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Quantitative Videofluoroscopy
A New Evaluation Tool for Tracheoesophageal Voice Production
Corina J. van As, MSc;
Bas M. R. Op de Coul, MD;
Frank J. A. van den Hoogen, MD, PhD;
Florien J. Koopmans–van Beinum, PhD;
Frans J. M. Hilgers, MD, PhD
Arch Otolaryngol Head Neck Surg. 2001;127:161-169.
ABSTRACT
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Objective To develop a quantitative videofluoroscopy protocol using well-defined
visual parameters and quantitative measures for the evaluation of anatomical
and morphologic characteristics of the neoglottis in relation to perceptual
evaluation of tracheoesophageal voice quality.
Design A patient survey.
Setting The Netherlands Cancer Institute, Amsterdam.
Patients Thirty-nine individuals with laryngectomies, 30 with standard total
laryngectomy and 9 with a partial or total pharynx reconstruction.
Interventions Videofluoroscopy, speech recordings.
Main Outcome Measures Well-defined visual parameters and quantitative measures based on videofluoroscopy
images should improve the evaluation of neoglottic characteristics in relation
to voice quality.
Results Quantitative measures were significantly related to visual assessment
outcomes. Tonicity (P=.02) and presence of a neoglottic
bar during phonation (P=.03) were significantly related
to voice quality, as were several quantitative measures, especially the minimal
distance between the neoglottic bar and anterior esophageal wall at rest (P<.001) and during phonation (P=.02),
and the index for the relative increase of the maximal subneoglottic distance
from rest to phonation (P=.01).
Conclusions This new quantitative videofluoroscopy protocol is a useful tool for
the study of the anatomy and morphology of the neoglottis. With this protocol,
characteristics relevant to tracheoesophageal voice quality can be defined.
The quantitative measures are promising for a more standardized evaluation
of the neoglottis in individuals who have undergone laryngectomy.
INTRODUCTION
SINCE THE introduction of the first useful voice prosthesis 2 decades
ago,1 tracheoesophageal puncture has become
a widely accepted and successful method of voice restoration after total laryngectomy.2 The main advantage of this type of vocal rehabilitation
compared with conventional esophageal speech is that it is pulmonary driven.
Tracheoesophageal speech has been proven to be closer to normal laryngeal
speech than esophageal speech regarding acoustical characteristics,3, 4, 5, 6 perceptual
characteristics,7 and intelligibility.8
Since tracheoesophageal voice rehabilitation has become the method of
choice after total laryngectomy,2 the main
issue in voice rehabilitation is no longer the ability to acquire speech:
up to 90% of the patients acquire a fair to excellent voice,9
whereas with esophageal speech, this figure is much lower and more variable,
as only 25% to 50% of these patients are able to develop functional esophageal
speech.10, 11, 12 However,
one should keep in mind that the tracheoesophageal voice is variable in quality.13
The new sound source, referred to as the neoglottis, pseudoglottis,
or pharyngoesophageal segment, is considered to play an important role in
voice production. Throughout this article the term neoglottis will be used. One of the methods frequently used for investigation
of the neoglottis is videofluoroscopy. Videofluoroscopic studies have been
performed far more often for esophageal voice14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
than for tracheoesophageal voice.25, 26
Previous studies on esophageal voice were conducted mainly to gain insight
on factors that influence the acquisition of speech and were also focused
on discovering the site or source of vibration of the substitute esophageal
voice. Several researchers found that sound originated at the level of the
cricopharyngeus muscle.14, 20, 27
It was also thought that it was not vibration of the mucous membrane that
caused the sound, but vibration of the accumulated mucus above the neoglottis.28 A number of researchers found that the ability to
acquire esophageal speech was related to the anatomical and morphologic characteristics
of the neoglottis, such as dilatability of the hypopharynx and shape of the
neoglottis,17 length and cervical level of
the neoglottis,15 form of the neoglottis,18 extent of surgery,21
and tonicity of the pharyngoesophageal segment.22, 24
Others could not find any relationship between good voice quality and variations
in the anatomy and morphology of the neoglottis.19
Some even thought that the acquisition of voice was merely related to psychological
factors.21, 29 The age of the patient
was also found to be an important factor in the ability to learn esophageal
speech.15, 16 Videofluoroscopic
studies regarding tracheoesophageal speech showed that the visual characteristics
of the vibratory segment of tracheoesophageal and esophageal speakers were
similar.25, 26 Unfortunately, both
these studies lacked the assessment of voice quality in relation to the observed
characteristics of the neoglottis.
