Keywords
Cleft Palate - Velopharyngeal Sphincter - Communication Disorders - Evaluation
Introduction
The velopharyngeal sphincter (VPS) is a muscle belt located between the oropharynx
and the nasopharynx and includes the muscles of the soft palate (anterior wall of
the VPS) and the lateral and posterior pharyngeal walls. The VPS comprises the levator
veli palatini, tensor veli palatini, muscle of uvula, superior pharyngeal constrictor,
palatopharingeus, palatoglossus, and salpingopharyngeus[1]. Among these muscles, those of the soft palate, especially the tensor veli palatine,
have an important role in the physiological function of the region. While the VPS
is not a sphincter by strict definition (a circular muscle band in a hollow viscera),
its physiological function is that of a sphincter, as it works like a valve, contracting
and occluding itself[2].
The VPS plays an extremely important role in allowing alternation between the respiratory
and digestive paths of the pharynx during swallowing[3]. Velopharyngeal closure, performed by the VPS, is essential in motor actions of
the region such as speaking, whistling, blowing, sucking, and swallowing[4]. Several studies have described inter-subject variability in velopharyngeal closure[1]
[5] and have identified 4 types of closure based on structure movement[6]
[7]
[1]
[5]. In the coronal type of closure, there is more participation of the soft palate.
Sagittal closure predominantly involves the lateral pharyngeal walls. In the circular
type of closure, the soft palate and lateral pharyngeal walls are involved. Finally,
the circular type closure with a Passavant ridge, is similar to the circular closure
except that a Passavant ridge is present on the posterior pharyngeal wall.
The configuration of the velopharyngeal region depends on the specific motor actions
performed. The raising of the soft palate and, concomitantly, the medial approximation
of the lateral pharyngeal walls promotes the partial or complete separation of the
nasal and oral portions of the pharynx. The velopharyngeal structures are thus important
for the production of speech, as they distribute and direct airflow to the oral cavity
to produce oral sounds and to the nasal cavity for the emission of nasal sounds[1]
[8]
[9].
Investigators have several types of tools to choose from when assessing VPS function[10]
[11]
[12]. A detailed description of the velopharyngeal mechanism was obtained only after
the availability of both direct and indirect assessment methods. Direct methods enable
the investigator to visualize the structures involved in velopharyngeal closure and
to observe how these structures move during different types of motor actions. Indirect
methods provide information on the functional repercussions of velopharyngeal action[13]
[12]
[14].
Videonasoendoscopy is one of the most widely used methods for studying velopharyngeal
function, allowing visualization of the nasal, pharyngeal, and laryngeal cavities.
Using dynamic images directly from the anatomical structures[15], this method has multiple applications, including diagnosis, prognosis, and postoperative
follow up[11]. This test can be used to observe the pattern of closure even during speech, which
involves wide variations in velum and pharyngeal wall motion. Videonasoendoscopy can
also be used to identify the presence of the gap corresponding to the residual orifice
during maximum contraction of the VPS[16]
[17].
As a counterpart to the use of more sophisticated tools for velopharyngeal assessment,
clinical judgment by means of hearing is still considered an extremely important diagnostic
tool for inferring velopharyngeal function[12]. Using this method, the investigator can assess a subject's oral communication performance
and determine the extent of speech impairments related to resonance[18]
[12]
[19]
[20]
[21].
Impaired velopharyngeal closure prevents separation of the oral and nasal cavities
during the production of oral phonemes, exposing the nasal cavity to the entry of
unexpected air flow. This impairment in velopharyngeal closure, known as velopharyngeal
dysfunction (VPD), can be congenital, as with cleft lip.
There is a widespread consensus among researchers and healthcare professionals that
the surgical and clinical findings of subjects with cleft lip/palate should be based
on an auditory-perceptual evaluation and at least one instrument-based evaluation
of velopharyngeal function[13]
[22]
[23]
[24]. The use of both assessment modalities is highly valuable and widely used in clinical
practice, as the findings of one method complement the other. Despite this common
practice, there are few studies comparing patient evaluations using videonasoendoscopy
(clinical estimation of gap size) and auditory-perceptual assessments (hypernasality).
