Keywords
surgery - endoscopy - larynx - technical variant
Introduction
Laryngeal microsurgery is the method of endoscopic treatment of laryngeal lesions.[1]
[2] When laryngoscopy is difficult, there may be no visualization of part or even of
all the vocal cords with the use of conventional laryngoscopy, in such a way as to
make laryngeal microsurgery difficult or even impossible to perform.[3]
The physical examination, in most cases, is enough to alert, even in the preoperative
stage, about potential problems in access to the airway. Some findings, such as micrognathia
and mandibular anteriorization, as well as measures of cervical circumference and
modified Mallampati index, are known for predicting the risk of difficult airway exposure.[4]
[5]
Laryngeal microsurgery promotes magnification of the image and the possibility of
visualization of the endolaryngeal anatomical structures, but with the view being
exclusively frontal, that is, in a straight line.[6] With the application of rigid and contact endoscopy developed by Andrea and Dias,
there was the possibility of angular oblique and retrograde visualization, allowing
better visualization and transoperative staging with greater reach of the anatomical
areas.[7]
D'Avila's study demonstrated that the anatomical area of lesser visualization during
difficult exposure of the larynx is the anterior area of the larynx (area I), which
corresponds to the anterior third of the vocal folds and anterior commissure region
([Fig. 1]).[8] To obtain visualization of this area, and in certain cases of area II, the application
of rigid endoscopes of 30 and 70 degrees becomes necessary.
Fig. 1 D'Avila's areas.
Once this more efficient viewing option was adopted, the next challenge to perform
the surgical procedure was instrumentation limitation. Generally, despite the surgical
lesions being visible with the use of the angled endoscope, there is difficulty or
even impossibility of performing the surgical act due to the incompatibility of the
angled path with the straight surgical tools.
A retrospective study was performed to analyze the medical records of 30 patients,
identifying 6 anatomical parameters of surgical patients submitted to laryngeal microsurgery,
namely: cervical circumference, oral opening, thyromental distance, modified Mallampati
classification, laryngeal anteriorization and micrognathia. Out of the 30 patients,
6 had difficulty in laryngeal exposure and were thus selected to be evaluated in relation
to these anatomical parameters.
The objective of this work is to demonstrate the efficiency of the variant of the
technique for laryngeal microsurgery with difficult laryngoscopy and to analyze the
new surgical instruments specific to the endoscopic procedure.
Methods
Study Design
This is a retrospective cross-sectional study of the medical records of 30 patients,
over 12 years old, with laryngeal lesions between the years of 2014 and 2015.
Place of Study
The study was performed in the city of Aracaju, capital of the state of Sergipe, located
in the Northeast region of Brazil. The data were collected at the Otorhinolaryngology
Service of a philanthropic hospital in the state of Sergipe, which is the same place
where the patients were treated surgically.
Study Population
The study group consisted of 32 patients with various larynx lesions and surgically
treated in the years 2014 and 2015. Of these, two did not sign the consent form and
were then excluded. In 24 subjects, the classic surgical technique was employed, and
in 6 of them, a technical variant was successfully adopted, which was used as a last
resort for adequate laryngeal exposure and worthy of subsequent analysis. Patients
younger than 12 years old were not included in the study due to the anatomical variability
of this age group.
Data Collection
We initially cataloged all the clinical and surgical records of the patients that
contained the data of the anthropometric measurements and the surgical technique used
(classic or variant) and whose individuals were older than 12 years. The material
for collection of the anthropometric measures was composed of tape measure, metallic
ruler and caliper ([Fig. 2]). The measurements collected were of oral opening, cervical circumference, thyromental
distance, as well as the presence or not of micrognathia, laryngeal anteriorization
and modified Mallampati index. The gender, age and weight of individuals were also
collected. All the mentioned data were found in the patient evaluation sheets attached
to the clinical and surgical charts.
Fig. 2 Material for collection of anthropometric measurements.
The measurement of the cervical circumference was obtained with inextensible tape
scaled in centimeters and at the level of the thyroid cartilage, in a neutral position
([Fig. 3]).
Fig. 3 Measurement of cervical circumference.
The oral opening measurement was obtained with the mouth opened at maximum, from the
tip of the upper to the lower incisors, by a caliper scaled in millimeters ([Fig. 4]).
Fig. 4 Measurement of oral opening.
