Assessing Brachial Plexus Injury: Bilateral Efferent Transmission via Neurophysiology

Cattin Vokurkova^*
*Correspondence: Cattin Vokurkova, Department of Neurology, Hallym University Sacred Heart Hospital, Chuncheon 24253, Republic of Korea, Email:

Introduction

The brachial plexus, a network of nerves originating from the spinal cord, plays a pivotal role in the motor and sensory functions of the upper limbs. Injuries to this intricate system can lead to significant functional impairments, affecting an individual’s quality of life. Assessing brachial plexus injuries requires a multifaceted approach that combines clinical evaluation, imaging techniques and advanced neurophysiological studies. Among these, the role of neurophysiology in assessing bilateral efferent transmission has gained prominence due to its ability to provide insights into the functional integrity of neural pathways. This article delves into the significance of neurophysiological methods in understanding brachial plexus injuries and their impact on efferent transmission [1].

Description

Brachial plexus injuries often result from trauma, such as motor vehicle accidents, falls, or sports-related incidents. These injuries may manifest as partial or complete loss of motor and sensory functions in the affected limb, depending on the severity and location of the damage. While clinical examination provides an initial assessment, it often fails to capture the full extent of neural dysfunction, especially in cases where the injury involves multiple levels or subtle disruptions in nerve signaling. This is where neurophysiological techniques, such as Electromyography (EMG) and Nerve Conduction Studies (NCS), become invaluable tools in the diagnostic arsenal.

Efferent transmission refers to the signals sent from the Central Nervous System (CNS) to the muscles via motor nerves. In the context of the brachial plexus, these signals are essential for executing precise and coordinated movements of the upper limb. When the brachial plexus is injured, efferent transmission can be disrupted, leading to weakness, paralysis, or atrophy of the muscles it innervates. Bilateral assessment of efferent transmission is particularly important in identifying compensatory mechanisms and understanding the overall impact of the injury on neural function. Neurophysiology offers a quantitative and objective approach to evaluating efferent transmission. Electromyography (EMG) is one of the cornerstone techniques used in this context. By inserting fine needle electrodes into specific muscles, clinicians can record the electrical activity generated by motor units [2,3].

Nerve conduction studies (NCS), on the other hand, focus on measuring the speed and strength of electrical signals traveling along the motor nerves. By stimulating the nerve at various points and recording the resulting muscle response, NCS can detect conduction block, demyelination, or axonal loss-key features of brachial plexus injuries. Additionally, NCS can be used to compare the affected and unaffected sides, enabling a bilateral assessment that highlights asymmetries in efferent transmission. Beyond EMG and NCS, advanced techniques such as Motor Evoked Potentials (MEPs) and transcranial magnetic stimulation (TMS) have expanded the scope of neurophysiological assessment.

MEPs involve stimulating the motor cortex and recording the resulting muscle response, providing insights into the integrity of the corticospinal pathways. In the case of brachial plexus injuries, MEPs can help determine whether the disruption is confined to the peripheral nerves or extends to central pathways. TMS, on the other hand, allows for non-invasive stimulation of specific cortical regions, enabling the assessment of motor cortical excitability and plasticity. These techniques complement traditional methods by offering a broader perspective on neural function and recovery potential. One of the challenges in assessing brachial plexus injuries is the presence of bilateral involvement, which can occur in severe trauma or conditions affecting both sides of the plexus. In such cases, neurophysiological studies must account for the complexity of bilateral efferent transmission. Comparing findings from both sides can reveal compensatory mechanisms, such as increased recruitment of motor units on the unaffected side or reorganization of cortical motor representations. These insights are critical for designing rehabilitation strategies that optimize functional recovery [4,5].

Conclusion

Despite its many advantages, neurophysiological assessment of brachial plexus injuries is not without limitations. The interpretation of findings requires specialized training and expertise, as well as a thorough understanding of the neuroanatomy and pathophysiology of the brachial plexus. Additionally, certain factors, such as pain, edema, or patient cooperation, can influence the accuracy of neurophysiological measurements. Therefore, these assessments should be conducted as part of a multidisciplinary approach that includes neurologists, neurosurgeons, physiatrists and rehabilitation specialists. Assessing brachial plexus injuries requires a comprehensive understanding of the neural pathways involved in efferent transmission. Neurophysiological techniques such as EMG, NCS, MEPs and TMS play a crucial role in evaluating the functional integrity of these pathways, providing objective data that guide diagnosis, prognosis and treatment planning. Bilateral assessment of efferent transmission offers unique insights into the compensatory mechanisms and recovery potential in cases of complex or bilateral injuries. By integrating neurophysiological findings with clinical and imaging data, clinicians can develop targeted interventions that maximize functional recovery and improve the quality of life for individuals affected by brachial plexus injuries. As advancements in technology and AI continue to enhance the precision and applicability of neurophysiological assessments, the future holds promise for even more effective management of these challenging injuries.

Acknowledgement

None.

Conflict of Interest

None.

References

1. Moran, Steven L., Scott P. Steinmann and Alexander Y. Shin. "Adult brachial plexus injuries: Mechanism, patterns of injury and physical diagnosis." Hand Clin 21 (2005): 13-24.

Google Scholar, Crossref, Indexed at

2. Malessy, Martijn JA, Willem Pondaag and J. Gert van Dijk. "Electromyography, nerve action potential and compound motor action potentials in obstetric brachial plexus lesions: Validation in the absence of a “gold standard”." Neurosurg 65 (2009): A153-A159.

Google Scholar, Crossref, Indexed at

3. Weber, Markus, Andrew A. Eisen and AAEM. "Magnetic stimulation of the central and peripheral nervous systems." Muscle Nerve 25 (2002): 160-175.

Google Scholar, Crossref, Indexed at

4. Stlberg, Erik and Björn Falck. "The role of electromyography in neurology." Electroencephalogr Clin Neurophysiol 103 (1997): 579-598.

Google Scholar, Crossref, Indexed at

5. Jones, S. J., CB Wynn Parry and A. Landi. "Diagnosis of brachial plexus traction lesions by sensory nerve action potentials and somatosensory evoked potentials." Inj 12 (1981): 376-382.

Google Scholar, Crossref, Indexed at