Ultrasonographic identification of nerve pathology in neuralgic amyotrophy: Enlargement, constriction, fascicular entwinement, and torsion

Neuralgic amyotrophy: An update in evaluation, diagnosis, and treatment approaches

Neuralgic amyotrophy (NA) is an underrecognized peripheral nerve disorder distinguished by severe pain followed by weakness in the distribution of one or more nerves, most commonly in the upper extremity. While classically felt to carry a favorable prognosis, updates in research have demonstrated that patients frequently endure delay in diagnosis and continue to experience long term pain, paresis, and fatigue even years after the diagnosis is made. A transition in therapeutic approach is recommended and described by this review, which emphasizes the necessity to target compensatory abnormal motor control and fatigue by focusing on motor coordination, energy conservation strategies, and behavioral change, rather than strength training which may worsen the symptoms. The development of structural hourglass-like constrictions (HGCs) on imaging can help confirm the suspected clinical diagnosis, and in association with persistent weakness and limited recovery on electrodiagnostic testing may be considered for surgical consultation. Given the complex nature of management, a multidisciplinary approach is described, which can provide an optimal level of care and support for patients with persistent symptoms from NA and allow more unified guidance of rehabilitation and surgical referrals.

Occupational nerve injuries

Occupational nerve injuries span a broad array of pathologies and contribute toward functional limitation, disability, and economic impact. Early and accurate recognition, treatment, and management of workplace factors rely on a thorough understanding of the anatomic and biomechanical factors that drive nerve injury. This review explores the interplay between anatomy, biomechanics, and nerve pathology common to occupational nerve injury and provides the treating physician with a rational, evidence-based approach to diagnosis and to occupational aspects of management. Assessment of potential occupational nerve injury begins with a detailed understanding of the employee's work duties through a biomechanical lens. One must consider likelihood of occupational causation while accounting for predisposing conditions or preexisting symptoms. Beyond overt crush injury or laceration, potential mechanisms of nerve injury, with effects compounded over time, include compression, stretch, vibration, and repetitive or high-force movements of regional muscles and joints. Injury often occurs at nerve locations that experience higher pressures, changes in pressure over time, or abrupt changes in trajectory, often near a tethered point. This understanding, coupled with condition-specific knowledge presented in this review, equips managing physicians to diagnose occupational nerve injury and enhance treatment recommendations with rational activity modifications or equipment that can protect the nerve or decrease likelihood of continued injury. Long-term management often involves follow-up to assess effectiveness of interventions in the setting of the work environment, with gradual progression of the worker toward return to unrestricted duty or to a point of maximal medical improvement.

Imaging of Peripheral Nerves: AJR Expert Panel Narrative Review

Peripheral nerve imaging provides information that can be critical to the diagnosis, staging, and management of peripheral neuropathies. MRI and ultrasound are the imaging modalities of choice for clinical evaluation of the peripheral nerves given their high soft-tissue contrast and high resolution, respectively. This AJR Expert Panel Narrative Review describes MRI- and ultrasound-based techniques for peripheral nerve imaging; highlights considerations for imaging in the settings of trauma, entrapment syndromes, diffuse inflammatory neuropathies, and tumor; and discusses image-guided nerve interventions, focusing on nerve blocks and ablation.

The Role of Neuromuscular Ultrasound in the Diagnosis of Peripheral Neuropathy

The classification of peripheral neuropathies has traditionally been based on etiology, electrodiagnostic findings, or histopathologic features. With the advent of modern imaging, they now can also be characterized based on their varied distribution of imaging findings. We describe the major morphologic patterns of these changes, which include homogeneous enlargement; homogeneous thinning; focal, multifocal, and segmental enlargement; and focal thinning and beading (multifocal thinning). Representative disorders in each of these categories are discussed, along with examples of the more complex imaging manifestations of neuralgic amyotrophy, nerve transection, and hereditary amyloidosis. An appreciation of the diverse morphologic manifestations of neuropathy can help neuromuscular clinicians conduct appropriate imaging studies with ultrasound and, when needed, order suitable investigations with magnetic resonance neurography.

[Therapeutic options in patients with neuralgic amyotrophy]

OBJECTIVE

To evaluate the outcomes of patients with neuralgic amyotrophy (NA) depending on the type of treatment received - surgical or glucocorticosteroid administration.

MATERIAL AND METHODS

The outcome of 101 patients with verified NA was analyzed. The mean age of NA patients was 38.21±16.09 years (8 to 76 years), of which 69.3% were males (n=70) and 30.7% were females (n=31). The diagnosis was confirmed by electromyography, cervical spine MRI, and clinical data evaluation: pain according to VAS, duration of pain, timing of diagnosis from the disease onset, and severity of muscle weakness using the MRC scale. Most patients had a classic form (50.5%, n=51), followed by a distal form (39.6%, n=40), and nerve damage above the elbow joint or cranial nerves (9.9%, n=10). Most patients were examined during the phase of pain and muscle weakness (59.4%, n=60) and in the recovery phase (40.6%, n=41). 48.5% (n=49) of patients received steroids. Surgical treatment was performed in 15.8% of cases (n=16). The median follow-up of all patients was 12 months (Q1-Q3 6.00-20.00).

RESULTS

Patients who received GCS recovered better - 67.7% had a complete recovery compared to patients who did not receive pathogenetic therapy. Regardless of the GCS use, the outcome also depended on the NA form and the initial severity of muscle weakness (p<0.001 and p=0.001, respectively). Comparing the outcomes in the groups with and without surgery showed no statistically significant differences. However, in the non-surgery group, a higher percentage of non-recovery was found (71.4%) compared to the group receiving surgical treatment (28.6%). In 97.4% (n=38) of cases of distal NA, ultrasound revealed focal changes in the nerves, which initially indicated a poor prognosis for recovery.

