Phrenic neuropathy and diaphragm dysfunction in neuralgic amyotrophy

Hourglass-like constrictions on MRI are common in electromyography-confirmed cases of neuralgic amyotrophy (Parsonage-Turner syndrome): A tertiary referral center experience

INTRODUCTION/AIMS

Hourglass-like constrictions (HGCs) of involved nerves in neuralgic amyotrophy (NA) (Parsonage-Turner syndrome) have been increasingly recognized with magnetic resonance neurography (MRN). This study sought to determine the sensitivity of HGCs, detected by MRN, among electromyography (EMG)-confirmed NA cases.

METHODS

This study retrospectively reviewed records of patients with the clinical diagnosis of NA, and with EMG confirmation, who underwent 3-Tesla MRN within 90 days of EMG at a single tertiary referral center between 2011 and 2021. "Severe NA" positive cases were defined by a clinical diagnosis and specific EMG criteria: fibrillation potentials or positive sharp waves, along with motor unit recruitment (MUR) grades of "discrete" or "none." On MRN, one or more HGCs, defined as focally decreased nerve caliber or diffusely beaded appearance, was considered "imaging-positive." Post hoc inter-rater reliability for HGCs was measured by comparing the original MRN report against subsequent blinded interpretation by a second radiologist.

RESULTS

A total of 123 NA patients with 3-Tesla MRN performed within 90 days of EMG were identified. HGCs were observed in 90.2% of all NA patients. In "severe NA" cases, based on the above EMG criteria, HGC detection resulted in a sensitivity of 91.9%. Nerve-by-nerve analysis (183 nerve-muscle pairs, nerves assessed by MRN, muscles assessed by EMG) showed a sensitivity of 91.0%. The second radiologist largely agreed with the original HGC evaluation, (94.3% by subjects, 91.8% by nerves), with no significant difference between evaluations (subjects: χ2 = 2.27, P = .132, nerves: χ2 = 0.98, P = .323).

DISCUSSION

MRN detection of HGCs is common in NA.

Hepatitis E and diaphragmatic dysfunction: Case series and review of the literature

INTRODUCTION

The causes of diaphragmatic paresis are manifold. An association between neuralgic amyotrophy (NA) and hepatitis E virus (HEV) infection has been reported. We wondered about the prevalence of diaphragmatic disfunction and hepatitis E infection in our clinic.

METHODS

From July 1st, 2020 to August 31st, 2023, patients presenting with diaphragmatic dysfunction and simultaneous clinical symptoms of an acute NA, or a history of NA, as well as patients with previously unexplained diaphragmatic dysfunction were examined for HEV infection.

RESULTS

By August 31st, 2023, 13 patients with diaphragmatic dysfunction and HEV infection were diagnosed (4 women, 9 men). Mean age was 59 ± 10 years. Liver values were normal in all patients. The median latency to diagnosis was five months (range: 1-48 months); nine patients, 4 of them with typical symptoms of NA, presented with acute onset three patients showed bilateral diaphragmatic dysfunction. All patients had a positive IgG immunoblot. Seven patients, three with NA, had an elevated hepatitis E IgM titer and six of them also a positive IgM immunoblot. In all cases, O2C hepatitis genotype 3 was identified. In eight cases, all those with a high IgG titer >125, the O2 genotype 1 was also detected.

CONCLUSION

NA that shows involvement of the phrenic nerve resulting in diaphragmatic dysfunction and dyspnoea, may be associated with HEV infection. The observation of 13 patients with diaphragmatic dysfunctions and HEV infection within a period of three years indicates a high number of undetected HEV-associated diaphragmatic dysfunction in the population, especially in the absence of NA symptoms. Therefore, even in diaphragmatic dysfunction without NA symptoms and causative damaging event, HEV infection should be considered, as it may represent a subform of NA with only phrenic nerve involvement. Therapy of HEV-associated diaphragmatic dysfunction in the acute phase is an open question. In view of the poor prognosis for recovery, antiviral therapy should be discussed. However, no relevant data are currently available.

