A study of borderline cases of velopharyngeal insufficiency using cephalometry and nasofibroscopy

Abstract

Background

Identification of borderline cases of velopharyngeal insufficiency (VPI) due to palatopharyngeal disproportion in the form of short palate or deep posterior pharyngeal wall is necessary particularly in preoperative assessment of adenotonsillectomy to prevent post-adenotonsillectomy velopharyngeal insufficiency and hypernasality.

Objective

To evaluate the role of fiberoptic nasopharyngoscopy and cephalometry for assessment of clinically suspected cases of palatopharyngeal disproportion (borderline VPI) cases to identify the craniofacial morphometric measurements of such cases that may be helpful as a prognostic indicator in predicting and preventing post-adenotonsillectomy velopharyngeal dysfunction.

Design

This is an observational cross-sectional study of 38 patients with suspected palatopharyngeal disproportion (24 male and 14 female) with ages ranging from 3 to 7 years who were referred to the phoniatrics unit at Assiut University Hospital for the assessment of the velopharyngeal valve before adenotonsillectomy operation. The control group consisted of 25 normal individuals. They were subjected to (1) auditory perceptual assessment (APA) of the patients’ speech, (2) fiberoptic nasopharyngoscopy, and (3) lateral cephalometry.

Results

Auditory perceptual assessment showed no statistically significant difference between both groups. Fiberoptic nasopharyngoscopic examination revealed a highly significant statistical difference between both groups as regards lateral pharyngeal wall mobility (p = 0.000). Lateral cephalometric assessment showed significant statistical differences for maxillary protrusion (P = 0.04) which was slightly wider in the study group than in the control group and bony pharyngeal depth (Ptm-Ba) (P = 0.03) which was deeper in the study group than in the control group.

Conclusion

Auditory perceptual assessment of speech, nasopharyngoscopy, and cephalometry are important tools that could be used for pre-adenotonsillectomy assessment of cases with palatopharyngeal disproportion to prevent the post-adenotonsillectomy velopharyngeal insufficiency and its consequences.

Background

Borderline velopharyngeal insufficiency sometimes called marginal velopharyngeal insufficiency or hidden velopharyngeal insufficiency is a condition in which vocal tract examination reveals a short palate or deep posterior pharyngeal wall in the absence of hypernasal speech and velopharyngeal aperture during nasopharyngoscopy which are masked by the presence of hypertrophied adenoid or tonsils. In such patients, adenotonsillectomy would unmask the velopharyngeal insufficiency that was well compensated preoperatively [1].

The most challenging issue frequently facing clinicians is the persistence of post-adenoidectomy hypernasality which is usually caused by a preoperative velopharyngeal disorder. Velopharyngeal insufficiency before surgery is among other red flags and risk factors for developing VPI. The preoperative presence of palatopharyngeal inadequacy increases the risk of hypernasality following adenoidectomy. Conditions such as congenitally short velum, deep pharynx, overt and occult cleft palate, cerebral palsy, facial paralysis, nasal regurgitation in childhood, Down syndrome, and family history of velopharyngeal inadequacy should be considered as possible predisposing factors regarding hypernasality after adenoidectomy [2]. Such risk factors should be identified to prevent the serious effects of adenotonsillectomy.

Unlike the normal adenoidal involution, adenoidectomy alters the nasopharyngeal proportions abruptly. It creates an increased anterior–posterior distance between the velum and the posterior pharyngeal walls, making it difficult for the velum to bridge and consequently causing hypernasality and/or nasal emission in some individuals [2].

Recent advances in velopharyngeal assessment have facilitated the comprehensive study of velopharyngeal function. Nasopharyngoscopy is widely used now in the evaluation of velopharyngeal function. Most clinicians feel that the results are superior to those obtained through videofluoroscopy because of the excellent clarity of the nasopharyngoscopy view [3].

Cephalometric radiography is a standardized technique for better understanding an individual’s craniofacial relationships [4]. Advances in computers have led to the digitalization of cephalometric analysis to avoid tracing errors and make it more rapid [5].