CONCLUSION

Steroid therapy affects muscle strength recovery in patients with NA. The NA form and the initial severity of motor deficit also affect the outcome. Surgical treatment is indicated for patients with distal NA.

Determining the degree of proximal nerve fascicle rotation in healthy controls using ultrahigh-frequency neuromuscular ultrasound: A pilot study

INTRODUCTION/AIMS

Ultrahigh-frequency ultrasound (UHFUS) allows improved visualization and higher resolution images of nerve fascicles than standard high-frequency ultrasound. Dynamic UHFUS may detect the presence of fascicular entwinement, the recently described sonographic phenomenon of pathologic fascicular rotation seen in neuralgic amyotrophy. This pilot study aims to establish normative reference values and degrees of fascicular rotation for the proximal portions of commonly involved upper limb nerves in healthy controls using UHFUS.

METHODS

Twenty healthy participants underwent sonographic examination of the median, musculocutaneous, and radial nerves on both upper limbs using UHFUS with a 48 MHz linear transducer. A single rater assessed the degree of fascicular rotation in each peripheral nerve.

RESULTS

Fascicular rotation appears to occur in the proximal portion of each of these nerves. The mean degree of fascicular rotation for each of the measured nerves was median 94.5°, musculocutaneous 97.9°, and radial 50.9°. The maximum observed fascicular rotation in each nerve was 180°. Age, sex, height, weight, body mass index, and race did not predict degree of fascicular rotation (all p > .103). A single-factor ANOVA test showed the degree of fascicular rotation differed in median, musculocutaneous, and radial nerves (F = 4.748, p = .011).

DISCUSSION

UHFUS allows quantification of fascicular rotation in healthy controls in the median, musculocutaneous, and radial nerves, and provides normative data. The data from this pilot study may serve as control data for future comparative studies in conditions where fascicular rotation occurs, such as neuralgic amyotrophy.

High-resolution ultrasound and superb microvascular imaging findings in a case of post-COVID-19 vaccine parsonage-turner syndrome with multiple nerves involvement

Parsonage-Turner syndrome (PTS) is an idiopathic condition that may be triggered by vaccination against SARS-CoV-2. High-resolution ultrasound can support the diagnosis and monitoring of PTS patients by demonstrating specific nerve abnormalities. The recently implemented superb microvascular imaging technology can help stratify the prognosis of these patients, with the potential to contribute to the clinical management of PTS.

High-resolution Ultrasound of Peripheral Nerve Disorders

Peripheral nerve disorders refer to any condition that damages the peripheral nervous system with variable presentations and numerous causes. The diagnosis is usually suspected clinically and then confirmed using electrophysiology. Yet electrodiagnostic studies lack precise anatomical delineation and often cannot determine the underlying cause of the peripheral neuropathy. However, thanks to recent technological advances, high-resolution ultrasound (HRUS) and magnetic resonance (MR) imaging have emerged as exceptional modalities to identify the exact site of pathology and demonstrate the underlying etiology. These developments have led to a multimodality approach to peripheral nerve disorders. Imaging provides anatomical and morphological information while functional evaluation remains derived from electrodiagnostic study. This article reviews the HRUS features of common as well as less frequent peripheral nerve disorders: entrapment neuropathies, traumatic injuries, neuralgic amyotrophy, polyneuropathies, and nerve tumors.

Early aggressive constriction resection for hourglass-like constriction of peripheral nerve in the upper extremity: a retrospective study

OBJECTIVES

The hourglass like constriction (HGC) of peripheral nerves is a characteristic pathological manifestation of Neuralgic Amyotrophy. Once identified, early surgical intervention is essential. However, the method of surgery is controversial, particularly regarding whether HGC needs to be excised. This study aims to explore the efficacy of early aggressive resection of HGC in the upper limb nerves.

MATERIALS AND METHODS

This retrospective study focuses on 13 nerves of spontaneous upper limb paralysis treated at our hospital from June 2019 to July 2023, in which HGC was identified during surgery. During surgery, epineurectomy and interfascicular neurolysis were performed on the constricted areas. Post-neurolysis, constriction excision was carried out if any of the following conditions were met: (1) A single constriction with constriction ≥75%. (2) Constriction combined with torsion. (3) The presence of ≥2 constrictions. Regular face-to-face follow-ups were conducted postoperatively.

RESULTS

Four cases with a single constriction of less than 75% underwent epineurotomy and interfascicular neurolysis; eight underwent constriction excision, of which four cases with a single constriction and associated torsion had direct end-to-end suturing after excision, and four had more than two constrictions treated with autologous sural nerve grafts. Postoperative follow-ups showed good recovery in all but one case, which had unique pathological features and had underwent only epineurectomy, showing moderate recovery.

CONCLUSIONS

For early surgical treatment of HGCs in peripheral nerves of the upper limbs, if severe constriction, constriction combined with torsion, or the presence of more than two constrictions are identified during surgery, aggressive constriction resection may be a better option.

Single center experience with hourglass-like constriction neuropathy of suprascapular nerve

INTRODUCTION/AIMS

Hourglass-like constriction (HGC) may occur in several peripheral nerves. However, data on the prognosis of motor weakness in patients with HGC of the suprascapular nerve (SSN) are limited compared with other nerves. Here, we aimed to describe the clinical and imaging features of HGC of the SSN.

