation for Bcl-2 immunohistochemical expression. Results 57.1% of the cases were strongly positive for Bcl-2 protein, 19% were weakly positive and 23.8 % were negative. A highly significant correlation was demonstrated between Bcl-2 expression and ganglion cell number ( P &amp;lt; 0.001 ) where all hyperganglionic specimens showed strong positivity in contrast to the hypoganglionic and adequately ganglionic ones. A positive association was also found between Bcl-2 expression and IND in comparison to other disorders of dysganglionsis (P = 0.04) and recurrent HD cases (P = 0.002). A significant correlation was also detected between ganglion cell number and nerve bundle hypertrophy (P = 0.02). Conclusion Bcl-2 immunohistochemistry can be used as a valuable tool in the diagnosis of Hirschsprung’s disease allied disorders through its expression in the immature ganglion cells which are difficult to be identified by conventional H &amp; E staining.

NEUROMUSCULAR AND VASCULAR HAMARTOMA SECONDARY TO ENDOMETRIOSIS AT APPENDICEAL TIP MISDIAGNOSED AS APPENDICEAL NEOPLASM: AN EXTREMELY RARE CASE REPORT WITH LITERATURE REVIEW

Background: Endometriosis of the appendix is reported to be 1 to 3 % of the total endometriosis. Neuromuscular and vascular hamartoma (NMVH) is a rare lesion with only 27 cases reported in intestine since its initial description in 1982 and only one reported case in the appendix until now. We present a 52-year-old Omani female patient complaining of chronic interm Case presentation: itted abdominal pain. On CT scan (computed tomography scan), there was appendiceal lesion near the tip suggestive of mucinous cystadenoma. Diagnostic laparoscopy with appendectomy was conducted. There was a well-dened lesion with central fatty area at appendiceal tip focally merge with the outer muscle layer and mostly embedded in the mesoappendix. Microscopic examination showed focal area of endometriosis at the outer longitudinal muscle layer of the appendix. This focally merge with a well-dened mass like lesion that is embedded in the mesoappendix. The lesion composed of benign random arranged smooth muscle bers, scattered nerve bundles, some of which showed ganglionic cells including degenerated one, adipose tissue, thin and thick-walled small blood vessels. Features were consistent with NMVH that appeared secondary to the nearby endometriosis. Conclusion: Endometriosis of bowel should be suspected in female with longstanding intermitted abdominal pain. NMVH is extremely rare in appendix, thus clinical and radiological suggestion of such diagnosis is difcult. Secondary neuromuscular hamartoma is reported in association with Crohn's disease as a consequence of the chronic inammation and thus could be suspected secondary to endometriosis

Application of 3D Image Technology in Motor and Sensory Nerve Classification

Objective. To explore the application of 3D image technology in motor and sensory nerve classification. Methods. A total of 200 sections of the 5cm-long popliteal fossa peroneal nerve from adult volunteers were cut and frozen. The slices were 10 m thick, and the interval between the slices was 0.25 mm. Acetylcholinesterase histochemical staining was used to observe the changes of nerve bundles under the microscope. The stained sections were transformed into digital images by the digital camera system, and the images were stitched to obtain a two-dimensional panoramic image 100 times magnified. The properties of the functional bundles were manually judged. Using Amira 3.1 three‐dimensional reconstruction software to realize the three-dimensional reconstruction and visualization of nerve can not only accurately perceive the complex three-dimensional surface structure of nerve, but also arbitrarily display, rotate, scale, and segment the three-dimensional structure inside nerve, and carry out three-dimensional measurement in time. It has made preliminary achievements in brachial plexus, lumbosacral plexus, neural stem functional bundle (group), and intramuscular nerve routing and distribution, including the regeneration process of sensory nerve and three-dimensional reconstruction and visualization of composite tissue containing sensory nerve. Conclusion. Based on histology and computer technology, the functional band of short peroneal nerve can be reconstructed in 3D, which provides a feasible basis for the three-dimensional reconstruction of the functional band of the long peripheral nerve.