Videofluoroscopy would gain in value if the visual assessment of anatomical
and morphologic characteristics of the neoglottis were standardized and if
these standards could be combined with quantitative measurements of the different
dimensions of the neoglottis. This would make easier the establishment of
a relationship between form and voice quality. Therefore, a novel assessment
protocol for quantitative videofluoroscopy was developed and evaluated in
relation to the perceptual evaluation of voice quality.
PATIENTS AND METHODS
PATIENTS
Thirty-nine patients who underwent laryngectomy, all of whom used tracheoesophageal
speech by means of the Provox2 voice prosthesis (Atos Medical AB, Hörby,
Sweden), were selected from a group of 173 patients with laryngectomies in
follow-up at the Netherlands Cancer Institute.9, 30
Special care was taken to compose a sample of patients in which all variations
normally encountered in this group were represented. Therefore, both male
and female patients, patients with poorer voice quality, and patients with
a reconstructed pharynx and/or esophagus were included in the study. Informed
consent was obtained from all patients we asked to participate after they
received written information about the purpose of the study. There were 29
men and 10 women. Ages varied from 47 to 82 years, with a mean of 67 years.
The postoperative follow-up varied from 11 months to 18 years, with a mean
of 6 years. Thirty patients had a standard wide-field total laryngectomy;
these patients constitute the standard group. Nine patients had a pharyngeal
reconstruction; these patients constitute the reconstruction group. Four patients
in the reconstruction group underwent partial repair with a myocutaneous pectoralis
major flap, and 5 received a total pharyngeal reconstruction (with a tubed
gastric pull-up in 2 patients, a full gastric pull-up in 1 patient, and a
tubed free radial forearm flap in 2 patients). In 22 patients in the standard
group, an attempt was made during surgery to influence the tonicity (ie, muscular
tension) of the neoglottis by performing either a myotomy of the cricopharyngeus
muscle31, 32 or a neurectomy of
the pharyngeal nerve plexus.33 In 5 patients
a myotomy of the cricopharyngeus muscle combined with a neurectomy of the
pharyngeal plexus was performed, while in 12 patients only a neurectomy of
the pharyngeal plexus was performed. A unilateral neck dissection was carried
out in 13 patients and a bilateral neck dissection in 5 patients. Sixteen
patients who underwent laryngectomy for a recurring tumor received primary
radiotherapy to treat their laryngeal cancer; 21 patients received radiotherapy
after their total laryngectomy; and 2 patients received no radiotherapy. Table 1 gives an overview of the clinical
information of the patients.
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Table 1. Clinical Parameters of the Patient Group (N = 39) Used in
This Study
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VIDEOFLUOROSCOPY
The videofluoroscopy recordings were obtained with a Philips Diagnost
92 system (Philips Medical Systems, Eindhoven, the Netherlands) together with
a Panasonic NV-HD650 video recorder (Matsushita Electric Industrial Co, Osaka,
Japan). Videofluoroscopic recordings were made of all patients vocalizing
2 phonations of the sustained vowel a at a comfortable
pitch and loudness level. All x-ray film recordings were made in lateral view;
patients were asked to swallow barium and phonate. A reference coin was stuck
to the cheeks of the patients to enable the quantification of the different
dimensions.
SPEECH RECORDINGS
Recordings for the perceptual evaluation were made of one fixed text
that was read aloud. The recordings were made with use of the Computerized
Speech Lab (CSL) (Kay Elemetrics, Lincoln Park, NJ). A standard headset microphone
that came with the equipment was used, and through the hardware of this system,
with use of the CSL software, the speech data were directly recorded on a
digital audiotape (DAT) by means of a Sony TCD-8 DAT recorder (Sony Electronics
Inc, Park Ridge, NJ). For the perceptual evaluation, the read-aloud texts
of all speakers were randomly recorded on another DAT. Each speaker repeated
the text until 2.5 minutes had been recorded on the tape.
