Parálisis diafragmática asociada al bloqueo interescalénico en cirugía de hombro: la utilidad de la ecografía diafragmática como herramienta diagnóstica / Phrenic paresis associated with interscalene block in shoulder surgery. Utility of diaphragm ultrasound examination

Introducción: El bloqueo interescalénico se utiliza de forma estandarizada durante la cirugía mayor de hombro, sin embargo, ninguna técnica realizada por encima de la clavícula ha demostrado reducir la tasa de bloqueo del nervio frénico por debajo del 20%. El interés en buscar una prueba diagnóstica que permita identificar la afectación del nervio frénico ha ido en incremento en los últimos años y varias han sido las pruebas diagnósticas empleadas. El objetivo de este trabajo es evaluar la utilidad clínica del ultrasonido para identificar la parálisis hemidiafragmática posterior al bloqueo interescalénico para la cirugía de hombro.Materiales y métodos: estudio diagnóstico observacional prospectivo en treinta y tres pacientes programados para cirugía de hombro. Se les realizó una espirometría forzada y se evaluó el grosor del músculo diafragma. Estas determinaciones se realizaron antes y a los veinte minutos de realizar el bloqueo interescalénico.Resultados: el total de los pacientes estudiados (100%) presentó bloqueo del nervio frénico según uno o los dos métodos utilizados en este estudio para su diagnóstico. Todos los pacientes presentaron variaciones en la ratio del grosor diafragmático en el lado del bloqueo frénico por debajo de 1.2.Conclusión: la exploración ecográfica del diafragma es una gran herramienta para la examinación de una víscera cuya alteración implica graves trastornos en el paciente crítico, a su vez el índice del grosor diafragmático <1.2 puede ser de utilidad en el diagnóstico de paresia frénica asociada al bloqueo del plexo braquial a nivel interescalénico. Tipo de Estudio: Diagnóstico prospectivo. Nivel de Evidencia: II

Introduction: the interscalene block is used in a standardized way during major shoulder surgery, however, no technique performed above the clavicle has been shown to reduce the rate of phrenic nerve block below 20%. The interest for a diagnostic test to allows identifying the involvement of the phrenic nerve has been increasing in recent years and several diagnostic tests have been used. The purpose of this article is to evaluate the clinical utility of ultrasound to identify hemidiaphragmatic paralysis after interscalene block for shoulder surgery.Materials and methods: prospective observational diagnostic study in thirty-three patients scheduled for shoulder surgery. A forced spirometry was performed and the thickness of the diaphragm muscle was evaluated with ultrasound. These determinations were made before and twenty minutes after performing the interscalene block.Results: all the patients studied (100%) presented phrenic nerve block according to one or the two methods used in this study for its diagnosis. All patients presented variations in the diaphragm thickness ratio on the side of the phrenic block below 1.2.Conclusion: the ultrasound examination of the diaphragm is a great tool for the examination of a viscera whose alteration implies serious disorders in the critical patient, in turn, the diaphragm thickness index <1.2 can be useful in the diagnosis of phrenic paresis associated with interscalene brachial plexus block. Level of Evidence: II

Aberrant branches of the subclavian artery and their relationship with the phrenic nerve and the brachial plexus / Ramas aberrantes de la arteria subclavia y su relación con el nervio frénico y el plexo braquial

SUMMARY: Variations in subclavian artery branches are relatively common and may impact surgical procedures and effects. During educational dissection of a male cadaver, we encountered an extremely rare variation of the right subclavian artery branches. The internal thoracic artery, the thyrocervical trunk, and the costocervical trunk arose from the third part of the right subclavian artery. In addition, the phrenic nerve displaced remarkably laterally by the thyrocervical trunk, and the course of the costocervical trunk was between the upper trunk and the middle trunk of the brachial plexus. These variations may pose a potential risk for nerve compression and increase the risk of arterial and nerve puncture. This case report would bring attention to the possibility of other similar cases, and early detection of these variations through diagnostic interventions is helpful to reduce postoperative complications.

