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Page 2 of 17 Priya et al. J Cancer Metastasis Treat 2021;7:70 https://dx.doi.org/10.20517/2394-4722.2021.122

[2]
the RLN and consequent temporary or permanent palsy has significant implications on quality of life .
Patients at high risk for RLN palsy include those with thyroid malignancies, especially invasive thyroid
[3]
cancers and bulky central compartment nodes . Patients undergoing surgeries for recurrent disease and
[4]
those undergoing completion surgery are also at a greater risk for RLN injury and permanent palsy . Even
though a number of palsies are temporary and many of these patients recover after a variable period [2,5,6] , any
means of minimizing this risk should be considered crucial, considering the negative impact RLN injury has
on quality of life with symptoms such as hoarseness, dysphagia, and stridor . The morbidity is particularly
[7]
[8]
severe when the palsy is bilateral .
Intraoperative nerve monitoring (IONM) is emerging as one such tool that could be a means of reducing
the incidence of this morbidity. While there can be no substitute for an inside-out familiarity with the
anatomy of the thyroid gland or of experience in these procedures, the IONM is a corroborative method
and useful adjunct for nerve identification, preservation, and prognostication of function in thyroid and
parathyroid surgeries.

Subsequent to technological advances, IONM apparatuses are now more compact and easily incorporated
[9]
into the operating room environment . However, the essentialities such as system setup, anesthesia
protocol modifications, and negotiation of the learning curve by the surgeon(s) as well the anesthetist(s)
and neurophysiologist remain the same .
[10]
TYPES OF INJURIES TO THE RLN DURING THYROIDECTOMY
Since the RLN lies in close approximation to the thyroid gland, a wide array of maneuvers can injure the
RLN. However, only about 14% of these injuries are visible at the time of surgery . Since cancer surgeries
[11]
mandate the removal of entire thyroid tissue even from difficult areas, the RLN is particularly vulnerable at
[12]
the ligament of Berry . Fortunately, most of the RLN injuries are transient and recover within six
[6]
months .

RLN injury can be classified as follows:

1. Based on duration:

a. Transient

b. Permanent

The time duration for categorizing vocal cord palsy as permanent varies in different series, ranging from 3
to 12 months .
[13]

2. Based on etiology:

a. Traction

b. Transection

c. Thermal (due to cauterization)