VISUAL ASSESSMENT OF ANATOMICAL AND MORPHOLOGIC CHARACTERISTICS OF
THE NEOGLOTTIS
In the pilot phase, 3 judges jointly viewed all videofluoroscopy recordings
using the definitions of tonicity proposed by McIvor et al24
and Van Weissenbruch.34 These definitions include
the tonicity not only during phonation, but also during swallowing and at
rest. It was extremely difficult to reach consensus among the 3 judges using
these definitions. A large number of our patients could not be categorized
into 1 tonicity group because they did not meet all the criteria for one particular
group or because they met the criteria for several groups.
Therefore, the assessment had to be adjusted considerably: the flattening
of the neoglottic bar during swallowing and the appearance of a neoglottic
bar at rest were judged separately from the tonicity of the neoglottis during
phonation. Also, the presence or absence of regurgitation and stasis of barium
contrast, as well as the level of the neoglottis relative to the cervical
vertebrae, were added. With these adjustments, consensus was reached much
more easily.
Apart from these more or less objective assessments, tonicity during
phonation was judged subjectively using the following criteria: The tonicity
of the neoglottis was judged normotonic when there
was closure of the neoglottis, ie, complete or almost complete dynamic contact
of the neoglottic bar with the anterior esophageal wall during phonation.
The tonicity of the neoglottis was judged as hypotonic
when there was no closure of the neoglottis during phonation and as hypertonic when the neoglottis was fully closed during
phonation combined with considerable dilation of the esophagus below the neoglottis. Spasm was defined as complete closure of the neoglottis
with extreme dilation of the esophagus below the neoglottis during attempted
phonation with no passage of air through the neoglottis. Stricture was defined as narrowing of the esophagus with no dynamic
changes in any of the situations judged separately.
QUANTITATIVE MEASUREMENTS OF THE NEOGLOTTIS
In addition to the visual assessment of the anatomical and morphologic
characteristics, metrical measures were also used in the evaluation protocol.
These quantitative measures of the neoglottis were obtained using a software
program called Drawer (developed by M. B. van Herk, physicist at the Netherlands
Cancer Institute/Antoni Leeuwenhoek Hospital, Amsterdam), which was initially
designed to measure tumor volumes for the purposes of radiotherapy. Relevant
frames of the neoglottis both at rest and during phonation were selected from
the recordings (Figure 1), digitalized
with a frame grabber, and saved as an image file. From these digitalized images,
the quantitative measures were calculated. Distances were measured (in pixels)
with a ruler-like tool. Areas were measured by indicating the region of interest
with a paintbrush tool, after which the computer program counted the number
of pixels in the region. Figure 2
shows the neoglottis, along with indications of the measures performed. All
measures in pixels were converted to millimeters or square millimeters using
a coin with a known diameter.
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Figure 1. Videofluoroscopy images of the
situation at rest (A) and during phonation (B).
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Figure 2. Schematic drawing of the videofluoroscopy
images in Figure 1.
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PARAMETERS MEASURED
The minimal distance (in millimeters) was measured as the distance between
the neoglottic bar and the anterior wall of the esophagus (ie, the width of
the neoglottis) at rest (MINREST) and during phonation (MINPHON). The maximal
subneoglottic distance (in millimeters) was measured as the maximal width
of the esophagus below the neoglottis at rest (MAXREST) and during phonation
(MAXPHON). The line on which the measurements were made was placed perpendicular
to the posterior wall. The surface area of the neoglottic bar in lateral view
(in square millimeters) was measured at rest (SURREST) and during phonation
(SURPHON) in the lateral view. The prominence of the neoglottic bar toward
the anterior wall (in millimeters) was measured at rest (PROMREST) and during
phonation (PROMPHON). The line on which the measurement was based was placed
perpendicular to the posterior wall at the most prominent point of the neoglottic
bar.
In addition to these quantitative measures, the MAXPHON-MAXREST index
was also calculated in order to reflect the increase of the maximal subneoglottic
distance during phonation. This index is thought to give an impression of
the tension of the closure of the neoglottis—tighter closure of the
neoglottis may reflect a larger increase in subneoglottic distance, although
this increase may also be dependent on the rigidity of the subneoglottic tissues.