Bilateral Phrenic Nerve Palsy Associated With Neuralgic Amyotrophy

Neuralgic amyotrophy (NA) is a multifocal inflammatory neuropathy accompanied by acute pain and muscle atrophy. NA commonly affects the upper extremities, but rarely affects the phrenic nerve. Here, we report a male with neck pain, orthopnea, difficulty sleeping in the supine position, and inability to slurp. His saturated oxygen level decreased from 97% to 86% in the supine position. His right shoulder showed muscle atrophy. Chest X-ray examination in the supine position and a nerve conduction study showed phrenic palsy. We diagnosed it as bilateral phrenic nerve palsy associated with NA. NA sometimes causes phrenic nerve palsy and may cause slurping difficulty.

Peripheral nervous system and neuromuscular disorders in the emergency department: A review

INTRODUCTION

Acute presentations and emergencies in neuromuscular disorders (NMDs) often challenge clinical acumen. The objective of this review is to refine the reader's approach to history taking, clinical localization and early diagnosis, as well as emergency management of neuromuscular emergencies.

METHODS

An extensive literature search was performed to identify relevant studies. We prioritized meta-analysis, systematic reviews, and position statements where possible to inform any recommendations.

SUMMARY

The spectrum of clinical presentations and etiologies ranges from neurotoxic envenomation or infection to autoimmune disease such as Guillain-Barré Syndrome (GBS) and myasthenia gravis (MG). Delayed diagnosis is not uncommon when presentations occur "de novo," respiratory failure is dominant or isolated, or in the case of atypical scenarios such as GBS variants, severe autonomic dysfunction, or rhabdomyolysis. Diseases of the central nervous system, systemic and musculoskeletal disorders can mimic presentations in neuromuscular disorders.

CONCLUSIONS

Fortunately, early diagnosis and management can improve prognosis. This article provides a comprehensive review of acute presentations in neuromuscular disorders relevant for the emergency physician.

Orthopnea secondary to brachial plexitis with bilateral diaphragmatic paralysis

BACKGROUND

Diaphragmatic paralysis can present with orthopnea. We report a unique presentation of bilateral diaphragmatic paralysis, an uncommon diagnosis secondary to an unusual cause, brachial plexitis. This report thoroughly describes the patient's presentation, workup, management, and outcome. It also reviews the literature on diaphragmatic paralysis and Parsonage-Turner syndrome.

CASE PRESENTATION

A 50-year-old male patient developed insidious orthopnea associated with left shoulder and neck pain over three months with no associated symptoms. On examination, marked dyspnea was observed when the patient was asked to lie down; breath sounds were present and symmetrical, and the neurological examination was normal. The chest radiograph showed an elevated right hemidiaphragm. Echocardiogram was normal. There was a 63% positional reduction in Forced Vital Capacity and maximal inspiratory and expiratory pressures on pulmonary function testing. The electromyogram was consistent with neuromuscular weakness involving both brachial plexus and diaphragmatic muscle (Parsonage and Turner syndrome).

CONCLUSIONS

Compared to unilateral, bilateral diaphragmatic paralysis may be more challenging to diagnose. On PFT, reduced maximal respiratory pressures, especially the maximal inspiratory pressure, are suggestive. Parsonage-Turner syndrome is rare, usually with unilateral diaphragmatic paralysis, but bilateral cases have been reported.