Vagus nerve bundle stimulation using 1505-nm laser irradiation in an in-vivo rat model.

Laser nerve stimulation using near-infrared laser irradiation has recently been studied in the peripheral nervous system as an alternative method to conventional electrical nerve stimulation. Bringing this method to the vagus nerve model could leverage this emerging stimulation approach to be tested in broader preclinical applications. Here, we report the capability of the laser nerve stimulation method on the rat vagus nerve bundle with a 1505-nm diode laser operated in continuous-wave mode. Studies of the stimulation threshold and laser-induced acute thermal injury to the nerve bundle were also performed to determine a temperature window for safe, reliable and reproducible laser stimulation of the rat vagus nerve bundle. The results show that laser stimulation of the vagus nerve bundle provides reliable and reproducible nerve stimulation in a rat model. These results also confirm a threshold temperature of >42°C with acute nerve damage observed above 46°C. A strong correlation was obtained between the laser time required to raise the nerve temperature above the stimulation threshold and the mean arterial pressure response. Advantages of the method such as non-contact delivery of external stimulus signals at mm scaled distance in air, enhanced spatial selectivity and electrical artefact-free measurements may indicate its potential to counteract the side effects of conventional electrical vagus nerve stimulation.

Nerve bundle formation during the promotion of peripheral nerve regeneration: collagen VI-neural cell adhesion molecule 1 interaction.

The formation of nerve bundles, which is partially regulated by neural cell adhesion molecule 1 (NCAM1), is important for neural network organization during peripheral nerve regeneration. However, little is known about how the extracellular matrix (ECM) microenvironment affects this process. Here, we seeded dorsal root ganglion tissue blocks on different ECM substrates of peripheral nerve ECM-derived matrix-gel, Matrigel, laminin 521, collagen I, and collagen IV, and observed well-aligned axon bundles growing in the peripheral nerve ECM-derived environment. We confirmed that NCAM1 is necessary but not sufficient to trigger this phenomenon. A protein interaction assay identified collagen VI as an extracellular partner of NCAM1 in the regulation of axonal fasciculation. Collagen VI interacted with NCAM1 by directly binding to the FNIII domain, thereby increasing the stability of NCAM1 at the axolemma. Our in vivo experiments on a rat sciatic nerve defect model also demonstrated orderly nerve bundle regeneration with improved projection accuracy and functional recovery after treatment with 10 mg/mL Matrigel and 20 μg/mL collagen VI. These findings suggest that the collagen VI-NCAM1 pathway plays a regulatory role in nerve bundle formation. This study was approved by the Animal Ethics Committee of Guangzhou Medical University (approval No. GY2019048) on April 30, 2019.

Visualization and analysis of whole depot adipose tissue neural innervation

SummaryLittle is known about the diversity and function of adipose tissue nerves, due in part to the inability to effectively visualize the tissue’s diverse nerve subtypes and the patterns of innervation across an intact depot. The tools to image and quantify adipose tissue innervation are currently limited. Here, we present a method of tissue processing that decreases tissue thickness in the z-axis while leaving cells intact for subsequent immunostaining. This was combined with autofluorescence quenching techniques to permit intact whole tissues to be mounted on slides and imaged by confocal microscopy, with a complementary means to perform whole tissue neurite density quantification after capture of tiled z-stack images. Additionally, we demonstrate how to visualize nerve terminals (the neuro-adipose nexus) in intact blocks of adipose tissue without z-depth reduction. We have included examples of data demonstrating nerve subtypes, neurovascular interactions, label-free imaging of collagen, and nerve bundle digital cross-sections.