PERCEPTUAL EVALUATION OF VOICE QUALITY
Four speech and language pathologists experienced in the treatment of
patients with laryngectomies were trained in the perceptual evaluation of
this patient group. The evaluation involved 19 bipolar semantic 7-point scales
and one overall judgment of voice quality in which the voice was judged as
good, reasonable, or poor. A good voice was defined as "almost similar to
a normal voice," a poor voice was defined as "very deviant from a normal voice,"
and a reasonable voice was defined as "somewhere in between both extremes."
At the time, the results of the extended perceptual evaluation of the semantic
scales were under investigation. In the present study, only the results of
the overall judgment were used. The interrater reliability calculated with
Cronbach  was .88. In order to compare the videofluoroscopy recordings,
the speakers were divided into 3 subgroups on the basis of overall voice quality.
A voice was considered good or poor if at least 2 of the 4 listeners evaluated
it as such. Voices that were judged good (or poor) by 1 listener and reasonable
by 3 listeners were considered reasonable. In no instance was a voice judged
good by one listener and poor by another.
STATISTICS
Statistical analysis was performed using the Statistical Package for
Social Sciences, version 7.5 (SPSS Inc, Chicago, Ill). Paired t tests were used to compare the quantitative measures between rest
and phonation, and  2 tests for linear-to-linear association
were used to investigate the relations between voice quality, visual assessment,
and clinical parameters, as well as the relations between visual assessment
and voice quality. For the relation between voice quality and tonicity, an
exact 2 test was used. Because of concerns
regarding assumptions of normality for the quantitative measurements MINREST
and MINPHON, nonparametric tests were used. Relations between the clinical
parameters and the quantitative measurements and between the visual assessment
(except for tonicity) and the quantitative measurements were investigated
by means of either a t test for independent samples
or a Mann-Whitney test, depending on the distribution of the observed values.
Relations between tonicity (3 subgroups) and the quantitative measurements
and between voice quality (3 subgroups) and the quantitative measurements
were investigated by means of analysis of variance followed by post hoc Tukey
tests or by means of Kruskal-Wallis tests followed by Mann-Whitney tests with
a Bonferroni correction, depending on the distribution of the observed values.
In the case of obvious differences between SDs according to the Levine test
of equality of variances, a modified t test was used.
RESULTS
VISUAL ASSESSMENT OF THE NEOGLOTTIS
Table 2 gives the results
of the visual assessment of the anatomical and morphologic characteristics
of the neoglottis for both speaker groups. At rest, 19 patients showed 1 neoglottic
bar and 4 patients showed 2 neoglottic bars. During phonation, 21 patients
showed 1 neoglottic bar and 3 patients showed 2 neoglottic bars. The number
of patients with 2 neoglottic bars at rest (n = 4) or during phonation (n
= 3) was too small for a separate evaluation in statistical analysis. Since
the voice quality of the groups with 1 and 2 neoglottic bars was thought to
be comparable, these groups were taken together in further analyses. The 1
patient with stricture was left out of the analysis regarding tonicity, since
no meaningful statistical analysis is possible with only one patient in a
subgroup.
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Table 2. Anatomical and Morphologic Characteristics of the Standard
and Reconstruction Groups*
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In the standard group, the neoglottis at rest was mostly situated around
cervical vertebrae C4 and C5. During phonation, however, the neoglottis was
situated somewhat higher in most speakers, with an upward shift from C4-5
to C3-4 (Table 3).
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Table 3. Cervical Level of the Neoglottis in the Standard and Reconstruction
Groups at Rest and During Phonation
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QUANTITATIVE MEASUREMENTS OF THE NEOGLOTTIS
Quantitative measurements are given in Table 4. Paired t tests between the measures
at rest and during phonation showed statistically significant differences
in the standard group for 2 measurements: MAXPHON was larger than MAXREST
(P<.001), and PROMPHON was larger than PROMREST
(P<.001). No differences were found in the reconstruction
group.
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Table 4. Quantitative Measures of the Neoglottis for the Standard and
Reconstruction Groups*
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VOICE QUALITY
Voice quality could be judged for 38 of the 39 patients, since 1 patient
died before the speech sample could be obtained. Voice quality was judged
as good for 13 patients, reasonable for 14, and poor for 11.