METHODS

We retrospectively reviewed patients diagnosed with suprascapular neuropathy using magnetic resonance imaging (MRI) or electrodiagnostic studies over 16 years. After excluding extrinsic causes, patients with HGC of the SSN detected using MRI were included.

RESULTS

Fourteen patients with HGC of the SSN were identified. MRI revealed that all HGCs were located between the origin of the SSN from the upper trunk of the brachial plexus and the suprascapular notch. Seven patients exhibited HGC precisely at the origin of the SSN from the brachial plexus. Four patients showed T2 hyperintensity of the SSN extending to the upper trunk of the brachial plexus or the extraforaminal cervical root. The initial treatments included observation (n = 1), steroid therapy (n = 12), suprascapular notch release (n = 1). Of the 12 patients with a sufficient follow-up period, nine fully recovered from motor weakness of the SSN with non-operative treatments. Six of the nine patients who recovered fully experienced their first clinical improvement more than 6 months after onset.

DISCUSSION

Treatment strategies for HGC differ depending on the affected nerve. For HGC of the SSN, due to the high spontaneous recovery rate observed in our study, conservative management for at least 6 months should be initially considered.

Neuralgic Amyotrophy

BACKGROUND

Neuralgic amyotrophy (NA) is a multifactorial, monophasic neuritis that mainly affects the nerves of the shoulder girdle. It is characterized by very severe pain and by weakness that arises some time after the pain. Its reported incidence is high (100 cases per 100 000 persons per year), but our data suggest that many or most cases are diagnosed late or not at all.

METHODS

This review of the epidemiology, pathophysiology, diagnosis, and treatment of NA is based on pertinent publications retrieved by a selective literature search, and on data provided by the scientific institute of AOK, a German statutory health-insurance carrier.

RESULTS

It is currently thought that the combination of a genetic predisposition, an immunological trigger factor, and mechanical stress on the affected nerve segment(s) is pathophysiologically determinative. The prognosis of untreated NA is poor, with 25% of patients remaining unable to work at three years. The main form of treatment is with corticosteroids that are administered as early as possible. If there is evidence of nerve constriction or torsion, surgery may also help. There have only been six controlled cohort studies on the treatment of NA, and no randomized trials. It is not uncommon for the acute phase to develop into a chronic pain syndrome requiring multidimensional treatment.

CONCLUSION

Particularly in view of the high incidence and improved therapeutic options, NA should be included in the differential diagnosis of all patients with suggestive symptoms.

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.

MR Neurography and Quantitative Muscle MRI of Parsonage Turner Syndrome Involving the Long Thoracic Nerve

BACKGROUND

Parsonage-Turner syndrome (PTS) is characterized by severe, acute upper extremity pain and subsequent paresis and most commonly involves the long thoracic nerve (LTN). While MR neurography (MRN) can detect LTN hourglass-like constrictions (HGCs), quantitative muscle MRI (qMRI) can quantify serratus anterior muscle (SAM) neurogenic changes.

PURPOSE/HYPOTHESIS

1) To characterize qMRI findings in LTN-involved PTS. 2) To investigate associations between qMRI and clinical assessments of HGCs/electromyography (EMG).

STUDY TYPE

Prospective.

POPULATION

30 PTS subjects (25 M/5 F, mean/range age = 39/15-67 years) with LTN involvement who underwent bilateral chest wall qMRI and unilateral brachial plexus MRN.

FIELD STRENGTH/SEQUENCES

3.0 Tesla/multiecho spin-echo T2-mapping, diffusion-weighted echo-planar-imaging, multiecho gradient echo.

ASSESSMENT

qMRI was performed to obtain T2, muscle diameter fat fraction (FF), and cross-sectional area of the SAM. Clinical reports of MRN and EMG were obtained; from MRN, the number of HGCs; from EMG, SAM measurements of motor unit recruitment levels, fibrillations, and positive sharp waves. qMRI/MRN were performed within 90 days of EMG. EMG was performed on average 185 days from symptom onset (all ≥2 weeks from symptom onset) and 5 days preceding MRI.

STATISTICAL TESTS

Paired t-tests were used to compare qMRI measures in the affected SAM versus the contralateral, unaffected side (P < 0.05 deemed statistically significant). Kendall's tau was used to determine associations between qMRI against HGCs and EMG.

RESULTS

Relative to the unaffected SAM, the affected SAM had increased T2 (50.42 ± 6.62 vs. 39.09 ± 4.23 msec) and FF (8.45 ± 9.69 vs. 4.03% ± 1.97%), and decreased muscle diameter (74.26 ± 21.54 vs. 88.73 ± 17.61 μm) and cross-sectional area (9.21 ± 3.75 vs. 16.77 ± 6.40 mm2). There were weak to negligible associations (tau = -0.229 to <0.001, P = 0.054-1.00) between individual qMRI biomarkers and clinical assessments of HGCs and EMG.

DATA CONCLUSION

qMRI changes in the SAM were observed in subjects with PTS involving the LTN.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 1.

Fascicular Involvement of the Median Nerve Trunk in the Upper Arm: Manifestation as Anterior Interosseous Nerve Syndrome With Unique Imaging Features

Selective fascicular involvement of the median nerve trunk above the elbow leading to anterior interosseous nerve (AIN) syndrome is a rare form of peripheral neuropathy. This condition has recently garnered increased attention within the medical community owing to advancements in imaging techniques and a growing number of reported cases. In this article, we explore the topographical anatomy of the median nerve trunk and the clinical features associated with AIN palsy. Our focus extends to unique manifestations captured through MRI and ultrasonography (US) studies, highlighting noteworthy findings, such as nerve fascicle swelling, incomplete constrictions, hourglass-like constrictions, and torsions, particularly in the posterior/posteromedial region of the median nerve. Surgical observations have further enhanced the understanding of this complex neuropathic condition. High-resolution MRI not only reveals denervation changes in the AIN and median nerve territories but also illuminates these alterations without the presence of compressing structures. The pivotal roles of high-resolution MRI and US in diagnosing this condition and guiding the formulation of an optimal treatment strategy are emphasized.

