The role of electromyography in the management of the brachial plexus palsy of the newborn

Clinical, electrophysiological, and imaging findings in childhood brachial plexus injury

AIM

To assess the prognostic capabilities of various diagnostic modalities for childhood brachial plexus injuries (BPIs) and brachial plexus birth injury (BPBI) and postneonatal BPI.

METHOD

In this single-center retrospective cross-sectional study, we examined children with BPIs diagnosed or confirmed by electrodiagnostic studies between 2013 and 2020, and compared the prognostic value of various components of the electrophysiologic findings, magnetic resonance imaging (MRI) data, and the Active Movement Scale (AMS). We developed scoring systems for electrodiagnostic studies and MRI findings, including various components of nerve conduction studies and electromyography (EMG) for electrodiagnostic studies.

RESULTS

We identified 21 children (10 females and 11 males) aged 8 days to 21 years (mean 8y 6.95mo) who had a total of 30 electrodiagnostic studies, 14 brachial plexus MRI studies, and 10 surgical procedures. Among the diagnostic modalities assessed, brachial plexus MRI scores, EMG denervation scores, and mean total EMG scores were the most valuable in predicting surgical versus non-surgical outcomes. Correspondingly, a combined MRI/mean total EMG score provided prognostic value.

INTERPRETATION

Brachial plexus MRI scores and specific electrodiagnostic scores provide the most accurate prognostic information for children with BPI. Our grading scales can assist a multidisciplinary team in quantifying results of these studies and determining prognosis in this setting.

WHAT THIS PAPER ADDS

A new scoring system to quantify results of electrodiagnostic and magnetic resonance imaging (MRI) studies is presented. Severity of denervation has good prognostic value for childhood brachial plexus injuries (BPIs). Composite electromyography scores have good prognostic value for childhood BPIs. Brachial plexus MRI has good prognostic value for childhood BPIs.

A Systematic Review of the Electrodiagnostic Assessment of Neonatal Brachial Plexus

Despite improvements in obstetric care, neonatal brachial plexus palsy continues to significantly impact infants’ lives worldwide, with an incidence of 1 to 4 per 1000 live births. While a majority of affected infants recover spontaneously by three months, 20-30% suffer permanent functional deficits that significantly impair their quality of life. Anatomical complexity of the brachial plexus results in varying degrees of injury and pathological changes at multiple levels within the plexus. Current clinical diagnosis relies on electrodiagnostic techniques such as nerve conduction (i.e., motor and sensory) and electromyography studies. These techniques not only aid clinicians to differentiate between axonal and demyelinating lesions, evident by changes in signal shape and conduction, but also provide prognostic information in cases of brachial plexus injuries. The presented study offers a comprehensive review of existing literature on electrodiagnostic techniques employed for assessing neonatal brachial plexus injuries.

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.

Bilateral radial nerve compression neuropathy in the newborn

PURPOSE

This study aims to discuss the diagnosis and management of radial nerve compression neuropathy in the newborn.

METHODS

A personal case is presented, followed by a review and analysis of clinically similar cases identified via a PubMed search of published medical literature.

RESULTS

We report a case of a term newborn with bilateral radial neuropathy at the humerus level. Despite severe axonal involvement in the electrophysiological evaluation, the patient showed complete bilateral recovery after 3 months of follow-up.

CONCLUSIONS

Isolated radial nerve palsy is a rare event in the newborn. The condition does not require surgical treatment and usually proceeds to full and rapid spontaneous recovery.

Update in electromyography

PURPOSE OF REVIEW

It is easy to forget the contribution of electromyography (EMG) to the investigation of paediatric peripheral neuromuscular disease, and this review highlights its continued importance.

RECENT FINDINGS

The discovery that Brown-Vialetto-van Leare disease, when associated with disorder of riboflavin metabolism, may be treatable has raised awareness of the importance of EMG for its early detection. Unexpected discovery of motor neuronopathy, which may be useful for the definition of the phenotype of several conditions, now has an added significance. The investigation of disorders of peripheral nerve cannot proceed without nerve conduction studies but particular interest has been shown in its role in the management of obstetric brachial plexus palsy, with investigation within 1 month now recommended. The key role of neurophysiology in identifying abnormalities of the neuromuscular junction, and therefore leading investigators to a diagnosis of myasthenia, is once again highlighted. EMG in muscle disease continues to have a role, particularly when identifying myotonia.

SUMMARY

Paediatric EMG, while a daunting technical challenge to some practitioners, remains a valuable investigative tool for the specialists in paediatric neuromuscular disorders and will continue to deliver important diagnostic information, often as quickly and accurately as other more recent innovations.

