Aerodynamic Phonatory Pattern as a New Sign

of Superior Laryngeal Nerve

Secundino Fernandez, MD, PhD (presenter); Juan M. Alcalde, MD, PhD; Peter M. Baptista, MD, PhD;

Luz Barona MD. Otolaryngology Department, Universidad de Navarra, Pamplona, SPAIN.

INTRODUCTION

RESULTS

Table 1. Group B subglottal pressure values. P<0.02

Figure 1. Rothemberg Mask

Figure 2. Example of acoustic and aerodynamic measurements

ABSTRACT

METHODS AND MATERIALS

DISCUSSION-CONCLUSIONS

REFERENCES

CONTACT

REPLACE THIS BOX

WITH YOUR

ORGANIZATION’S

HIGH RESOLUTION

LOGO

Reduced quality of life after thyroid

surgery is multifactorial and may

include the need of lifelong different

treatments. About 1 in 20 patients

experience voice changes, and it is

very frequent that these changes

may not be caused by neural lesions.

We studied 58 thyroidectomized

patients with neither apparent neural

cause of thyroidectomy-related

dysphonia nor recurrent laryngeal

nerve injury nor external

branch of the superior laryngeal

nerve (EBSLN) injury. Afterward,

acoustic and aerodynamic measure-

ments were made.

We describe 2 different groups of

patients with different aerody-namic

pattern in voice production that

correlates with voice quality. In 66%

of patients there was no change and

in 34% the glottal pressure and

laryngeal resistance decreased as a

result of lower tension in the vocal

fold as a consequence of an injury of

the EBSLN.

This aerodynamic phonatory pattern

that may be understood by objective

aerodynamic measurements could

be another new sign of EBSLN injury. Maximum phonation time, speech rate and

articulation rate were also registered. All

measurements were made using Voice Plus from

Alamed Corporation software. Recording was done

in the Voice Research Laboratory (a quiet non-

sound treated room approximately 5*4m) at the

Otolaryn-gology Head and Neck Surgery

Department of the University of Navarra. The four

Signals pressure, flow, sound pressure-microphone,

electroglo-ttograph were digitized by an A/D

converted board (DT 2821). The digitized signal

was imported to the Alamed Voice Plus Analysis

System on a PC for the aerodynamic study. The

acoustic analysis was ma-de with SoundSope on

G4 Mac computer. Intensity was evaluated with a

sonometer or sound level meter. STATA software

was used to analyze variables.

We studied 58 thyroidectomized patients with

neither apparent neural cause of thyroidectomy-

related dysphonia nor recurrent laryngeal nerve

injury nor external branch of the EBSLN injury.

The patients were asked to produce sustained

vowels, syllables, and sentences. Three items

were recorded in upright and sitting positions.

We ask every patient for a sustained phonation

of Spanish vowels /a/ & /i/.

The syllables: /pa/ & /pi/ and two sentences: “Papá pinta la pared de color púrpura con la pintura

que compró por la tarde”

“El domingo por la mañana voy a la bodega de mi

hermano, a mediodía mi hermano y yo bebemos vino”.

During each task the subject held the pneumo-

tachograph mask (Rothemberg Mask) firmly in

place over the nose and mouth with the pressure

tube between the lips (Figure1). Acoustic and

aerodynamic measurements were made:

fundamental frequency, jitter, shimmer, intensity,

harmonic/noise ratio, spectrographic analysis,

subglottic pressure, mean transglottic flow, and

laryngeal resistance (Figure 2).

Postoperative voice changes may be an impor-

tant part of the outcome of the patients

undergoing thyroidectomy. Deterioration and

amelioration of acoustic parameters can be

observed, and those changes may occur

differently among male and female patients.

Physicians should take the patient’s sex into

consideration when informing the patient about

possible voice alterations after thyroidectomy.

Preoperative and postoperative acoustic and

aerodynamic analyses may be helpful in

revealing any voice abnormality already

present before the surgery and any possible

alteration occurring after the surgery.

Aerodynamic phonatory pattern charac-terized

by subglottal pressure and laryngeal

resistance decreased as a result of lower

tension in the vocal could be a new sign of

EBSLN injury.

Reduced quality of life after thyroid surgery is

Multifactorial and may include the need of

lifelong different treatments. Studies have shown

that subjective voice disturbance after thy-

roidectomy is very common, even without injury

to the recurrent laryngeal nerves.

One possible cause for postoperative dysphonia

is injury to the external branch of the superior

laryngeal nerve (EBSLN). The EBSLN supplies

the cricothyroid muscle, which acts to lengthen

the vocal folds during phonation. Post-

operatively, patients with a lesion of the EBSLN

typically complain of voice fatigue, problems

reaching high-pitch sounds that they were used

to reach, and the need of an extra effort to

speak; they can also complain of various rates of

dysphagia. The awareness to these symptoms,

that may be subliminal to common people, might

be more evident to the so-called “professional

speakers”.

Several studies have investigated post-operative

rates of EBSLN injury varying from 0 to as much

as 58% a result that reflects the need for

standardized protocol slooking forward a more

accurate evaluation of this complication, even if

the impairments coming from such lesions are

the less prone to be improved with specific

postoperative treatments. Currently, videostro-

boscopy and/or electromyography of the crico-

thyroid are the only instrumental tools that might

allow to achieve good diagnostic standards

although both are invasive methods, responsible

for some discomfort to the patients.The purpose

of this study is to describe aerodynamic

phonatory features in thyroidectomized patients

in order to determine what mechanisms are

involved in voice changes in these patients and

what are the best rehabilitative options.

1. Lombardi CP, Raffaelli M, D’Alatri L, et al. Voice and

swallowing changes after thyroidectomy in patients without

inferior laryngeal nerve injuries. Surgery. 2006;

140(6):1026-1032.

2. Sinagra DL, Montesinos MR, Tacchi VA, et al. Voice

changes after thyroidectomy without recurrent laryngeal

nerve injury. J Am Coll Surg. 2004;199(4):556-560

3. Cernea CR, Ferraz AR, Furlani J, et al. Identification of the

external branch of the superior laryngeal nerve during

thyroidectomy. Am J Surg. 1992;164(6):634-639.

4.Varaldo E, Ansaldo GL, Mascherini M, et al. Neurological

complications in thyroid surgery: a surgical point of view on

laryngeal nerves. Front Endocrinol (Lausanne). 2014 Jul

15;5:108

Name: Secundino Fernandez

Org.: Universidad de Navarra

Email: sfgonzalez@unav.es

Phone: +34 948255400 ext.(4681)

Website: www.unav.es

We describe 2 different groups (Figures 3 &4) of

patients with different aerodynamic pattern in voice

production that correlate with voice quality.

In 66% of patients there was no change (group A)

and in 34% (group B) the glottal pressure and

laryngeal resistance decreased as a result of lower

tension in the vocal fold as a consequence of an

injury of the EBSLN (Table 1).

Subglottic pressure

(mm H2O) Mean Std-error Lower Upper

Pre Thyroidectomy 93.27 4.48 84.26 120.29

Post Thyroidectomy 72.43 4.22 63.94 80.93

/pa/…/pa/…/pa/…

Figure 4. Example of aerodynamic pattern Group B.

Figure 3. Example of aerodynamic pattern Group A.