Cerebral palsy (CP) is a group of nonprogressive neuromotor disorders that affect the development of the fetal brain. They are present at birth and persist throughout the patient’s lifetime. Prevalence is 2.1 per 1000 live births1.

CP involves limitations in the development of movement, posture, and motor function. It can also be accompanied by epilepsy; intellectual disability; impaired vision; cognitive, communication, and behavioral disorders; and swallowing alterations2.

Swallowing is a complex process that involves muscles of the mouth, larynx, and esophagus, with the participation of different levels of the central nervous system. It is made up of three phases that occur sequentially: the oral phase, the pharyngeal phase, and the esophageal phase3.

Dysphagia is difficulty swallowing and can be classified as oropharyngeal dysphagia (OPD) due to the dysfunction of the pharynx and the upper esophageal sphincter or as esophageal dysphagia due to dysfunction of the lower esophagus4.

The grouped prevalence of OPD in patients with CP reported in a meta-analysis was 50.4% and gradually increased with the severity of the CP5. OPD in patients with CP favors the appearance of infectious, respiratory, and nutritional complications that increase mortality6.

Videofluoroscopy (VFS) is the best radiologic study for diagnosing OPD. It enables visualization of the anatomy of the oral cavity, pharynx, larynx, and upper esophagus, as well as the function and integration of the phases of swallowing7,8.

At our institution, Quiñones-Pacheco et al.9 conducted a descriptive study on 25 patients with infantile CP that underwent VFS for OPD diagnosis. They found that 64% of the patients had vallecular residue and pyriform sinus stasis and 52% presented with pulmonary aspiration.

The relation of certain variables in children with CP and OPD has been studied in developed countries10–12, but the frequency and interaction of the variables can be different, according to region. Therefore, the aim of the present study was to determine the factors associated with OPD diagnosed through VFS in children with CP.

Sixty-four patients with CP between 8 months and 15 years of age were invited, through their parents, to participate in the study. Four patients were excluded; three due to lack of cooperation by the children and one because the parent did not accept barium administration for the child. The final sample was made up of 60 subjects: 30 patients with OPD and 30 patients with no OPD.

In the 30 cases with OPD, the signs of the disorder identified by VFS were vallecular residue, stagnation in the pyriform sinuses, nasopharyngeal reflux, penetration, aspiration, and silent aspiration. Twenty-six patients (87%) had more than one sign. Three signs were simultaneously identified per patient on average. Six patients (20%) had the maximum number of signs in a single patient and 4 patients (13%) had the minimum of one sign in a single patient.

In the VFS, the most frequent texture utilized was nectar and was accompanied by nasopharyngeal reflux, vallecular residue, and stagnation in the pyriform sinuses. However, the liquid texture was the most common in all the signs evaluated, when it was included in the combination of textures (Table 1).

Seventeen of the patients with OPD (57%) and 16 of the patients with no OPD (53%) were females (p=0.795).

The distribution of age at the time of the study was symmetric between the two groups and ranged from 8 months to 15 years.

The mean age was 6.7±1.7 years in the patients with OPD and 7.8±1.1 years in the patients with no OPD (p=0.972). The age of 26 patients with OPD (86%) and 20 with no OPD (66%) was between 2 and 12 years. Two cases (7%) and 2 controls (7%) were under 2 years of age and 2 cases with OPD (7%) and 8 with no OPD (27%) were above 12 years of age.

Fifteen patients with OPD (50%) and 22 with no OPD (73%) had a low middle socioeconomic status (p=0.063) and all the other patients belonged to the middle socioeconomic group.

The gestational age at birth had a normal distribution, with a mean age of 34.7±3.7 months in the neonates with OPD and 35.2±2.9 months in the neonates with no OPD (p=0.517).

Birthweight was symmetrically distributed, with a mean weight of 2299±829g in the cases and 2330±572 g in the controls (p=0.863).

There was a similar distribution between the two study groups regarding the frequency of the data perceived by the mothers during at-home feeding, such as feeding duration above 30 min, inability to keep the lips together, coughing during or after meals, and choking during or after meals. Only the higher frequency of difficulty in food bolus transport in the OPD group showed a statistically significant difference (Table 2).

Distribution was similar between the two study groups, regarding the factors that could be associated with OPD, such as the frequency of the manifestations related to the topographic CP classification (monoplegia, diplegia, quadriplegia, and hemiplegia), muscle tone types (spastic, dyskinetic, ataxic, and mixed), and comorbidities (epilepsy, gastroesophageal reflux, constipation, and malnutrition). In addition, there was a statistically significant higher number of patients with OPD with level V of the GMFCS13,14, compared with level IV (p=0.003) (Table 3) and level V was associated with a greater frequency of OPD (OR 5.7; 95% CI 1.8–17.5).

The frequency of hypotonic muscle tone was higher in the patients with no OPD and was statistically significant (Table 3).

Other comorbidities, such as constipation and orthopedic, auditory, and endocrine problems, were similarly distributed in the two study groups.