The thyromental distance was measured with a metal ruler scaled in centimeters and
with the patient in a position of slight extension of the neck, from the mental prominence
to the prominence of the thyroid cartilage ([Fig. 5]).
Fig. 5 Measurement of thyromental distance.
The evaluation of laryngeal anteriorization was obtained through the patients' profile
photograph, in a neutral position.
The presence of micrognathia was determined by means of profile photography, in neutral
position.
The registration of the modified Mallampati index was obtained through the direct
inspection of the patients' pharynges by the researcher himself, asking them to open
the mouth as proposed in the literature for this type of examination, and following
the following parameters: grade 1 = visible tonsils, pillars and soft palate; grade
2 = only uvula, pillars and upper pole of tonsils visible; grade 3 = partially visible
soft palate; grade 4 = only hard palate visible.
Implementation of the Technical Variant
After evidencing the lack of possibility of visual access to the D'Avila's Areas,
especially Area I, which corresponds to the anterior third of the vocal folds and
the anterior commissure of the larynx, it was introduced the first and important parameter
for the execution of the variant surgery, which was applied by the rigid endoscopies
of Andrea and Dias.[9]
Using the 30- and 70-degree endoscopes, anatomical structures were identified in angular
visual form, a possibility that does not exist with the straight vision of the optical
microscopy.
The second parameter of great relevance for the execution of the surgery would be
the need to have surgical instruments also angled, which could reach the lesions to
be resected. The lack of access to angled instruments to perform these procedures,
guided the development of this type of material ([Fig. 6]).
Fig. 6 Material developed for the technical variant.
That is, angled forceps, suction pumps, retractors and scissors were designed and
developed and have been successfully applied in these procedures in surgical execution.
Variables Analyzed
Two types of variables were analyzed: categorical variables (oral opening, cervical
circumference and thyromental distance) and non-categorical variables (micrognathia,
laryngeal anteriorization and modified Mallampati index). In addition to those mentioned
and chosen as the object of our study because they were the most relevant in clinical
practice, it was opted to analyze, in a complementary way, the weight and the age
of all the participants of the sample. The surgical technique used was recorded, whether
conventional (using microscopy and straight instruments) or variant (with angled instruments
and rigid endoscopes with varied angulations), the latter used as a last resort for
satisfactory laryngeal exposure during surgery. Thus, the relation between the variables
collected and a difficult intraoperative laryngeal exposure was analyzed.
Statistical Analyzes
The data were statistically analyzed by means of simple and percentage frequencies
when categorical variable or mean and standard deviation when continuous variable.
Fisher's Exact test was used to evaluate the existing associations, and these were
graphically represented by multiple correspondence analysis. The mean differences
were tested by the Mann-Whitney test. Relative risks were adjusted to their respective
confidence intervals through univariate Cox Regression and the software used was the
R Core Team 2017, with a significance level of 5%.
Ethical Aspects
The project was submitted to the Ethics Committee in Research involving human beings
of the Federal University of Sergipe - CEP/UFS and approved under the CAAE 55215416.5.0000.5546.
The participants signed the Term of Free and Informed Consent, and the complete confidentiality
of the collected data was ensured.
Results
Thirty patients were analyzed, among which 15 were male and 15 female. Their ages
ranged from 14 to 81 years. The majority of the individuals in our study were between
18 and 59 years old (76.6% of the total), with a mean age of 48 years. The weight
of the individuals varied between 42 and 91 kg, with the majority of individuals being
between 50 and 75 kg.
All the variables collected as possible predictive factors of difficult laryngeal
exposure were analyzed statistically and correlated to the surgical technique used
([Table 1]).