This study aimed to determine whether the findings of videonasoendoscopy in patients
with cleft lip/palate are associated with demographic features, clinical factors,
or the findings of auditory-perceptual assessments.
Methods
This retrospective, cross-sectional study assessed 49 individuals, of both genders,
with cleft lip/palate who were followed up at the Otorhinolaryngology Service and
at the Speech Therapy outpatient clinic of Hospital de Clínicas de Porto Alegre (HCPA).
The study was approved by the HCPA Research Ethics Committee under protocol number
10-0490.
The population consisted of individuals follow up at the HCPA in the Plastic Surgery
Service, Craniofacial Surgery outpatient clinic; Otorhinolaryngology and at the “SpeechTherapy
and Craniofacial Malformations” outpatient clinic. This group of patients was primarily
treated at HCPA and at other institutions.
The present study compared the results of 2 methods for evaluating velopharyngeal
function. The auditory-perceptual evaluation by speech therapy screening is reported
as speech findings. This assessment was carried out by a speech therapist with more
than 10 years of experience in the area. The results of videonasoendoscopy were analyzed
by 2 experienced evaluators. The speech therapy screening and videonasoendoscopy data
were collected in October 2012. The inclusion criterion was assessment by speech therapy
screening and videonasoendoscopy between September 2011 and August 2012. We excluded
from the study patients with blurred videonasoendoscopy images and those with excess
secretion from the nasal cavity or missing data.
The speech therapy screening assessed the following auditory-perceptual parameters:
resonance, presence, and severity of hyponasality and hypernasality (mild, moderate,
severe)[25]; speech disorders, identified as compensatory (such as glottal stops) or obligatory
(weak intraoral pressure, facial mimicry, audible nasal air emission, nasal snoring).
For analysis purposes, hypernasality and its severity were included as obligatory
disorders[26]. During screening, the speech therapist used a speech sample comprising 2 sentences
with phonetic predominance of oral plosive phonemes/p/ (“papai pediu pipoca”) and
fricative phonemes/s/ (“o saci sabe assobiar” The patients also performed a segment
of continuous speech, counting from 1 to 10.
Using videonasoendoscopy, we analyzed the portion of the test related to the sustained
emission of the /s/ phoneme, chosen because it leads to complete closure of the VPS,
thereby minimizing misinterpretations due to interference by the production of another
phoneme. The evaluators made a clinical estimation of the VPS gap size using an adapted
version of a protocol described in previous studies[10]
[27]. The VPS gap size was classified according to the following scale: 1, no gap (complete
velopharyngeal closure); 0.8–0.9, small gap (efficient closure); 0.4–0.7, moderate
gap (intermediate closure); 0.1–0.3 large gap (inefficient closure); 0, very large
gap (lack of closure). This protocol assessed the following: presence or absence of
adenoids contributing to velopharyngeal closure; presence or absence of mobility of
the palate and lateral and posterior pharyngeal walls; VFS closure type (coronal,
sagittal, circular, or circular with Passavant ridge).
Quantitative variables were described as mean and standard deviation or median and
interquartile range. Categorical variables were described as absolute or relative
frequencies. The Pearson's chi-square test was used to evaluate the association between
videonasoendoscopy and perceptual-hearing evaluation. The McNemar's test was applied
to assess the differences between evaluators, and the kappa coefficient was applied
to assess inter-evaluator agreement. Student's t-test (quantitative variables with symmetric distribution), Mann–Whitney test (quantitative
variables with asymmetric distribution), and Pearson's chi-square and Fisher's exact
tests (categorical variables) were applied to investigate the association between
clinical factors and examination methods. Poisson's regression model was used to control
confounding factors. The criterion for including a variable in the model was a p value < 0.10
in the bivariate analysis. We considered significance to be 5% (p d” 0.05). Analyses
were performed using SPSS (Statistical Package for the Social Sciences) version 17.0.
Results
The median age at the time of evaluation was 11 years, with the majority of the cohort
between 9 and 16 years. The cohort was predominantly male (61.2%). Speech therapy
treatment was ongoing in 14.3% of the subjects.
The most common cleft type was the left unilateral complete cleft (30.6%, n = 15),
followed by bilateral complete cleft lip/palate (28.6%, n = 14), right unilateral
(20.4%, n = 10), cleft palate (14.3%, n = 7), and submucosal cleft (6.1 %, n = 3).