RELATION BETWEEN CLINICAL PARAMETERS AND VISUAL ASSESSMENT OF THE NEOGLOTTIS
The neoglottic bar at rest was more often visible in the standard group
than in the reconstruction group (P = .003). Furthermore,
patients with a standard total laryngectomy more often had a normotonic or
hypertonic neoglottis during phonation than patients with a reconstructed
pharynx (P = .02).
Within the standard group, there was no relation between visual assessment
of the neoglottis and the clinical parameters myotomy, neurectomy, radiotherapy,
neck dissection, age, postoperative follow-up, and sex. Relations with visual
assessments were investigated only within the standard group; either the reconstruction
group was too small or the parameters were invalid.
RELATION BETWEEN CLINICAL PARAMETERS AND QUANTITATIVE MEASURES OF THE
NEOGLOTTIS
The SURREST and SURPHON measurements were larger in the standard group
than in the reconstruction group (SURREST, P = .02;
SURPHON, P = .01), and the PROMREST measurements
were smaller in the reconstruction group than in the standard group (P = .01). The MINREST and MINPHON measurements were smaller
in the standard group (MINREST, P = .001; MINPHON, P = .01) than in the reconstruction group.
Results within the standard group also revealed a relationship between
clinical parameters and quantitative measures. Whether the patient had a radical
neck dissection appeared to influence some measurements of the neoglottis.
The MINPHON measurement was smaller in the subgroup without neck dissection
(P = .04), indicating that this group had a more
closed neoglottis. Age was another factor that was associated with differences
in the measurements; the MINREST measurement appeared smaller in the younger
patient group (<70 years) (P = .048), indicating
a narrower neoglottis in the younger patient group and a looser neoglottis
in the older patient group. The clinical parameters myotomy, neurectomy, postoperative
follow-up, radiotherapy, and sex were not associated with any differences
in the quantitative measurements.
RELATION BETWEEN CLINICAL PARAMETERS AND VOICE QUALITY
The 2 tests for linear-to-linear association did not
reveal any relation between voice quality and the clinical parameters reconstruction,
myotomy, neurectomy, radiotherapy, neck dissection, age, postoperative follow-up,
and sex.
RELATION BETWEEN VISUAL ASSESSMENT AND QUANTITATIVE MEASURES OF THE
NEOGLOTTIS
Relations between visual assessment and quantitative measures of the
neoglottis were based on the results for all of the speaker groups, since
the type of surgery was irrelevant. In the subgroup with the appearance of
a neoglottic bar at rest, SURREST and SURPHON, PROMREST and PROMPHON, and
MAXPHON were larger (SURREST, SURPHON, and PROMREST, P<.001;
PROMPHON, P = .003; MAXPHON, P = .03) and MINREST was smaller (P = .01)
than in the subgroup without the appearance of a neoglottic bar at rest.
The assessment of the appearance of a neoglottic bar during phonation
showed several relationships with the quantitative measures. In the subgroup
with a neoglottic bar during phonation, SURPHON and SURREST, PROMPHON and
PROMREST, and MAXPHON and MAXPHON/MAXREST were larger (SURPHON, PROMPHON,
PROMREST, P<.001; SURREST, P = .01; MAXPHON, MAXREST, P = .01) and MINREST and MINPHON were smaller (P<.001) than in the subgroup without a neoglottic bar during phonation.
These results indicate that the presence of a neoglottic bar during phonation
was related to a shorter distance between the neoglottic bar and the anterior
wall of the esophagus. Likewise, a larger subneoglottic distance during phonation
was related to a larger SURPHON and a greater PROMPHON, as well as a relatively
larger increase in MAXPHON.
The tonicity of the neoglottic bar during phonation, when divided into
the subgroups hypotonicity, normotonicity, and hypertonicity, also showed
a relationship with the quantitative measures (Table 5), with a clear distinction between the 3 levels of tonicity.
For instance, whereas SURPHON, PROMPHON, MINREST, and MINPHON were distinctive
between hypotonicity and normotonicity and between hypotonicity and hypertonicity,
MAXREST and MAXPHON were distinctive between hypotonicity and hypertonicity
and between normotonicity and hypertonicity.