Table 1
Comparative analysis of the presence of predictive factors of difficult laryngeal
exposure between the samples submitted to the technical variant and to the classic
technique
|
Technical variant(n = 6)
|
Classical technique (n = 24)
|
p-value
|
RCR (95%CI)
|
|
Laryngeal anteriorization (%)
|
|
|
|
|
|
Yes
|
03 (50%)
|
0 (0%)
|
0.005
|
9 (1.82–44.6)
|
|
No
|
03 (50%)
|
24 (100%)
|
|
|
|
Micrognathia (%)
|
|
|
|
|
|
Yes
|
03 (50%)
|
0 (0%)
|
0.005
|
9 (1.82–44.6)
|
|
No
|
03 (50%)
|
24 (100%)
|
|
|
|
Cervical circumference
|
|
|
|
|
|
Mean (SD)
|
39.42 (±3.92)
|
37.19 (±2.79)
|
0.102[*]
|
|
|
> 40 cm (%)
|
03 (50%)
|
2 (8.3%)
|
0.041
|
5 (1.01–24.8)
|
|
≤ 40 cm (%)
|
03 (50%)
|
22 (91.7%)
|
|
|
|
Oral opening
|
|
|
|
|
|
Mean (SD)
|
4.33 (±0.60)
|
4.87 (±0.69)
|
0.092[*]
|
|
|
< 4.5 cm (%)
|
04 (66.7%)
|
7 (29.2%)
|
0.156
|
3.45(0.63–18.9)
|
|
≥ 4.5 cm (%)
|
02 (33.3%)
|
17 (70.8%)
|
|
|
|
Thyromental distance
|
|
|
|
|
|
Mean (SD)
|
6.25 (±1.17)
|
6.26 (±1.24)
|
0.975[*]
|
|
|
< 6 cm (%)
|
02 (33.3%)
|
7 (29.2%)
|
1.000
|
1.17 (0.21–6.37)
|
|
≥ 6 cm (%)
|
04 (66.7%)
|
17 (70.8%)
|
|
|
|
Mallampati index (%)
|
|
|
|
|
|
Classes III and IV
|
5 (83.3%)
|
5 (20.8%)
|
0.009
|
10 (1.17–85.6)
|
|
Classes I and II
|
1 (16.7%)
|
19 (79.2%)
|
|
|
Abbreviations: 95%CI, 95% confidence interval; RCR, relative conditional risk; SD,
standard deviation.
* Mann-Whitney test.
It was concluded that, of the 30 patients submitted to laryngeal microsurgery, there
were 6 cases with difficult surgical exposure, which made it necessary to employ the
technical variant. The impossibility of partial and/or total exposure of the larynx
guided the development of a technical variant, which not only allowed visualization
of the organ and its respective disease, but also allowed the execution of the proposed
surgical procedure.
The focus of our research is the study of these six cases in which the technical variant,
described below, was minutely used. Was used the standard of normality described in
the literature for each anatomical parameter searched.
Case 01
A.V.A., 46 years old, male gender, 74 kg.
Surgical disease: bilateral leukoplakia vocal fold
Case 02
M. H. B. S., 46 years old, female gender, 56 kg.
Surgical disease: bilateral Reinke edema
Case 03
A.S.S.E., 57 years old, male gender, 95 kg.
Surgical disease: Cyst right vocal fold
Case 04
M.J.J.S., 46 years old, female gender, 82 kg.
Surgical Disease: vocal folds nodules
Case 05
J.A.S., 37 years old, male gender, 61 kg
Surgical Disease: polyp right vocal fold
Case 06
J.D.M.A., 55 years old, male gender, 80 kg.
Surgical disease: bilateral leukoplakia vocal fold
In [Table 2], we can see that three patients presented altered measurements of cervical circumference
(greater than the reference value), four had a lower oral opening, and two were the
patients who presented lower thyromental distance, laryngeal anteriorization and micrognathia.
Four patients presented alteration of the classification of modified Mallampati, being
2 in class 3 and 2 in class 4.
Table 2
Presence of predictive factors of difficult laryngeal exposure in the sample submitted
to the technical variant
|
Patient
|
Cervical circumference
|
Oral opening
|
Thyromental distance
|
Modified Mallampati classification
|
Laryngeal anteriorization
|
Micrognathia
|
|
RV*
|
REAL
|
RV
|
REAL
|
RV
|
REAL
|
RV
|
FOUND
|
YES or NO
|
YES or NO
|
|
A.V.A
|
< 40 cm
|
41 cm
|
> 4.5 m
|
4.0 cm
|
> 6.0 cm
|
7.0 cm
|
CLASS
1 or 2
|
CLASS
3
|
NO
|
YES
|
|
M.H.B.S
|
< 40cm
|
33.5cm
|
> 4.5 m
|
5.5 cm
|
6.0 cm
|
6.5 cm
|
CLASS
1 or 2
|
CLASS
4
|
NO
|
NO
|
|
A.S.S.E
|
< 40cm
|
44 cm
|
> 4.5m
|
4.0cm
|
> 6.0 cm
|
6.0 cm
|
CLASS
1 or 2
|
CLASS
3
|
NO
|
YES
|
|
M.J.J.S
|
< 40cm
|
40 cm
|
> 4.5 m
|
4.0cm
|
> 6.0 cm
|
5.0 cm
|
CLASS
1 or 2
|
CLASS
3
|
NO
|
NO
|
|
J.A.S
|
< 40 cm
|
36 cm
|
> 4.5 m
|
4.5cm
|
> 6.0 cm
|
5.0 cm
|
CLASS
1 or 2
|
CLASS
1
|
YES
|
NO
|
|
J.D.M.A
|
< 40 cm
|
42 cm
|
> 4.5 m
|
4.0cm
|
> 6.0 cm
|
8.0 cm
|
CLASS
1 or 2
|
CLASS
4
|
YES
|
YES
|
Abbreviation: RV, reference value in the literature.
