Cognitive functions in Arabic-speaking children with velopharyngeal insufficiency and their impact on speech intelligibility

Patients with orofacial cleft are at high risk for neurobehavioral problems including learning disability, impaired language function, psychosocial adjustment issues, and persistently reduced academic achievement. All these factors may be related to decrease intellectual abilities of those patients. The presence of velopharyngeal insufficiency (VPI) leads to affection of speech intelligibility due to atypical consonant productions, abnormal nasal resonance, nasal air emission, compensatory articulatory mechanism, and facial grimace. This study aimed at assessing the cognitive functions of patients with (VPI) and their effect on speech intelligibility. Fifty patients with (VPI) were selected from the Outpatient Clinic of the Phoniatric Unit in Assiut University Hospital. All patients were evaluated by protocol of nasality assessment including auditory perceptual assessment of speech, assessment of overall intelligibility of speech, nasoendoscopy, and psychometric evaluation. The mean intelligence quotient (IQ) of patients with VPI was 75.2 ± 14.5 with a range between 41 and 107. The main defect was present in quantitative potential and then verbal ability followed by visual ability with memory having the highest mean. Patients with repaired cleft palate had the highest score (86.53 ± 9.96), while the least score was reported among those with velopharyngeal disproportion (72.50 ± 9.59). There was a nonsignificant negative correlation between IQ degree and speech unintelligibility (p = 0.82). About half of the patients with (VPI) have below average mentality. Patients with repaired cleft palate had the highest (IQ) score. Increased (IQ) score was accompanied by decreased speech unintelligibility, although it does not reach the level of significance.


Background
Velopharyngeal insufficiency (VPI) refers to structural defects which result in a gap in the velopharyngeal valve.This is often because the velum is short relative to the position of the posterior pharyngeal wall.
Velopharyngeal insufficiency has many causes, including cleft palate, submucous cleft, velopharyngeal disproportion, and acquired defects following various surgical procedures (after adenoidectomy, oral and pharyngeal tumors removal) [1].VPI implies the presence of hypernasality, inappropriate nasal escape, and decreased air pressure during the production of oral speech sounds with decreased speech intelligibility [2].The term intelligibility refers to "speech clarity" or the proportion of a speaker's output that a listener can readily understand.Reduced speech intelligibility leads to misunderstanding, frustration, and loss of interest by communication partners.As a result, communication decreases or remains at a low level [3].Patients with mild and moderate intellectual disabilities showed distinct difficulties in their speech production that affect both the quality and intelligibility of their verbal output.Their speech is characterized by an overall high error rate and the occurrence of both typical and atypical phonological processes [4].
Children with cleft palate performed more poorly on cognitive-intellectual measures than their peers [4].A number of studies suggest that the cognitive deficits may be secondary to linguistic deficits.They found that children with cleft palate have lower scores on verbal IQ measures than on performance measures [5][6][7].
Some studies have tried to identify specific patterns of cognitive difficulty in children with clefts.They found problems with visual perceptual skills [7][8][9], while others have shown no deficit in these skills [10,11].This study aimed to evaluate the cognitive functions of Arabicspeaking children with velopharyngeal insufficiency and their impact on speech intelligibility.

Methods
Fifty patients aged 3-27 years presenting with velopharyngeal insufficiency due to repaired/unrepaired cleft palate or cleft lip and palate or due to velopharyngeal disproportion were recruited from the Outpatient Clinic of the Phonatric Unit at Assiut University Hospital during the period from April 2019 to April 2020.They were free from syndromic cleft palate, hearing impairment (sensorineural hearing loss), neurological diseases, attention-deficit hyperactivity disorder (ADHD), delayed language development, and no history of speech therapy.All patients were evaluated by the following protocol of nasality assessment:  [14] were performed.E. Flexible nasoendoscopy: (Storz Tele pack X LED-TP100) to assess the movement of the velum, lateral and posterior pharyngeal walls, the movement of each component is given a score of (0-4): (0) = the resting (breathing) position, (2) = half the distance to the corresponding wall, and (4) = the maximum movement reaching and touching the opposite wall.Also, the pattern of closure of the velopharyngeal port, whether coronal, sagittal, circular, or other, the velopharyngeal gap and its size, the presence of adenoid and its size, and the presence of Passavant's ridge were assessed.F. Language evaluation: By Arabic language test [15] and articulation test [16].G. Psychometric evaluation: By Stanford Binet intelligence quotient 4th edition with its four subtests assessing (verbal ability, visual ability, quantitative potential, and memory) [17].H. Audiologic assessment I. Nasometry: Nasometer 6200 (Kay Elemetrics/PEN-TAX) was used to measure nasal resonance.

