Anatomic Variation of the Phrenic Nerve and Brachial Plexus Encountered during 100 Supraclavicular Decompressions for Neurogenic Thoracic Outlet Syndrome with Associated Postoperative Neurologic Complications.

BACKGROUND: The objective of this study was to characterize phrenic nerve and brachial plexus variation encountered during supraclavicular decompression for neurogenic thoracic outlet syndrome and to identify associated postoperative neurologic complications. METHODS: A multicenter retrospective review was performed to evaluate anatomic variation of the phrenic nerve and brachial plexus from November 2010 to July 2018. After initial characterization, the following two groups were identified: variant anatomy (VA) group and standard anatomy (SA) group. Complications were analyzed and compared between the two groups. RESULTS: In total, 105 patients were identified, and 100 patients met inclusion criteria. Any anatomic variation of the standard course or configuration of the phrenic nerve and/or brachial plexus was encountered in 47 (47%) patients. Phrenic nerve anatomic variations were identified in 28 (28%) patients. These included 9 duplicated nerves, 6 lateral accessory nerves, 8 medial displacement, and 5 lateral displacement. Brachial plexus anatomic variation was found in 34 (34%) patients. The most common variant configuration of a fused middle and inferior trunk was identified in 25 (25%) patients. Combined phrenic nerve and brachial plexus anatomic variation was demonstrated in 15 (15%) patients. The VA and SA groups consisted of 47 and 53 patients, respectively. Transient phrenic nerve injury with postoperative elevation of the ipsilateral hemidiaphragm was documented in 3 (6.4%) patients in the VA group and 6 (11.3%) patients in the SA group (P = 0.49). Permanent phrenic nerve injury was identified in 1 (2.1%) patient in the VA group (P = 0.47) and none in the SA group. Transient brachial plexopathy was encountered in 1 (1.9%) patient in the SA group (P = 1.0) with full recovery to normal function. CONCLUSIONS: Anatomic variability of the phrenic nerve and brachial plexus are encountered more frequently than previously reported. While the incidence of nerve injury is low, surgeons operating within the thoracic aperture should be familiar with variant anatomy to reduce postoperative complications.

Congenital diaphragmatic eventration with absent left phrenic nerve in the fetal pig.

We encountered a fetal pig with eventration of the diaphragm and pulmonary hypoplasia accompanied by phrenic nerve agenesis. The fetal pig was female measuring 34 cm in crown-rump length and about 1500 g in body weight. The diaphragm was a complete continuous sheet, but comprised a translucent membrane with residual muscular tissue only at the dorsolateral area of the right leaf of the diaphragm. The left leaf protruded extraordinarily toward the thoracic cavity. The left phrenic nerve was completely absent, while there was a slight remnant of the right phrenic nerve that supplied the dorsolateral muscular area of the right leaf. Both lungs were small, and the number of smaller bronchioles arising from the bronchioles was decreased to about half of that of the normal lung. Additionally, the right and left subclavius muscles and nerves could not be identified. These findings imply that the diaphragm, the subclavius muscle and nerves innervating them comprise a developmental module, which would secondarily affect lung development. It is considered that the present case is analogous to the animal model of congenital eventration of the diaphragm in humans.

Origin and prevalence of the accessory phrenic nerve: A meta-analysis and clinical appraisal.

The accessory phrenic nerve (APN) is a common anatomical variant with differing reports of prevalence in the literature. It can be injured during operative procedures to the neck and thorax or by regional anesthetic techniques in its vicinity. Our aim was to provide a comprehensive evidence-based assessment of the prevalence and origins of the APN. The databases PubMed, China National Knowledge Infrastructure, ScienceDirect, EMBASE, BIOSIS, SciELO, and Web of Science were searched comprehensively, followed by assessment of eligibility and extraction of data concerning the APN. The data were pooled into a meta-analysis. A total of 17 studies were included in the meta-analysis. Fourteen studies (n = 1,941 hemi-necks) reported data on APN prevalence resulting in an overall pooled prevalence estimate of 36.5%. Nine studies (n = 941 APNs) reported data on the origin of the APN. Most commonly the APN originated from the ansa cervicalis (16.5%) followed by the nerve to the subclavius (15.8%). Subgroup analysis on the basis of laterality and geographic region revealed no statistically significant findings. The APN is a highly variable anatomical structure present in over one third of the population, most often originating from the ansa cervicalis or the nerve to the subclavius. Clinicians need to be aware of the varying constellation of symptoms that can arise from APN injury. Ultimately, knowledge of APN variation could provide for better outcomes and reduction of iatrogenic injuries, particularly in high-risk patients prone to long-term complications from diaphragmatic dysfunction. Clin. Anat. 30:1077-1082, 2017. © 2017 Wiley Periodicals, Inc.