RESUMEN: Las variaciones en las ramas de la arteria subclavia son relativamente comunes y pueden afectar los procedimientos y efectos quirúrgicos. Durante la disección educativa de un cadáver masculino, encontramos una variación extremadamente rara de las ramas de la arteria subclavia derecha. La arteria torácica interna, el tronco tirocervical y el tronco costocervical nacían de la tercera parte de la arteria subclavia derecha. Además, el nervio frénico se desplazaba lateralmente por el tronco tirocervical, y el trayecto del tronco costocervical se encontraba entre el tronco superior y el tronco medio del plexo braquial. Estas variaciones pueden suponer un riesgo potencial de compresión nerviosa y aumentar el riesgo de punción arterial y nerviosa. Este reporte de caso llamaría la atención sobre la posibilidad de otros casos similares, y la detección temprana de estas variaciones a través de diagnósticos es útil para reducir las complicaciones postoperatorias.

Pulmonary capacity of patients with total traumatic injury of the brachial plexus submitted to neurotization with the phrenic nerve: a case series / Capacidade pulmonar de pacientes com lesão traumática total do plexo braquial submetidos à neurotização com o nervo frênico: uma série de casos

Total traumatic injury often requires surgical intervention such as neurotization using the phrenic nerve with the aim to recover the elbow function. However, its repercussions on the respiratory kinematics are unknown. Objective: To evaluate the ribcage volume in tricompartments division, kinematics of Duty Cycle, and shortening velocity of the respiratory muscles after nerve phrenic transfer. Methods: Five participants (4 male), aged 18 to 40 years old (32±2), diagnosed with total brachial plexus injury and with nerve phrenic transfer. The optoelectronic plethysmography (OEP) was the instrument to evaluate volume in quiet breathing (QB), inspiratory capacity (IC) and vital capacity (VC) of the rib cage in its tricompartments division (pulmonary rib cage, abdominal rib cage and abdomen rib cage) and in each hemithorax, as well as the shortening velocity of the respiratory muscles, and respiratory rate. Assessments occurred 30 days prior and 30 days after surgery. Results: There was a decrease in the total compartmental distribution in QB with statistical difference only in the abdominal compartment (p <0.05). Four patients showed a reduction in the shortening speed of the left diaphragm muscle. It was not possible to perform a group analysis of respiratory kinematics and volumes in CV, IC due to the variation found in each patient analyzed. Conclusion: There was a reduction in volume in the rib cage as well as a change in the speed of shortening of the respiratory muscles after the transfer of the phrenic nerve one month after surgery.

A lesão traumática total freqüentemente requer intervenção cirúrgica, como neurotização usando o nervo frênico, com o objetivo de recuperar a função do cotovelo. No entanto, suas repercussões na cinemática respiratória são desconhecidas. Objetivo: Avaliar o volume da caixa torácica na divisão dos tricompartimentos, a cinemática do Duty Cycle e a velocidade de encurtamento dos músculos respiratórios após a transferência do nervo frênico. Métodos: Cinco participantes (4 do sexo masculino), com idade entre 18 e 40 anos (32 ± 2), com diagnóstico de lesão total do plexo braquial e transferência do nervo frênico. A pletismografia optoeletrônica (OEP) foi o instrumento para avaliar o volume na respiração silenciosa (QB), a capacidade inspiratória (IC) e a capacidade vital (VC) da caixa torácica em sua divisão tricompartimental (caixa torácica pulmonar, caixa torácica abdominal e caixa torácica do abdômen ) e em cada hemitórax, bem como a velocidade de encurtamento dos músculos respiratórios e a frequência respiratória. As avaliações ocorreram 30 dias antes e 30 dias após a cirurgia. Resultados: Houve diminuição da distribuição compartimental total no QB com diferença estatística apenas no compartimento abdominal (p <0,05). Quatro pacientes apresentaram redução da velocidade de encurtamento do músculo diafragma esquerdo. Não foi possível realizar uma análise de grupo da cinemática respiratória e dos volumes em CV, IC devido à variação encontrada em cada paciente analisado. Conclusão: Houve redução do volume da caixa torácica e também alteração da velocidade de encurtamento dos músculos respiratórios após a transferência do nervo frênico um mês após a cirurgia.

