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.

Increased 18 F-FDG uptake in denervated muscles in a case of Parsonage-Turner syndrome.

BACKGROUND: Parsonage-Turner Syndrome (PTS) is a rare brachial plexopathy characterized by the sudden onset of pain in the shoulder girdle followed by upper limb weakness. PTS is frequently under-recognized or misdiagnosed as other more common neurological disorders presenting in a similar fashion, such as cervical radiculopathy which may require surgical intervention. Accurate diagnosis and prompt management implicate a good prognosis. Although electrophysiological studies are considered the most important for evaluating peripheral nerve injuries, it usually takes time, up to 3 weeks after the initial insult of the nerve for electromyogram (EMG) and nerve conduction studies (NCS) to display abnormalities. In the cases of PTS, especially when initial EMG/NCS and magnetic resonance neurography (MRN) results are inconclusive, 18 F-FDG positron emission tomography and computed tomography (18 F-FDG PET-CT) may be useful in helping the early detection of muscle denervation. CASE PRESENTATION: A 60-year-old right-handed Taiwanese woman presented with sudden onset of intense and sharp left shoulder girdle pain without radiating to the arm, followed by muscle weakness of her left arm in abduction and elevation 3 days after the onset of pain. A detailed neurological examination and EMG and NCS suggested the clinical diagnosis of left brachial plexopathy. MRN imaging revealed no significant abnormality. 18 F-FDG PET-CT showed increased uptake in denervated muscles (supraspinatus, deltoid, and biceps muscles). Treatment with oral prednisolone and physiotherapy significantly improved pain and muscle weakness. CONCLUSIONS: We present increased 18 F-FDG uptake in denervated muscles detected by 18 F-FDG PET-CT. 18 F-FDG PET-CT may serve as an adjunct examination to evaluate PTS, which has been suggested previously but rarely reported.

The role of ultrasonography in diagnosis of neuralgic amyotrophy.

OBJECTIVE: To investigate the value of high frequency ultrasound in diagnosis of neuralgic amyotrophy. MATERIALS AND METHODS: From January 2010 to December 2020, the ultrasonographic images of 117 patients with neuralgic amyotrophy diagnosed by the Department of Neurology and hand & foot surgery of Shandong Provincial Hospital Affiliated to Shandong First Medical University were retrospectively analyzed. The ultrasonographic features were summarized. RESULTS: High frequency ultrasound could clearly show the degree of the affected nerves: No ultrasonic findings were found in 12 cases (10%). The affected nerves were thickening and hypoechogenicity with loss of normal fascicular definition in 28 cases (24%). The affected nerves showed hourglass-like changes, including constriction and torsion in 77 cases (66%). In addition, ultrasound can determine the extent of the lesion, and microvascular imaging can display small blood flow signal within the nerve. There was a significant statistical difference between the diameter of the thickened nerve fascicle and the diameter of the nerve fascicle at the corresponding site of the contralateral normal limb. CONCLUSIONS: High frequency ultrasound is a valuable imaging method for diagnosis of neuralgic amyotrophy.

Parsonage-Turner Syndrome Following COVID-19 Vaccination: MR Neurography.

Vaccination is one of the several known triggers of Parsonage-Turner syndrome (PTS). This case series describes two individuals with clinical presentations of PTS whose symptoms began 13 hours and 18 days following receipt of the Pfizer-BioNTech BNT162b2 and Moderna mRNA-1273 COVID-19 vaccine, respectively. The diagnosis of PTS was confirmed by using both electrodiagnostic testing and 3.0-T MR neurography. Although research is needed to understand the association between PTS and COVID-19 vaccination, MR neurography may be used to help confirm suspected cases of PTS as COVID-19 vaccines continue to be distributed worldwide.

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.

Multiphasic presentation of neuralgic amyotrophy associated with hepatitis E virus infection.

BACKGROUND: The aim of this study was to further characterize the clinical phenotype of hepatitis E virus (HEV)-associated neuralgic amyotrophy (NA). METHODS: Three patients with HEV-associated NA underwent clinical, electrodiagnostic, and ultrasound assessment. RESULTS: In all patients, symptoms developed in several phases within a time span of 4-6 weeks, with three or more nerves involved. Symptoms were bilateral in two. In two patients, nerves of the trunk and the lower limb were affected as well. In one patient, three bouts occurred, each heralded by an increase in pain. In the other two, pain subsided quickly and nerve damage developed in two phases. Segmental enlargement with or without hourglass-like constrictions of the nerves was demonstrated by ultrasound in all. CONCLUSIONS: The multiphasic presentation, together with the extensive multi-nerve involvement, may reflect a severe and protracted inflammation of the nerves in HEV-associated NA.

Ultrasound of peripheral nerves in neuralgic amyotrophy.

INTRODUCTION: Neuralgic amyotrophy (NA) can often be difficult to diagnose. Nerve ultrasound (US) is potentially useful, but it is operator-dependent, especially for small nerves. METHODS: Fifty-one consecutive patients with NA (mean duration 16 months) and 50 control subjects underwent US of the brachial plexus and major nerves of the upper extremity at predefined sites. We compared cross-sectional areas (CSAs) of affected and unaffected sides with controls and sides within patients. RESULTS: The median nerve and radial nerve at the level of the upper arm were enlarged on the affected sides compared with controls and the unaffected sides of patients. Enlargement was most pronounced for affected sides vs. controls (median 44%, radial 67%). DISCUSSION: NA patients showed increased CSAs, especially in the major nerves of the upper limb, even after longer disease duration. This could make US a useful adjunct in diagnosing NA. Muscle Nerve 59:55-59, 2019.

Ultrasound imaging of brachial plexus trauma in gunshot injury.