Twenty-four patients with OPD (80%) and 25 with no OPD (83%) had some degree of malnutrition but the differences in the frequencies of mild, moderate, and severe malnutrition between the two study groups were not statistically significant. Six patients (20%) in the OPD group and 5 patients in the group with no OPD (155) had severe malnutrition and the majority of the patients in both study groups were diagnosed with moderate malnutrition.

The present study showed that OPD was associated with level V of the five-level GMFCS14,15. Difficulty in food bolus transport perceived by the mothers of the patients with OPD during at-home feeding was also statistically significant.

In the present study, OPD was associated with greater severity measured by the GMFCS, as proposed by Palisano et al.14,15 Said finding has also been reported by other authors that documented OPD through questionnaires19−21 and by researchers that diagnosed OPD through VFS6,22,23.

Regarding the diagnosis of OPD through questionnaires, in a Dutch study conducted by Calis et al.19 on 166 children from 2 to 19 years of age with CP levels IV and V measured by the GMFCS, they found that level V was more frequent in patients that had greater OPD severity (p<0.001). In Northern Ireland, Parkes et al.20 reported that patients with level IV measured by the GMFCS had nearly 5-times more probability of presenting with OPD (OR=4.8, p<0.001) and those with level V had 15-times more probability of presenting with OPD (OR=15.7, p<0.001). In an Australian study, Benfer et al.21 described an incremental relation of OPD severity to the level of gross motor function impairment and the children with GMFCS level V had 17-times more probability of presenting with OPD than the patients with level I (OR=17.9, p=0.036).

In addition, researchers that diagnosed OPD by VFS have reported a relation of OPD to the severity of motor function impairment. In a South Korean study, Kim et al.6 found alterations in the oral and pharyngeal phases of swallowing in 20% of the subjects with levels I and II, in 28.6% of the subjects with level III, and in 91.7% of the subjects with levels IV and V, measured by the GMFCS (p<0.001). In their Iranian study, Asgarshirazi et al.22 reported that 73% of the patients with GMFCS levels IV and V had important symptoms of OPD, compared with 21% of the patients with levels I and II (p<0.001). In Australia and Bangladesh, Benfer et al.23 found that the probability of presenting with OPD was nearly 1.9–3.5-times greater with each increase in GMFCS level in children with CP between 18 and 36 months of age, across all gross motor severity levels.

The age of the patients in the present study was similar to that reported in previous studies6,19,20,22, with only Benfer et al.21,23 including younger patients (18–36 months of age). Benfer et al.24 were also the only authors that quantified the intensity of the association of OPD diagnosed by VFS with greater severity of motor function impairment (OR 3.8; 95% CI 3.2–4.3), a lower figure than that found in the present study (OR 5.7; 95% CI 1.8–17.5).

The largely voluntary alterations in the oral phase of swallowing are a result of damage to the cortical neuronal networks and problems in the pharyngeal phase of swallowing result from disorders in the automatic swallowing components. Both situations can occur due to subcortical cerebral and basal ganglia injury24. Therefore, the association of OPD severity with higher levels of gross motor function impairment is likely due to the fact that when there is greater neurologic injury from CP, there is also less control of voluntary and involuntary movements of the buccofacial muscles and the tongue.

The frequency of difficulty in food bolus transport perceived by the mothers of the patients during at-home feeding (87% in the cases and 30% in the controls) documented in the present study was higher than the results reported by other researchers6,12, who found a frequency ranging from 33% to 52% in patients with OPD. Those differences could be due in part to the different manners of collecting said datum and the heterogeneity of the different grades of CP and OPD severity.

Notably, 87% of the patients with OPD in our study presented with two or more signs of alteration at the pharyngeal level, signifying a high probability of presenting with the serious problem of airway aspiration.

The results of the present analysis are important, given that, to the best of our knowledge, there are no studies in Latin America that investigate the factors associated with OPD diagnosed by VFS in children with CP. In addition, the case-control design enabled us to have more evenly matched study groups, better measure the differences of the frequencies of the variables between the study groups, and to explore the possible association of a dependent variable with the independent variables. Studies conducted in other countries6,8,10–12,19–23 have descriptive and cross-sectional designs.

A limitation of the present research was the fact that the clinical data perceived by the mothers of the patients was obtained through questionnaires, as occurred in some of the studies reviewed19–21, but having video recordings of the at-home feedings of the patients would have been more reliable. A larger sample size would also have enabled the effect on OPD of the less frequent factors to be analyzed, rather than just the level of gross motor impairment.

Despite the abovementioned limitations, the present study concluded that there is an association between OPD documented by VFS and the severity of gross motor function impairment, which could be due to the relation of greater neurologic injury to increased alteration of the control of voluntary and involuntary movements of the buccofacial muscles and the tongue.

No specific grants were received from public sector agencies, the business sector, or non-profit organizations in relation to this study.

All authors declare that each of them meets the authorship requisites and has reviewed and approved the final version of the manuscript.

The authors declare that there is no conflict of interest.