All patients had undergone primary palatoplasty at a mean age of 19.5 months. Secondary
palatoplasty was performed in only 4.1% of the subjects, at a median age of 18.5 years.
[Table 1] shows the results from the speech therapy screening, including the assessment of
resonance as well as compensatory and obligatory articulation disorders. We found
that 77.6% of the subjects presented with hypernasality, which was moderately severe
in 36.7% and mildly severe in 28.6% of these subjects. As illustrated in Table 1,
articulation disorders were found in 81.6% of subjects, 75.5% of whom had obligatory
disorders and 57.1% of whom had compensatory disorder (glottal stops). The most frequently
observed obligatory disorder was weak intraoral pressure, which was present in 75.7%
of the subjects. The second more frequent disorder was audible nasal air emission
(62.2%).
Table 1.
Auditory-perceptual evaluation results*.
|
Speech disorder, n (%)
|
|
|
Present
|
44 (89.8)
|
|
Absent
|
5 (10.2)
|
|
Type of disorder*, n (%)
|
|
|
Obligatory
|
43 (87.8)
|
|
Compensatory
|
28 (57.1)
|
|
Types of obligatory disorders*, n (%)
|
|
|
Audible nasal air emission
|
23 (62.2)
|
|
Weak intraoral pressure
|
28 (75.7)
|
|
Facial mimicry
|
11 (29.7)
|
|
Nasal snoring
|
2 (5.4)
|
|
Hypernasality
|
38 (77.6)
|
|
Resonance, n (%)
|
|
|
Balanced
|
11 (22.4)
|
|
Mild hypernasality
|
14 (28.6)
|
|
Moderate hypernasality
|
18 (36.7)
|
|
Severe hypernasality
|
6 (12.2)
|
*n = 49
**multiple-choice question
Inter-evaluator comparison of the findings of the videonasoendoscopy, as well as comparison
of these test results with those of the auditory-perceptual evaluation was assessed
using the emission of the /s/ phoneme.
The inter-rater agreement was established using the Kappa agreement coefficient, matching
the findings of one rater with those of the other. In this study, the Fleiss' kappa
agreement coefficients[28] were interpreted as previously reported[29]: <0.00, no agreement; 0.00–0.20, poor agreement; 0.21–0.40, fair agreement; 0.41–0.60,
moderate agreement; 0.61–0.80, substantial agreement; and 0.81–1.00, perfect (or almost
perfect) agreement.
An almost perfect agreement (kappa of 0.83–1.00) was observed regarding the contribution
of adenoids in velopharyngeal closure, mobility of pharyngeal walls, predominant type
of movement, closure type, and VPS gap size during emission of the /s/ phoneme. The
predominant closure type was coronal. One evaluator's results indicated that 20.4%
of the subjects had no VPS gap, 40.8% had a small gap, 16.3% had a moderate gap, and
22.4% had a large gap.
Demographic data indicated that the subjects with more severe velopharyngeal closure
impairment underwent later primary palatoplasty; the presence of a moderate to large
gap was significantly associated with an age at primary palatoplasty of over 23 months.
All individuals requiring secondary palatoplasty (n = 2) showed impairment in velopharyngeal
closure, although this result was not statistically significant. There were no other
statistically significant associations between variables.
We compared the VPS gap size as estimated by clinical and auditory-perceptual assessments
([Table 2]). We also investigated the relationship between the gap size and both the severity
of hypernasality and the presence of speech disorders (compensatory and obligatory
disorders).
Table 2.
