Evaluation of Infantile Brachial Plexopathy Using 3T MRI and High-Resolution Ultrasound: Experience From a Tertiary Care Centre

BACKGROUND

Currently, clinical assessment is the main tool for the evaluation of brachial plexus injury, complemented by electrophysiologic studies (EPS), and imaging studies whenever available. Imaging plays an important role as it enables the differentiation of pre-ganglionic and postganglionic injuries, and adds objectivity to presurgical evaluation.

OBJECTIVES

The primary objective was to evaluate the utility of magnetic resonance imaging (MRI) and high-resolution ultrasonography (USG) in the localization and characterization of brachial plexus injury in infants.

MATERIALS AND METHODS

In this prospective study, 34 infants with signs and symptoms of brachial plexus injury were evaluated by clinical examination, EPS, MRI, and USG. Imaging findings were correlated with intraoperative findings in infants who underwent surgical management. The association between EPS and MRI findings, and USG and MRI findings were assessed using Fisher's exact test. Semi-quantitative subjective analysis of various MRI sequences was done as well.

RESULTS

The most common findings of preganglionic injury and postganglionic injury, in our study, were pseudomeningocele and nerve thickening, respectively. MRI detection of injuries had a significant association with EPS findings. All MRI-detected injuries had a muscle power of grade 3 or less. muscle. Three-dimensional (3D) short tau inversion recovery (STIR) sequence was found to be superior for detecting postganglionic injuries (P < 0.05).

CONCLUSION

Imaging studies enable localization of the site of injury, determining the extent, and nature/morphology of injury. The gamut of findings obtained from MRI is far wider compared to that from USG. USG can be used as the first-line screening investigation.

Radiographic imaging modalities for perinatal brachial plexus palsy: a systematic review

PURPOSE

Perinatal brachial plexus palsy (PBPP) has a wide spectrum of clinical symptoms that can range from incomplete paresis of the affected extremity to flaccid arm paralysis. Although there is a high rate of spontaneous recovery within the first two years of life, it remains challenging to determine which patients will benefit most from surgical intervention. The diagnostic and predictive use of various imaging modalities has been described in the literature, but there is little consensus on approach or algorithm. The anatomic, pathophysiological, and neurodevelopmental characteristics of the neonatal and infant patient population affected by PBPP necessitate thoughtful consideration prior to selecting an imaging modality.

METHODS

A systematic review was conducted using six databases. Two reviewers independently screened articles published through October 2021.

RESULTS

Literature search produced 10,329 publications, and 22 articles were included in the final analysis. These studies included 479 patients. Mean age at time of imaging ranged from 2.1 to 12.8 months and investigated imaging modalities included MRI (18 studies), ultrasound (4 studies), CT myelography (4 studies), and X-ray myelography (1 study). Imaging outcomes were compared against surgical findings (16 studies) or clinical examination (6 studies), and 87.5% of patients underwent surgery.

CONCLUSION

This systematic review addresses the relative strengths and challenges of common radiologic imaging options. MRI is the most sensitive and specific for identifying preganglionic nerve injuries such as pseudomeningoceles and rootlet avulsion, the latter of which has the poorest prognosis in this patient population and often dictates the need for surgical intervention.

Risk factors for neonatal brachial plexus palsy attributed to anatomy, physiology, and evolution

The inherent variable anatomy of the neonate and the uniquely-shaped maternal birth canal that is associated with the evolution of human bipedalism constitute risk factors for neonatal brachial plexus palsy (NBPP). For example, those neonates with a prefixed brachial plexus (BP) are at greater risk of trauma due to lateral neck traction during delivery than those with a normal or postfixed BP. Compared to adults, neonates also have extremely large and heavy heads (high head: body ratio) set upon necks with muscles and ligaments that are weak and poorly developed. Accordingly, insufficient cranial stability can place large torques on the cervical spinal nerves. In addition, the pelvic changes necessary for habitual bipedal posture resulted in a uniquely-shaped, obstruction-filled, sinusoidal birth canal, requiring the human fetus to complete a complicated series of rotations to successfully traverse it. Furthermore, although there are many risk factors that are known to contribute to NBPP, the specific anatomy and physiology of the neonate, except for macrosomia, is not considered to be one of them. In fact, currently, the amount of lateral traction applied to the neck during delivery is the overwhelming legal factor that is used to evaluate whether a birth attendant is liable in cases of permanent NBPP. Here, we suggest that the specific anatomy and physiology of the neonate and mother, which are clearly not within the control of the birth attendant, should also be considered when assessing liability in cases of NBPP.

Managing uncommon and unexpected findings during neuromuscular ultrasound

One barrier to widespread adoption of neuromuscular ultrasound by clinical neurophysiologists is concern over how to identify and manage non-neuromuscular findings. This review addresses this concern by describing the sonographic appearance of a variety of commonly observed pathologies and anatomic variants in dermal, subcutaneous, bony, glandular, lymphatic, vascular, and other superficial tissues. Additionally, it outlines techniques to ensure proper clinical and ultrasound evaluation of unexpected or uncommon findings. Finally, it highlights strategies to manage unexpected findings, including how to best communicate findings to patients and referring clinicians to avoid unnecessary testing and ensure appropriate follow-up. Ultrasound extends the ability of the neuromuscular sonographer-clinician to contribute to patient care.

Ultrasonography of cervical nerve roots: cross-sectional reference values according to age

INTRODUCTION

The aim of this study is to describe the normal cross-sectional area (CSA) and appearance of cervical nerve roots in ultrasound, correlating it to age and other patient somatic parameters.

