The Role of Intraoperative Neuromonitoring in Brachial Plexus Repair: An Overview

 Aisha Khan & Faisal R. Jahangiri

Damage to the brachial plexus is often associated with short-term or permanent sensory and motor deficits in the upper extremity. Injuries of this nature can lead to life-altering issues for the patient. Intraoperative neurophysiological monitoring (IONM) can be utilized within a multimodal approach to assess nerve root avulsions. IONM has been valuable when determining the functionality of a nerve root that may have been prematurely labeled as avulsed on preoperative assessment. Traumatic brachial plexus injuries such as motor vehicle accidents or breech delivery can cause a nerve root to lose its function. Confirming this notion is an ample decision when moving forward with surgical intervention. IONM can aid intraoperatively in confirming the nerve root is functioning using somatosensory evoked potentials (SSEP), motor evoked potentials (MEP), and electromyography (EMG). During a nerve root rupture and avulsion, the peripheral motor neuron’s cell body is disconnected from the skeletal muscle and axon. This can then lead to paralysis of the root’s myotome. IONM can be utilized to identify the damaged roots and help the surgeon in successful nerve grafting.

The brachial plexus is an intricate network of nerves that serves to provide functionality to the upper extremity. It is divided into roots, trunks, divisions, and cords. The cords are then broken down into the major nerve branches. The premise of diagnosing the brachial plexus function is mainly within a clinical examination and a plethora of neurophysiological studies. These modalities and the Seddon clinical classification of nerve root injury in three categories, neurapraxia, axonotmesis, and neurotmesis, can be used to determine the type and severity of brachial plexus damage. MEPs and triggered electromyography (t-EMG) provide a deeper understanding of the proximal damage and can be used as an additional tool when confirming the extent and location of the injury.

There are also limitations in place when utilizing IONM within brachial plexus surgery. Overall, IONM has become an important practice within brachial plexus repair, especially when identifying the viability of a nerve root. There are many research publications in which IONM has aided in diagnosing and treating brachial plexus injuries.

References:

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• Zelenski NA, Oishi T, Shin AY. Indications and Technique for the Use of Intraoperative Neuromonitoring in Brachial Plexus Surgery. J Hand Surg Am. 2023 Jul;48(7):726-731. doi: 10.1016/j.jhsa.2023.01.019. Epub 2023 Mar 11. PMID: 36914452.