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Table 5. Relations Between Quantitative Measures and Tonicity*
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The assessment of regurgitation of barium during phonation was also
related to the quantitative measures. In the subgroup in which regurgitation
of barium was observed during phonation, SURREST, SURPHON, PROMREST, PROMPHON,
and MAXPHON were smaller (P = .02, P = .01, P = .02, P<.001,
and P = .02, respectively) and MINREST and MINPHON
were larger (MINREST, P = .003; MINPHON, P<.001) than in the subgroup in which no regurgitation of barium
was observed during phonation.
These results indicate that regurgitation occurred when the neoglottic
bar was small or not present as well as when the neoglottis was wide.
Regarding the cervical level of the neoglottis, stasis of barium above
the neoglottic bar during phonation, and flattening of the neoglottic bar
during swallowing, no relations with the quantitative measures were found.
RELATION BETWEEN VOICE QUALITY AND VISUAL ASSESSMENT OF THE NEOGLOTTIS
The visual assessment of the appearance of a neoglottic bar during phonation
(Table 6) and the tonicity of
the neoglottis (Table 7) showed
significant relations with voice quality (P = .03
for appearance of a neoglottic bar; P = .02 for tonicity),
such that a good voice was related to the appearance of a neoglottic bar during
phonation.
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Table 6. Relations Between Appearance of a Neoglottis During Phonation
and Voice Quality*
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Table 7. Relations Between Tonicity of the Neoglottis During Phonation
and Voice Quality*
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Regarding tonicity, a good voice was related to a normotonic or hypertonic
neoglottis. Among the good voices, a hypotonic neoglottis was never observed.
The number of speakers in this analysis was 37, since 1 speaker with stricture
also fell in the poor group; this speaker was not included in the statistical
analysis.
The assessment of the appearance of the neoglottis at rest, regurgitation
of barium during phonation, stasis of barium on the neoglottis during phonation,
and flattening of the neoglottic bar during swallowing showed no relations
with voice quality.
RELATION BETWEEN VOICE QUALITY AND QUANTITATIVE MEASURES OF THE NEOGLOTTIS
The index MAXPHON-MAXREST (P = .01), MINPHON (P<.001), and MINREST (P = .01) were different between the speaker groups (Table 8). On the basis of these 3 quantitative
measures, a distinction can be made between a poor and a good voice, or between
a reasonable and a good voice. The MINREST and MINPHON measures were smaller
during phonation for a good voice than for a poor voice (MINREST, P<.001; MINPHON, P = .02), and better speakers
showed a relatively larger increase in the MAXPHON-MAXREST index (P = .01). For the other quantitative measures, no relations with the
overall judgment of voice quality were found.
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Table 8. Relations Between Quantitative Measures and Voice Quality*
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COMMENT
Videofluoroscopy has proven to be an important tool for the assessment
of the neoglottis for both esophageal and tracheoesophageal speech.14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26
Although videofluoroscopy is clinically valuable on the level of the individual
patient, the descriptive nature of the evaluation and the lack of objective
measures have hampered its widespread use as a research tool. The present
study was started in order to develop videofluoroscopy into a more objective
and reproducible evaluation instrument for the analysis of anatomical and
morphologic characteristics of the neoglottis. Another objective of this study
was the correlation of videofluoroscopy results with voice quality in tracheoesophageal
speech, which has been lacking so far.
Visual assessment of the anatomical and morphologic characteristics
of the neoglottis appears to be facilitated by judging the different phases
of movement of the neoglottis (at rest, during phonation, and when swallowing)
separately. With the method used by others,22, 24
in which this distinction was not applied, consensus judgments appeared to
be less easy and efficient. The method presented herein leaves only one subjective
parameter—tonicity of the neoglottis during phonation. The remaining
parameters are more or less objective because of their use of clear dichotomies
and/or numbers.
