Abstract
This clinical case study describes the velopharyngeal anatomy and physiology in a patient who presented with SATB2-associated syndrome (SAS) and velopharyngeal insufficiency (VPI) in the absence of an overt cleft palate. The clinical presentation, treatment, outcome, and the contribution of anatomical findings from MRI to surgical treatment planning for this rare genetic disorder, SAS, are described. This case study contributes to our current understanding of the anatomy and physiology of the velopharyngeal mechanism in an individual born with SAS and non-cleft VPI. It also details the changes following bilateral buccal myomucosal flaps in this patient.
Keywords: SATB2-associated-syndrome, MRI, VPI
Introduction
Numerous studies have documented the genotype, natural history, and phenotypic characteristics associated with SATB2-associated syndrome (SAS).1–21 Although the presence of cleft palate is one of the most cited features associated with SAS - palate anomalies in individuals with SAS include cleft palate (40%), a high-arched palate (25%), and bifid uvula (3%) - less is known about the speech consequences related to velopharyngeal insufficiency (VPI), the possibility of non-cleft VPI, and surgical treatment in this population.2,22 Non-cleft VPI, the presence of hypernasality and/or nasal emission with a normal-appearing palate, occurs in approximately 10% of individuals with SAS.23 The anatomic and physiologic underpinnings of VPI in individuals with SAS and non-cleft VPI are poorly understood, and this limits the ability of clinicians to predict response to treatment.
Thomason et al. reported the presence of abnormal resonance in patients with SAS but were not able to link the presence of VPI to the velopharyngeal anatomy or physiology.23 The use of velopharyngeal MRI during VPI evaluation provides direct evaluation of velopharyngeal structures including levator veli palatini muscle anomalies and quantitative evaluation of palate length and pharyngeal depth. These MRI findings provide anatomic information that is not available using traditional VPI imaging tools. In the present clinical case, the application of MRI as part of the clinical evaluation process provided anatomic and physiologic details that have not been previously described to guide surgical treatment planning in a patient who presented with SAS and VPI in the absence of an overt cleft palate.
MRI was performed pre-operatively to examine the velopharyngeal anatomy at rest and during sustained phonation. MRI findings were used in combination with traditional evaluation methods to plan treatment. MRI was also performed 18-months post-operatively to examine changes in the velopharyngeal anatomy and function, and to correlate these with speech outcomes. The clinical process, treatment decision, and the contribution of anatomical findings from MRI to surgical treatment planning for a rare genetic disorder, SAS, are described.
Case Report
A 7 year-11-month-old Caucasian male with a new diagnosis of SATB2 gene mutation was referred for hypernasality in the absence of an overt cleft palate. The patient was born at 35 weeks gestation and required a 3 week stay in the neonatal intensive care unit secondary to respiratory issues. He weighed 4 pounds, 9 ounces at birth. At presentation his medical history included global developmental delay, hypotonia, mildly small head circumference, mild micrognathia, high arched palate, mild pectus excavatum with scapular winging, and bilateral clinodactyly. He had no prior surgical history and no family history of cleft palate, VPI, or speech disorders.
Pre-surgical evaluation (7;11 years of age)
Perceptual evaluation.
The patient was seen by a cleft team speech-language pathologist (with over 8 years of experience in cleft palate assessments) for a standardized perceptual speech evaluation that included articulation testing, oral peripheral examination, perceptual evaluation, and Nasometric assessment. He presented with an articulation disorder characterized by developmental speech errors for “th” and phonological error patterns (gliding, stopping, pre-vocalic voicing, intermittent backing, and intermittent initial consonant deletion). No compensatory misarticulations were produced. The palate was intact with no evidence of a submucous cleft. The patient was rated as moderately hypernasal with frequent audible nasal emission on high pressure consonants.24 There was no hyponasality or voice disorder. Nasalance scores were elevated, with all four oral passages of the Picture-Cued Subtest above threshold values (Table 1).
Table 1.
Nasometer scores for patient at the time of the pre-surgical evaluation. The MacKay-Kummer Simplified Nasometric Assessment Procedures Test-Revised (SNAP-R) was completed using a Pentax Nasometer II.27,28
| Oral Passages | Pre-Surgical Score (Threshold: ≥ 22) | Post-Surgical Score (Threshold: ≥ 22) |
|---|---|---|
| Bilabial Plosives /p, b/ | 43 | 21 |
| Lingual-Alveolar Plosives /t, d/ | 41 | 21 |
| Velar Plosives /k, g/ | 41 | 22 |
| Sibilant Fricatives /s, z/ | 37 | 21 |
| Nasal Passage | Score (Threshold: ≤45) | Score (Threshold: ≤45) |
| Nasals | 62 | 65 |
Nasopharyngoscopy evaluation.