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

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

Idiopathic clitoromegaly: Reduction clitoroplasty at Al-Rahma Hospital Zanzibar Tanzania: A case report and review of the literature

We present a case of 5 years old female with of idiopathic clitoromegaly managed by reduction clitoroplasty, preserving the dorsal neurovascular bundle and extensive network of nerves around the corpora to the glans Clitoromegaly is an embarrassing condition causing psychological stress, requiring intervention. The goals of clitoroplasty are to achieve normal genital anatomy and to preserve tactile sensation with a satisfactory sexual response.

Intercostal nerve cryoablation during surgical stabilization of rib fractures.

Intercostal nerve cryoablation (IC) offers potential for targeted and durable analgesia for patients with traumatic rib fractures. Our pilot study aimed to investigate thoracoscopic IC's safety, feasibility, and preliminary efficacy for patients undergoing surgical stabilization of rib fractures (SSRF). We hypothesized that concurrent surgical stabilization of rib fractures and intercostal nerve cryoablation (SSRF-IC) is a safe and feasible procedure without immediate or long-term complications. We retrospectively evaluated patients 18 years or older who underwent SSRF (with or without IC) for acute rib fractures at our level I trauma center between September 1, 2019, and September 30, 2020. We performed IC under thoracoscopic visualization (-70°C for 2 minutes per intercostal nerve bundle). Among patients whose only operative procedure during hospitalization was SSRF, we evaluated post-SSRF length of stay, operative times, opioid requirements (oral morphine equivalents), and pain scores (Numerical Rating Scale). Generalized estimating equations compared SSRF and SSRF-IC group outcomes (population mean [robust standard error]). We assessed long-term outcomes of patients who underwent SSRF-IC. Thirty-four patients (144 ribs) underwent SSRF; of these, 20 patients (135 ribs) underwent SSRF-IC. Patients who did and did not undergo concurrent IC had no significant difference demographic, injury, or hospitalization characteristics. Among 20 patients who did not undergo other operations, 12 underwent SSRF-IC. We did not find significant difference between SSRF and SSRF-IC groups' median operative times or post-SSRF length of stay. Compared with SSRF group, SSRF-IC group did not have statistically significant change in pain score (0.2 [1.5] lower) or opioid use (43.9 [86.1] mg/d greater) between 12 hours before SSRF and last 24 admission hours. Among 17 SSRF-IC patients who followed-up postdischarge (median [range], 160 [9-357] days), one reported mild chest wall paresthesia; no other complications were reported. This pilot study performing 135 intercostal nerve cryoablations on 20 patients suggests that IC is safe and feasible for patients undergoing SSRF. Evaluating IC's analgesic efficacy for rib fractures requires further study. Therapeutic, Level V.

Radiofrequency thermocoagulation of trigeminal nerve assisted by nerve bundle extraction and image fusion based on hamilton-jacobi equation

Background and Objective: Radiofrequency thermocoagulation is an effective method for treating classic trigeminal neuralgia. However, the accurate positioning of thermocoagulation is difficult. The purpose of this study was to design an optimal strategy for performing adjuvant surgery.Methods: A total of 60 patients with trigeminal neuralgia were divided into two groups. One group received conventional computed tomography (CT) guided treatment (CT group). In the other group, neural fiber bundles were firstly extracted based on the Hamilton-Jacobi equation. Then, the MRI, CT, and fiber bundle images were fused to visualize the relationship among semilunar ganglion, trigeminal nerve, and puncture needle (fusion group).Results: Trigeminal fiber bundles were extracted quickly by the contour tracking method, and different types of image fusion were realized for radiofrequency surgery navigation. In the fusion group, 13.3% of patients could not reach semilunar ganglion, and 76.9% of the remaining cases reached the ideal damage area. In the CT group, the preoperative design shows that 26.7% of patients may have puncture difficulty, and 54.5% of remaining cases reached the ideal damage area.Conclusion: The technique of neural bundle extraction and image fusion based on the Hamilton-Jacobi equation can be used to plan the personalized puncture path targeting the semilunar ganglion.