Neuromuscular ultrasound: Impact on diagnosis and management

INTRODUCTION/AIM

High-resolution ultrasound (HRUS) is increasingly used in evaluating neuromuscular conditions. Its potential advantages include its ability to discern anatomic information and make specific etiological diagnoses. Although many studies have demonstrated HRUS effectiveness, especially in mononeuropathies, more information is needed to better determine how often and to what extent useful information is obtained; how it influences diagnosis, clinical decision-making, and patient management; and how it is used with electrodiagnostic (EDx) studies.

METHODS

A retrospective cohort study was performed on patients referred for HRUS at a university laboratory during 2021. Demographic information, referral diagnoses, clinical information, HRUS findings, and follow-up patient management were analyzed. For patients who had EDx, results were compared with HRUS. Determinations were made whether HRUS did or did not aid in the diagnosis. For patients in whom HRUS resulted in a diagnosis, determination was made whether it confirmed the diagnosis made clinically or by EDx but did not change management; added additional important information; and/or made a decisive impact on subsequent management.

RESULTS

Five hundred two patients were analyzed, most referred for mononeuropathy, brachial plexopathy, and polyneuropathy. HRUS was abnormal in 81.7% of patients. HRUS added additional useful information in 79.0% and was decisive in management in 62.7%. In patients who also had abnormal EDx, HRUS resulted in decisive management in 49.5%.

DISCUSSION

HRUS is an effective diagnostic tool that frequently adds localizing and structural information that is otherwise not obtainable by clinical and EDx evaluation. In a substantial number of patients selected for HRUS, it is decisive in guiding further management.

Another step forward for neuromuscular ultrasound

See article on pages 295–302 in this issue.

[Neuralgic amyotrophy: an inflammatory neuropathy and its surgical treatment]

BACKGROUND

Neuralgic amyotrophy (NA) is a monofocal or oligofocal inflammatory neuropathy whose incidence has been significantly underestimated. A connection between constrictions and torsions of peripheral nerves with this disease has been increasingly established in recent years. Modern imaging techniques such as high-resolution nerve ultrasound and MR neurography have contributed to a better understanding of the pathophysiology and a better assessment of the prognosis of the disease. This has led to the concept of treating patients with such focal changes surgically in order to improve the prognosis. This review presents current ideas on the pathophysiology, clinical presentation, diagnosis and treatment of the disease.

PATIENTS AND METHODS

In a retrospective study, pre-, intra- and postoperative findings of 22 patients with 23 constrictions/torsions of peripheral nerves of the upper extremity were analysed. The patients underwent surgery at a nerve surgery centre over a period of 3.5 years (Dec. 2019-May 2023). The median nerve was most frequently affected (N=9), followed by the suprascapular nerve (N=6) and radial nerve (N=4). The axillary nerve (N=3) and the accessory nerve (N=1) were also involved. Surgical exploration revealed nerve torsions (N=9), nerve constrictions (N=5), fascicular torsions (N=12) and fascicular constrictions (N=9). Depending on the intraoperative findings, epineuriotomies (N=1), epi- and perineuriotomies (N=33), end-to-end sutures (N=2), and one epi- and one perineural suture were performed.

RESULTS

After an average follow-up of 10 months (3-28 months), 17 patients were re-examined. All of them reported a clear subjective improvement in motor deficits. Clinically and electromyographically, a reinnervation and significant increase in strength from a pre-existing strength grade of M0 to at least M3 in the vast majority of affected muscles was demonstrated in these patients.

SUMMARY

The incidence of NA continues to be underestimated and, in a significant proportion of patients, leads to permanent motor deficits, most likely due to constrictions and torsions of affected nerves. Surgical treatment is recommended as early as possible. Very good results can usually be achieved with epi- and perineuriotomy. In rare cases, end-to-end neurorrhaphy or nerve grafting is required.

Neuralgic amyotrophy with multiple hourglass-like constrictions of anterior interosseous nerve: a case report

Hourglass-like constrictions (HLCs) of peripheral nerves in the upper extremity were a rare form of neuralgic amyotrophy, often characterized by the sudden onset of pain in the shoulder or arm, followed by muscle weakness and amyotrophy, with limited sensory involvement. We present a case of multiple HLCs of the anterior interosseous nerve (AIN) in a 22-year-old female with left upper arm pain, finger numbness, and limited activity for 1 month. Physical examination showed weakness of the left index flexor digitorum profundus and flexor pollicis longus, with mild hypoesthesia in the first three fingers and the radial half of the ring finger. Electromyography suggested a median nerve (mainly AIN) lesion. Ultrasonographic imaging of the median nerve shows AIN bundle swelling and multiple HLCs at left upper arm. Despite conservative treatment, which included 15 days of steroid pulse therapy, Etoricoxib, and oral mecobalamin, the patient still complained of extreme pain at night without relief of any symptoms. Operation was recommended for this patient with thorough concerns of surgical advantages and disadvantages. During surgery, a total of 7 HLCs were found in her median nerve along and above the elbow joint. Only Interfascicular neurolysis was performed because the nerve constrictions were still in the early stage. The pain was almost relieved the next day. One month after surgery, she could bend her thumb and index fingers, although they were still weak. 4 months after the surgery, she was able to bend affected fingers, with muscle strength M3 level. At the same time, her fingers had fewer numbness symptoms. There was still controversy regarding treatment strategy; however, early diagnosis and surgical treatment for nerve HLCs might be a better choice to promote nerve recovery.