Abnormal Origin and Course of the Accessory Phrenic Nerve: Case Report.

In the current cadaveric study an unusual sizeable accessory phrenic nerve (APN) was encountered emerging from the trunk of the supraclavicular nerves and forming a triangular loop that was anastomosing with the phrenic nerve. That neural loop surrounded the superficial cervical artery which displayed a spiral course. The form of a triangular loop of APN involving the aforementioned artery and originating from the supraclavicular nerve to the best of our knowledge has not been documented previously in the literature. The variable morphological features of the APN along with its clinical applications are briefly discussed.

Marked lateral deviation of the phrenic nerve due to variant origin and course of the thyrocervical trunk: a cadaveric study.

Phrenic nerve impairment can often lead to serious respiratory disorders under various pathological conditions. During routine dissection of an 88-year-old Japanese male cadaver, a victim of heart failure, we recognized an extremely rare variation of the right thyrocervical trunk arising from the subclavian artery laterally to the anterior scalene muscle. In addition to that, the ipsilateral phrenic nerve was drawn and displaced remarkably laterad by this vessel. We examined all of the branches arising from subclavian arteries, phrenic nerves and diaphragm muscles. The embryological background of this arterial variation is considered. The marked displacement with prolonged strain had a potential to cause phrenic nerve impairment with an atrophic change of the diaphragm muscle. Recently many image diagnostic technologies have been developed and are often used. However, it is still possible that rare variations like this case may be overlooked and can only be recognized by intimate regional examination while keeping these rare variations in mind.

Distocia de hombros y eventración diafragmática / Shoulder dystocia and diaphragmatic hernia

La distocia de hombros es un evento impredecible que puede ser leve o grave. En el período neonatal constituye el factor de riesgo más importante para lesión del plexo braquial y una causa excepcional de eventración diafragmática por injuria del nervio frénico. Se presenta un recién nacido producto de parto distócico por distocia de hombros, que nace severamente deprimido y en su evolución requiere soporte ventilatorio prolongado. El estudio fluoroscópico concluyó una eventración diafragmática derecha, permaneciendo con un síndrome de dificultad respiratoria de aproximadamente un mes de evolución y sin requerir tratamiento quirúrgico hasta el momento actual. Las complicaciones más frecuentes fueron la bronconeumonía y las atelectasias a repetición. Se realizó una revisión actualizada del tema destacándose diagnóstico etiológico. Se presentan fotos previo consentimiento familiar(AU)

Shoulder dystocia is an unpredictable event that can be mild or severe. In the neonatal period is the most important risk factor for brachial plexus injury and an exceptional cause of diaphragmatic hernia by phrenic nerve injury. A newborn is presented after a shoulder dystocia delivery, born severely depressed and whose evolution requires prolonged ventilatory support. In the fluoroscopic study we concluded right diaphragmatic hernia, with respiratory distress syndrome approximately of one month of evolution and without requiring surgical treatment to date. The most frequent complications were repeated bronchopneumonia and atelectasis. An updated review of the literature highlighting etiologic diagnosis was made. Photos are presented prior parental consent(AU)

The right ovarian artery arising from the right inferior phrenic artery: a case report.

OBJECTIVE: To report a case of the right ovarian artery arising from the right inferior phrenic artery. MATERIAL AND METHOD: The authors carried out the standard dissection survey of 810 embalmed female cadavers between 1983 and 2010. RESULTS: The authors encountered a case of the right ovarian artery arising from the right inferior phrenic artery in a donated cadaver aged 53 years at decease. CONCLUSION: With the advent of intra-abdominal laparoscopic techniques, the anatomy of the ovarian artery has assumed much more importance.