Does a preoperative cone beam CT reduce complication rates in the surgical removal of complex lower third molars? A retrospective study including 486 cases

BackroundThis study was designed to analyse the value of preoperative Cone Beam CTs (CBCT) prior to the surgical removal of complex lower third molars. Furthermore, the aim was to assess injuries to the inferior alveolar nerve (IAN) bundle and postoperative neurological disorders depending on the position of the lower third molar and the inferior alveolar nerve bundle.MethodsIn this retrospective examination preoperative Cone Beam CTs and Orthopantomographs (OPT) of 324 patients were analysed concerning the location of the lower third molars in relation to the mandible and the inferior alveolar nerve bundle. Surgery protocols of all patients who underwent the surgical removal of at least one complex lower third molar were analysed concerning patient data, length of surgery, intraoperative haemorrhage, intraoperative exposure of the inferior alveolar nerve bundle, postoperative swelling and postoperative neurological disorders. The data was then compared to data from international studies.ResultsIn all 324 patients a permanent neurological damage was not found. Temporary neurological damage was recorded in 13 cases (2.6%). A caudal nerve position with no measurable distance to the root of the lower third molar was associated with the highest risk of a temporal neurological damage. A vestibular touching nerve route also correlated with postoperative sensitivity impairment. If a mesioangulation (Winter) or a Pell and Gregory Type IIIC appears in the OPT, risk of neurological damage is at its highest.ConclusionsThree-dimensional radiographic imaging, in our patient group, does not significantly affect the risk for complications during the surgical removal of complex lower third molars. Therefore, it should only be utilized for risk assessment, especially in cases of symptom-free lower third molars.A preoperative orthopantomogram still can be accepted as standard for radiographic imaging.An intraoperative exposure of the IAN bundle does not necessarily predict simultaneous neurological damage. Exposure of the IAN bundle is no indication for a discontinuation of the surgery.

Long-term outcomes in children with Hirschsprung's disease and transition zone bowel pull-through: impact of surgical techniques and role for conservative approach.

Presence of transition zone (TZ) in the pulled colon can impact the outcome of surgery in children with Hirschsprung's disease. There is a wide variation in terminology used to define TZ and its management. We present our series of managing 11 such children with considerations for conservative management. Eleven of 114 children operated for Hirschsprung's disease had features of TZ on the 4-quadrant doughnut assessment of proximal anastomosing margin. They were followed up for development of obstructive symptoms, failure of pull-through procedure or bowel-related complications. Intervention done were observation with laxatives, dilatation, Botox injection and redo pull-through. Of the 11 children, 6 underwent Duhamel's procedure and 5, transanal endorectal pull-through (TERP). Features identified on HPE were presence of hypertrophic nerve bundles involving 2 or 3 quadrants in the circumferential doughnut biopsy of proximal anastomosing margin. Observed symptoms included constipation, enterocolitis, increased bowel frequency and soiling. Intervention done were use of laxatives with bowel management program in six and Botox injections in four. Only one child with TZ in 3 quadrants required redo surgery. Mean follow-up was 5.2years with resolution of symptoms in most. This study highlights the role of conservative management with good outcomes in children with TZ bowel pull-through having hypertrophic nerve fibers and normal ganglion pattern. Children who underwent Duhamel's procedure had little impact with the presence of TZ at anastomotic margin and majority of those undergoing TERP benefitted from Botox injection. Conservative management can be attempted successfully to prevent redo surgical interventions as they can lead to poorer outcomes. Only those children not responding to conservative measures need to be planned for revision surgery.