Nerve conduction studies and needle EMG in very small children

Nerve conduction studies and needle EMG in children under two years of age present a considerable technical challenge to the neurophysiologist. However, with adaptations of both the equipment used and the methods applied, useful results can be obtained in most cases. Normative data exists against which results can be compared exists but are not comprehensive and often the experience of the practitioner is most important for interpretation of the results. Conditions, which are diagnosed fall under the broad categories of disorders of nerve, anterior horn cell, muscle or neuromuscular junction, with certain conditions seen more commonly than in older children. Examples include hypomyelinating neuropathy, SMARD, myotonic dystrophy, congenital myasthenic syndrome, and neonatal brachial plexopathy. While few practitioners perform EMG in children so young the rewards may be considerable with information obtained that is almost always important in the management of the children. It is feasible for any trained neurophysiologists to do and more should be encouraged to offer this service which comprises one quarter of the author's clinical case load.

Utility of electrodiagnostic testing and computed tomography myelography in the preoperative evaluation of neonatal brachial plexus palsy

OBJECT

The rate of neonatal brachial plexus palsy (NBPP) remains 0.4%-4% despite improvements in perinatal care. Among affected children, the extent of brachial plexus palsy differs greatly, as does the prognosis. Controversial elements in management include indications and timing of nerve repair as well as type of reconstruction in patients in whom function will ultimately not be recovered without surgical intervention. Differentiating preganglionic (avulsion) from postganglionic (rupture) lesions is critical because preganglionic lesions cannot spontaneously recover motor function. Distinguishing between these lesions at initial presentation based on clinical examination alone can be difficult in infants. The purpose of the present study was to determine the sensitivity of preoperative electrodiagnostic studies (EDSs) and CT myelography (CTM) in determining the presence of nerve root rupture and avulsions in infants with NBPP.

METHODS

After receiving institutional review board approval, the authors conducted a retrospective review of patients referred to the Neonatal Brachial Plexus Program between 2007 and 2010. Inclusion criteria included children who underwent brachial plexus exploration following preoperative EDSs and CTM. The CTM scans were interpreted by a staff neuroradiologist, EDSs were conducted by a single physiatrist, and intraoperative findings were recorded by the operating neurosurgeon. The findings from the preoperative EDSs and CTM were then compared with intraoperative findings. The sensitivities and 95% confidence intervals were determined to evaluate performance accuracy of each preoperative measure.

RESULTS

Twenty-one patients (8 male amd 13 female) met inclusion criteria for this study. The sensitivity of EDSs and CTM for detecting a postganglionic rupture was 92.8% (CI 0.841-0.969) and 58.3% (CI 0.420-0.729), respectively. The sensitivity for EDSs and CTM for preganglionic nerve root avulsion was 27.8% (CI 0.125-0.509) and 72.2% (CI 0.491-0.875), respectively. In cases in which both CTM and EDSs gave concordant results, the sensitivity for both modalities combined was 50.0% (CI 0.237-0.763) for avulsion and 80.8% (CI 0.621-0.915) for rupture. Overall, EDSs were most useful in identifying ruptures, particularly in the upper plexus, whereas CTM was most sensitive in identifying avulsions in the lower plexus.

CONCLUSIONS

Knowledge of the spinal nerve integrity is critical for early management of patients with NBPP. Surgical management, in the form of nerve repair/reconstruction, and optimal prognostication of NBPP depend on the accurate diagnosis of the level and type of lesion. Both EDSs and CTM scans must always be interpreted in the context of a comprehensive evaluation of the patient. They provide supplemental information (in addition to the physical examination) for early detection of nerve root rupture and avulsion injuries, aiding surgical decision making and preoperative planning for NBPP. Continued advances in imaging, EDSs, and microsurgical nerve repair techniques will allow surgeons to achieve greater success for functional recovery in management of NBPP.

Paediatric electromyography in the modern world: a personal view

Paediatric electromyography (EMG) is an invaluable diagnostic test for the investigation of neuromuscular disease, but its use is inconsistent between and within different countries. One perception is that the procedure is painful; however, in comparison with common investigations performed routinely in children, EMG is better tolerated. While some developments, such as those within clinical genetics, would appear to mark its demise, paradoxically the more genetic abnormalities that are discovered in conditions such as hereditary neuropathy, the more precise a delineation of the phenotype is required. EMG has particular strengths in the diagnosis of neuropathies, motor neuronopathy and neuromuscular transmission disorders such as myasthenia. Also, it can supplement the investigation of myopathies. Areas of development include the diagnosis of myasthenia, delineation of bulbar palsy as a cause of dysphagia, more accurate and earlier prediction of prognosis in neonatal brachial palsy and investigation of channelopathies. It is a valuable diagnostic tool in developed countries and those with limited resources.

MR imaging findings in brachial plexopathy with thoracic outlet syndrome

The BPL is a part of the peripheral nervous system. Many disease processes affect the BPL. In this article, on the basis of 60 patients, we reviewed MR imaging findings of subjects with brachial plexopathy. Different varieties of BPL lesions are discussed.