Complicated bronchiolitis: another use for your bedside ultrasound in the emergency department.

Diaphragmatic eventration or diaphragmatic herniations are congenital defect that involve abnormal development of the diaphragm and stretching of the muscular fibers leading to protrusion of abdominal organs into the thoracic cavity. Left sided defects will lead to stomach contents into the chest cavity while, right sided defects will have bowel or liver in the thoracic cavity. Infants with Congenital diaphragmatic hernia often present with respiratory distress that can be life-threatening unless treated appropriately. Bedside ultrasound in the Emergency Department, performed by the Emergency Physician can be a very useful tool in diagnosing conditions such as this one. We present a case of diaphragmatic eventration in a two month old male sent to Emergency Department (ED) by his primary care physician due to a severe case of bronchiolitis.

Incidence of accessory phrenic nerve and its clinical significance: a cadaveric study.

UNLABELLED: The description of accessory phrenic nerve (APN) in the standard textbooks and available literature is vague and sometimes limited to few lines. The incidence of APN varies a great deal from 17.6 % to 80.9 % in the available literature. The aim of the present study was to calculate the incidence and variation of APN in Indian population. MATERIAL AND METHODS: Forty five adult formalin-fixed cadavers (35 male, 10 female; 90 sides) used for gross anatomy dissection for undergraduates; during the 2 year period 2006-2007 were considered. Findings were recorded at different stages of the dissection. RESULTS: Out of 90 body sides studied, the APN was present in 48 sides (53.3 %). In 17 of the above sides the APN was confined to the cervical region (Cervical type) and in 31 sides the APN entered the thorax (Thoracic type), all anterior to the subclavian vein (SV). In eleven specimens the APN was found bilaterally. CONCLUSION: The incidence of APN, with its course and relation to the various structures in cervical and thoracic region will help the surgeons while performing internal thoracic artery (ITA) grafting and other radical neck surgery.

A variation of the phrenic nerve: case report and review.

During routine dissection in the department of anatomy, the following anatomical variations of the phrenic nerve were observed on the right side of the neck of a 30-year-old male cadaver. The phrenic nerve, in its early course close to its origin, gave a communicating branch to the C5 root of the brachial plexus. At the level of the root of neck just before entering the thorax, the phrenic nerve was located anterior to the subclavian vein. This unique case of phrenic nerve variation gains tremendous importance in the context of subclavian vein cannulation, implanted venous access portals, and supraclavicular nerve block for regional anaesthesia.

Technical considerations for myocardial revascularization in congenital bilateral hypoplasia of the pericardium.

Congenital hypoplasia of the pericardium is a rare clinical condition that is typically encountered as an incidental finding during routine thoracic imaging or cardiothoracic surgery. Chest pain symptoms, when they occur, are often initially attributed to coronary ischemic syndromes, but herniation of cardiac structures through the pericardial defect, ischemia from torsion of great vessels, or compression of pulmonary parenchyma through defects between the aortic and pulmonary arteries can occur. Careful attention to cannulation techniques, conduit length, and the aberrant course of the phrenic nerves, typically through pericardial fibrous bands, is critical to the successful conduct of cardiac surgery.

Aberrant morphology and residual transmitter release at the Munc13-deficient mouse neuromuscular synapse.

In cultured hippocampal neurons, synaptogenesis is largely independent of synaptic transmission, while several accounts in the literature indicate that synaptogenesis at cholinergic neuromuscular junctions in mammals appears to partially depend on synaptic activity. To systematically examine the role of synaptic activity in synaptogenesis at the neuromuscular junction, we investigated neuromuscular synaptogenesis and neurotransmitter release of mice lacking all synaptic vesicle priming proteins of the Munc13 family. Munc13-deficient mice are completely paralyzed at birth and die immediately, but form specialized neuromuscular endplates that display typical synaptic features. However, the distribution, number, size, and shape of these synapses, as well as the number of motor neurons they originate from and the maturation state of muscle cells, are profoundly altered. Surprisingly, Munc13-deficient synapses exhibit significantly increased spontaneous quantal acetylcholine release, although fewer fusion-competent synaptic vesicles are present and nerve stimulation-evoked secretion is hardly elicitable and strongly reduced in magnitude. We conclude that the residual transmitter release in Munc13-deficient mice is not sufficient to sustain normal synaptogenesis at the neuromuscular junction, essentially causing morphological aberrations that are also seen upon total blockade of neuromuscular transmission in other genetic models. Our data confirm the importance of Munc13 proteins in synaptic vesicle priming at the neuromuscular junction but indicate also that priming at this synapse may differ from priming at glutamatergic and gamma-aminobutyric acid-ergic synapses and is partly Munc13 independent. Thus, non-Munc13 priming proteins exist at this synapse or vesicle priming occurs in part spontaneously: i.e., without dedicated priming proteins in the release machinery.