Troisier sign and Virchow node: the anatomy and pathology of pulmonary adenocarcinoma metastasis to a supraclavicular lymph node

ABSTRACT: Metastatic spread of cancer via the thoracic duct may lead to an enlargement of the left supraclavicular node, known as the Virchow node (VN), leading to an appreciable mass that can be recognized clinically ­ a Troisier sign. The VN is of profound clinical importance; however, there have been few studies of its regional anatomical relationships. Our report presents a case of a Troisier sign/VN discovered during cadaveric dissection in an individual whose cause of death was, reportedly, chronic obstructive pulmonary disease. The VN was found to arise from an antecedent pulmonary adenocarcinoma. Our report includes a regional study of the anatomy as well as relevant gross pathology and histopathology. Our anatomical findings suggest that the VN may contribute to vascular thoracic outlet syndrome as well as the brachial plexopathy of neurogenic thoracic outlet syndrome. Further, the VN has the potential to cause compression of the phrenic nerve, contributing to unilateral phrenic neuropathy and subsequent dyspnea. Recognition of the Troisier sign/VN is of great clinical importance. Similarly, an appreciation of the anatomy surrounding the VN, and the potential for the enlarged node to encroach on neurovascular structures, is also important in the study of a patient. The presence of a Troisier sign/VN should be assessed when thoracic outlet syndrome and phrenic neuropathy are suspected. Conversely, when a VN is identified, the possibility of concomitant or subsequent thoracic outlet syndrome and phrenic neuropathy should be considered.

Cardiac resynchronization therapy: overcoming anatomical challenges / Terapia de ressincronização cardíaca: superando desafios anatômicos

A anatomia venosa coronária pode dificultar ou impossibilitar o implante com sucesso de um dispositivo de terapia de ressincronização cardíaca. O objetivo desta revisão foi o de apresentar uma abordagem interventiva com muitas técnicas e ferramentas que precisam ser aprendidas e conhecidas para melhorar os resultados desta terapia e a saúde dos pacientes

Coronary venous anatomy can make successful implantation of a cardiac resynchronization therapy device difficult or impossible. The aim of this review is introduce an interventional approach with many techniques and tools that are needed to be learned and known in order to improve the results of this therapy and the health of patients

Methanolic extract of Rhinella schneideri (Anura: Bufonidae) poison causes ultrastructural changes in nerve terminals of phrenic nerve-diaphragm preparations in mice / Extracto metanólico de Rhinella schneideri (Anura: Bufonidae) causa cambios ultraestructurales en las terminaciones nerviosas de preparaciones de nervio frénico de ratón

Abstract Rhinella schneideri (or Bufo paracnemis), popularly known in Brazil as cururu toad, is also found in other countries in South America. The cardiovascular effects of this poison are largely known and recently was shown that it is capable to affect the neuromuscular junction on avian and mice isolated preparation. In this work, we used transmission electron microscopy to investigate the ultrastructure of the motor nerve terminal and postsynaptic junctional folds of phrenic nerve-hemidiaphragm preparations incubated for either 5 or 60 min with the methanolic extract of R. schneideri (50 µg/mL). In addition, the status of the acetylcholine receptors (AChR) was examined by TRITC-α-bungarotoxin immunofluorescence location at the endplate membrane. The results show that 5 min of incubation with the gland secretion extract significantly decreased (32 %) the number of synaptic vesicles into the motor nerve terminal, but did not decrease the electron density on the top of the junctional folds where nicotinic receptors are concentrated; however, 60 min of incubation led to significant nerve terminal reloading in synaptic vesicles whereas the AChR immunoreactivity was not as marked as in control and after 5 min incubation. Muscle fibers were well-preserved but intramuscular motor axons were not. The findings corroborated pharmacological data since the decrease in the number of synaptic vesicles (5 min) followed by recovery (60 min) is in accordance with the transient increase of MEPPs frequency meaning increased neurotransmitter release. These data support the predominant presynaptic mode of action of the R. schneideri, but do not exclude the possibility of a secondary postsynaptic action depending on the time the preparation is exposed to poison. Rev. Biol. Trop. 66(3): 1290-1297. Epub 2018 September 01.