A retrospective cephalometric comparative study between 39 patients with velopharyngeal dysfunction after adenoidectomy and 80 normal subjects using lateral cephalometric assessment has been done by Kassem et al. to identify the characteristics of craniofacial morphology in patients who have no sign of any palatal defect, but who have persistent VPD following adenoidectomy. The mean age was 8.0 ± 3.5 for the study group and 8.7 ± 2.8 for the control group. Several linear, angular, and triangular cephalometric parameters have been estimated. They have found a significant statistical difference between the two groups as regards nasopharyngeal angle (Ba-S-Ptm), nasopharyngeal triangle sides (S-Ba and S-Ptm), velar length (Ptm-P), and nasopharyngeal and cranial base triangle areas. They concluded that cephalometry may reveal risk factors for persistent VPD among children following adenoidectomy which was mainly apparent in measurements of the nasopharyngeal space angle and velar length [6].

Identification of borderline cases of velopharyngeal insufficiency is mandatory, especially in those who will undergo adenoidectomy or adenotonsillectomy. For this purpose, comprehensive (subjective and objective) assessment is necessary to detect vulnerable borderline cases of VPI who are scheduled for adenotonsillectomy.

Therefore, this study aimed to evaluate the role of fiberoptic nasopharyngoscopy and cephalometry for the assessment of clinically suspected cases of palatopharyngeal disproportion (borderline VPI) cases to identify the craniofacial morphometric measurements of such cases that may be helpful as a prognostic indicator in predicting and preventing post-adenotonsillectomy velopharyngeal dysfunction.

Methods

Subjects

Study group

The study included 38 patients with suspected palatopharyngeal disproportion referred to the phoniatrics unit of Assiut University Hospital especially those referred for assessment of the velopharyngeal valve before adenotonsillectomy operation. Any patient 3–7 years old with palatopharyngeal disproportion (short palate or deep posterior pharyngeal wall or both) diagnosed clinically through vocal tract examination by 3 experienced phoniatricians was included. Any patient with mental retardation, neurological deficit affecting speech, cleft palate, hearing impairment, or craniofacial anomalies were excluded.

Study design

Observational cross-sectional study.

Control group

It includes 25 patients (age-matched and sex-matched) with normal velopharyngeal function referred to the Phoniatric Unit, ENT Department at Assiut University Hospital for pre-adenotonsillectomy assessment.

Methods

All participants were submitted to the following protocol of velopharyngeal assessment applied in the Phoniatric Unit of Assiut University Hospital:

Elementary diagnostic procedures

Patients’ and parents’ interview: it includes personal history, natal history, prenatal history, post-natal history, and developmental milestones.

Auditory perceptual assessment (APA) of the patients’ speech: the subjective evaluation of patient’s speech in a free conversation and analysis of speech samples such as single sounds, syllable repetition, and connected speech. Three experienced phoniatricians assessed the following: the existence of hyper or hypo nasality, degree of nasality, consonant precision, the compensatory articulatory mechanisms (glottal and pharyngeal articulation), facial grimace, audible nasal emission of air, and the overall intelligibility of speech. All were graded on a 5-point scale where 0 = normal and 4 = severe [7].

Visual assessment of the vocal tract including lips, bite, alveolus, tongue, tonsils, hard palate, pharyngeal walls, soft palate, and larynx.

Simple clinical tests (Gutzman’s a/i test and Czermak’s cold mirror test): quickly performed tests to detect the presence of hypernasality and nasal emission of air.

Clinical diagnostic aids

Documentation of visual assessment: All patients were examined using videorhinolaryngoscopy (STORZ Tele pack X LED-TP100). The velopharyngeal valve movement was documented during different speech samples [7]:

• Repetition tasks: (/ma-ma-ma/, /pa-pa-pa/, /ta-ta-ta/, /ka-ka-ka/, /mi-mi-mi/, /pipi-pi/, /ti–ti-ti/ and /ki-ki-ki/).

• Sound prolongation: (/sssss/, /fffff/, /zzzzz/, and /vvvvv/).

• Nasal-oral blend /ʕɑmbɑr/.

• Arabic phrases:

  • ◦ Nasal sentence /mɑmɑ betnai:m manal/.

  • ◦ Oral sentence /ʕali rɑ:ħ jlʕab ko:rɑ/.

  • ◦ Combined oral-nasal sentence /sɑ:mi ʃɑ:f fostɑ:n semsem/.