Discussion
The preoperative evaluation of the surgical patient, using classification parameters
and measures, favors the identification of possible difficulties of surgical exposure.
In the general population, the reported rate of difficult larynx exposure is 5.8%,
according to standardized ratings of Cormack and Lehanne.[10] This situation must be reported to the patient. The same has the right to know about
the possibility of surgical difficulty or even suspension of this act due to the lack
of accessibility. In addition to respecting ethical principles regarding the patient,
this attitude promotes legal protection of the medical team in case of failure.
The variables analyzed in this study are similar to those of other correlated studies,
but the most relevant ones were selected for this study based on the 30-year experience
of the referral service in laryngeal surgery, where the research was developed.
The surgical technique adopted was distributed as classic or conventional in 24 individuals
(80%) and variant of the technique in 6 individuals (20%), successfully adopted in
all cases that presented difficulty of surgical larynx exposure. Their results are
demonstrated in another article.
The most common pathologies in our sample were vocal cysts and polyps, with 5 cases
each (17%), followed by Reinke edema, squamous cell carcinoma, vocal dysplasia and
vocal nodules, with 4 cases each (13%). There were also 2 cases of vocal granuloma
(7%) and 1 case of vallecula cyst and another case of laryngeal papillomatosis (3%
each). Studies on this subject are scarce in our country, but our findings are corroborated
by Ballin et al,[11] who found a prevalence of polyps in their study (36.84%), followed by intracordial
cysts and laryngeal papillomatosis (15.79% each), with cases of vocal nodules and
Reinke edema, among others.
The researched sample composed of 30 individuals was enough to present statistical
relevance. The sample size matches perfectly the number of individuals surgically
treated in the 12-month period at the referral service in laryngeal surgery in the
state where the study was developed. Some factors contribute to the reduced number
of laryngeal surgeries performed annually, among them the small population of the
state in which the research was performed, as well as the lack of knowledge of the
population regarding the importance of vocal health.
It is noteworthy that the application of this technical variant could allow adequate
surgical accessibility without causing iatrogenic lesions due to a forced exposure
attempt. Despite the existence of suspension laryngoscopes with a variety of angulations
and calibers, it is important to understand that the limits for their application
must be respected. In this way, iatrogenic lesions, such as those affecting the palate,
tongue, epiglottis, pharyngeal lateral wall and several dental structures, can be
avoided with the use of this technical variant.
As an important limiting factor of this variant, we defined the use of only one hand
to manipulate the instrument, since the surgeon's other hand must necessarily be holding
the angled endoscopes. The possibility of attaching these endoscopes to allow the
use of both hands was ruled out because these surgical procedures are essentially
dynamic and require constant mobilization. Studies have shown that the addition of
an adapter to the laryngoscope to support the rigid and angled endoscope seems to
be the pathway for bimanual standard laryngeal surgery.[12]
[13]
As an important finding in this series of cases, we refer to the repetition of vocal
fold leukoplakia (two cases). The variability of diseases associated with differentiated
predictive factors guides the surgeon to routinely perform the preoperative analysis
of the predictive factors of difficult laryngeal exposure regardless of the surgical
indication.
In spite of these surgical limitations, in cases in which the technical variant was
applied, removal of the surgical lesion was fully performed in the sample. The use
of angular surgical instruments demonstrated efficacy and respect to the principles
of the phonomicrosurgery.
Conclusion
The association of rigid endoscopy with angled instruments promoted full visualization
of the surgical lesion and operative resolution.
