This exploratory clinical trial aims to investigate the mechanism of sequential muscle contractions during normal swallowing processes, including spoon, straw, and cup feeding, in children aged 2 to under 10 years without swallowing disorders. Surface electromyography (sEMG) will be used to evaluate activation patterns of the orbicularis oris, submental, and hyoid muscles during liquid, semi-solid, and solid intake.

The study seeks to characterize the timing, duration, amplitude, and coordination of swallowing-related muscle activity in typically developing children. Findings from this study are expected to provide foundational physiological data to inform the development of pediatric-specific neuromuscular electrical stimulation (NMES) protocols for dysphagia treatment.

Background and Rationale

Swallowing is a complex neuromuscular process requiring coordinated and sequential activation of orofacial and suprahyoid muscles. While neuromuscular electrical stimulation (NMES) has been widely applied in adult dysphagia rehabilitation, pediatric-specific physiological data on swallowing muscle activation patterns remain limited. Current clinical practice often extrapolates adult treatment protocols to pediatric populations, despite developmental differences in anatomy, neuromuscular control, and feeding mechanisms.

Understanding the normative sequential activation patterns of swallowing-related muscles in children is essential for developing age-appropriate therapeutic protocols. This study aims to establish baseline physiological data on muscle activation sequencing during various feeding methods in typically developing children.

Study Design

This is an exploratory, single-center clinical study enrolling 30 children aged 2 to under 10 years without diagnosed swallowing disorders. Participants will undergo non-invasive surface electromyography (sEMG) assessments during standardized feeding tasks.

Study Procedures

1. Spoon Feeding Mechanism Assessment

   Participants will consume:

   3-5 cc of liquid using a spoon

   3-5 cc of yogurt (semi-solid consistency) using a spoon

   Solid food using a spoon

   Surface EMG electrodes will be placed over the:

   Orbicularis oris

   Submental muscle group

   Hyoid-related musculature

   Muscle activation patterns during swallowing will be recorded.

2. Straw Feeding Mechanism Assessment

   Participants will consume 5-10 cc of liquid using a straw while sEMG signals are recorded from the same muscle groups.

3. Cup Drinking Mechanism Assessment

Participants will consume 5-10 cc of liquid from a cup with simultaneous sEMG recording.

Data Collection Observational Variables

Name

Age

Birth history (gestational age, birth weight, delivery method)

Sex

Race

Height and weight

Medical history

Surgical history

Medication use

History of pneumonia

Diagnosis of swallowing disorder

Anthropometric Measurements

Distance from mandible midpoint to hyoid bone

Distance between bilateral angles of the mandible

Distance from hyoid bone to clavicle

Bilateral neck width at the level of the thyroid cartilage

Surface Electromyography (sEMG) Outcome Measures

Primary electrophysiological variables include:

Onset latency

Offset latency

Duration of muscle contraction

Peak amplitude

Area Under the Curve (AUC)

The primary outcome measure is the sequential activation pattern of swallowing-related muscles (orbicularis oris, submental, and hyoid muscles).

Statistical Analysis

Descriptive statistics will be reported as mean ± standard deviation. Normality will be assessed using the Shapiro-Wilk test.

Comparisons of non-nutritive versus nutritive swallowing within the same participant will be analyzed using the Wilcoxon signed-rank test.

Sequential muscle activation order (e.g., onset timing differences among muscles) will be analyzed using the Friedman test.

A p-value < 0.05 will be considered statistically significant.

Expected Significance

This study aims to clarify the physiological mechanisms of sequential muscle activation during swallowing in typically developing children. The findings are expected to provide essential normative data for the development of pediatric-specific NMES protocols for dysphagia treatment. Establishing age-appropriate stimulation parameters may ultimately contribute to more effective and developmentally tailored therapeutic interventions in pediatric populations.

Inclusion Criteria:

• Children aged 2 to under 10 years
• Children without a diagnosis of dysphagia
• Children without congenital brain lesions or respiratory conditions (e.g., bronchopulmonary dysplasia [BPD], respiratory distress syndrome [RDS]) that may affect the swallowing process
• Children whose legal guardians provide informed consent for participation
• Participants who meet all of the above inclusion criteria

Exclusion Criteria:

• Refusal to provide consent for participation in the study
• Refusal to undergo the study procedures or assessments
• Determined by the principal investigator to be unsuitable for participation -Meeting any of the above exclusion criteria -

Pediatric participants aged 2 years to less than 10 years who have not been diagnosed with dysphagia and have no medical conditions known to affect the swallowing process, such as congenital brain lesions or respiratory diseases, will be enrolled. Participants will be recruited from the outpatient and inpatient services of the Department of Rehabilitation Medicine at Seoul National University Bundang Hospital. Both male and female participants will be included.