2018 Section 6 - Laryngology, Voice Disorders, and Bronchoesophalogy

S.-K.

Baek et

al.

/ Auris

Nasus

Larynx

44

(2017)

583 – 589

the dissection of

the

thyroid

superior pole,

similar

to

the

during

3.5.

Comparison

between

open

thyroidectomy

and

there was no definite

traditional surgical method. Consequently,

thyroidectomy

robotic/endoscopic

to

the

EBSLN

in

the

study

population.

However,

injury

F0, Maximal

pitch,

GRBAS

scale,

and

VHI-30

score

The

that

the

F0

and Maximum

pitch,

which

may

be

considering

not

significantly

different

between

two

groups

of

the

were

the

function

of EBSLN,

exhibited

a

significant

associated with

who

underwent

open

thyroidectomy

or

robotic/

patients

difference

according

to

IONM,

even

if

identification

and

thyroidectomy

(Supplementary

Tables

2

and

3,

endoscopic

of

the

EBSLN

were

not

performed

directly,

neuromonitoring

0.05). When

the study population was divided based on the

p >

IONM may

render minimal damage of

the nerve potentially

the

techniques,

the

number

of

patients

in

each

group was

surgical

avoidable.

and may

be

associate with

this

insignificant

results.

small

it may

be

difficult

to

identify

the mechanism

to

Although

the

risk

of EBSLN

injury

through

IONM

of

the RLN, the RLN anatomical

decrease

be

associated with

the

anatomical

finding

that

it may

4. Discussion

innervate

the

cricothyroid

muscle.

Previous terminal

can

Phonation

studies

change

after

thyroidectomy

has

been

considered

of

cadaver

larynges

revealed

that

branches

of

result

from

numerous

factors,

including

laryngeal

neural

EBSLN

communicate with

branches

of

the RLN,

and

this

to

the

endotracheal

intubation

trauma,

cricothyroid

dysfunc-

is

called

the

human

communicating

nerve

[17 –

damage,

branch

strap

muscle

malfunction,

laryngotracheal

fixation,

and

When

the

EBSLN

is

electrically

stimulated,

activation

tion,

19] .

reaction laryngeal

to

the

operation

[5,8 – 10] .

In

particular,

the

endolaryngeal

muscles

was

revealed

in

70% – 80%

of

psychological

of

damage that may numerous to

the

nerve

is

one

of

the

critical morbidities

and [4] .

this phenomenon

is used

as

the

IONM method demonstrated

for

patients, EBSLN

result

in a significant effect on

the quality of

life. Thus,

In

contrast,

a

previous activated

study

that

studies

have

examined

whether

IONM

during nerve

can

be

by

the

RLN

via

reverse

cricothyoid muscles

thyroidectomy

communication

is

beneficial

in

reducing

the

laryngeal

of

the

human

communicating

nerve

[20] . As

a

rate.

Although

a

non-randomized

study

suggested

reversible

damage

of RLNs

by minimal

trauma,

such

as of

paralysis

result,

rates

of in

postoperative

RLN

paralysis

in

patients resulted

with

or

heating, may

result

in

the

temporary

dysfunction

lower IONM

traction

[11] ,

other

randomized

studies,

IONM

in

no

cricothyroid muscles. NIM system emits

reduction

in

permanent

RLN

paralysis

compared

audible

sound

and

shows

EMG

signal

significant

visualization

alone,

even

in

high

risk

patients

with

subtle

stimulations

such as

traction or heating

that

with

change under

resection

or

reoperation

due

to

recurrent

thyroid

occur

nerve

damage, which may of RLN. Actually, in

be

useful

to

prevent

the

extended diseases significant temporary

can

[12 – 14] .

However,

IONM

resulted

in

a

statistically

trauma

present

study,

operators

minimal

discontinued

decrease EBSLN

in

the

risk

of

early

phonation

changes

or

surgical

procedure

to minimize

traumas

of

RLN

injury

after

surgery

[13,15] .

NIM

system

indicated

impending

trauma

of

RLN

and

when

the

present

study,

female

patients

without

evidence

of

reassume

operation

after

confirming

the

safety

of

RLN.

In

then

nerve

paralysis

were

evaluated

using

various

voice

this

effort

to prevent minimal

trauma of

the RLN

through

laryngeal analysis

Thus,

methods

after

thyroidectomy.

Similar

to

previous

explain

the

significant

reduction of

early phonation

IONM may

a

significant

decrease

in

phonation

changes was

seen

after

thyroidectomy.

studies, during

changes

the

early

period

within

postoperative

1

month.

In

the

total

thyroidectomy

group

had

significant according

particular, differences

5.

Limitation

of

the

study

in F0

and

the maximum pitch of

the VRP

IONM

in

comparison

with

the

hemithyroidectomy

group.

the

present

study,

we

did

not

routinely

identify

and

In

to

this

difference

between

hemithyroidectomy

and

the EBSLN when

dissecting

the

thyroid

superior

pole. voice voice

Expectedly,

monitor Further outcome

thyroidectomy groups may

result

from

the

larger

extent of

study

is

needed

to

evaluate

the

differences

in

total

dissection

in

total

thyroidectomy. the maximum

after

thyroid

surgery

using

multi-parametric

surgical

reduction

in F0

and

pitch

of

the VRP

are

depending

on

the

use

of

IONM

for

the

EBSLN.

The

evaluation

associated with EBSLN

injury

[16] . Even

if

the

clinical of RLN

mainly

of EBSLN

injury

are

less

critical

than

those

symptoms

6.

Conclusion

injury,

the

reduced

F0

and and

difficulty important

in

producing

high-pitch

sensitive

issues

in

female patients.

that IONMduring

thyroid surgery resulted

Our study suggests

sound may be

the

study population of

the present subjective

study was

restricted

to

better

outcomes

regarding

the F0

and

high-pitch

voice

in

the

Thus,

in

patients.

Even

if

the

assessments significantly

of

voice,

postoperative

period,

particularly

in

total

thyroidectomy

female

early

as

GRBAS

and

VHI,

were

not

different

Although

it

may

not

benefit

the

permanent

voice

such

patients. outcome thyroid transient

to

the

use

of

IONM,

the

assessment

scores

showed

a

from

3 months

after

operation,

use

of

IONM

during reduce

according tendency

to

increase during

the early period. However, although

surgery

appears

to

be

an

effective

method

to

in

subjective

findings were not definite,

the

reductions

voice

alteration

after

thyroid

surgery.

changes

in objective values,

including

the F0

and

the maximum pitch of

indicate a partial

impairment of EBSLN

function. the RLN

the VRP may

Acknowledgments

the

present

study, we performed

IONM

for only

In

ligation of

superior

thyroid vessels with capsular

research

was

supported

by

the

Korea

Health through

and peripheral

This

to minimize

the

injury

to

the EBSLN

(grant

number: HI14C0748)

dissection was performed

Technology R&D Project

116