Motor nerve-conduction studies in obstetric brachial plexopathy for a selection of patients with a poor outcome

BACKGROUND

The criteria and timing for nerve surgery in infants with obstetric brachial plexopathy remain controversial. Our aim was to develop a new method for early prognostic assessment to assist this decision process.

METHODS

Fifty-four patients with unilateral obstetric brachial plexopathy who were ten to sixty days old underwent bilateral motor-nerve-conduction studies of the axillary, musculocutaneous, proximal radial, distal radial, median, and ulnar nerves. The ratio between the amplitude of the compound muscle action potential of the affected limb and that of the healthy side was called the axonal viability index. The patients were followed and classified in three groups according to the clinical outcome. We analyzed the receiver operating characteristic curve of each index to define the best cutoff point to detect patients with a poor recovery.

RESULTS

The best cutoff points on the axonal viability index for each nerve (and its sensitivity and specificity) were <10% (88% and 89%, respectively) for the axillary nerve, 0% (88% and 73%) for the musculocutaneous nerve, <20% (82% and 97%) for the proximal radial nerve, <50% (82% and 97%) for the distal radial nerve, and <50% (59% and 97%) for the ulnar nerve. The indices from the proximal radial, distal radial, and ulnar nerves had better specificities compared with the most frequently used clinical criterion: absence of biceps function at three months of age.

CONCLUSIONS

The axonal viability index yields an earlier and more specific prognostic estimation of obstetric brachial plexopathy than does the clinical criterion of biceps function, and we believe it may be useful in determining surgical indications in these patients.

Severe chronic morbidity following childbirth

Three special, chronic morbidities of childbirth are reviewed with the most up-to-date knowledge in this article. Firstly, obstetric fistulas secondary to prolonged obstructed labour are still prevalent tragedies in underdeveloped countries. The damage is not only physical but psychosexual and social. The surgical skill and technology required to prevent and to treat obstetric fistulas are simple, but culture-social antagonism, geographic distance, political instability and financial constraint have to be overcome before effective management can take place. Congenital brachial plexus palsy is associated with shoulder dystocia and macrosomia, and both excessive exogenous traction and strong endogenous pushing forces contribute to its occurrence. As shoulder dystocia and macrosomia are not easily predictable, regular training and drill is essential to ensure proper management of shoulder dystocia. Most of the babies with brachial palsy will recover in 3 months but a minority of patients will suffer a more severe degree of damage, requiring early micro-neurosurgical intervention. Finally, although birth asphyxia is not the major cause of cerebral palsy, brain injury resulting from acute intrapartum hypoxic-ischemic insult is potentially alleviated by early neonatal hypothermic therapy. Both clinical and radiological assessments are essential in selecting suitable candidates for this innovative neuroprotective strategy.

Cortical dysplasia and obstetrical brachial plexus palsy

We report 2 patients with obstetrical brachial plexus palsy, ipsilateral leg weakness, and contralateral motor cortical dysplasia. To our knowledge, this is the first description of such an association. In both cases, the diagnosis of obstetrical brachial plexus palsy was established clinically shortly after birth and later confirmed neurophysiologically. Motor cortex dysplasia was diagnosed by magnetic resonance imaging (MRI). The association of obstetrical brachial plexus palsy and contralateral motor cortex dysplasia, a condition known to produce congenital hemiparesis, raises the possibility that the cortical dysplasia was a predisposing factor for obstetrical brachial plexus palsy in these cases.

Infantile myofibromatosis: a nontraumatic cause of neonatal brachial plexus palsy

Most injuries to the neonatal brachial plexus occur acutely at birth, and are iatrogenic in origin. However, when weakness is accompanied by atrophy, nontraumatic etiologies should be considered. The differential diagnosis of chronic congenital brachial plexopathy includes cervical bone malformations, humeral osteomyelitis, varicella, and compression from various types of infantile tumors. An illustrative male infant delivered at 37 weeks of gestation with wasted musculature of the left upper arm, ipsilateral Horner's syndrome, and a hemidiaphragm is presented. On further examination, this patient manifested an underlying cervical tumor compressing the brachial plexus. Diagnostic steps leading to the pathologic identification of a solitary cervical myofibroma included physical examination, electromyography, radiographic imaging, and open biopsy. This report emphasizes the importance of differentiating acute from chronic congenital plexus palsy and of recognizing the possibility that infection or neoplasm may underlie the latter.

