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Genioglossus activity in children with obstructive sleep apnea during wakefulness and sleep onset
1Division of Respiratory Diseases, Department of Medicine, Children's Hospital Boston, MA 02115, USA. eliot.katz@tch.harvard.edu
Insights
Children with obstructive sleep apnea syndrome (OSAS) show increased genioglossal muscle activity during wakefulness. This muscle activity declines during sleep onset, suggesting a loss of protective reflexes in pediatric OSAS.
Area of Science:
- Pediatric Pulmonology
- Sleep Medicine
- Neuromuscular Control
Background:
- Obstructive sleep apnea syndrome (OSAS) in children is linked to upper airway neuromuscular control.
- Airway obstruction in pediatric OSAS is absent during wakefulness and rare during non-REM sleep.
Purpose of the Study:
- To investigate genioglossal electromyography (EMGgg) activity during wakefulness, sleep onset, and stable non-REM sleep in children with OSAS.
- To compare EMGgg activity between children with OSAS and normal controls.
Main Methods:
- Utilized a custom intraoral surface electrode for genioglossal electromyography (EMGgg) recording.
- Normalized EMGgg activity with a maximal maneuver.
- Studied 10 children with OSAS and 6 healthy controls across different sleep-wake states.
Main Results:
- Children with OSAS exhibited significantly higher wakeful EMGgg activity compared to controls (3.6% vs. 1.6% maximum).
- EMGgg activity showed a greater decline during sleep onset in children with OSAS.
- During stable non-REM sleep, EMGgg increased above baseline in some OSAS patients, unlike controls.
Conclusions:
- Increased wakeful EMGgg in pediatric OSAS may represent neuromuscular compensation for an anatomically narrowed airway.
- The decline in EMGgg at sleep onset suggests a loss of protective reflexes in OSAS.
- Elevated EMGgg during stable non-REM sleep in severe OSAS indicates persistent compensatory mechanisms.
Abstract:
A prominent role for upper airway neuromuscular control mechanisms in the pathophysiology of pediatric obstructive sleep apnea syndrome (OSAS) is suggested by the observation that obstruction does not occur during wakefulness and is infrequently seen during non-REM sleep. Using a custom intraoral surface electrode to record genioglossal activity (genioglossal electromyography [EMGgg]), normalized with a maximal maneuver, we studied 10 children with OSAS and 6 normal control subjects to determine EMGgg activity during (1) wakefulness, (2) the sleep onset period, and (3) stable non-REM sleep. We observed that the EMGgg activity in patients with OSAS compared with control subjects was significantly greater during wakefulness (3.6 +/- 1.8 vs. 1.6 +/- 1.8% maximum, p < 0.05) and had a greater decline during the early and late sleep onset period (p < 0.05). During stable non-REM sleep, EMGgg remained below the wakeful baseline in all normal control subjects but increased above the baseline in four of the patients with OSAS. We speculate that the increased EMGgg activity during wakefulness represents a reflex-driven neuromuscular compensation for an anatomically compromised airway. Furthermore, the larger decline in EMGgg at sleep onset observed in patients with OSAS is consistent with the relative loss of this reflex. Finally, the return of EMGgg activity above baseline in patients with severe OSAS suggests that some chemical or mechanical compensatory mechanisms remain active during stable non-REM sleep in children.