Statistical analysis
Data analysis has been performed using SPSS model 20 IBM SPSS (IBM Corp., Armonk, New York, USA).Categorical data have been offered such as number and percent.Quantitative data with normal distribution are expressed as mean ± standard deviation and range.Student t-test was used to compare quantitative data of two groups, while in the case of more than two groups, ANOVA was used.Quantitative data with abnormal distribution expressed as median (minimum-maximum) and compared by Mann-Whitney U-test was used.The correlation tests were conducted using Spearman's correlation coefficient to correlate between abnormally distributed data and different parameters.The statistical differences were considered significant when P was lower than 0.05.

Subtypes of intelligence quotient among studied patients
The main defect was present in quantitative potential (76.04 ± 13.01) and then verbal ability (79.62 ± 12.11) followed by visual ability (79.88 ± 14.3) with memory having the highest mean (82.02 ± 12.73) (Table 4).

Distribution of subtypes of IQ, nasality degree, speech unintelligibility, and different causes of VPI
There was no significant difference between different causes of VPI and IQ degree.There was no significant difference between different causes of VPI and nasality degree.There was a moderate significant difference between causes of VPI and speech unintelligibility, as patients with BCLP had the highest grade of speech unintelligibility while patients with velopharyngeal disproportion had the least grade of speech unintelligibility (Table 5).

IQ degree among repaired and unrepaired cases of VPI
It was found that different causes of VPI had highly significant effect on IQ degree (p < 0.001).In general,  patients with repaired cleft palate had the highest score (86.53 ± 9.96), followed by unrepaired cleft palate, while the least score was reported among those with velopharyngeal disproportion (72.50 ± 9.59) (Fig. 2).

Distribution of IQ degree and speech unintelligibility
It was found that different grades of speech unintelligibility had no significant differences with IQ degree (p = 0.82).But in general, patients with no speech unintelligibility had the highest IQ (86.19 ± 8.89), while the least value was reported among those with moderate unintelligibility (67.10 ± 9.54) (Table 6).

Correlation matrix between IQ degree, nasality degree, and speech unintelligibility
There was a significant positive correlation between the degree of nasality and speech unintelligibility (p = 0.04).Increased nasality degree is accompanied by increased speech unintelligibility (r = 0.492).There was a nonsignificant negative correlation (p = 0.82) between IQ degree and speech unintelligibility.Also, there was a nonsignificant negative correlation between IQ and nasality degree (p = 0.845) (Table 7).