Parsonage-Turner Syndrome and Hereditary Brachial Plexus Neuropathy

Parsonage-Turner syndrome and hereditary brachial plexus neuropathy (HBPN) present with indistinguishable attacks of rapid-onset severe shoulder and arm pain, disabling weakness, and early muscle atrophy. Their combined incidence ranges from 3 to 100 in 100,000 persons per year. Dominant mutations of SEPT9 are the only known mutations responsible for HBPN. Parsonage and Turner termed the disorder "brachial neuralgic amyotrophy," highlighting neuropathic pain and muscle atrophy. Modern electrodiagnostic and imaging testing assists the diagnosis in distinction from mimicking disorders. Shoulder and upper limb nerves outside the brachial plexus are commonly affected including the phrenic nerve where diaphragm ultrasound improves diagnosis. Magnetic resonance imaging can show multifocal T2 nerve and muscle hyperintensities with nerve hourglass swellings and constrictions identifiable also by ultrasound. An inflammatory immune component is suggested by nerve biopsies and associated infectious, immunization, trauma, surgery, and childbirth triggers. High-dose pulsed steroids assist initial pain control; however, weakness and subsequent pain are not clearly responsive to steroids and instead benefit from time, physical therapy, and non-narcotic pain medications. Recurrent attacks in HBPN are common and prophylactic steroids or intravenous immunoglobulin may reduce surgical- or childbirth-induced attacks. Rehabilitation focusing on restoring functional scapular mechanics, energy conservation, contracture prevention, and pain management are critical. Lifetime residual pain and weakness are rare with most making dramatic functional recovery. Tendon transfers can be used when recovery does not occur after 18 months. Early neurolysis and nerve grafts are controversial. This review provides an update including new diagnostic tools, new associations, and new interventions crossing multiple medical disciplines.

[Neuralgic amyotrophy: a common cause of unilateral and bilateral diaphragmatic pareses]

There are several causes for unilateral or bilateral diaphragmatic paresis. The most common cause is an (intraoperative) injury to the phrenic nerve.However, in up to 20% of cases, no explanation can be found despite extensive workup. Neuralgic amyotrophy (NA, also known as Parsonage-Turner syndrome) is a common underdiagnosed multifocal autoimmune-inflammatory disease that predominantly affects proximal nerve segments of the upper extremities. Classic symptoms include acute onset of severe pain in the shoulder girdle with delayed onset of paresis of the shoulder and arm muscles. In at least 7% of cases, the phrenic nerve is also affected. Based on the annual incidence of NA of 1:1000, the entity as a cause of diaphragmatic dysfunction is probably not as uncommon as previously thought. However, clinical experience shows that this diagnosis is often not considered, and diaphragmatic paresis gets wrongly classified as idiopathic.This is particularly disastrous because in the early stage of NA, medical therapy with corticosteroids is mostly not considered and the possibility that surgical repair of the diaphragm may be performed prematurely, given that the condition may resolve spontaneously many months after symptom onset.The aim of the present article is to raise awareness of the entity of NA as a cause of diaphragmatic paresis and to establish a standardized approach to diagnosis and treatment.

Neuralgic amyotrophy detected by magnetic resonance neurography: subclinical, bilateral, and multifocal brachial plexus involvement

INTRODUCTION

Neuralgic amyotrophy (NA) is a painful non-traumatic peripheral nervous system condition affecting the brachial plexus. Signal abnormalities in nerves and muscles have been detected in these patients using magnetic resonance neurography (MRN).

METHODS

Electronic medical records and MRN images obtained in a 3 T scanner, in 14 adult patients diagnosed with NA at our Neurological institution (Neuromuscular Disorders Section), between December 2015 and December 2019 were retrospectively reviewed. The study was first approved by our Institutional Ethics Committee.

RESULTS

Subclinical, multifocal, and bilateral nerve signal anomalies were recorded in the brachial plexus of these patients. We identified four different types of nerve constriction without entrapment, which we categorized as follows: incomplete focal (type I), complete focal or hourglass (type II), multifocal or string of pearls (type III) and segmental (type IV).

CONCLUSIONS

Given that MRN is an accurate diagnostic tool to detect nerve damage, we believe abnormal findings could improve early detection of NA patients.

Parsonage-Turner Syndrome Post-COVID-19 Oxford/AstraZeneca Vaccine Inoculation: A Case Report and Brief Literature Review

Parsonage-Turner syndrome (PTS) is a rare brachial plexus neuropathy that typically presents as a severe, sudden-onset pain followed by atrophic weakness with slow recovery, which may occur after an identifiable triggering event. Vaccination is one of several known triggers of PTS, and this syndrome has already been reported in other patients who were vaccinated against coronavirus disease. We report the case of a 75-year-old Caucasian man who received the third dose of the coronavirus disease 2019 (COVID-19) Oxford/AstraZeneca vaccine and was diagnosed with PTS. A week after inoculation, the patient, with no history of trauma, developed a sudden-onset left shoulder mechanical pain and later reported an abduction deficit. Neurological examination showed an atrophy of the proximal muscles of the left upper limb. No bulbar weakness or pathological upper motor neuron signs were seen. The MRI excluded rotator cuff pathology, including ruptures and tendinopathy. Electroneuromyography findings carried out 10 months after the onset of symptoms indicated left brachial panplexopathy, suggestive of PTS. The raised consciousness of PTS and vaccine association is crucial for prompt identification and diagnosis and, therefore, better clinical outcomes.