METHODS

One hundred healthy volunteers were included. We aimed to achieve uniform representation throughout all age groups. Ultrasound of the cervical nerve roots was performed bilaterally. CSA and margins description were obtained.

RESULTS

C5 nerve, 8.32 ± 2.30; C6 nerve, 11.88 ± 3.36; C7 nerve, 12.79 ± 3.85; C8 nerve, 11.20 ± 3.45. Significant correlation between CSA and age was demonstrated, but not for body mass index. Blurred margins were present in up to 23.71% cervical nerves, more frequently in older individuals and in C7 nerve.

DISCUSSION

If ultrasound morphology of cervical nerve roots is used as a diagnostic parameter, the normal range of CSA values and percentage of blurred margins according to age should be considered.

Sonographic measurements of normal C5-C8 nerve roots in children

Introduction

The aim of this study was to use ultrasound to measure the cervical nerve roots in normal children to determine normal reference values.

Methods

A total of 441 children of different ages at the Children's Hospital of Chongqing Medical University were examined by ultrasound. The diameter, circumference, and cross‐sectional area of the nerve roots were measured.

Results

Ultrasonographic measurements were consistent with the ranking C5 < C6 < C7. The C8 nerve root was thicker than C7 in 60% of the participants. The nerve root measurements increased with increasing age, height, weight, and body surface area.

Discussion

Normal reference ranges of the cervical nerve roots in children of different ages were established, and can serve as the basis for measurement in future studies.

Neuromuscular Ultrasound: Clinical Applications and Diagnostic Values

Advances in high-resolution ultrasound have provided clinicians with unique opportunities to study diseases of the peripheral nervous system. Ultrasound complements the clinical and electrophysiology exam by showing the degree of abnormalities in myopathies, as well as spontaneous muscle activities in motor neuron diseases and other disorders. In experienced hands, ultrasound is more sensitive than MRI in detecting peripheral nerve pathologies. It can also guide needle placement for electromyography exam, therapeutic injections, and muscle biopsy. Ultrasound enhances the ability to detect carpal tunnel syndrome and other focal nerve entrapment, as well as pathological nerve enlargements in genetic and acquired neuropathies. Furthermore, ultrasound can potentially be used as a biomarker for muscular dystrophy and spinal muscular atrophy. The combination of electromyography and ultrasound can increase the diagnostic certainty of amyotrophic lateral sclerosis, aid in the localization of brachial plexus or peripheral nerve trauma and allow for surveillance of nerve tumor progression in neurofibromatosis. Potential limitations of ultrasound include an inability to image deeper structures, with lower sensitivities in detecting neuromuscular diseases in young children and those with mitochondrial myopathies, due to subtle changes or early phase of the disease. As well, its utility in detecting critical illness neuromyopathy remains unclear. This review will focus on the clinical applications of neuromuscular ultrasound. The diagnostic values of ultrasound for screening of myopathies, neuropathies, and motor neuron diseases will be presented.

Neuromuscular Ultrasound: A New Tool in Your Toolbox

Neuromuscular ultrasound is a rapidly evolving technique for diagnosing, monitoring and facilitating treatment of patients with muscle and nerve disorders. It is a portable point-of-care technology that is non-invasive, painless and without ionizing radiation. Ultrasound can visualize muscle texture alterations indicating dystrophy or denervation, changes in size and anatomic continuity of nerve fascicles, and its dynamic imaging capabilities allow capturing of contractions and fasciculations. Ultrasound can also provide real-time guidance for needle placement, and can sometimes make a diagnosis when electromyography is not tolerated or not informative anymore. This review will focus on the technical and practical aspects of ultrasound as an imaging technique for muscles and nerves. It will discuss basic imaging principles, hardware and software setup, and provide examples of ultrasound use for visualizing muscle and nerve abnormalities with accuracy and confidence. The review is intended as a practical "how-to" guide to get started with neuromuscular ultrasound in daily practice.

Utility of ultrasound in noninvasive preoperative workup of neonatal brachial plexus palsy

BACKGROUND

Ultrasound has been utilized in the evaluation of compressive and traumatic peripheral nerve pathology.

OBJECTIVE

To determine whether US can provide comprehensive evaluation of the post-ganglionic brachial plexus in the setting of neonatal brachial plexus palsy and whether this information can be used to guide preoperative nerve reconstruction strategies.

MATERIALS AND METHODS

In this retrospective cohort study, preoperative brachial plexus ultrasonography was performed in 52 children with neonatal brachial plexus palsy who were being considered for surgery. The 33 children who had surgery compose the patient cohort. The presence and location of post-ganglionic neuromas were evaluated by US and compared to the surgical findings. US evaluation of shoulder muscle atrophy was conducted as an indirect way to assess the integrity of nerves. Finally, we correlated glenohumeral joint laxity to surgical and clinical management.

RESULTS

Ultrasound correctly identified 21 of 25 cases of upper trunk and middle trunk neuroma involvement (84% sensitivity for each). It was 68% sensitive and 40% specific in detection of lower trunk involvement. US identified shoulder muscle atrophy in 11 of 21 children evaluated; 8 of these 11 went on to nerve transfer procedures based upon the imaging findings. US identified 3 cases of shoulder joint laxity of the 13 children evaluated. All 3 cases were referred for orthopedic evaluation, with 1 child undergoing shoulder surgery and another requiring casting.

CONCLUSION

Ultrasound can provide useful preoperative evaluation of the post-ganglionic brachial plexus in children with neonatal brachial plexus palsy.