Discussion
Cognitive dysfunction in children with clefts of the lip and palate has been documented for decades [18].Some studies reported that children with non-syndromic clefts had lower IQs [19,20] and lower scholastic achievement [20] than that of the general population.In this study, the mean IQ was (75.2 ± 14.5) with a range between 41 and 107.So, there is obvious downgrading in the cognitive function of patients with VPI.This agreed with Persson et al. [21] who found that the group with cleft palate alone had a significantly lower They have smaller brain volumes, with the frontal lobes and certain subcortical nuclei (caudate, putamen, and globus pallidus) being most affected [22].The brain of adults with isolated cleft palate (ICP) showed normal cerebral volumes, but an abnormality in tissue distribution in which the frontal and parietal lobes were substantially increased in volume compared with normal, and the temporal and occipital lobes were significantly decreased in volume.The cerebellum was also decreased in volume [23].These differences in brain volume and structure may be related to the cognitive problems in people with orofacial clefts [24].In this study, patients with UCLP had the least IQ score (70.67 ± 25.93) followed by patients with velopharyngeal disproportion (72.43 ± 8.75) and then patients with CPO (75.74 ± 14.86), while patients with BCLP had the highest IQ score (78 ± 14.3).This disagrees with Nopoulos et al. [25] who found a relationship between severity of clefting and severity of cognitive deficit in which subjects with bilateral CLP (most extensive clefting) were the most severely affected cognitively, while subjects with CPO (least extensive clefting) were the least affected.However, this may be due to the small number of subjects in each clefting group in this study.Also, Nopoulos et al. [26] showed that adult males with non-syndromic cleft lip and/or palate have a specific pattern of cognitive deficits.Subjects with clefts were found to have general IQ scores below that of their matched controls.Subjects with clefts had specific and significant abnormalities in verbal abilities.On the other hand, motor skills, verbal memory, executive function, and performance on a visuospatial task were not different from their matched control group.
Richman and Eliason stated that overall intellectual functioning is within the average range.However, there were specific cognitive deficits or delays in children with clefts.These deficits appear to affect the verbal abilities and visual-motor function, but the nonverbal and visualperceptual functions are generally intact [27].
We found that patients with repaired cleft lip and palate had the highest IQ score.This may be attributed to better psychological consequences of early vs. later repair.That is in line with Murray et al. [28] who found lowered cognitive scores in infants having late cleft lip and palatal repair.As the disfigurement caused by unrepaired clefts not only makes these children less appealing to look at but also makes it difficult for parents to interpret infant expressions, early repair helps better faceto-face play and influences the quality of life of infants   as they might be accepted better by their families.Also, parents of infants having early cleft lip repair may find it easier to respond to infant social cues [28].
In our study, the different grades of speech unintelligibility had no significant differences with IQ degree.However, patients with no speech unintelligibility had the highest IQ, while the least value was reported among those with moderate unintelligibility.This may be explained by Coppens-Hofman et al. [4] who showed a strong association between the severity of intellectual dysfunction and speech intelligibility.Patients with intellectual disabilities have difficulties in their speech production that affect both the quality and intelligibility of their verbal output.Their speech is characterized by multiple phonological processes.As short-term and long-term verbal memories are both highly involved in speech production, the two systems are impaired in people with intellectual dysfunction.An additional factor to consider as a potential cause of reduced intelligibility is poor auditory feedback due to deficient auditory processing.
There was a significant positive correlation between nasality degree and speech unintelligibility.This may be explained by the fact that hypernasality affects vowel production and causes modification of the spectrum of F1 and F2 such as weakening of formants, decrease in the strength and enhanced bandwidth of F1 and F2, lower in the amplitude of F1 and F2, introduction of pole/zero pairs in the vicinity of F1, and shifts in the formant frequencies.These spectral modifications in the hypernasal speech will have an impact on the articulatory dynamics while producing vowels resulting in vowel centralization and in turn affecting speech intelligibility [29].This finding agrees with Saervold et al. [30] who found that the presence of hypernasality and reduced intelligibility were clearly associated with speech in cleft palate patients.Children with speech difficulties appear to have higher risk of delayed phonological awareness development, associated literacy problems, and delays in the acquisition of reading skills [31].

Conclusion
Patients with VPI show mild overall cognitive deficit with particular deficit in quantitative potential.These deficits may be due to the same factors that underline the facial cleft-abnormal development.Speech intelligibility is affected by the degree of hypernasality, the degree of cognitive deficit, and the type of VPI.Early intervention for patients with cleft lip and palate prevents the deterioration of speech problem and helps better personality selfconfidence and scholastic achievement.

Fig.
Fig. IQ degree among repaired and unrepaired types of VPI

Table 1
Demographic data of studied patients Data expressed as frequency (percentage).Test of significance: chi-square test

Table 2
Distribution of the patients according to the cause of VPI

Table 3
Auditory perceptual assessment (APA) of patient's speech Degree of total IQ and its among studied patients score on the general intellectual capacity test than the control group.This may be explained by some research that found children and adults with cleft lip and palate (CLP) have abnormal brain structure and function.

Table 4
Subtypes of intelligence quotient among studied patientsData expressed as mean (SD).IQ intelligence quotient.Test of significance: chi-square test

Table 5
Distribution of subtypes of IQ, nasality degree, speech unintelligibility, and different causes of VPI Test of significance: chi-square test, ** moderate significance VPI velopharyngeal insufficiency, IQ intelligence quotient, CPO cleft palate only, UCLP unilateral cleft lip and palate, BCLP bilateral cleft lip and palate

Table 6
Distribution of IQ degree and speech unintelligibility

Table 7
Correlation matrix between IQ degree, nasality degree, and speech unintelligibility p-value was significant if < 0.05.Test of significance: Pearson correlation,** moderate significant