Resumen Rhinella schneideri (o Bufo paracnemis), conocido popularmente en Brasil como sapo cururu, también se encuentra en otros países de América del Sur. Los efectos cardiovasculares de este veneno son ampliamente conocidos y recientemente se demostró que es capaz de afectar la unión neuromuscular en la preparación aislada de aves y ratones. En este trabajo, utilizamos microscopía electrónica de transmisión para investigar la ultraestructura de la terminación nerviosa motora y pliegues de unión postsináptica de preparaciones de nervio frénico-hemidiafragma incubadas durante 5 o 60 min con el extracto metanólico de R. schneideri (50 μg/mL). Además, se examinó el estado de los receptores de acetilcolina (AChR) mediante la ubicación de inmunofluorescencia de TRITC-α-bungarotoxina en la membrana de la placa terminal. Los resultados muestran que 5 min de incubación con el extracto de secreción de glándula disminuyeron significativamente (32 %) el número de vesículas sinápticas en el terminal del nervio motor, pero no disminuyeron la densidad electrónica en la parte superior de los pliegues de unión donde se concentran los receptores nicotínicos. Sin embargo, 60 min de incubación condujeron a una recarga significativa de los terminales nerviosos en las vesículas sinápticas, mientras que la inmunorreactividad del AChR no fue tan marcada como en el control y después de 5 min de incubación. Las fibras musculares estaban bien conservadas, pero los axones motores intramusculares no. Los hallazgos corroboraron los datos farmacológicos ya que la disminución en el número de vesículas sinápticas (5 min) seguida de recuperación (60 min) está de acuerdo con el aumento transitorio de la frecuencia de MEPPs, lo que significa una mayor liberación de neurotransmisores. Estos datos apoyan el modo de acción presináptico predominante de R. schneideri, pero no excluyen la posibilidad de una acción postsináptica secundaria dependiendo del tiempo en que la preparación esté expuesta al veneno.

Is phrenic nerve conduction affected in patients with difficult-to-treat asthma? / A neurocondução do nervo frênico está alterada na asma de difícil controle?

ABSTRACT Objective The aim of this study was to obtain data on phrenic neuroconduction and electromyography of the diaphragm muscle in difficult-to-treat asthmatic patients and compare the results to those obtained in controls. Methods The study consisted of 20 difficult-to-treat asthmatic patients compared with 27 controls. Spirometry, maximal inspiratory and expiratory pressure, chest X-ray, phrenic neuroconduction and diaphragm electromyography data were obtained. Results The phrenic compound motor action potential area was reduced, compared with controls, and all the patients had normal diaphragm electromyography. Conclusion It is possible that a reduced phrenic compound motor action potential area, without electromyography abnormalities, could be related to diaphragm muscle fiber abnormalities due to overload activity.

RESUMO Objetivo O objetivo do presente estudo foi obter dados da neurocondução do frênico e exame com agulha do diafragma em pacientes com asma de difícil controlee comparar com um grupo normal. Métodos O estudo consiste em realizar radiografia de tórax, espirometria, pressão máxima inspiratória e expiratória, neurocondução do nervo frênico e eletromiografia do músculo diafragma em 20 pacientes asmáticos de difícil controle e comparar com 27 controles. Resultados Encontramos redução da área do potencial de ação muscular composto do nervo frênico e a eletromiografia do musculo diafragma estava normal em todos os pacientes. Conclusão É possível que a redução da área do potencial de ação muscular composto do nervo frênico nos pacientes com asma de difícil controle associado a eletromiografia normal do músculo diafragma esteja relacionada as alterações da fibra muscular do mesmo devido à sobrecarga de atividade.