A standardized ultrasound approach in neuralgic amyotrophy

Neuralgic amyotrophy (NA), also referred to as idiopathic brachial plexitis and Parsonage-Turner syndrome, is a peripheral nerve disorder characterized by acute severe shoulder pain followed by progressive upper limb weakness and muscle atrophy. While NA is incompletely understood and often difficult to diagnose, early recognition may prevent unnecessary tests and interventions and, in some situations, allow for prompt treatment, which can potentially minimize adverse long-term sequalae. High-resolution ultrasound (HRUS) has become a valuable tool in the diagnosis and evaluation of NA. Pathologic HRUS findings can be grouped into four categories: nerve swelling, swelling with incomplete constriction, swelling with complete constriction, and fascicular entwinement, which may represent a continuum of pathologic processes. Certain ultrasound findings may help predict the likelihood of spontaneous recovery with conservative management versus the need for surgical intervention. We recommend relying heavily on history and physical examination to determine which nerves are clinically affected and should therefore be assessed by HRUS. The nerves most frequently affected by NA are the suprascapular, long thoracic, median and anterior interosseous nerve (AIN) branch, radial and posterior interosseous nerve (PIN) branch, axillary, spinal accessory, and musculocutaneous. When distal upper limb nerves are affected (AIN, PIN, superficial radial nerve), the lesion is almost always located in their respective fascicles within the parent nerve, proximal to its branching point. The purpose of this review is to describe a reproducible, standardized, ultrasonographic approach for evaluating suspected NA, and to share reliable techniques and clinical considerations when imaging commonly affected nerves.

Autoimmune polyneuropathies

The autoimmune peripheral neuropathies with prominent motor manifestations are a diverse collection of unusual peripheral neuropathies that are appreciated in vast clinical settings. This chapter highlights the most common immune-mediated, motor predominant neuropathies excluding acute, and chronic inflammatory demyelinating polyradiculoneuropathy (AIDP and CIDP, respectively). Other acquired demyelinating neuropathies such as distal CIDP and multifocal motor neuropathy will be covered. Additionally, the radiculoplexus neuropathies, resulting from microvasculitis-induced injury to nerve roots, plexuses, and nerves, including diabetic and nondiabetic lumbosacral radiculoplexus neuropathy and neuralgic amyotrophy (i.e., Parsonage-Turner syndrome), will be included. Finally, the motor predominant peripheral neuropathies encountered in association with rheumatological disease, particularly Sjögren's syndrome and rheumatoid arthritis, are covered. Early recognition of these distinct motor predominant autoimmune neuropathies and initiation of immunomodulatory and immunosuppressant treatment likely result in improved outcomes.

Diaphragmatic Dysfunction due to Neuralgic Amyotrophy After SARS-CoV-2 Vaccination: A Case Report

Neuralgic amyotrophy is an idiopathic neuropathy characterized by acute-onset pain, typically in the upper extremity or shoulder, followed by weakness of the associated muscles. Phrenic nerve involvement is rare. We report a 63-year-old man who presented with dyspnea and right shoulder pain after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. His chest radiograph showed an elevated right hemidiaphragm that was absent before vaccination. A pulmonary function test showed a restrictive pattern with a significant reduction (40%) in forced vital capacity in the supine position. Diaphragm ultrasonography revealed a reduction in both diaphragmatic excursion and a thickening fraction of the right hemidiaphragm. Electrophysiological studies suggested a right upper brachial plexopathy. Considering the temporal relationship between the vaccination and absence of other causes, SARS-CoV-2 vaccination was thought to be the reason for neuralgic amyotrophy with diaphragmatic dysfunction. As there was no evidence of hypoventilation or sleep disturbance that may require noninvasive ventilation, the patient was followed with conservative treatment with analgesics. During 8 months of follow-up, his shoulder pain was relieved significantly but dyspnea improved only slightly. Neuralgic amyotrophy is an under-diagnosed etiology of diaphragmatic dysfunction and should be considered in patients with dyspnea and shoulder pain.