Neuralgic Amyotrophy and Hourglass Nerve Constriction/Nerve Torsion: Two Sides of the Same Coin? A Clinical Review

Neuralgic amyotrophy, also called Parsonage-Turner syndrome, in its classic presentation is a brachial plexopathy or a multifocal neuropathy, involving mainly motor nerves of the upper limb with a monophasic course. Recently, a new radiological entity was described, the hourglass constriction, which is characterized by a very focal constriction of a nerve, or part of it, usually associated with nerve thickening proximally and distally to the constriction. Another condition, which is similar from a radiological point of view to hourglass constriction, is nerve torsion. The pathophysiology of neuralgic amyotrophy, hourglass constriction and nerve torsion is still poorly understood, and a generic role of inflammation is proposed for all these conditions. It is now widely accepted that nerve imaging is necessary in identifying hourglass constrictions/nerve torsion pre-surgically in patients with an acute mononeuropathy/plexopathy. Ultrasound and MRI are useful tools for diagnosis, and they are consistent with intraoperative findings. The prognosis is generally favorable after surgery, with a high rate of good motor recovery.

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.

[Diagnostics and treatment of hourglass-like nerve constrictions and torsions in neuralgic amyotrophy]

Neuralgic amyotrophy is a disease of the peripheral nervous system characterized by severe neuropathic pain followed by peripheral paralysis. A distinction is made between a hereditary and an idiopathic form, which is assumed to have an autoimmunological origin. Conservative medicinal treatment mainly consists of nonsteroidal anti-inflammatory drugs (NSAID), opioids and glucocorticoids; however, despite treatment, symptoms in the form of pain or paralysis persist in over 50% of cases. Inflammation can lead to strictures and torsions of peripheral nerves, which can be visualized by imaging using nerve sonography or magnetic resonance (MR) neurography and confirmed intraoperatively during surgical exploration. Based on the currently available data, patients with strictures and torsions of peripheral nerves can benefit from neurosurgical treatment.

[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.

Application of a nerve stereoscopic reconstruction technique based on ultrasonic images in the diagnosis of neuralgic amyotrophy

Objective: To propose a nerve stereoscopic reconstruction technique based on ultrasound imaging for site diagnosis, intuitive reflection of disease severity, and classification of neuralgic amyotrophy (NA). Methods: We enrolled 44 patients with NA who underwent high-frequency ultrasonography examination. Multiple sites on the normal side and the affected side were scanned to calculate the ratio of the cross-section area (CSA) of the affected side to the normal side at each location measured, i.e., the cross-section area swelling ratio (CSASR). The CSASR of 44 patients and 30 normal controls was analyzed to determine their threshold value for the diagnosis of NA. Then, ultrasound images of the cross-section were used to reconstruct the stereoscopic model of the nerve on the affected side and the normal side. Using the CSASR values in each measurement location, a CSASR stereoscopic model was developed. Results: The threshold value of CSASR for ultrasound diagnosis of NA was 1.55. The average diseased segments per patient was 2.49 ± 1.97, with an average overall length of 10.03 ± 7.95 cm. Nerve stereoscopic reconstruction could be conducted for swelling, torsion, incomplete constriction, and complete constriction. Conclusion: The ultrasound image reconstruction method proposed in this study can accurately determine the site, range, and type of neuropathies in patients with NA, and simultaneously provide complete and accurate data information and intuitive morphological information.

Persistent Hourglass Constriction in Recovered Anterior Interosseous Nerve Palsy Due to Neuralgic Amyotrophy: A Case Report

The current articles recommended the interfascicular neurolysis for anterior interosseous nerve (AIN) palsy with hourglass-like fascicular constrictions (FCs) detected by ultrasonography or surgical exploration to realign to the fascicular torsion for those who failed to recover spontaneously. We present the case report of spontaneous AIN palsy recovered after conservative treatment; however, ultrasonographic findings showed persistent FCs of AIN in the arm at the beginning, at 6 weeks, and subsequent 3-year follow-ups, even after complete clinical recovery of palsy. This finding calls into question the current notion that AIN paralysis is due to FCs and that neurolysis is the best surgical treatment when spontaneous recovery does not occur for a considerable observation period. Level of Evidence: Level V (Therapeutic).

Nerve Torsion as a Pattern of Parsonage-Turner Syndrome: Literature Review and Two Representative Cases

(1) Background: Parsonage-Turner Syndrome (PTS) is a rare peripheral nerve disease characterized by different degrees of nerve impairment. The recent development of nerve ultrasound has enabled the use of new data in the diagnosis of the disease. The aim of this study is to conduct a literature review about the ultrasound evaluation of PTS and present two clinical cases that are characteristic of the disease. (2) Methods: A review of the literature from the last 10 years on the topic containing data regarding nerve ultrasound was performed. In addition, two cases of patients on whom nerve ultrasound was performed at the first evaluation and at follow-up after the indicated treatment were described. (3) Results: The results of our review show that although it is defined as plexopathy, PTS is most often a form of multifocal neuropathy. We also report the most frequently used ultrasound classification and possible prognostic correlations and report our experience with the description of two paradigmatic clinical cases. (4) Conclusions: Further studies are needed to understand the true prognostic power of each degree of nerve impairment and the possible implications in clinical practice regarding treatment indications.