The effect of magnesium sulfate concentration on the effective concentration of rocuronium, and sugammadex-mediated reversal, in isolated left phrenic nerve hemi-diaphragm preparations from the rat / 대한마취과학회지

BACKGROUND: Perioperative magnesium sulfate (MgSO4) is used for analgesic, anti-arrhythmic, and obstetric purposes. The effects of MgSO4 on the neuromuscular blockade (NMB) induced by rocuronium, and the sugammadex reversal thereof, have not been clearly quantified. We investigated the effect of various MgSO4 concentrations on the NMB by rocuronium, and sugammadex reversal, in isolated left phrenic nerve hemi-diaphragm (PNHD) preparations from the rat. METHODS: Rat PNHD preparations were randomly allocated to one of four groups varying in terms of MgSO4 concentration (1, 2, 3, and 4 mM, each n = 10, in Krebs solution). The train-of-four (TOF) and twitch height responses were recorded mechanomyographically. The preparations were treated with incrementally increasing doses of rocuronium and each group’s effective concentration (EC)50, EC90, and EC95 of rocuronium were calculated via nonlinear regression. Then, sugammadex was administered in doses equimolar to rocuronium. The recovery index, time to T1 height > 95% of control, and the time to a TOF ratio > 0.9 after sugammadex administration were measured. RESULTS: The EC50, EC90, and EC95 of rocuronium fell significantly as the magnesium level increased. The EC50, EC90, and EC95 of rocuronium did not differ between the 3 and 4 mM groups. The recovery index, time to T1 height > 95% of control, and time to a TOF ratio > 0.9 after sugammadex administration did not differ among the four groups. CONCLUSIONS: Increases in the magnesium concentration in rat PNHD preparations proportionally enhanced the NMB induced by rocuronium but did not affect reversal by equimolar amounts of sugammadex.

Thoracoscopic Patch Insulation for Phrenic Nerve Stimulation after Permanent Pacemaker Implantation

One of the complications of permanent pacemaker implantation is unintended phrenic nerve stimulation. A 15-year-old boy with a permanent pacemaker presented with chest discomfort due to synchronous chest wall contraction with pacing beats. Even after reprogramming of the pacemaker, diaphragmatic stimulation persisted. Therefore, we performed thoracoscopic phrenic nerve insulation using a Gore-Tex patch to insulate the phrenic nerve from the wire. A minimally invasive approach using a thoracoscope is a feasible option for retractable phrenic nerve stimulation after pacemaker implantation.

Treatment of Lung Cancer-Related Intractable Hiccups Using Pulsed Radiofrequency: Clinical Experience / 한국호스피스완화의료학회지

While most benign hiccups can be controlled with empirical therapy, intractable hiccups lasting longer than one month tend to have significant adverse effects with obscure etiology. Treatment strategies for intractable hiccups have not been established. Only a few sporadic cases of bilateral phrenic nerve blockage have been reported. Here, we report a case of intractable hiccups that lasted five weeks in a 56-year-old male patient with a lung cancer above the right diaphragm. We hypothesized that his intractable hiccups were caused by irritation and mass effect caused by the lung cancer. We performed an ultrasound-guided right unilateral phrenic nerve pulsed radiofrequency treatment, and the patient's intractable hiccups were successfully managed without complication.

Usefulness of phrenic nerve conduction study in early diagnosis of isolated respiratory onset amyotrophic lateral sclerosis

Isolated respiratory onset amyotrophic lateral sclerosis (ALS) is a rare clinical manifestation and the diagnosis can be challenging. A 72-year-old man presented with dyspnea and hypercapnia that had started 11 months earlier. A phrenic nerve study was conducted and he was diagnosed promptly with ALS with no significant time delay. The phrenic nerve study is a noninvasive and useful tool in the diagnosis of respiratory onset ALS that can be applied easily in an emergency department.

Phrenic Nerve Clipping in a Stroke Patient with Intractable Hiccup: a Case Report

Hiccup is an intermittent, involuntary and erratic contraction of the diaphragm, immediately followed by a laryngeal closure. Persistent and intractable hiccups are rare but severe, keeping a person from doing daily activities; these can result in depression, fatigue, impaired sleep, dehydration, weight loss, malnutrition, and aspiration. Therefore, proper treatments are necessary. We present a case with intractable hiccup treated with an unusual treatment. A 61-year-old man presented with intractable hiccups, which started 6 years ago after subarachnoid and intraventricular hemorrhage. Conventional pharmacologic treatments including metoclopramide, gabapentin, and baclofen were unsuccessful. Cooperating with cardiothoracic surgeons, phrenic nerve clipping operation was done under intraoperative electrophysiologic monitoring. This method was successful that the symptoms were relieved. Reversible clipping done under intraoperative electrophysiologic monitoring can be a promising therapeutic method for persistent and intractable hiccups in patients with stroke.