Relationship between auditory-perceptual assessment and gap size.
|
Variables
|
Complete/efficient closure
|
Intermediate/inefficient closure
|
p
|
|
Speech disorder, n (%)
|
|
|
0.636
|
|
Present
|
26 (86.7)
|
18 (94.7)
|
|
|
Absent
|
4 (13.3)
|
1 (5.3)
|
|
|
Moderate/severe hypernasality + other speech disorders, n (%)
|
|
|
0.035
|
|
Yes
|
10 (33.3)
|
13 (68.4)
|
|
|
No
|
20 (66.7)
|
6 (31.6)
|
|
|
Type of disorder, n (%)
|
|
|
0.157
|
|
Obligatory
|
12 (46.2)
|
4 (22.2)
|
|
|
Compensatory
|
1 (3.8)
|
0 (0.0)
|
|
|
Obligatory + compensatory
|
13 (50.0)
|
14 (77.8)
|
|
|
Types of obligatory disorders*, n (%)
|
|
|
|
|
Audible nasal air emission
|
13 (43.3)
|
10 (52.6)
|
0.733
|
|
Weak intraoral pressure
|
17 (56.7)
|
11 (57.9)
|
1.000
|
|
Facial mimicry
|
4 (13.3)
|
7 (36.8)
|
0.081
|
|
Nasal snoring
|
2 (6.7)
|
0 (0.0)
|
0.515
|
|
Hypernasality
|
21 (70.0)
|
17 (89.5)
|
0.165
|
|
Resonance, n (%)
|
|
|
0.021
|
|
Balanced
|
9 (30)
|
2 (10.5)
|
|
|
Mild hypernasality
|
11 (36.7)
|
3 (15.8)
|
|
|
Moderate hypernasality
|
9 (30)
|
9 (47.4)
|
|
|
Severe hypernasality
|
1 (3.3)
|
5 (26.3)**
|
|
*multiple choice question; **statistically significant association by the test of
residuals adjusted to a 5% of significance level.
Our results indicate that more severe impairment of velopharyngeal closure was observed
more often in subjects with moderate/severe hypernasality, with statistical significance
for severe hypernasality (p = 0.021). In addition, we found severe hypernasality was
significantly associated with the presence of other speech disorders (p = 0.035),
whether compensatory and/or obligatory, increasing the likelihood of having a moderate
to large gap (intermediate to inefficient velopharyngeal closure).
Ten subjects (20.4%) showed discrepant results with regard to velopharyngeal function,
having moderate/severe hypernasality + other speech disorders together with complete
and efficient gap closure. Conversely, 6 subjects (12.2%) had intermediate/inefficient
closure with no moderate/severe hypernasality.
These discrepant findings may be due to the differences in the analytical parameters
(speech and continuous sound emission), although both parameters involve velopharyngeal
function. The auditory-perceptual evaluation assessed a larger speech sample (counting
of numbers and 2 sentences focusing on /s/ and /p/ phonemes). The instrumental evaluation
observed the sustained emission of the /s/ phoneme, which provides maximum VPS contraction.
In such cases that present physical evidence of closure but indicate abnormal resonance,
it is very important for the interdisciplinary team to re-evaluate the findings to
perform a differential diagnosis of velopharyngeal dysfunction. Therefore, it can
be inferred that the maintenance of motor action in speech is not consistent.
Discussion
The physiology of the velopharyngeal mechanism has been investigated in several disciplines[30]
[31]. Studies comparing different methods of assessing velopharyngeal function report
conflicting results. Few of these investigations have considered the following factors
in the same study: (1) protocols for clinical and instrument-based assessments recommended
in the literature, including a detailed description of the criteria used for analysis
of the variables under study; (2) inter-evaluator agreement for assessments using
videonasoendoscopy; (3) the possible variables interfering with velopharyngeal closure
(participation of adenoids and speech therapy treatment for velopharyngeal occlusion).
Our study assessed hypernasality, compensatory articulation disorders, and other obligatory
disorders[26]. These speech anomalies are of interest to researchers who investigate speech production
in individuals with cleft lip/palate[32]
[33]
[34]
[35]
[25].
A recently study[26] has emphasized that obligatory disorders should receive attention from a structural
point of view and not only from the perspective of velopharyngeal function; the identification
of velopharyngeal dysfunction can help to establish whether speech therapy intervention
is indicated for individuals with cleft lip/palate. The auditory-perceptual evaluation
used in the present study took these structural features of obligatory disorders into
account. Hypernasality was reported in 77.6% of our subjects, the severity of which
was moderate in 36.7% and mild in 28.6%. Speech disorders were identified in 89.8%
of the subjects, of whom 87.8% had obligatory disorders and 57.1% compensatory disorder
(glottis stop). One of the most frequent obligatory disorders was weak intraoral pressure,
present in 75.7% of the subjects. Our findings corroborate those in the literature
reporting a higher occurrence of weak intraoral pressure, hypernasality, and glottis
stop[37]
[4]
[37]. The results of this study thus suggest that the weak intra-oral pressure caused
by VPD produces audible nasal air emission and hypernasality in speech. In turn, glottis
stops may occur as a consequence of poor articulation habits learned in childhood
that do not necessarily reflect physical or neuromuscular changes[38].