The nasopharyngoscopy procedure was done by an experienced phoniatrician. Before inserting the scope, the patient was seated or held by the mother/caregiver in an upright position on a chair in front of the examiner, the most patent nasal side was determined and topical anesthetic (lidocaine gel) was applied 5 min before examination for an easy and a comfortable passage of the scope. The scope is guided up through the middle meatus (the nasal space that lies between the inferior turbinate and middle turbinate) to allow better visualization of the velopharyngeal port. After the scope was passed through the choana, the tip of the scope was turned downwards with the control lever perpendicular to the velopharyngeal port. The child was asked to repeat the speech samples after the examiner. If the child is uncooperative, he was asked only to repeat the sustained sounds for assessment.

The following items were assessed during the nasopharyngoscopy by three experienced phoniatricians who agreed on the overall assessment of each item [7]:

• a. Velopharyngeal sphincter: velar mobility and lateral pharyngeal wall mobility were assessed on a 4-point scale [where 0 indicates the resting (breathing) position or no movement and 4 indicates the maximum movement]. Also, the closure pattern was assessed whether circular, coronal, or sagittal.

• b. Velo-pharyngeal gap: whether it was present or not and if it was present, the size, site, and shape of the gap were assessed

• c. Adenoid size [8]:

  • 0%:25%

  • 26%:50%

  • 51%:75%

  • 76%:100%

Cephalometry: NewTom GiANO was used to capture a lateral cephalometric radiograph of the head which was taken during rest (no phonation) with the X-ray beam perpendicular to the patient’s sagittal plane. During the experimental procedure, a Wehmer head holder was employed to stabilize the subject’s head position.

The cephalometric film obtained from each subject was traced digitally on computer-based software called NNT Viewer (Fig. 1) version 7.2. Each cephalometric parameter was estimated by selecting the appropriate tool and identifying its reference points. The following reference points were identified (Fig. 2):

• 1. Sella (S): sella tursica center

• 2. Nasion (N): the junction of the nasal and frontal bones at the most posterior point on the curvature of the bridge of the nose

• 3. Point (A): an arbitrary measure point on the innermost curvature from the maxillary anterior nasal spine to the crest of the maxillary alveolar process. A-point is the most anterior point of the maxillary apical base.

• 4. Point (B): an arbitrary measure point on the anterior bony curvature of the mandible. B point is the innermost curvature from the chin to the alveolar junction.

• 5. Point (PNS): the most posterior point on the bony hard palate in the midsagittal plane (posterior nasal spine).

• 6. Point (P): tip of the soft palate.

• 7. Point (PW): posterior pharyngeal wall along the palatal plane line.

• 8. Basion (Ba): the most antro-inferior point of the margin of the foramen magnum.

• 9. Point (Ptm): the intersection between the inferior point of the pterygomaxillary fissure and the palatal plane.

Fig. 1

NNT software user interface

Fig. 2

The reference cephalometric points and cephalometric parameters. (S): Sella tursica center, (N): the junction of the nasal and frontal bones at the most posterior point on the curvature of the bridge of the nose, A an arbitrary point on the innermost curvature from the maxillary anterior nasal spine to the crest of the maxillary alveolar process, B An arbitrary measure point on the anterior bony curvature of the mandible. B point is the innermost curvature from the chin to the alveolar junction, (PNS): The most posterior point on the bony hard palate in the midsagittal plane, (P) the tip of the soft palate, (PW) the posterior pharyngeal wall along the palatal plane line, (Ba): The most antro-inferior point of the margin of the foramen magnum, (Ptm): The intersection between the inferior point of the pterygomaxillary fissure and the palatal plane

The following cephalometric measurements were assessed by three experienced phoniatricians who agreed on the overall assessment of each item [6]:

• A. Linear parameters:

  • 1. PNS-P: soft palate length = distance from the posterior nasal spine (PNS) to the tip of soft palate (P).

  • 2. MPT: soft palate thickness = a line passing through the thickest area of the soft palate measured on a line perpendicular to the PNSP line.

  • 3. PNS-PW: pharyngeal depth = the linear distance between the posterior nasal spine (PNS) and posterior pharyngeal wall (PW).

  • 4. Ptm-Ba (bony pharyngeal depth): distance from Ptm point to Basion.

• B. Angular parameters:

  • 1. SNA: {angle measurement from sella (S) to nasion (N) to point A} which reflects the state of the maxilla whether protruding or receding.