Following perceptual evaluation, nasopharyngoscopy was completed using a 2.4mm Pentax Fiber Nasopharyngolaryngoscope that was inserted with sterile lubricant into the right naris. Imaging revealed an intact nasal surface of the palate with no evidence of notching or overt submucous cleft palate. A coronal movement pattern with asymmetry was appreciated. Adenoid irregularity was observed which resulted in a consistent gap on the right side of the velopharyngeal port that varied in size depending on the speech context; a medium size gap was observed during single word and phrase level productions and a small gap was observed on sustained phonation (Figure 1). Touch contact of the palate with the adenoid pad was observed on the left side of the velopharyngeal port. No compensatory articulation errors were produced during the examination that would impact interpretation of results.
Figure 1.
The velopharyngeal port visualized during nasopharyngoscopy at rest, during single word production, and during sentence production pre-surgery. A gap can be visualized on the patient’s right side across speech tasks.
Magnetic resonance imaging.
A whole head MRI examination was performed without sedation using a 3T Phillips Scanner. Measures obtained from these images were compared to normative data matched for age from data reported by Perry et al. and are presented in Table 2.25 T2-weighted images were obtained with an in-plane isotropic resolution of 0.9. Three-dimensional MR images were obtained at rest (~4 minutes), and two-dimensional MR images were obtained in the oblique coronal and midsagittal planes during rest and during phonation of /i/ and /s/ (~8 seconds each). MRI measurements were obtained by a speech-language pathologist with over 15 years of experience performing VPI MRI studies; this speech-language pathologist was blinded to other instrumental assessment results.
Table 2.
Patient Pre-surgical MRI data at rest, during sustained phonation of /i/ and /s/.25
| Measure | Normative Data for 8yo | Patient Data (rest) |
Patient Data (phonation “ee”) |
Patient Data (phonation “ss”) |
|---|---|---|---|---|
| Mean Levator length (mm) Mean extravelar Total intravelar |
41.5 (3.1) | 36.9* 24.1 25.6 |
31.7 20.2 23.05 |
34.0 20.9 26.1 |
| Origin-origin distance (mm) | 56.7 (2.5) | 52.3* | -- | -- |
| Angle of origin (°) | 54.7 (3.5) | 58 | 45 | 45 |
| Sagittal angle (°) | 47.4 (6.7) | 31.7* | -- | -- |
| Mean Levator thickness | -- | 2.7 | 2.5 | 2.2 |
| Velar length (mm) | 27.5 (3.2) | 24.2 | 23.25 | 22.1 |
| Velar thickness (mm) | 9.1 (1.6) | 6.1* | 5.6 | 7.3 |
| Adenoid size (mm) | 10.2 (2.3) | 5.8* | -- | -- |
| Palate-PPW/adenoids (mm) “pharyngeal depth” |
18.3 (2.3) | 24.1* | -- | -- |
| Velar knee-PPW (mm) | 9.7 (1.6) | 10.9 | 0 | 1.3 |
| PNS-levator (mm) “effective velar length” |
10.1 (1.6) | 9.2 | 11.3 | 11.1 |
Notes on Table Measures: the range of Velar knee-PPW represents any gap size observed during phonation. Posterior palate-levator measure during speech represents any observed velar stretch (as noted as the difference from the rest to phonation position). The use of – is indicated for measures that are unchanged during phonation (e.g., bony structure measures).
indicates measures 1 standard deviation outside of the normative range.
Velopharyngeal MRI demonstrated (Table 2 and Figure 2), the levator veli palatini muscle was cohesive through the velar midline. The muscle position relative to the hard palate was not significantly different from age-matched controls. The levator muscle was slightly reduced in length and more vertically oriented. The patient’s pharyngeal depth was significantly larger than expected based on the patient’s age. During phonation, the levator veli palatini muscle shortened, the velum stretched posteriorly, and there was a visible velar knee.
Figure 2.
Demonstration of the sagittal and oblique coronal images at rest, during phonation of /i/ (“eee” sound), and during phonation of /s/ (“sss” sound). During phonation, a gap can be visualized. In the sagittal images, this is represented by a bright line coursing along the posterior pharyngeal wall; and in the oblique coronal images, arrows depict gap location.