Only 3 of 30 patients showed a double neoglottic bar during phonation,
which contrasts with the findings of others, who have described this phenomenon
in 5 of 16 and 3 of 4 patients.25, 26
The neoglottis was located at the level of C4-5 in the majority of our patients,
which is more cranial than the C5-6 level reported for the majority of patients
in studies of esophageal speech.15, 18, 29
In our study, this level tended to rise by approximately half a vertebra from
rest to phonation, a phenomenon that was not observed in esophageal speech.29 It is likely that this upward shift in tracheoesophageal
voice was caused by the greater aerodynamic effect in the pulmonarily driven
tracheoesophageal speech.
Our method of obtaining quantitative measures was easy and straightforward,
using digital images and special image evaluation software with a reference
marker to allow calculation of exact distances and surface areas. The quantitative
measures showed a large variability in the speaker group that was reflected
in the relatively high SDs. Differences were found between rest and phonation
for the maximal subneoglottic distance and the prominence of the neoglottis
in the standard group, indicating a dynamic change of the neoglottis from
rest to phonation.
Perceptual evaluation is still the gold standard for the evaluation
of voice quality.13 In the method applied,
4 trained judges distinguished 3 voice quality subgroups: 11 speakers with
poor voices, 14 with reasonable voices, and 13 with good voice quality. Voice
quality is not easily defined. In this study, a voice that was considered
close to normal was called good, and a voice that was very deviant from normal
was judged as poor. A voice that was not very close to normal but also not
very deviant, for instance, slightly bubbly or rough, was judged as reasonable.
The high interrater reliability of the perceptual evaluation shows that our
subgroupings were consistent and reliable and therefore useful for comparison
with the other outcome measures in this study.
Some correlations were observed between clinical parameters and quantitative
measures. The differences between the standard and reconstruction groups were
not surprising because of the larger extent of surgery in the latter group.
Our results suggest that the present reconstruction techniques result in less
favorable conditions of the neoglottis. Furthermore, our quantitative measures
indicate that neck dissection and age have an influence.
The MINPHON measure was smaller in the group without neck dissection
and the MINREST measure was smaller in patients under 70 years of age. These
quantitative measures are correlated with good voice quality. The finding
that neck dissection seems to influence the anatomy of the neoglottis has
not been reported earlier for tracheoesophageal voice and needs to be studied
in larger series before any conclusions can be drawn, especially since results
for esophageal voice quality are conflicting. Smith et al16
found that patients with a laryngectomy only had better voice results than
patients with an additional neck dissection, whereas Richardson21
did not find any such influence.
Investigating the relationship between the results of the visual assessment
and the quantitative measures was one of the main objectives of this study.
Replacement of the more subjective visual assessments of the neoglottic characteristics
by more objective and precise quantitative measures could allow the evaluation
of videofluoroscopy recordings in a more consistent and standardized manner,
and the results within and between studies could become easier to compare
in the future. It is noteworthy that relations between quantitative measures
and visual assessment were found for all parameters except for flattening
of the neoglottic bar during swallowing and stasis of barium above the neoglottic
bar during phonation. This suggests that the majority of the visual assessments
might be replaceable by these quantitative measures.
Another important part of this study was to investigate the possible
relations between the neoglottis and voice quality. To the best of our knowledge,
this particular study has not yet been performed for tracheoesophageal speech.
Results showed that voice quality was related to the appearance of a neoglottic
bar during phonation and to the tonicity of the pharyngoesophageal segment.
This is most obvious in the good group, members of which always had a visible
neoglottic bar during phonation; none were hypotonic, but some were hypertonic.
All 3 types of tonicity were seen in the poor and reasonable voice groups,
which suggests that tonicity is not as clear an indicator of voice quality
as might be expected. However, these results make it clear that hypotonicity
is an unfavorable condition of the neoglottis regarding voice quality and
should be avoided. On the other hand, hypertonicity of the neoglottis is clinically
much less of a problem, since it still can be associated with a good voice
and, in relevant cases, can be fixed relatively easily by surgical intervention
(myotomy)31, 32 or medical intervention
(botulinum toxin type A injection [Botox; Allergan Inc, Irvine, Calif]).35 Hypotonicity can be fixed only by exerting digital
pressure on the external neck, thereby enabling approximation of the esophageal
tissues during phonation. Other forms of surgical intervention or phonosurgery
of the neoglottis are not yet available for this problem. Since it is common
nowadays to perform a neurectomy of the pharyngeal plexus and/or a myotomy
of the pharyngeal muscles during total laryngectomy,31, 32, 33
it should be stressed that care should be taken to avoid overcorrection, which
could result in hypotonicity.