Revision Reverse Total Shoulder Arthroplasty With Pectoralis Major Transfer for Anterior Deltoid Deficiency: A Case Report

CASE

A 70-year-old male patient presented with anterior deltoid weakness from Parsonage-Turner neuropathy status post failed nerve transfer and a failed total shoulder arthroplasty with pseudoparalysis. The patient underwent revision to a reverse total shoulder arthroplasty with concomitant pectoralis major transfer to substitute for the anterior deltoid. An excellent functional result was attained as early as 6 weeks after surgery.

CONCLUSION

Pectoralis major transfer can be an effective treatment option for isolated anterior deltoid insufficiency, even in the setting of a reverse total shoulder arthroplasty.

Electrophysiological assessment of respiratory function

While the traditional lung function tests are used to assess lung capacity and pulmonary function, they cannot evaluate respiratory driving function and the integrity of the conduction pathway from the central nervous system to the respiratory motor neuron in the spinal cord and to the diaphragm. The inspiratory trigger is sent from the central nervous system through the phrenic nerve and drives the diaphragm to generate inspiratory movement. Therefore, phrenic nerve stimulation and diaphragmatic electromyography are two fundamental methods to assess respiratory function. There are several useful tools to assess respiratory motor system including electrical or magnetic phrenic nerve stimulation, diaphragmatic needle electromyography, and diaphragmatic ultrasound. By these means, physicians can assess current respiratory status in different neurological diseases that affect respiratory muscles, follow-up of the severity of respiratory impairment, help to predict the chance of successfully weaning from ventilatory support, and confirm clinical diagnoses such as diaphragmatic myoclonus. Although some of these tests require special training, applying these neurophysiological assessments in clinical practice is highly recommended.

Neuralgic Amyotrophy: Its Importance in Orthopedics Practice

The present academic work aims to contribute to an early diagnosis of neuralgic amyotrophy (NA) because of its high prevalence in the population. This disease is a neuromuscular syndrome with unclear etiology; it affects mostly the brachial plexus, causing acute pain in the affected shoulder, paralysis, and disabilities. Considering the importance of an early treatment that can modify the prognosis of the patient, knowing the last updates about the syndrome as its clinical presentation is important. Data analysis was conducted through an online non-systematic review that indicated the epidemiology, pathophysiology, and differential diagnosis and prognosis of NA. Knowledge of the clinical features of NA is not common; however, it is important in orthopedic practice because it requires differentiation from spine pathologies.

[Parsonage-Turner syndrome following severe SARS-CoV-2 infection]

Introduction

Les complications de l’infection par le SARS-CoV-2 peuvent affecter la sphère neurologique ; il s’agit habituellement de cas de polyradiculonévrite aiguë inflammatoire ou de plexite.

Observation

Le cas clinique rapporté concerne un patient de 20 ans sans comorbidités, atteint d’une infection sévère à la COVID-19 compliquée d’un syndrome de détresse respiratoire aiguë, avec manifestations thromboemboliques et surinfection bactérienne. Ce patient souffrait également d’un trouble neurologique non spécifique lié au SARS-Cov-2 avec une paralysie pseudobulbaire (IRM, EMG et ponction lombaire étaient normaux), associé à des troubles neurologiques persistants 4 mois plus tard, caractérisés par un déficit à prédominance motrice de l’épaule gauche et une insuffisance respiratoire. Le bilan respiratoire et neurologique conclut à un syndrome de Parsonage-Turner, ou amyotrophie névralgique, affectant les racines nerveuses en C5-C6, le nerf pectoral latéral et le nerf phrénique à l’origine de l’amyotrophie de la ceinture scapulaire et de la paralysie du diaphragme gauche.