  • 2. SNB: {angle measurement from sella (S) to nasion (N) to point B} which reflects the state of the mandible whether protruding or receding.

  • 3. Ptm-S-Ba: {nasopharyngeal area angle = angle measurement from Ptm to sella (S) to basion (Ba)}.

  • 4. Ba-S–N: {Cranial base angle = angle measurement from Basion (Ba) to sella (S) to nasion (N)}

• C. Triangular parameters

  • 1. Nasopharyngeal triangle area (Ptm_S-Ba): the area of the triangle between the three points Ptm, S, and Ba.

  • 2. Cranial base triangle area (Ba-S–N): the area of the triangle between the three points Ba, S, and N.

• D. Ratios

  • 1. The ratio between pharyngeal depth and velar length.

  • 2. The ratio between bony pharyngeal depth and velar length.

Analysis and statistics

The collected data were revised, organized, tabulated, and statistically analyzed using a statistical package for social science (SPSS) version 22 for Windows. Shapiro-Wilk test was used as a test of normality. Numerical variables were presented as mean ± standard deviation (SD). Categorical variables were presented as frequency and percentage. If applicable, categorical variables were compared using the chi-square test and Fisher’s exact test. Numerical variables were compared using the independent sample t-test for parametric data and the Mann-Whitney U test for non-parametric data. The significance level was accepted if the P value was less than 0.05.

Results

This study was conducted on 63 patients at the Phoniatrics Unit, Assiut University Hospital between October 2017 and February 2020 who were referred for pre-adenotonsillectomy, tonsillectomy, or adenoidectomy assessment.

Demographic data

The study group was 38 children with a mean age of 5.17 ± 1.0 years and an age range of 3–7 years. Males represent 63.1% (n = 24) of the study group while females represent 36.9% (n = 14). The control group was 25 children with a mean age of 5.64 ± 1.29 years. Seventy-six percent (n = 19) of the control group were males while 24% (n = 6) were females. There was no statistically significant difference in age (P = 0.1) or gender (P = 0.2) between the two groups (Table 1).

Table 1 Demographic characteristics of the study and control groups

Auditory perceptual assessment of speech

Regarding auditory perceptual characteristics, most of the participants of the study group had normal resonance (n = 23) (60.5%) while only 15 (39.5%) had closed nasality. This was also observed in the control group where most of the participants (n = 17) (68%) had normal resonance and only 8 participants (32%) had closed nasality. None of the participants either from the control or study group had any other speech abnormalities. Also, there was no statistically significant difference between the auditory perceptual assessment of both groups (Table 2).

Table 2 Auditory perceptual characteristics of the study and control groups

Fiberoptic nasopharyngoscopy: (Table 3)

Table 3 Comparison between study and control groups as regards Nasopharyngoscopic examination

Fiberoptic nasopharyngoscopic examination revealed that patients of the study group had a mean adenoid size of 72.37 ± 15.97 while those of the control group had a mean adenoid size of 64.8 ± 20.59.

As regards velar mobility in the study group, there was 1 subject (2.6%) had velar mobility grade I, 9 patients (23.7%) had velar mobility grade II, 24 patients (36.1%) had velar mobility grade III and 4 patients (10.5%) had velar mobility grade IV while control group showed no patients (0%) had velar mobility grade I, 12 patients (48%) had velar mobility grade II, 9 patients (36%) had velar mobility grade III and 4 patients (16%) had velar mobility grade IV. The study group had lateral pharyngeal wall mobility grade 0, I, II, and III were 15 (39.5%), 21 (55.3%), 2 (0.5%), and 0 (0%) respectively while those of the control group had lateral pharyngeal wall mobility grade 0, I, II and III were 3 (12%), 10 (40%), 10 (40%), and 2 (8%) individuals respectively.

The velopharyngeal closure type was veloadenoidal in most of the study group patients 89.5% (n = 34) and velopharyngeal in only 10.5% (n = 4). Whereas, in the control patients the closure type was also veloadenoidal in most of them 75% (n = 20), and velopharyngeal in only 25% (n = 5) of them.

All patients in the study group did not have a velopharyngeal gap, Passavant’s ridge, or posterior pharyngeal wall mobility, and the velopharyngeal closure type was coronal on nasopharyngoscopy.