MRI findings were consistent with nasopharyngoscopy, with a coronal closure pattern, touch closure during sustained phonation (1–2mm), and a more predominant gap on the patient’s right side. The asymmetry of the velopharyngeal gap during phonation appeared to be related to irregularities in the adenoid tissue at the level of velopharyngeal closure. More specifically, the right and left levator muscle contracted to the same degree causing symmetrical velar movement.
Treatment Decision.
The patient’s imaging obtained via nasopharyngoscopy and VPI MRI were reviewed by the evaluating speech pathologist and treating surgeon. The MRI findings of an intact and functioning levator veli palatini muscle with a deep pharynx and insufficient velar length led the treating providers to recommend palatal lengthening using bilateral buccal myomucosal flaps to treat the patient’s VPI. It was predicted that increased palatal length would compensate for the deep pharynx, enabling complete velar closure against the posterior pharyngeal wall. This operation was selected over pharyngeal flap or sphincter pharyngoplasty to avoid the risk of obstructive sleep apnea.
Palate lengthening with bilateral buccal myomucosal flaps was performed as described by Hens et al.26 A transverse incision was made through the soft palate just posterior to the hard palate. This resulted in posterior displacement of the central aspect of the soft palate by approximately 1 cm. The levator veli palatini was identified laterally on both the right and the left. It was slightly diminutive in diameter but was intact across the midline. The inset bilateral buccinators myomucosal flaps were 13 mm wide. At the end of the procedure the base of the uvula easily touched the base of the adenoid pad.
Post-surgical evaluation (18 months post-surgery; 10;5 years of age)
Perceptual evaluation.
The patient was seen for 6-, 12- and 18-month post-operative speech evaluations. During that time, he continued articulation and language therapy through school-based services and outpatient therapy with both speech-language pathologists sharing goals and progress. At his 18-month post-operative speech evaluation, he presented with improved articulation skills compared to the pre-operative evaluation; however, he still presented with developmental errors of “th” and the following phonological processes: gliding, stopping. At the post-operative evaluation, he was rated as having normal resonance and occasional audible nasal air emission. These findings demonstrate improvement from initial assessment of moderate hypernasality and frequent nasal emission pre-operatively. There was no hyponasality or voice disorder. Post-operative Nasometric scores are presented in Table 1. Prior to surgical management, all four oral passages on the SNAP-R were above threshold.27,28 Following surgical management, three of four scores were below threshold with one score falling at threshold. These improved nasalance scores for the oral passages were consistent with perceptual ratings.
Magnetic resonance imaging.
As seen in Figure 3 and Table 3, post-operative MRI demonstrated the levator muscle was cohesive through the velar midline and within normative range for all measures. The muscle had slightly increased (2 mm) in length from the prior MRI at 8 years of age. The levator muscle had moved posteriorly relative to bony palate by 5 mm compared to the pre-operative MRI. The velum had lengthened by 4mm compared to the pre-operative MRI. While velar thickness taken at the position of the velar knee remained similar to the pre-surgery scan, velar thickness was significantly greater at the location of buccal flap inset just posterior to the hard palate. The adenoids have increased in size since the pre-surgery MRI, which created a smaller pharyngeal depth (palate-PPW measure). A gap of 2 mm was visible in the post-surgery MRI for phonation of /i/ and remained more prominent on the patient’s right side, as was noted on the pre-surgery MRI. There was no velopharyngeal gap during /s/ sustained production, where full velopharyngeal closure was observed.
Figure 3.
Demonstration of the sagittal and oblique coronal images at rest, during phonation of /i/ (“eee” sound), and during phonation of /s/ (“sss” sound). A gap can be visualized in sagittal and oblique coronal images during phonation of /i/. An arrow depicts this gap location in the oblique coronal plane.
Table 3.