Conclusion

Ce cas montre que la dyspnée persistante après une infection à la COVID-19 doit faire rechercher une cause diaphragmatique et que celle-ci n’est pas toujours secondaire à la neuropathie de réanimation, mais peut aussi être le témoin d’une amyotrophie névralgique.

Neuralgic amyotrophy

PURPOSE OF REVIEW

This review focuses on the current insights and developments in neuralgic amyotrophy (NA), an auto-immune multifocal peripheral nervous system disorder that leaves many patients permanently impaired if not recognized and treated properly.

RECENT FINDINGS

NA is not as rare as previously thought. The phenotype is broad, and recent nerve imaging developments suggest that NA is the most common cause of acute anterior or posterior interosseous nerve palsy. Phrenic nerve involvement occurs in 8% of all NA patients, often with debilitating consequences. Acute phase treatment of NA with steroids or i.v. immunoglobulin may benefit patients. Long-term consequences are the rule, and persisting symptoms are mainly caused by a combination of decreased endurance in the affected nerves and an altered posture and movement pattern, not by the axonal damage itself. Patients benefit from specific rehabilitation treatment. For nerves that do not recover, surgery may be an option.

SUMMARY

NA is not uncommon, and has a long-term impact on patients' well-being. Early immunomodulating treatment, and identifying phrenic neuropathy or complete nerve paralysis is important for optimal recovery. For persistent symptoms a specific treatment strategy aiming at regaining an energy balance and well-coordinated scapular movement are paramount.

Phrenic Nerve Involvement in Neuralgic Amyotrophy (Parsonage-Turner Syndrome)

Neuralgic amyotrophy is a poorly understood neuromuscular disorder affecting peripheral nerves mostly within the brachial plexus distribution but can also involve other sites including the phrenic nerve. In the classic form of the syndrome it causes proximal upper limb and neck pain on the affected side with subsequent muscle weakness that can be highly heterogeneous. Nocturnal noninvasive ventilation support is a first-line treatment after phrenic mononeuropathy. The regular monitoring of diaphragm function with spirometry and diaphragm ultrasound can help determine prognosis and inform decision-making.

Brachial and lumbosacral plexopathies: A review

Diseases of the brachial and lumbosacral plexus are uncommon and complex. The diagnosis of plexopathies is often challenging for the clinician, both in terms of localizing a patient's symptoms to the plexus as well as determining the etiology. The non-specific clinical features and similar presentations to other root, nerve, and non-neurologic disorders emphasize the importance of a high clinical index of suspicion for a plexopathy and comprehensive clinical evaluation. Various diagnostic tests, including electrodiagnostic (EDX) studies, neuroimaging (including ultrasound, MRI, or PET), serologic studies, and genetic testing, may be used to confirm a plexopathy and assist in identifying the underlying etiology. EDX testing plays an important role in confirming a plexopathy defining the localization, pathophysiology, chronicity, severity, and prognosis. Given the complexity of the plexus anatomy, multiple common and uncommon NCS and an extensive needle examination is often required, and a comprehensive, individualized approach to each patient is necessary. Treatment of plexopathies often focuses on symptomatic management although, depending on the etiology, specific targeted treatments may improve outcome. This article reviews the clinical features, EDX approaches, and evaluation and treatment of brachial and lumbosacral plexopathies.

Atypical Presentation of Parsonage-Turner Syndrome

Parsonage-Turner syndrome, also known as idiopathic brachial neuritis, is a multifocal, complex inflammatory disorder of the brachial plexus. It is an under-recognized diagnosis that requires increased vigilance to diagnose. We present a case of an abnormal presentation of Parsonage-Turner syndrome 10 weeks after a rotator cuff tear repair surgery. To diagnose this condition, other potential causes should be ruled out effectively with modalities such as magnetic resonance imaging (MRI) of the cervical spine and shoulder, electromyography (EMG), or recent history of inciting events.

Phrenic neuropathy water immersion dyspnea: Clinical findings and need for patient counseling

OBJECTIVE

To investigate the following among patients with phrenic neuropathy: (1) occurrences of water immersion activity-induced dyspnea; (2) clinical, electrophysiologic, sonographic, and pulmonary function test abnormalities; and (3) frequency of documented counseling regarding the risks of water immersion activities.

