Pharyngeal stimulus-induced reflexes are impaired in infants with perinatal asphyxia: Does maturation modify?

BACKGROUND

Development of pharyngo-esophageal protective reflexes among infants with hypoxic ischemic encephalopathy (HIE) is unclear. Our aim was to distinguish these reflexes from controls and examine the maturational changes in HIE infants.

METHODS

We evaluated 14 HIE infants (seven males) at 41.4±0.6 (HIE Time-1) and 46.5±0.6 (HIE Time-2) weeks postmenstrual age (PMA). Seven controls (three males) were evaluated at 43.5±1.3 weeks PMA. Graded pharyngeal stimulation with liquids (0.1, 0.3, 0.5 mL in triplicate) concurrent with high-resolution manometry was used to analyze sensory-motor components of pharyngeal reflexive swallowing (PRS), upper esophageal sphincter (UES), contractile reflex (PUCR), and esophageal body characteristics. Linear mixed and generalized estimating equation models were used for comparison among groups.

KEY

RESULTS

Compared to controls, HIE infants (Time-1 and Time-2) exhibited decreased number of pharyngeal peaks and latency to terminal swallow. HIE Time-1 infants showed increased UES resting tone and distal latency, compared to controls and HIE Time-2. Contractile vigor was increasingly abnormal during maturation, compared to healthy controls. Threshold volumes and frequency distribution of primary responses (PRS: PUCR: None) were not significant among all groups.

CONCLUSIONS & INFERENCES: Compared to controls, HIE infants display significant hypertonicity of skeletal muscle components, impairment of pharyngeal provocation-induced reflexes and smooth muscle contractile vigor, reflecting poor propagation with maturation. These mechanisms may be responsible for inadequate clearance of secretions, ascending refluxate, and oropharyngeal bolus in HIE infants.