INTRODUCTION: Brachial plexus trauma related to gunshot (GS) injury requires early examination and characterization to ensure appropriate treatment. Magnetic resonance imaging (MRI) may be contraindicated when there are metal fragments in a patient's body. Ultrasound (US) may present an alternative to imaging GS-related brachial plexus injury. METHODS: Three patients with GS-related brachial plexus injury who underwent US imaging evaluation at our institution were identified. A retrospective review of the patients' medical records was performed. RESULTS: US characterization of nerve abnormalities after GS injury to the brachial plexus was in agreement with electrodiagnostic and intraoperative findings. DISCUSSION: Information from the US reports was useful in preparation for brachial plexus reconstruction surgery. As such, US has unique utility when MRI cannot be performed. US imaging can provide useful characterization of the brachial plexus after GS injury when performed by an experienced operator. Muscle Nerve 59:707-711, 2019.

Visceral disseminated varicella zoster virus infection with brachial plexus neuritis detected by fluorodeoxyglucose positron emission tomography and computed tomography.

Varicella zoster virus (VZV) infection sometimes result in visceral disseminated VZV infection (VD-VZV), which is a fulminant disease featured by abdominal pain and the absence of skin lesions, particularly occurs in the immunosuppressive patients. Brachial plexus neuritis (BPN) is another rare type of VZV infection usually appears without blisters. Few diagnostic images of both VD-VZV and BPN-VZV have been reported. A 25-year-old woman receiving allogeneic hematopoietic stem cell transplantation (HSCT) for acute myeloid leukemia. Unexplained severe pain in the left upper extremity followed by severe stomachache, liver dysfunction and unconsciousness appeared on day 344 post-HSCT. Computed tomography (CT) showed left brachial plexus hypertrophy and edematous changes to the hepatoduodenal ligament, fluorodeoxyglucose positron emission tomography (FDG-PET) showed increased uptake in both lesions. Intravenous acyclovir therapy was started and successfully resolved all symptoms. Several days later, blisters appeared all over the body and positive VZV DNA from blood using polymerase chain reaction test was obtained. FDG-PET and CT may offer supportive findings for detecting or diagnosing blister-less VZV infectious diseases.

Brachial plexitis or neuritis? MRI features of lesion distribution in Parsonage-Turner syndrome.

INTRODUCTION: This study seeks to characterize lesion distribution in Parsonage-Turner Syndrome (PTS) using high-resolution MRI. METHODS: MRIs of 27 patients with clinically confirmed PTS were reviewed. Two radiologists independently evaluated the brachial plexus proper, side and terminal plexus branches, and more distal, upper extremity nerves. RESULTS: All patients had at least 1 clinically involved nerve. MRI revealed that the plexus appeared normal in 24 of 27 patients; in 3 other patients, signal hyperintensity was seen immediately proximal to the take-off of abnormal side or terminal branch nerves. Focal intrinsic constrictions were detected in 32 of 38 nerves. MRI interobserver agreement was high (Cohen's κ = 0.839). DISCUSSION: MRI findings, corroborated by electrodiagnostic testing, localized abnormalities to plexus branches and peripheral nerves, suggesting that PTS is characterized by 1 or more mononeuropathies rather than changes involving a portion of or the complete plexus proper. These results may improve diagnosis, prognostication, and management. Muscle Nerve 58: 359-366, 2018.

An unusual cause of shoulder pain and weakness.

Shoulder pain and weakness are common presenting Emergency Department complaints. Patients are often diagnosed with fractures, dislocations, bursitis, and muscle strain. Here we present an unusual cause of shoulder pain in an athletic and otherwise healthy young patient that does not respond to typical treatments for musculoskeletal pain.

Ultrasonography in neuralgic amyotrophy: Sensitivity, spectrum of findings, and clinical correlations.

INTRODUCTION: The aim of this study was to assess the value of ultrasonography in neuralgic amyotrophy. METHODS: Fifty-three patients with 70 affected nerves were examined with high-resolution ultrasound. RESULTS: The most commonly affected nerve was the anterior interosseous (23%). Ultrasonographic abnormalities in the affected nerves, rather than in the brachial plexus, were observed, with an overall sensitivity of 74%. Findings included the swelling of the nerve/fascicle with or without incomplete/complete constriction and rotational phenomena (nerve torsion and fascicular entwinement). A significant difference was found among the categories of ultrasonographic findings with respect to clinical outcome (P = 0.01). In nerves with complete constriction and rotational phenomena, reinnervation was absent or negligible, indicating surgery was warranted. DISCUSSION: Ultrasonography may be used as a diagnostic aid in neuralgic amyotrophy, which was hitherto a clinical and electrophysiological diagnosis, and may also help in identifying potential surgical candidates. Muscle Nerve 56: 1054-1062, 2017.

Neuroimaging of classic neuralgic amyotrophy.

INTRODUCTION: Neuralgic amyotrophy (NA) often imposes diagnostic problems. Recently, MRI and high-resolution ultrasound (HRUS) have proven useful in diagnosing peripheral nerve disorders. METHODS: We performed a chart and imaging review of patients who were examined using neuroimaging and who were referred because of clinically diagnosed NA between March 1, 2014 and May 1, 2015. RESULTS: Six patients were included. All underwent HRUS, and 5 underwent MRI. Time from onset to evaluation ranged from 2 weeks to 6 months. HRUS showed segmental swelling of all clinically affected nerves/trunks. Atrophy of muscles was detected in those assessed >1 month after onset. MRI showed T2-weighted hyperintensity in all clinically affected nerves, except for the long thoracic nerve, and denervation edema of muscles. CONCLUSIONS: HRUS and MRI are valuable diagnostic tools in NA. This could change the diagnostic approach from one now focused on excluding other disorders to confirming NA through imaging markers. Muscle Nerve 54: 1079-1085, 2016.