METHODS

We identified all patients with test-confirmed phrenic neuropathy seen from January 1, 2000, to December 31, 2018, at Mayo Clinic.

RESULTS

Of 535 patients with phrenic neuropathy, documentation of dyspnea with water activities was identified in 4% (22/535). The risks of water immersion were only documented in patients having experienced this problem. The majority had isolated phrenic neuritis or neuralgic amyotrophy syndrome (77.3%), mean age was 55 years (range 31-79), and most patients were men (81.9%). Patients had right-sided (45.5%) or bilateral (54.5%) phrenic neuropathy. None had isolated left phrenic involvement. Near-fatal drowning occurred in 18.2% (4/22), with persons needing assistance to be rescued from the water, following diving into water. Dyspnea with water immersion was the only symptom in 4.5% (1/22) and the presenting respiratory symptom in 36.4% (8/22). A range of electrophysiologic, sonographic, and pulmonary function test abnormalities including mild abnormalities were seen and not found to be significantly different from those in patients in whom water-induced dyspnea was not recorded.

CONCLUSION

Respiratory distress with water immersion activities is a serious complication of phrenic neuropathies. Physician-documented counseling is lacking. Isolated phrenic neuritis, neuralgic amyotrophy, and right-sided and bilateral phrenic involvement are most commonly implicated, but the range of severity and testing abnormalities suggest that all patients with neuralgic amyotrophy or phrenic neuropathy should be warned especially about diving into water.

Use of Noninvasive Ventilation with Volume-Assured Pressure Support in Neuralgic Amyotrophy with Bilateral Diaphragmatic Paralysis

Neuralgic Amyotrophy (NA) is a rare, acute onset inflammatory brachial plexopathy that frequently presents with acute pain followed by shoulder girdle muscle weakness. Phrenic nerve involvement affecting the diaphragms occurs in 7-10% of cases. We present the case of a 52-year-old man with neuralgic amyotrophy with phrenic nerve involvement and bilateral diaphragmatic paralysis with marked respiratory symptoms and sleep hypoventilation, who was treated with non-invasive ventilation with volume assured pressure support mode. By 21 months post disease onset, the patient had experienced marked improvement in orthopnea, sleep quality and functional status. This is the first reported case of the use of this mode of noninvasive ventilation in neuralgic amyotrophy.

Bilateral phrenic neuropathy responsive to intravenous immunoglobulin treatment

The aetiology of phrenic neuropathy is often unknown, but immune mechanisms may play a role. In a typical case of bilateral phrenic neuropathy with paradoxical breathing (video), an inflammatory pathogenesis was suggested by prolonged distal latency of phrenic nerve compound muscle action potentials in nerve conduction studies and a clear-cut albumin-cytologic dissociation. This encouraged us to treat the patient with a standard dose of intravenous immunoglobulin. After obtaining a strong improvement at spirometry, we repeated the second cycle of intravenous immunoglobulin and observed normalization of symptoms within few weeks and no relapse after 3 years. This case suggests that lumbar puncture should be performed in the acute phase of phrenic neuropathies to detect potential responders to immunomodulatory treatment.

Nerve ultrasound can identify treatment-responsive chronic neuropathies without electrodiagnostic features of demyelination

Introduction

We present a case series of six treatment‐naive patients with clinical phenotypes compatible with chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy without electrodiagnostic features of demyelination but with abnormal peripheral ultrasound findings who responded to treatment.

Methods

All six patients underwent a complete set of ancillary investigations, including extensive nerve conduction studies. We also performed standardized nerve ultrasound of median nerves and brachial plexus as part of a larger effort to evaluate diagnostic value of sonography.

Results

Nerve conduction studies did not show conduction block or other signs of demyelination in any of the six patients. Sonographic nerve enlargement was present in all patients and was most prominent in proximal segments of the median nerve and brachial plexus. Treatment with intravenous immunoglobulin resulted in objective clinical improvement.

Discussion

Our study provides evidence that nerve ultrasound represents a useful complementary diagnostic tool for the identification of treatment‐responsive inflammatory neuropathies.