Obstetrical brachial plexus palsy

Obstetrical brachial plexus palsy, one of the most complex peripheral nerve injuries, presents as an injury during the neonatal period. The majority of the children recover with either no deficit or a minor functional deficit, but it is almost certain that some will not regain adequate limb function. These few cases must be managed in an optimal way. Considerable medical and legal debate has surrounded the etiologic factors of this traumatic lesion, and obstetricians are often considered responsible for the injury. According to recent studies, spontaneous endogenous forces may contribute substantially to this type of neonatal trauma. All obstetric circumstances that predispose to brachial plexus damage and that could be anticipated should be assessed. Correct diagnosis is necessary for the accurate estimation of prognosis and treatment. The most important aspect of therapy is timely recognition and referral, to prevent the various possible sequelae affecting the shoulder, elbow, or forearm. Since the early 1990s, research has increased the understanding of obstetrical brachial plexus palsy. Further research is needed, focused on developing strategies to predict brachial injury. This review focuses on emerging data relating to obstetrical brachial plexus palsy and discusses the present controversies regarding natural history, prognosis, and treatment in infants with brachial plexus birth palsies.

Magnetic resonance neurography in children with birth-related brachial plexus injury

BACKGROUND

Magnetic resonance neurography (MRN) enables visualization of peripheral nerves. Clinical examination and electrodiagnostic studies have been used in the evaluation of birth-related brachial plexus injury. These are limited in their demonstration of anatomic detail and severity of injury.

OBJECTIVE

We investigated the utility of MRN in evaluating birth-related brachial plexus injury in pediatric patients, and assessed the degree of correlation between MRN findings and physical examination and electromyographic (EMG) findings.

MATERIALS AND METHODS

The MRN findings in 11 infants (age 2 months to 20 months) with birth-related brachial plexus injury were evaluated. A neuroradiologist blinded to the EMG and clinical examination findings reviewed the images. Clinical history, examination, EMG and operative findings were obtained.

RESULTS

All infants had abnormal imaging findings on the affected side: seven pseudomeningoceles, six neuromas, seven abnormal nerve T2 signal, four nerve root enlargement, and two denervation changes. There was greater degree of correlation between MRN and physical examination findings (kappa 0.6715, coefficient of correlation 0.7110, P < 0.001) than between EMG and physical examination findings (kappa 0.5748, coefficient of correlation 0.5883, P = 0.0012).

CONCLUSION

MRN in brachial plexus trauma enables localization of injured nerves and characterization of associated pathology. MRN findings demonstrated a statistically significant correlation with physical examination and EMG findings, and might be a useful adjunct in treatment planning.

Management of brachial plexus injuries

Most brachial plexus lesions are traction injuries sustained during birth, but in adolescents and older people they are usually caused by traffic accidents or following a fall in the home. A minority are the result of penetrating injury after civilian assault or trauma encountered during wartime. Birth palsy cases (obstetric brachial plexus palsy) and the remaining cases (traumatic briachial plexus palsy) are viewed differently with regard to treatment and outcome and so these two groups are usually discussed in separate chapters. In this paper we treat both groups in parallel because as far as primary (= nerve) surgery is concerned, many treatment problems and solutions are present in both groups and are therefore comparable.

Extremity shortness in obstetric brachial plexus lesion and its relationship to root avulsion

A total of 73 patients with obstetric brachial plexus palsy and extremity shortness were evaluated clinically, electrophysiologically, and with cervical magnetic resonance imaging. Patients were separated into groups according to age and the level of lesion. The differences of the length of the humerus, ulna, radius, and the second and fifth metacarpal bones were significant between the involved and uninvolved extremities. The difference in shortness increased in relation to the age of the groups and stabilized to approximately 10% in the groups aged 4 to 8 years and 8+ years. A significant relationship was observed between bone length differences and lesion levels. Differences in bone lengths were statistically significant in patients with avulsion in the group aged 8+ years. Extremity shortness appears to be related to avulsion and the level of lesion. The effect of avulsion on extremity shortness gradually increases with age. Finally, root avulsion can be an important factor in extremity shortness of obstetric brachial plexus palsy patients.

Clinical-electromyography correlation in infants with obstetric brachial plexopathy

PURPOSE

The real utility of needle electromyography (EMG) for evaluation of infants with obstetric brachial plexopathy remains controversial. The objective of this paper is to evaluate how EMG correlates with clinical evaluation of these patients.

METHODS

We performed EMG in 41 infants (42 arms) with severe obstetric brachial plexopathy who were from 3 to 12 months of age. We correlated the EMG interference pattern with the clinical assessment of infraspinatus, deltoid, biceps, triceps, and extensor digitorum communis muscles.

RESULTS

Motor unit potentials were always present, and abnormal spontaneous activity was not common in proximal muscles. The correlation between EMG interference pattern and clinical assessment was not good, except for extensor digitorum communis. EMG showed higher scores than clinical evaluation for infraspinatus, deltoid, and biceps muscles. Respiratory synkinesis was present in 19 patients, or 45% of the affected arms, and it could involve any muscle innervated from C5 to T1.

CONCLUSIONS

Needle EMG fails to estimate or overestimates clinical recovery in proximal muscles in this age group.