We believe that the high occurrence of hypernasality and other articulation disorders
in our cohort is related to their referrals from speech therapy, indicating that they
had an issue involving oral communication. Although these patients were followed up
for a longer time by the HCPA interdisciplinary team that provides a variety of services,
a speech therapy outpatient clinic linked to Universidade Federal do Rio Grande do
Sul was added in 2011 to treat patients with cleft lip/palate. Before the creation
of this outpatient clinic, the patients were treated just by a speech therapist from
HCPA, with a period of care limited to one shift for this population. As it constitutes
a curricular internship, in which undergraduate and graduate students practice the
activity, the response to this demand is still limited.
Reports in the literature point out that experience is crucial in both the conduction
and analysis of the videonasoendoscopy test. Accordingly, we assessed the inter-evaluator
agreement with regard to gap size in the emission of the /s/ phoneme, observing that
it was almost perfect (kappa, 0.83–0.95). We thus conclude that the evaluation team
is highly qualified. This result also illustrates that the criteria adopted for interpreting
the findings were very homogeneous between the raters. These findings corroborate
those described in other scientific studies using this protocol[10], indicating that the data are in accordance with the proposed objective[39]
[40]
[41].
We observed that 20.4% of the subjects did not have a VPS gap; 40.8% had a small gap,
16.3% had a moderate gap, and 22.4% had a large gap. Thus, 61.2% of the total cohort
had complete or efficient velopharyngeal closure. The predominant velopharyngeal closure
type was coronal (69.4%, n = 34) which has greater mobility of the anterior wall of
the VPS corresponding to the soft palate. The prevalence of the sagittal type was
24.5%[12], and the circular type was 6.1%[3]. Studies have demonstrated that the coronal pattern is also the most frequent among
individuals without cleft lip/palate[42]
[22]
[30]
[7], but individuals with cleft palate tend to have a broader distribution between the
other patterns of closure[43]
[7]
[44].
Among the associations related to demographic and clinical data, only age at the time
of primary palatoplasty was associated with the clinical estimation of VPS gap size.
Our findings indicate that the later primary palatoplasty is performed the greater
the compromise in velopharyngeal closure (moderate to large gap size), with a significant
associated with ages above 23 months (p = 0.016). However, when analyzing the variables
independently associated with intermediate/inefficient velopharyngeal closure (by
controlling confounding factors), age at primary palatoplasty was not significantly
associated but was near the threshold (PR = 1.01; 95% CI, 1.00–1.02; p = 0.088). The
trend in the data indicates that every additional month until the performance of the
first palatoplasty leads to a 2% increase in the prevalence of inefficient closure.
The author of a previous study[46] proposes that the appropriate time for surgical repair of the palate is 12–18 months
of age, taking into account maxillary growth and velopharyngeal function. One report
on the association between various clinical factors and velopharyngeal closure in
cleft lip/palate found that velopharyngeal closure was higher among individuals with
deciduous dentition than among those with mixed or permanent dentition[47].
The present study aimed to compare the findings of auditory-perceptual evaluation
and those of videonasoendoscopy. Our data indicate that subjects with more compromised
velopharyngeal closure have a higher incidence of moderate and severe hypernasality,
showing that both tests indicated the compromise in velopharyngeal function. A statistically
significant association was found between severe hypernasality (p = 0.021) and intermediate/inefficient
closure with a gap size ranging from moderate to large.
We found one study that aimed to evaluate auditory-perceptual assessment, but the
authors adopted a different classification system for the findings of videonasoendoscopy
and did not relate them to the efficiency of velopharyngeal closure. A retrospective
study investigated the relationship between the auditory-perceptual characteristics
of speech and velopharyngeal gap size[20], and the authors concluded that information regarding velopharyngeal gap size can
be predicted from speech assessment alone. Confidence in the prediction was stronger
when the patient had moderate to severe hypernasality, which was more commonly associated
with a large gap. This last finding was similar to that reported in our study.