Results of the investigation of the relations between voice quality
and quantitative measures were interesting. The most important factor appeared
to be MINPHON—the closer the neoglottis, the better the voice quality.
This shows the relevance of closure for sound production, something that is
already well known for normal laryngeal voices. Surprisingly, this measure
was not used in earlier studies regarding esophageal speech. However, some
quantitative measures were performed in some studies. They were always performed
during phonation, and consisted of the length of the neoglottis,25
the prominence of the neoglottis,18 the dilatability
of the esophagus below the neoglottis,29 and
the width of the hypopharynx.17 The only measure
comparable to one of those used in our study was the "dilatability" of the
esophagus, expressed by the MAXPHON-MAXREST index, which appeared to influence
voice quality.29 These authors observed a relation
between the acquisition of esophageal speech and the width of the esophagus,
indicating that a wider subneoglottic distance was related to a better voice.
They presumed that a greater amount of air would be obtained within the lumen,
providing a sufficient amount of air for voice production. In the present
study, we also found that the MAXPHON-MAXREST index differed between the voice
quality groups. The good speakers showed a relatively larger increase in MAXPHON
compared with MAXREST. Presumably, in tracheoesophageal speech, the increase
in maximal subneoglottic distance is related to the tension of the neoglottic
closure together with the flexibility of the tissues of the neck. In this
respect, it should be noted that tension of the neoglottis that is too high
(ie, extreme hypertonicity or spasm) led to a relatively large increase in
the maximal subneoglottic distance, with very poor or even absent voice. Since
there was a clear correlation between the visual assessment and the quantitative
measures, it seems possible to substitute for the classic visual parameters
the quantitative measures MINREST and MINPHON, as well as the MAXPHON-MAXREST
index. The only exception was the situation in which there was hypertonicity
or spasm of the neoglottis in conjunction with fibrosis of the surrounding
tissues in the neck. In such a case, hypertonicity did not lead to extreme
dilatation of the subneoglottic region.
The finding that the quantitative measures showed no difference between
the bad and the reasonable group can be explained best by the assumption that
the neoglottic characteristics leading to a judgment of a poor or reasonable
voice quality are diverse. Problems with saliva interference and/or regurgitation
may decrease voice quality substantially, irrespective of the tonicity of
the neoglottis.
In conclusion, this study showed that it is possible to analyze videofluoroscopy
images in a more quantitative manner and that some objective measures can
be applied to replace the descriptive parameters formerly used to assess the
neoglottis. The clear correlation of the videofluoroscopy results with good
voice quality and the objective nature of the proposed assessment protocol
may increase the usefulness of this imaging technique for the rehabilitation
of individuals with laryngectomies.
AUTHOR INFORMATION
Accepted for publication July 13, 2000.
Maurits and Anna de Kock Stichting provided financial support for the
equipment needed for the speech recordings and the listening experiment.
We thank Louis Pols, PhD, for his critical review of the manuscript;
the patients for their participation in this study; Guus Hart, MSc, for his
help with the statistics; and M. B. van Herk, PhD, for providing and adapting
the Drawer software for the quantitative measures. We also thank Benita Scholtens,
BS, Rianne Polak, BS, Marike Koster, BS, and Brigitte Boon-Kamma, BS, speech
pathologists, for their participation in the data collection.
From the Department of Otolaryngology–Head and Neck Surgery,
the Netherlands Cancer Institute/Antoni van Leeuwenhoek Hospital, Amsterdam
(Drs van As and Hilgers), Institute of Phonetic Sciences, University of Amsterdam,
Amsterdam (Drs van As and Koopmans–van Beinum), and Department of Otolaryngology/Head
and Neck Surgery, University Hospital St Radboud, Nijmegen (Drs Op de Coul
and van den Hoogen), the Netherlands.
Corresponding author and reprints: Frans J. M. Hilgers, MD, PhD,
Department of Otolaryngology-Head and Neck Surgery, The Netherlands Cancer
Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands (e-mail: fhilg{at}nki.nl).
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