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Page 18 of 20 Kobylarz et al. Plast Aesthet Res 2023;10:2 https://dx.doi.org/10.20517/2347-9264.2022.38

eminence, but only stimulation of the ulnar nerve would also activate the hypothenar muscles. Assessment
of the integrity of nerve function can also be achieved by means of stimulation within the surgical field. The
surgeon can stimulate and record the NAPs or CMAPs along the course of a nerve. If there exists a location
where the responses are no longer detected, this could indicate a nonfunctioning portion of the nerve.
However, if the NAPs or CMAPs can be elicited throughout the course, including across scar tissue at least
several months after injury, this suggests that ongoing reinnervation is occurring. Therefore, it may be best
to leave this area alone or to perform neurolysis, rather than a nerve graft. It should be noted that false
negative CMAPs and NAPs can occur for reasons that have been stated previously, e.g., current shunting,
technical issues, muscle relaxants or ischemia. If tourniquets are utilized during surgery, they should be
deflated for up to 30 minutes before performing electrodiagnostic testing distally in the limb [18,29] .

CONCLUSION
There is sufficient evidence that EMG and NCS can provide the surgeon with useful information regarding
the neurophysiologic status of spinal nerve roots, the brachial and lumbosacral plexuses, and peripheral
nerves pre-operatively, as well as during surgery. IONM can help the surgeon to accurately identify neural
structures and assess their functionality, as well as guide a safe and successful dissection or resection, nerve
repair or placement of spinal instrumentation. Intraoperative EMG and NCS provide an effective method
for minimizing intraoperative risks to the nervous system for procedures where nervous tissue is
manipulated, thereby improving outcomes in terms of postoperative neurologic function. The advantages
offered by pre-operative electrodiagnostic testing are significant and include improved
sensitivity/specificity, potentially precise localization, duration of injury, severity and prognostic data. The
loss of recruitment of motor unit potentials in the setting of full activation/effort during contraction of a
muscle is a compelling indication for nerve grafting, while the demonstration of recruitment allows for a
more conservative approach. Inconsistencies in clinical or radiologic data in the pre-operative setting,
particularly when considering a high-risk surgical approach, should prompt a re-examination of pre-
operative data with the outpatient electromyographer; errors and limitations in the interpretation of data
must always be considered. The sources of type 1 error in diagnostic studies include over-reliance on subtle
or equivocal electrodiagnostic changes, anatomic variation, patchy or fascicular injury, poor effort during
muscle contraction and measurement errors. An insufficient number of sampled muscles, limitations of
study due to poor tolerance or concomitant anticoagulation and overlapping innervation can result in
misdiagnosis. Similarly, during IONM, errors can result from localized ischemia, excess fluid/blood in the
recording field and electrical interference from surgical equipment. That said, the pre-operative assessment
and continuous monitoring of the nervous system can allow for more aggressive surgical interventions to be
achieved.

It should be emphasized that in the end, the value of pre-operative and intraoperative electrodiagnostic
studies depends on a collaborative interaction and effective communication between the neurophysiologist
and surgeon such that the neurophysiologic information is incorporated during pre-operative planning and
crucial stages of the surgical procedure. Close cooperation among all members of the surgical team is of
utmost importance for preventing intraoperative neural compromise and optimizing postoperative
outcomes. As surgical techniques progress in advancing the field of surgical management of nerve, plexus
and root injuries, studies aimed at correlating pre-operative electrodiagnostic localization and intra-
operative electrodiagnostic function with outcomes will facilitate a better understanding of the relevance of
some of the errors discussed in this review. This has particular relevance in an appreciation of the
redundancy of myotomal innervation and the extent of anomalous innervation. This not only has potential
implications for surgical fields but also for nerve and muscle disorders.