Hourglass-like constriction of the anterior interosseous nerve in the left forearm: A case report

BACKGROUND

Hourglass-like constriction neuropathy is a rare neurological disorder. The main clinical manifestation is peripheral nerve injury with no apparent cause, and the pathomorphological change is an unexplained narrowing of the diseased nerve. The diagnosis and treatment of the disease are challenging and there is no accepted diagnostic or therapeutic approach.

CASE SUMMARY

This report describes a rare hourglass constriction of the anterior interosseous nerve in the left forearm in a 47-year-old healthy male who was treated surgically and gradually recovered function over a 6-mo follow-up period.

CONCLUSION

Hourglass-like constriction neuropathy is a rare disorder. With the development of medical technology, more examinations are now available for diagnosis. This case aims to highlight the rare manifestations of Hourglass-like constriction neuropathy and provides a reference for enriching the clinical diagnosis and treatment experience.

Clinical Spectrum of Postsurgical Parsonage-Turner Syndrome: A Perspective From an Electrodiagnostic Laboratory

BACKGROUND

Parsonage-Turner syndrome (PTS) is an underdiagnosed disorder characterized by the acute onset of severe pain in the shoulder/scapula/arm followed by muscle weakness/numbness in the distribution of nerves derived from the brachial plexus (BP). Surgical procedures are one of several antecedent events of PTS. This study describes the clinical spectrum of postsurgical Parsonage-Turner syndrome (PSPTS) in a large cohort of patients.

MATERIALS AND METHODS

Charts of patients diagnosed with PTS during a 16-year (2006-2022) retrospective review were analyzed to identify cases of PSPTS. The clinical criteria for PSPTS included the new onset of severe pain two days to four weeks after a surgical procedure followed by weakness of muscles innervated by one or more nerves arising from the BP. EDX criteria consist of denervation localized to branches of the BP. PSPTS cases were subdivided into two categories: definite PSPTS (surgery at a remote site) and probable PSPTS (surgery of the ipsilateral upper extremity or the cervical spine).

RESULTS

Of 202 patients (204 episodes) diagnosed with PTS, 111 (54%) were idiopathic and 61 (30%) were PSPTS. Of the 61 PSPTS episodes, 26 were definite and 35 were probable PSPTS. The anterior interosseous nerve (AIN) was most affected, followed by the posterior interosseous (PIN), and suprascapular nerve.

CONCLUSION

In this series, surgery was the most commonly recognized antecedent event for PTS, and the AIN and PIN were the most frequent nerves affected. Surgeons should consider PTS in patients who develop postoperative severe shoulder pain and weakness of muscles innervated by the BP.

Parsonage-Turner Syndrome Following SARS-CoV-2 Infection: A Systematic Review

Parsonage-Turner syndrome (PTS) is an inflammatory disorder of the brachial plexus. Hypothesized underlying causes focus on immune-mediated processes, as more than half of patients present some antecedent event or possible predisposing condition, such as infection, vaccination, exercise, or surgery. Recently, PTS was reported following the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We aimed to investigate data on PTS triggered by SARS-CoV-2 infection to provide an extensive perspective on this pathology and to reveal what other, more specific, research questions can be further addressed. In addition, we aimed to highlight research gaps requiring further attention. We systematically reviewed two databases (LitCOVID and the World Health Organization database on COVID-19) to January 2023. We found 26 cases of PTS in patients with previous SARS-CoV-2 infection. The clinical and paraclinical spectrum was heterogeneous, ranging from classical PTS to pure sensory neuropathy, extended neuropathy, spinal accessory nerve involvement, and diaphragmatic palsy. Also, two familial cases were reported. Among them, 93.8% of patients had severe pain, 80.8% were reported to present a motor deficit, and 53.8% of patients presented muscle wasting. Paresthesia was noted in 46.2% of PTS individuals and a sensory loss was reported in 34.6% of patients. The present systematic review highlights the necessity of having a high index of suspicion of PTS in patients with previous SARS-CoV-2 infection, as the clinical manifestations can be variable. Also, there is a need for a standardized approach to investigation and reporting on PTS. Future studies should aim for a comprehensive assessment of patients. Factors including the baseline characteristics of the patients, evolution, and treatments should be consistently assessed across studies. In addition, a thorough differential diagnosis should be employed.

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.

Imaging of neuralgic amyotrophy in the acute phase

INTRODUCTION/AIMS

Hourglass-like constrictions (HGCs) occur in neuralgic amyotrophy (NA), but the earliest time at which they can be recognized by imaging is poorly understood. We aimed to determine the prevalence of abnormal imaging findings in the acute phase of NA.

METHODS

Magnetic resonance neurography (MRN) and high-resolution ultrasound (US) examinations were performed at five sites. The investigation included 39 patients with acute NA who underwent imaging within 31 days of symptom onset. Correlation between imaging and electromyography (EMG) findings was measured.

RESULTS

US was performed in 29 patients and MRN in 23; 16 patients underwent US only, 10 MRN only, and 13 had both. US and MRN showed nerve abnormalities within 1 mo from NA onset in 90% of patients. HGCs were found in 74% (29/39) of the patients: 4 within 1 wk, 8 within 2 wk, 5 within 3 wk, and 12 within 4 wk. The earliest HGC on US was found within 12 h, and on MRN within 3 days from symptom onset. MRN demonstrated a denervation edema pattern of affected muscles in 91% of the patients. The shortest time to observe an edema pattern on MRN was 8 days. EMG was performed in 30 patients and revealed fibrillation potentials in affected muscles in 22 (73%). A denervation edema pattern on MRN was significantly associated with the presence of HGCs both on MRN and US, and with fibrillation potentials on EMG.