Patient Post-surgical MRI data at rest, during sustained phonation of /i/ and /s/.25
| Measure | Normative Data for 10yo | Patient Data (rest) |
Patient Data (phonation “ee”) |
Patient Data (phonation “ss”) |
|---|---|---|---|---|
| Mean Levator length (mm) Mean extravelar Total intravelar |
42.4 (4.0) -- -- |
38.9 24.9 28.1 |
35.4 23.2 24.5 |
32.5 21.2 22.6 |
| Origin-origin distance (mm) | 55.7 (3.6) | 54.2 | -- | -- |
| Angle of origin (°) | 57.5 (3.0) | 57 | 49 | 47 |
| Sagittal angle (°) | 45.4 (8.3) | 44 | -- | -- |
| Mean Levator thickness | -- | 3.25 | 3.3 | 3.37 |
| Velar length (mm) | 31.4 (3.5) | 28.2 | 30.1 | 28.4 |
| Velar thickness (mm) | 9.5 (1.2) | 6.6* | 6.4 | 7.8 |
| Adenoid size (mm) | 10.2 (2.3) | 8.1 | -- | -- |
| Palate-PPW/adenoids (mm) “pharyngeal depth” |
23.3 (3.4) | 20.2 | -- | -- |
| Velar knee-PPW (mm) | -- | 4.47 | 2.1 | 0 |
| PNS-levator (mm) “effective velar length” |
10.4 (0.9) | 14.3* | 14.3 | 14.4 |
Notes on Table Measures: the range of Velar knee-PPW represents any gap size observed during phonation. Posterior palate-levator measure during speech represents any observed velar stretch (as noted as the difference from the rest to phonation position). The use of – is indicated for measures that are unchanged during phonation (e.g., bony structure measures).
Discussion
The use of MRI as part of the clinical evaluation process provided valuable insight on the velopharyngeal anatomy that strongly influenced treatment decisions for this patient presenting with SAS and VPI in the absence of an overt cleft palate. More specifically, MRI provided details related to the relative position, integrity, and function of the levator veli palatini muscle, which were not available through other imaging modalities. Nasopharyngoscopy alone cannot provide such details related to the velar muscles nor can quantitative measures be obtained. Findings from MRI data were consistent with observations during surgery and from nasopharyngoscopy. MRI data revealed a cohesive levator sling that was reduced is size (mean levator thickness of 2.7mm pre-surgery and 3.25mm post-surgery), which was confirmed during the VPI surgery. A coronal closure pattern was observed on both the MRI and nasopharyngoscopy with the velopharyngeal gap being more prominent on the patient’s right side secondary to irregularity of the adenoids. MRI was able to quantify the exact size and position of the velopharyngeal gap and determine the factor(s) that were and were not contributing to the asymmetry of the velopharyngeal gap.
The presence of moderate hypernasality with nasal air emission along with the clinical indications of an intact levator veli palatini muscle, deep pharynx, and relatively short velum led to the surgical decision for palate lengthening. The use of bilateral buccal myomucosal flaps in this patient resulted in a posterior movement of the levator muscle of 5 mm, 4 mm increase in the velar length, and an absence of hypernasality during perceptual speech assessment. Post-surgery nasometry scores also reflected an improvement in post-operative outcomes. Occasional audible nasal air emission remained. This improved velopharyngeal function and inconsistent presence of VPI symptoms was consistent with anatomic and physiologic observations from the MRI in which full closure was observed during the sustained production of /s/ and a small gap remained during /i/ production.
The use of MRI in examining rare genetic disorders is particularly important when an overt cleft or submucous cleft palate is not an associated feature and anatomic variations are the likely cause of VPI. This study demonstrated the clinical process that can be used, and specifically the application of MRI data to support surgical treatment decisions, in a rare genetic disorder commonly associated with craniofacial anomalies. In this particular patient, VPI was observed in the presence of an intact palate and cohesive levator veli palatini muscle. Other MRI studies examining the anatomies of individuals with genetic disorders and non-cleft VPI have also demonstrated significant anatomic variations. For example, individuals with 22q11.2 deletion syndrome have been reported to have a shorter and thinner velum, hypoplastic levator muscle, and deep pharynx.29–32 Individuals with Pierre Robin sequence demonstrate shorter hard and soft palate length and more anteriorly positioned levator veli palatini muscle.33As these examples demonstrate, MRI offers valuable information about the velar muscles that directly contribute to understanding the causes of improper velopharyngeal function; MRI should be strongly considered during the clinical evaluation, particularly with challenging cases or rare disorders such as the present case. It is important to note that cleft and craniofacial centers may encounter barriers when implementing a velopharyngeal MRI protocol, such as access to MRI scanners and training staff how to collect necessary images of velopharyngeal anatomy.
This case study contributes to our current understanding of the anatomy and physiology of the velopharyngeal mechanism in an individual born with SAS and non-cleft VPI. It also details the anatomic and physiologic changes following bilateral buccal myomucosal flaps to treat VPI in a patient with SAS. Finally, this case study shows the utility of MRI for evaluation and treatment planning in patients with VPI. As MRI methodology expands to connected speech in the coming years, the utility of MRI during the VPI evaluation will continue to expand, particularly in complex clinical cases.
Footnotes
Declaration of Conflict of Interest:
The authors declare that there is no conflict of interest.
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