On comparison between the study and control groups, fiberoptic nasopharyngoscopic examination revealed only a highly significant statistical difference as regards lateral pharyngeal wall mobility (p = 0.000). However, no significant statistical differences were observed regarding the adenoid size, velar mobility, or closure type.

Cephalometry

On comparison of the angular cephalometric data between the study and control groups, there were no significant statistical differences for all cephalometric parameters except for maxillary protrusion (SNA) (P = 0.04) which was slightly wider in the study group than in the control group (Table 4).

Table 4 Comparison between study and control groups as regards angular cephalometric parameters

On comparison of the linear cephalometric data between the study and control groups, there were no significant statistical differences for all cephalometric parameters except for bony pharyngeal depth (Ptm-Ba) (P = 0.03) which was deeper in the study group than in the control group (Table 5).

Table 5 Comparison between study and control groups as regards linear cephalometric parameters

On comparison between the study and control groups as regards cephalometric triangular areas, the ratio between pharyngeal depth (PNS-PW) and velar length (PNS-P) and ratio between bony pharyngeal depth (Ptm-Ba) and velar length (PNS-P) there were no significant statistical differences for both nasopharyngeal triangle area and cranial base triangle area as well as both ratios (Table 6).

Table 6 Comparison between study and control groups as regards cephalometric triangular areas, the ratio between pharyngeal depth (PNS-PW) and velar length (PNS-P), and the ratio between bony pharyngeal depth (Ptm-Ba) and velar length (PNS-P)

Discussion

There is increasing evidence that a child who does not have an overt cleft palate is also at risk of developing VPI and resultant hypernasal speech. This child may have an unrecognized submucous cleft or subtle palatal abnormalities such as palatopharyngeal disproportion [9]. Early diagnosis of such cases will avoid the inevitable post-adenotonsillectomy open nasality and here is the core of the problem particularly in surgical decision-making of adenotonsillectomy in such apparently normal individuals.

Van Gelder [10] estimated the incidence of hypernasal speech after adenoidectomy alone to be as low as 1 per 10,000 and after adenotonsillectomy to be 1 per 3000; however, Gibb [11] found it to be as high as 1 per 1450.

Identification of the child at risk of VPI after adenotonsillectomy is not always an easy task. A careful examination of the patient and thoughtful consideration of the indications for surgery are essential parts of every preoperative evaluation. The evaluation should include digital palpation of the hard and soft palate and careful inspection of the velum. However, the other tools of objective assessment of the velopharyngeal port such as flexible nasopharyngoscopy, nasometry, videofluoroscopy, and cephalometry are also necessary.

For prevention of post-adenotonsillectomy velopharyngeal dysfunction in such cases with palatopharyngeal disproportion, we conduct this study to evaluate the role of fiberoptic nasopharyngoscopy and cephalometry for assessment of clinically suspected cases of palatopharyngeal disproportion (borderline VPI) cases to identify the craniofacial morphometric measurements of such cases that may be helpful as a prognostic indicator in predicting and preventing post-adenotonsillectomy velopharyngeal dysfunction.

Auditory perceptual assessment revealed no significant statistical difference between the study and the control groups which denotes that cases with borderline velopharyngeal insufficiency might have normal resonance 60.5% (n = 23) or closed nasality 39.5% (n = 15). The detected hyponasality could be explained by the presence of a huge adenoid tissue and tonsils which reduces the velopharyngeal port size, especially the adenoid which forces the velum to close easily against it (veloadenoidal closure). Also, this adenoid tissue may extend choanally and obstruct the nasal patency which prevents the transmission of nasal sounds. Our results were consistent with that of Skolnick et al., who postulated that it is often difficult to perceive speech of borderline cases auditorily and that we find ourselves “straining our ears” to hear excess nasality in the “borderline” speaker [12].

Fiberoptic nasopharyngoscopy provides three-dimensional information about the velopharyngeal closure mechanism. The current study showed a significant statistical difference between the study group and control group as regards lateral pharyngeal wall mobility which could be explained by the presence of a large adenoid tissue (mean ± SD = 72.37 ± 15.97) and tonsils in most patients of the study group that could easily limit the lateral pharyngeal wall mobility mechanically.

These results were inconsistent with Wu et al., who found that borderline cases of VPI have better lateral pharyngeal wall mobility during nasopharyngoscopy [13]. This could also be explained by the presence of a large adenoid tissue and hypertrophied tonsils in our study group, as mentioned.