DISCUSSION

In the early phase of NA, US and MRN are useful diagnostic techniques for demonstrating nerve abnormalities.

Nerve Ultrasonography for the Diagnosis and Evaluation of Neuralgic Amyotrophy: A Case Report

Neuralgic amyotrophy (NA) is a peripheral nervous system disorder involving multifocal distribution. Although nerve ultrasonography has shown potential for detecting NA lesions, no established detection method exists for distal forearm NA. A 59-year-old man presented with weakness of the muscles innervated by the left posterior interosseous nerve (PIN), median nerve (MN), anterior interosseous nerve (AIN), and ulnar nerve (UN), following severe left shoulder pain. This case suggests that nerve ultrasonography can help accurately diagnose distal forearm NA.

Incorporating Blood Flow in Nerve Injury and Regeneration Assessment

Peripheral nerve injury is a significant public health challenge, with limited treatment options and potential lifelong impact on function. More than just an intrinsic part of nerve anatomy, the vascular network of nerves impact regeneration, including perfusion for metabolic demands, appropriate signaling and growth factors, and structural scaffolding for Schwann cell and axonal migration. However, the established nerve injury classification paradigm proposed by Sydney Sunderland in 1951 is based solely on hierarchical disruption to gross anatomical nerve structures and lacks further information regarding the state of cellular, metabolic, or inflammatory processes that are critical in determining regenerative outcomes. This review covers the anatomical structure of nerve-associated vasculature, and describes the biological processes that makes these vessels critical to successful end-organ reinnervation after severe nerve injuries. We then propose a theoretical framework that incorporates measurements of blood vessel perfusion and inflammation to unify perspectives on all mechanisms of nerve injury.

Moderner Ultraschall in der Diagnostik Neuromuskulärer Erkrankungen

Der neuromuskuläre Ultraschall hat sich in den letzten Jahren zu einem festen Bestandteil in der neurologischen Diagnostik entwickelt. Dazu tragen auch die fortwährende technische Weiterentwicklung der Methode und ihr unkomplizierter und nebenwirkungsfreier Einsatz direkt am Patienten bei. Im klinischen Alltag wird der Ultraschall in der Diagnostik und Differentialdiagnostik sowie in der Verlaufskontrolle traumatischer Nervenläsionen, sekundärer und dynamischer nervaler Kompressionssyndrome, hereditärer und akuter sowie chronisch autoimmuner Polyneuropathien, Motoneuron- und Muskelerkrankungen verwendet. Dabei spielt die Ultraschalldiagnostik auch zunehmend eine Rolle für Therapieentscheidungen, v.a. im Hinblick auf die operative Versorgung und den Einsatz oder die Fortführung immunmodulatorischer Medikamente. In den nächsten Jahren ist eine weitere interdisziplinäre Verbreitung und fortwährend zunehmende Standardisierung der Methode zu erwarten.

Neuromuscular Ultrasound: Indications in the Electrodiagnostic Laboratory

ABSTRACT

Accurate assessment of neuromuscular disorders is critical to facilitate timely treatment and achieve the best outcomes. Historically, electrodiagnostic studies have filled this role, but recently, neuromuscular ultrasound is being used in the electrodiagnostic laboratory. This review discusses the uses of neuromuscular ultrasound in the electrodiagnostic laboratory that have strong evidence, emphasizing those that could be adopted in a typical electrodiagnostic laboratory with a reasonable level of equipment and training. The evidence currently supports using neuromuscular ultrasound to diagnose carpal tunnel syndrome and ulnar neuropathies at the elbow and as a supplementary test when electrodiagnostic studies are suspected to be falsely negative or in axonal nonlocalizing lesions. Neuromuscular ultrasound can identify the causes of focal mononeuropathies, which can change treatment in specific cases. It is sensitive at identifying fasciculations and providing complementary evidence of autoimmune demyelinating polyneuropathies. It is particularly helpful in assessing nerves after trauma. Neuromuscular ultrasound is likely to prove even more useful in the electrodiagnostic laboratory as the technology continues to advance.

Ultrasound of the Radial Nerve: A Pictorial Review

This pictorial review focuses on the ultrasound (US) appearance of the normal and pathological radial nerve (RN) and its branches and provides tips with which to locate them and avoid misinterpretation of normal findings. A wide range of our pathological cases are reviewed and presented to help in familiarizing the reader with common and uncommon clinical scenarios that affect the RN and its main branches.

Isolated Anterior Interosseous Neuropathy Affecting Only the Flexor Digitorum Profundus to the Index Finger After Shoulder Arthroscopy: A Case Report and Review of the Literature

ABSTRACT

Anterior interosseous nerve neuropathy is an uncommon neuropathy with multiple potential etiologies. We present a rare case of anterior interosseous nerve neuropathy affecting only the flexor digitorum profundus to the index finger and occurring after shoulder arthroscopy. This unique presentation used a combination of both electrodiagnostic testing and neuromuscular ultrasound to obtain an accurate diagnosis and highlights the importance of these complementary tests in the evaluation of nerve disorders. To our knowledge, anterior interosseous nerve neuropathy after shoulder arthroscopy affecting only the flexor digitorum profundus to the index finger has not been previously described in the literature.