Phrenic nerve conduction studies: normative data and technical aspects / Aspectos técnicos e normatização da neurocondução do nervo frênico

ABSTRACT Objective: The aim of the present study was to define normative data of phrenic nerve conduction parameters of a healthy population. Methods: Phrenic nerve conduction studies were performed in 27 healthy volunteers. Results: The normative limits for expiratory phrenic nerve compound muscle action potential were: amplitude (0.47 mv - 0.83 mv), latency (5.74 ms - 7.10 ms), area (6.20 ms/mv - 7.20 ms/mv) and duration (18.30 ms - 20.96 ms). Inspiratory normative limits were: amplitude (0.67 mv - 1.11 mv), latency (5.90 ms - 6.34 ms), area (5.62 ms/mv - 6.72 ms/mv) and duration (13.77 ms - 15.37 ms). Conclusion: The best point of phrenic nerve stimulus in the neck varies among individuals between the medial and lateral border of the clavicular head of the sternocleidomastoid muscle and stimulation of both sites, then choosing the best phrenic nerve response, seems to be the appropriate procedure.

RESUMO Objetivo: O objetivo do presente estudo foi definir os dados normativos de condução do nervo frênico de uma população saudável. Métodos: Foram realizados estudos de condução do nervo frênico em 27 voluntários saudáveis. Resultados: Os limites normais do potencial de ação muscular composto do nervo frênico durante a expiração foram: amplitude (0.47 mv - 0.83 mv), latência (5.74 ms - 7.10 ms), área (6.20 ms/mv - 7.20 ms/mv) e duração (18.30 ms - 20.96 ms). E durante a inspiração os limites normais foram: amplitude (0.67 mv - 1.11 mv), latência (5.90 ms - 6.34 ms), área (5.62 ms/mv - 6.72 ms/mv) e duração (13.77 ms - 15.37 ms). Conclusão: O melhor ponto de estímulo do nervo frênico no pescoço varia entre a borda medial e lateral da cabeça clavicular do músculo esternocleidomastóideo. Estimular ambos os locais e escolher a melhor resposta do nervo frênico parece ser o procedimento mais adequado.

Motor Neuron Disease Presenting With Acute Respiratory Failure: A Case Study

Motor neuron diseases (MNDs) refer to a heterogeneous group of progressive neurologic disorders caused by degeneration of motor neurons. The diseases affect either the upper motor neurons, lower motor neurons, or both, and are characterized by weakness, atrophy, fasciculation, spasticity, and respiratory failure. We report a case of a 61-year-old male patient with no past history of cardiovascular or pulmonary disease, who presented with only dyspnea, and no indication of any other symptom such as muscle weakness, atrophy, or bulbar dysfunction. Neuromuscular conduction study, including a study of the phrenic nerve, confirmed the diagnosis of MND. The patient greatly improved giving respiratory assistance at night, using a noninvasive ventilator. This case indicates that MNDs should be considered as differential diagnoses for patients showing acute respiratory failure of unknown causes. This report will aid in the prompt diagnosis and treatment of MNDs.

Left Side Otalgia Caused by Acute Myocardial Infarction / 대한이비인후과학회지

Otalgia consists of primary otalgia associated with disorders of the ear itself and referred otalgia due to disorders of organs that share the same innervation with the ear. Disorders of the oral cavity and laryngopharynx served by the glossopharyngeal and vagus nerves are common causes of referred otalgia. Chest pain from myocardial infarction spreads through the afferent pain pathway, especially through the sympathetic nerves in the cardiac plexus and the phrenic nerve, resulting in a typical chest pain or referred pain in the left upper extremity. However, pain spreading through the vagus nerve can theoretically cause referred otalgia. This association between the heart and ear has not been widely acknowledged, even though a referred otalgia can occasionally be the only symptom of the tragic disease, myocardial infarction, and should be taken seriously. We report a patient who complained of left otalgia as the only symptom of myocardial infarction.