Closure type was veloadenoidal in most patients, 89.5% of the case (n = 34) and 75% of the control (n = 20) groups which could be explained by the presence of adenoid tissue behind the velum at the site of natural velar contact which may compensate for borderline VPI and achieve a competent closure.

Our results were consistent with that of Hubbard et al., who had done a retrospective study on 27 patients (12 unilateral cleft lip and palate, 6 bilateral cleft lip and palate, and 9 isolated cleft palate) with average age of 6.6 years after cleft palate repair and concluded that the adenoid pads were involved in VP closure in about 74% of their patients while only about 26% of their patients did not significantly use the adenoid pad for VP closure [14].

As regards cephalometry, the significant statistical difference between study and control groups for SNA (maxillary protrusion) and (Ptm-Ba) bony pharyngeal depth means that patients of the study group had a degree of maxillary protrusion resulting in anteriorly located palate and hence deep pharynx.

Kassem et al. have done a comparative study between velopharyngeal dysfunction patients after adenoidectomy and normal patients using lateral cephalometric assessment, their results were consistent with our results as regards velar thickness, and opposite to our results regarding velar length, bony pharyngeal depth, nasopharyngeal angle, nasopharyngeal, and cranial base triangle area which may be due to post-operative scarred soft palate that occurs due to overstitching of the palate especially the posterior pillar resulting in overstretched short soft palate [6].

Ren et al. also used cephalometry to compare 16 children with post-adenoidectomy hypernasal speech without any signs of palatal defect and compared them to children who maintain normal speech postoperatively. The mean age at adenoidectomy was 5.5 years ranging from 4 to 9 years. They have selected 3 cephalometric parameters which are velar length, pharyngeal depth, and depth to length ratio. Their results were consistent with our results as regards their 3 cephalometric parameters [1].

Assessment of the velopharyngeal port starts with vocal tract examination which is the basic tool to suspect palatopharyngeal disproportion by identifying a short palate and deep pharynx. Fiberoptic nasopharyngoscopic examination of the velopharyngeal port is an efficient and effective instrument for observing velopharyngeal movements and closure mechanisms during connected speech. The procedure is easily tolerated and can be repeated as necessary. In addition, there is no exposure to radiation or obstruction of the normal flow of speech which makes it one of the most important assessment tools in velopharyngeal insufficiency; however, in certain situations as in agitated uncooperative children, the procedure might be difficult to perform and there comes the role of cephalometry which is rather a non-invasive tool and does not require much cooperation.

Accordingly, we can conclude that although cephalometric examination of the velopharyngeal port could define the parameters contributed to velopharyngeal insufficiency which is maxillary protrusion and increased bony pharyngeal depth however, it is not readily available in every center also it carries the risk of radiation exposure so its role could be limited only for Young agitated children who can’t tolerate the procedure of the nasopharyngoscopy.

Many other tools such as Nasometry and videofluoroscopy are valuable and effective for assessment of the velopharyngeal port. Nasometry could quantify nasal acoustic energy in speech and generate a nasalance score that could be compared to normative nasometric values to detect hypernasality or VPI [15]. Also, videofluoroscopy is an important radiological instrument that could be used for examination of the velopharyngeal port to assess the shape and mobility of the velum, lateral pharyngeal wall mobility, velopharyngeal closure, and gap [16]. One limitation of this study is that both tools were not available at our institution at the time of this study so, were not used. We recommend a further study using both tools on borderline cases of velopharyngeal disproportion which may add other prognostic indicators of postoperative VPI or substitute the craniofacial morphologic measurements by cephalometry.

Conclusion

Vocal tract examination, nasopharyngoscopy, and cephalometry could be used for pre-adenotonsillectomy assessment in cases with palatopharyngeal disproportion. A stepwise approach should be considered starting with vocal tract examination which is the simplest tool and advancing to the other tools which are flexible nasopharyngoscopy and cephalometry according to the patient’s need.

However, cephalometric examination has shown increased maxillary protrusion and deep bony pharyngeal wall in cases of borderline velopharyngeal insufficiency. The craniofacial measurements by cephalometry might be helpful in syndromic VPI cases with craniofacial and cervical anomalies rather than in clinically diagnosed cases of velopharyngeal disproportion.