Regulation of Systemic Metabolism by Autonomic Nerve-Mediated Inter-Organ Networks

Autonomic nerves, including sympathetic nerves and parasympathetic nerves, innervate organs and modulate those function, thereby regulating systemic metabolism. Autonomic nerve bundles contain both afferent and efferent nerve fibers, and both fibers play important roles in regulating systemic metabolism for maintenance of homeostasis at the whole-body level. Furthermore, recently-obtained evidence unraveled the metabolic regulatory systems through autonomic nerve-mediated inter-organ networks. In these systems, afferent innervations of autonomic nerves transmit metabolic information from peripheral organs to the central nervous system (CNS), and the CNS regulates organ functions based on the transmitted metabolic information through efferent innervations of autonomic nerves. In this review, autonomic nerve-mediated inter-organ networks that are involved in systemic metabolism are introduced, especially focusing on the liver-brain-pancreatic β-cell inter-organ network.

Squamous and Respiratory Metaplasia After Olfactory Mucosal Resection.

Resection of the olfactory mucosa (OM) is sometimes unavoidable during surgery; however, it is not known whether the OM can completely recover thereafter. The aim of this study was to uncover whether the OM fully recovers after mucosal resection and describe the process of OM regeneration. 8-week-old male Sprague–Dawley rats (n = 18) were subjected to OM resection at the nasal septum; six rats were euthanized for histological examination 0, 30, and 90 days after surgery. Immunohistochemistry was performed to identify olfactory receptor neuron (ORN) lineage cells [mature and immature ORNs and ORN progenitors, and olfactory ensheathing cells (OECs)], as well as dividing and apoptotic cells. Squamous and respiratory metaplasia and inflammatory cell infiltration were also assessed. On day 30 after resection, the mucosa had regenerated, and mainly contained thin nerve bundles, basal cells, and immature ORNs, with a few mature ORNs and OECs. On day 90, the repaired nasal mucosa had degenerated into stratified squamous or ciliated pseudostratified columnar epithelia, with reducing ORNs. The lamina propria contained numerous macrophages. Partial regeneration was observed within 1 month after OM resection, whereas subsequent degeneration into squamous and respiratory epithelia occurred within 3 months. Given the poor persistence of ORNs and OECs, OM resection is likely to result in olfactory impairment. Overall, surgeons should be cautious not to injure the OM during surgery.

Electron Microscopic and Histopathological Study of the Overacting Inferior Oblique Muscle of the Human Eye

ABSTRACTBackground: Inferior oblique muscle overaction is a common disorder that has a correlation with the anatomical changes of the muscle itself. The changes differ according to the grade of the overaction.Objective: To correlate between the histopathological alternations of the inferior oblique muscle and the different degrees of clinical overaction.Patients and methods: Ten biopsies from inferior oblique muscles were taken during the surgery of strabismus after determining the clinical degree of the overaction. One muscle biopsy was taken during enucleation surgery and considered as a control. All biopsies were examined by light and transmission electron microscopes.Results: By light microscopy, grade II and grade III inferior oblique overaction showed many histopathological findings as muscle fibers degeneration, variable size of muscle fibers, nerve bundles hypertrophy and fibro-fatty infiltrations. Grade III inferior oblique overaction showed fibrosis of perimysium and endomysium, mononuclear infiltration and fatty infiltration. By transmission electron microscopy the muscle fibers showed increased mitochondrial number and mitochondrial variability in shape and size, also showed increased vacuoles and fat droplets.Conclusion: Histopathological alternations in the inferior oblique muscle correlate to the clinical grades of the muscle overaction.

Sympathetic innervation of the mouse kidney and liver arising from prevertebral ganglia.