Sonoanatomical Change of Phrenic Nerve According to Posture During Ultrasound-Guided Stellate Ganglion Block

OBJECTIVE: To evaluate the risk of phrenic nerve injury during ultrasound-guided stellate ganglion block (US-SGB) according to sonoanatomy of the phrenic nerve, and determine a safer posture for needle insertion by assessing its relationship with surrounding structure according to positional change. METHODS: Twenty-nine healthy volunteers were recruited and underwent ultrasound in two postures, i.e., supine position with the neck extension and head rotation, and lateral decubitus position. The transducer was placed at the anterior tubercle of the C6 level to identify phrenic nerve. The cross-sectional area (CSA), depth from skin, distance between phrenic nerve and anterior tubercle of C6 transverse process, and the angle formed by anterior tubercle, posterior tubercle and phrenic nerve were measured. RESULTS: The phrenic nerve was clearly identified in the intermuscular fascia layer between the anterior scalene and sternocleidomastoid muscles. The distance between the phrenic nerve and anterior tubercle was 10.33±3.20 mm with the supine position and 9.20±3.31 mm with the lateral decubitus position, respectively. The mean CSA and skin depth of phrenic nerve were not statistically different between the two positions. The angle with the supine position was 48.37°±27.43°, and 58.89°±30.02° with the lateral decubitus position. The difference of angle between the two positions was statistically significant. CONCLUSION: Ultrasound is a useful tool for assessing the phrenic nerve and its anatomical relation with other cervical structures. In addition, lateral decubitus position seems to be safer by providing wider angle for needle insertion than the supine position in US-SGB.

Risk of Encountering Dorsal Scapular and Long Thoracic Nerves during Ultrasound-guided Interscalene Brachial Plexus Block with Nerve Stimulator

BACKGROUND: Recently, ultrasound has been commonly used. Ultrasound-guided interscalene brachial plexus block (IBPB) by posterior approach is more commonly used because anterior approach has been reported to have the risk of phrenic nerve injury. However, posterior approach also has the risk of causing nerve injury because there are risks of encountering dorsal scapular nerve (DSN) and long thoracic nerve (LTN). Therefore, the aim of this study was to evaluate the risk of encountering DSN and LTN during ultrasound-guided IBPB by posterior approach. METHODS: A total of 70 patients who were scheduled for shoulder surgery were enrolled in this study. After deciding insertion site with ultrasound, awake ultrasound-guided IBPB with nerve stimulator by posterior approach was performed. Incidence of muscle twitches (rhomboids, levator scapulae, and serratus anterior muscles) and current intensity immediately before muscle twitches disappeared were recorded. RESULTS: Of the total 70 cases, DSN was encountered in 44 cases (62.8%) and LTN was encountered in 15 cases (21.4%). Both nerves were encountered in 10 cases (14.3%). Neither was encountered in 21 cases (30.4%). The average current measured immediately before the disappearance of muscle twitches was 0.44 mA and 0.50 mA at DSN and LTN, respectively. CONCLUSIONS: Physicians should be cautious on the risk of injury related to the anatomical structures of nerves, including DSN and LTN, during ultrasound-guided IBPB by posterior approach. Nerve stimulator could be another option for a safer intervention. Moreover, if there is a motor response, it is recommended to select another way to secure better safety.

Delayed Onset Transient Diaphragmatic Paralysis after Pacemaker Implantation

A 77-year-old woman presented with exertional dyspnea six days after left pectoral pacemaker implantation. Chest radiography at presentation showed that her left diaphragm was elevated when compared to earlier films. A fluoroscopic sniff test confirmed left diaphragmatic paralysis. Thoracic computed tomography did not reveal any major vascular or lung parenchymal injury; however, phrenic nerve injury on direct needle puncture during the original surgery was suspected. The patient's small body size may have increased the risk of this injury. Delayed-onset unilateral diaphragmatic paralysis appears to be a rare complication of cardiac device implantation.