"Pes anserinus" of the right phrenic nerve innervating the serous membrane of the liver: a case report (anatomical study).

During the preparations of cadavers for educational purposes we followed the course of the right phrenic nerve. On one of them and especially a female cadaver aged 72-year-old we found a branch arising from the thoracic portion of the right phrenic and passing through the two layers of the falciform ligament distributed to the upper surface of the serous layer of the liver in the form of "pes anserinus". As it is known, pain referred from the diaphragmatic peritoneum is classically felt in the shoulder tip but pain from thoracic surfaces supplied by the phrenic nerve is usually located there albeit vaguely. We believe that the above anatomical finding is the explanation of distinct radiating pain from the hepatic region to the right shoulder in some patients. The stimulations is carried through the phrenic nerve to the fourth cervical neurotome from were arise the supraclavicular nerves which are distributed to the shoulder region.

Anatomical variations of the phrenic nerve and its clinical implication for supraclavicular block.

This paper reports a case of simultaneous diaphragmatic and brachial plexus stimulation followed by a successful nerve block using the supraclavicular approach. An explanation for the qualitative differences in phrenic nerve block between interscalene and supraclavicular block is postulated, based on known anatomical variations.

Roles of neurotransmitter in synapse formation: development of neuromuscular junctions lacking choline acetyltransferase.

Activity-dependent and -independent signals collaborate to regulate synaptogenesis, but their relative contributions are unclear. Here, we describe the formation of neuromuscular synapses at which neurotransmission is completely and specifically blocked by mutation of the neurotransmitter-synthesizing enzyme choline acetyltransferase. Nerve terminals differentiate extensively in the absence of neurotransmitter, but neurotransmission plays multiple roles in synaptic differentiation. These include influences on the numbers of pre- and postsynaptic partners, the distribution of synapses in the target field, the number of synaptic sites per target cell, and the number of axons per synaptic site. Neurotransmission also regulates the formation or stability of transient acetylcholine receptor-rich processes (myopodia) that may initiate nerve-muscle contact. At subsequent stages, neurotransmission delays some steps in synaptic maturation but accelerates others. Thus, neurotransmission affects synaptogenesis from early stages and coordinates rather than drives synaptic maturation.

Bronchial trifurcation in a congenital pulmonary venolobar syndrome.

Congenital malformations of the tracheobronchal tree and the related arterial blood supply are a complex group of lesions in which there are abnormalities of the venous drainage and lung parenchyma. These malformations are examples of congenital pulmonary venolobar syndrome (CPVS). Tracheal trifurcation is an extremely rare anomaly associated with CPVS. We report on an unusual case of lower right extralobar sequestration connected to the trachea, plus a type I posterior laryngeal cleft, an aberrant systemic artery, and an anomalous route of the phrenic nerve. This paper discusses the place of this unusual abnormality in the spectrum of congenital bronchopulmonary vascular malformations.

Complete left pericardial defect with dual passage of the phrenic nerve: a challenge to the widely accepted embryogenic theory.

We report a patient with complete left pericardial defect whose phrenic nerve, split into two portions, passes both ventral and dorsal to the defect. The dorsal part of the phrenic nerve passes over the ventral surface of the pulmonary artery and veins, indicating that the pericardio-pleural foramen has been obliterated. Contrary to the widely accepted embryogenic theory that pericardial defect results from persistence of the pericardiopleural foramen, we consider that the defect in this patient resulted from a tear in the pericardio-pleural membrane immediately lateral to the common cardinal vein.