We found a statistically significant interaction (p = 0.035) of the severity of hypernasality
and the presence of other articulation disorders with the clinical estimate of VPS
gap size. The interaction of both changes identified in the auditory-perceptual evaluation
increased the likelihood of the presence of a moderate to large gap. Multivariate
analysis confirmed this association (PR = 1.26; 95% CI: 1.03–1.54; p = 0.026). This
result is observed in the clinical practice, as the presence of hypernasality is usually
associated with at least one articulation change, whether obligatory or compensatory.
The articulation changes associated with hypernasality reflect the difficulty in acquiring
and maintaining velopharyngeal closure[47].
To gain a better understanding of these cases, we investigated velopharyngeal physiology
during the motor action related to speech. Although no statistically significant difference
was found, 2 interesting situations were observed. First, 10 subjects (20.4%) had
complete/efficient velopharyngeal closure but also had moderate/severe hypernasality.
Second, 6 subjects (12.2%) had intermediate/inefficient closure with no moderate/severe
hypernasality.
Although both videonasoendoscopy and auditory-perceptual evaluation assess velopharyngeal
function, this study used different samples and speech extensions. The videonasoendoscopy
analyzed only the sustained emission of the /s/ phoneme, using a comfortable intensity
for the patient that was audible for the examiner. This phoneme was chosen because
its emission requires the action of all velopharyngeal walls and their maximum contraction
to achieve complete velopharyngeal closure. This information allows the examiner to
identify the presence or absence of a VPS gap.
Velopharyngeal closure differs during different motor actions and during speech[4]. The observation that some patients have unsatisfactory findings in the auditory-perceptual
evaluation and good findings in videonasoendoscopy suggests that resonance in continuous
speech is unaffected. However, articulation disorders can hamper accurate assessment
of hypernasality severity. Hypernasality is often associated with the length of time
required for VPS opening and not directly with the degree of opening or even with
the air flow that escapes from the nasal cavity[48]. For example, patients with adequate velopharyngeal closure as assessed by instrument-based
assessment may have hypernasality because of the abnormalities in the temporal spectrum
of velopharyngeal closure.
The great physiological variability of the VPS may be related to factors such as speed
of speech, characteristics of isolate phoneme emission, and association of different
phonemes (consonant-vowel)[1]. This variability may account for the patients who have intermediate/inefficient
closure but no moderate/severe hypernasality. Further factors may explain this versatility
in velopharyngeal closure as follows: the action of several muscles associated with
the levator veli palatini (palatoglossus, palatopharingeus, and superior pharyngeal
constrictor); mechanical factors, especially the position of the tongue in the oral
cavity; and the specific phonological rules of each linguistic system[49]
[5].
In summary, we recommend that patients with discrepant results between evaluations
and those with unsatisfactory results should be referred to interdisciplinary clinical
evaluations to determine the best course of action.[26]. X et al. Emphasizes that obligatory and compensatory articulation disorders affect
speech, and that obligatory disorders should receive attention from both the structural
and functional points of view[26]. Therefore, by identifying velopharyngeal dysfunction, appropriate therapeutic strategies
can be devised.
Conclusions
It was found that our patient cohort had a high prevalence of hypernasality and compensatory
and articulation disorders. In addition, we observed a high frequency of individuals
with a small gap, and a predominance of the coronal type closure. The individuals
with more severe velopharyngeal closure impairment underwent late palatoplasty, although
this comparison did not remain significant after adjustment by the multivariate model.
Comparison of the 2 evaluation methods showed that subjects with moderate/severe hypernasality
had more severely impaired velopharyngeal closure. Hypernasality is more closely associated
with clinical estimation of gap size than are other obligatory and compensatory disorders.
The interaction between hypernasality severity and the presence of other disorders
increases the likelihood of having a gap ranging from moderate to large. Although
we found cases with discrepancies between the findings of the auditory-perceptual
and instrument-based evaluations, we observed an association between the findings
of these 2 evaluation methods.