The sympathetic nervous system (SNS) plays a crucial role in the regulation of renal and hepatic functions. Although sympathetic nerves to the kidney and liver have been identified in many species, specific details are lacking in the mouse. In the absence of detailed information of sympathetic prevertebral innervation of specific organs, selective manipulation of a specific function will remain challenging. Despite providing major postganglionic inputs to abdominal organs, limited data are available about the mouse celiac-superior mesenteric complex. We used tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DbH) reporter mice to visualize abdominal prevertebral ganglia. We found that both the TH and DbH reporter mice are useful models for identification of ganglia and nerve bundles. We further tested if the celiac-superior mesenteric complex provides differential inputs to the mouse kidney and liver. The retrograde viral tracer, pseudorabies virus (PRV)-152 was injected into the cortex of the left kidney or the main lobe of the liver to identify kidney-projecting and liver-projecting neurons in the celiac-superior mesenteric complex. iDISCO immunostaining and tissue clearing were used to visualize unprecedented anatomical detail of kidney-related and liver-related postganglionic neurons in the celiac-superior mesenteric complex and aorticorenal and suprarenal ganglia compared with TH-positive neurons. Kidney-projecting neurons were restricted to the suprarenal and aorticorenal ganglia, whereas only sparse labeling was observed in the celiac-superior mesenteric complex. In contrast, liver-projecting postganglionic neurons were observed in the celiac-superior mesenteric complex and aorticorenal and suprarenal ganglia, suggesting spatial separation between the sympathetic innervation of the mouse kidney and liver.

A New Concept of Safety Distance to Place Implants in the Area of the Inferior Alveolar Canal to Avoid Neurosensory Disturbance.

Inferior alveolar nerve (IAN) damage following implant placement is a severe complication that can compromise a patient's quality of life. Previous studies have suggested that a safety zone of 2 mm, if maintained, might avoid this problem. This retrospective study evaluates implants placed in closer proximity to the IAN without resulting in any postoperative neurologic complications and suggests a new concept of safety distance. A total of 60 consecutive patients receiving 101 mandibular implants < 2 mm from the IAN were included in this study. All enrolled patients had a CBCT scan done for radiologic assessment before implant placement and following final restoration. Measurements were obtained through cross-sectional views using Simplant software. In patients without neurologic disturbances, a mean distance of +0.75 mm was seen from the closest portion of the implant to the nerve bundle. In cases where a direct transection and/or compression of the nerve was not observed, the patients did not experience neurosensory disturbances.

In-vivo application of low frequency alternating currents on porcine cervical vagus nerve evokes reversible nerve conduction block

BackgroundThis paper describes a method to reversibly block nerve conduction through direct application of a 1 Hz sinusoidal current waveform delivered through a bipolar nerve cuff electrode. This low frequency alternating current (LFAC) waveform was previously shown to reversibly block the effects of vagal pulse stimulation evoked bradycardia in-vivo in the anaesthetised rat model (Mintch et al. 2019). The present work measured the effectiveness of LFAC block on larger caliber myelinated vagal afferent fibers in human sized nerve bundles projecting to changes in breathing rate mediated by the Hering-Breuer (HB) reflex in anaesthetized domestic swine (n=5).MethodsTwo bipolar cuff electrodes were implanted unilaterally to the left cervical vagus nerve, which was crushed caudal to the electrodes to eliminate cardiac effects. A tripolar recording cuff electrode was placed rostral to the bipolar stimulating electrodes on the same nerve to measure changes in the compound nerve action potentials (CNAP) elicited by the vagal pulse stimulation and conditioned by the LFAC waveform. Standard pulse stimulation was applied at a sufficient level to induce a reduction in breathing rate through the HB reflex. If unblocked, the HB reflex would cause breathing to slow down and potentially halt completely. Block was quantified by the ability of LFAC to reduce the effect of the HB reflex by monitoring the respiration rate during LFAC alone, LFAC and vagal stimulation, and vagal stimulation alone.ResultsLFAC achieved 87.2 ±8.8% block (n=5) at current levels of 1.1 ±0.3 mAp (current to peak), which was well within the water window of the working electrode. CNAP showed changes that directly correlated to the effectiveness of LFAC block, which manifested itself as the slowing and amplitude reduction of components of the CNAP.ConclusionThese novel findings suggest that LFAC is a potential alternative or complementary method to other electrical blocking techniques in clinical applications.