ACR Appropriateness Criteria® Plexopathy: 2021 Update

Plexopathy may be caused by diverse pathologies, including trauma, nerve entrapment, neoplasm, inflammation, infection, autoimmune disease, hereditary disease, and idiopathic etiologies. For patients presenting with brachial or lumbosacral plexopathy, dedicated plexus MRI is the most appropriate initial imaging modality for all clinical scenarios and can identify processes both intrinsic and extrinsic to the nerves. Other imaging tests may be appropriate for initial imaging depending on the clinical scenario. This document addresses initial imaging strategies for brachial and lumbosacral plexopathy in the following clinical situations: nontraumatic plexopathy with no known malignancy, traumatic plexopathy (not perinatal), and plexopathy occurring in the context of a known malignancy or posttreatment syndrome. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Posterior Interosseous Fascicular Constriction Within the Radial Nerve in a Diabetic Patient With Bilateral Neuralgic Amyotrophy: A Case Report

Background: Neuralgic amyotrophy (NA) is an acute, monophasic, painful inflammatory dysimmune focal, or multifocal mononeuropathy. The lesion in NA is not always restricted to the brachial plexus but also involves individual nerves or branches. The prognosis of NA is less favorable than previously assumed, but the reasons for poor recovery remain unknown. Nerve constriction may be one of the causes of poor prognosis in NA.

Case Presentation: Herein, we described a 54-year-old male with a history of type 2 diabetes in whom bilateral neuralgic amyotrophy developed with constriction of the posterior interosseous fascicle within the radial nerve. The patient experienced sudden-onset severe pain in both shoulders followed, 2 days later, by weakness in bilateral shoulders and the left forearm extensors over the subsequent month. The left forearm extensors were more severely affected than both shoulder girdle muscles. He noted a 7-kg weight loss for 1 month before pain onset. After diagnosing diabetic NA based on the clinical symptoms, imaging, and electrophysiological studies, treatment with systemic steroids improved pain and weakness in both shoulder muscles. Weakness in the left forearm extensors persisted after 1 month of steroid treatment. Follow-up ultrasound revealed constriction of the posterior interosseous fascicle within the main trunk of the left radial nerve at the elbow. Surgical exploration at 6 months after onset identified fascicle constriction, for which neurolysis was performed. Weakness in the extensors of the wrist and fingers did not improve during the 16-month follow-up.

Conclusion: A single constriction of the fascicle within a peripheral nerve may often be under-recognized if NA presents with variable degrees of weakness in bilateral upper limbs. Furthermore, fascicular constriction without edema of the parent nerve may be easily missed on the initial ultrasound. A lack of early recognition of nerve constriction and delay in surgical intervention can result in unfavorable outcomes. The physician should consider the possibility of the fascicular constriction when evaluating patients suspected of brachial NA with significant weakness in the distal upper limb compared to the proximal weakness or weakness of the distal upper limb that does not improve over time.

Review Article "Spotlight on Ultrasonography in the Diagnosis of Peripheral Nerve Disease: The Evidence to Date"

Neuromuscular ultrasound is rapidly becoming incorporated into clinical practice as a standard tool in the assessment of peripheral nerve diseases. Ultrasound complements clinical phenotyping and electrodiagnostic evaluation, providing critical structural anatomical information to enhance diagnosis and identify structural pathology. This review article examines the evidence supporting neuromuscular ultrasound in the diagnosis of compressive mononeuropathies, traumatic nerve injury, generalised peripheral neuropathy and motor neuron disease. Extending the sonographic evaluation of nerves beyond simple morphological measurements has the potential to improve diagnostics in peripheral neuropathy, as well as advancing the understanding of pathological mechanisms, which in turn will promote precise therapies and improve therapeutic outcomes.

Anterior Interosseous Nerve Syndrome Reconsidered: A Critical Analysis Review

Anterior interosseous nerve syndrome (AINS) represents a form of neuralgic amyotrophy (Parsonage-Turner syndrome). AINS does not originate from external compression of the AIN in the forearm. Fascicular constrictions (FCs) of the median nerve are identified within the anterior interosseous fascicular group at or above the medial epicondyle. Spontaneous recovery is not ensured, leaving up to 30% of patients with permanent weakness or palsy. Fascicular microneurolysis of the median nerve, performed at or above the elbow, is a treatment option for patients who do not recover spontaneously.

HEV-Associated Neuralgic Amyotrophy: A Multicentric Case Series

Background: Neuralgic amyotrophy (NA) has been described as a possible extrahepatic manifestation of hepatitis E virus (HEV) infection. Usually, HEV-associated NA occurs bilaterally. The clinical characteristics determining the course of HEV-associated NA have still not been defined. Methods: In this retrospective multicentric case series, 16 patients with HEV-associated NA were studied and compared to 176 HEV patients without NA in terms of their age, sex, and ALT levels. Results: Neither gender distribution (75% vs. 67% male) nor age (47 vs. 48 years median) differed significantly between the NA patients and controls. Eight NA patients (50%) presented with bilateral involvement—seven of these had right-side dominance and one had left-side dominance. Thirteen cases (81%) were hospitalized. Eight of these patients stayed in hospital for five to seven days, and five patients stayed for up to two weeks. The time from the onset of NA to the HEV diagnosis, as well as the diagnostic and therapeutic proceedings, showed a large variability. In total, 13 (81%) patients received treatment: 1/13 (8%) received intravenous immunoglobulins, 8/13 (62%) received glucocorticoids, 3/13 (23%) received ribavirin, and 6/13 (46%) received pregabalin/gabapentin. Patients with ages above the median (47 years) were more likely to be treated (p = 0.001). Conclusion: HEV-associated NA causes a relevant morbidity. In our case series neither the type of treatment nor the time of initiation of therapy had a significant effect on the duration of hospitalization or the course of the disease. The clinical presentation, the common diagnostic and therapeutic procedures, and the patients’ characteristics showed large variability, demonstrating the necessity of standardized protocols for this rare but relevant disease.

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.