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Page 14 of 17 Priya et al. J Cancer Metastasis Treat 2021;7:70 https://dx.doi.org/10.20517/2394-4722.2021.122

RECENT ADVANCES AND FUTURE DIRECTIONS
CIONM
CIONM, with real time monitoring, alerts the surgeon to an impending injury before actual insult to the
nerve. It removes the risk to the nerve due to the temporal gap (interval between stimulations) and spatial
gap (distance between the site of stimulation and the site of injury) that can happen in intermittent IONM
(IIONM) . Thus, the probability of permanent vocal cord palsy with CIONM is less than that of
[57]
[46]
IIONM . The lower risk of injury to the RLN translates into higher conversion to total thyroidectomy with
the use of CIONM, as was concluded by Schneider et al. in their study of 1314 nerves at risk. The caveat is
[46]
the need for extra dissection not just of the carotid sheath but also 360-degree release of the vagus for
mounting and accommodating the stimulating electrode. It has been nonetheless found to be safe with
respect to voice outcomes even in professional voice users . Additionally, continuous albeit low-voltage
[58]
stimulation of the vagus was feared to potentially increase the risk of heart blocks especially in a patient with
heart disease. This has been negated by available data which suggest safety even in patients with heart
blocks .
[59]
Monitoring of the external branch of superior laryngeal nerve
The International Neuromonitoring Study Group has defined the role of monitoring of External Branch of
Laryngeal Nerve (EBSLN) . Several workers have demonstrated the feasibility and efficacy of IONM in
[60]
mapping the EBSLN [61,62] . The identification of the EBSLN has been shown to be consistently better with
[63]
IONM as compared to visual identification . There may, however, be technical and instrumental
modifications required for the proper recording of the EBSLN readings and these are still evolving.

Use of IONM in remote access thyroidectomy
IONM has been demonstrated to be useful in endoscopic and robotic thyroidectomies via all
approaches [64,65] . The voice outcomes are similar to non-IONM procedures though the recovery to normal
speech has been seen to be more rapid with the use of IONM. CIONM is more easily integrated in such
[66]
surgeries. However, there may be difficulties involved , and the rate of artifacts and false positives may be
higher than in open surgeries.

CONCLUSION
IONM is a useful adjunct in thyroid surgeries, particularly in difficult thyroid cancers, as has been
highlighted in the literature [67,68] . It helps not only to identify but also to preserve and prognosticate nerve
injury with advances in precision recording. The learning curve of this technique is not unsurmountable.
Having achieved that, incorporation of the IONM has a bearing on critical intraoperative decision-making
with regards to patient safety. Continuing innovation in IONM design as well as the fast-emerging role of
CIONM will further enhance the efficacy and applicability of this tool even in remote access
thyroidectomies.

DECLARATIONS
Authors’ contributions
Made substantial contributions to conception and design of study, data analysis and interpretation:
Priya SR, Dandekar M
Performed data acquisition, technical and material support: Garg S, Priya SR, Dandekar M

Availability of data and materials
Not applicable.