Background: The swallowing reflex is well coordinated
with breathing patterns in normal humans. However, patients with
obstructive sleep apnea syndrome (OSAS) may have a swallowing disorder
that reflects the abnormal function of nerves and muscles in the
Objective: To examine the
relationship between the swallowing function and sleep-disordered
breathing in patients with OSAS.
patients with OSAS with a mean (± SD) age of 53.4 ± 8.9 years old,
and 20 age-matched control subjects with a mean age of 51.4 ± 9.1
Methods: OSAS was diagnosed using
the recordings of overnight polysomnography. The swallowing function in
the subject was tested using a swallowing provocation test. The
swallowing reflex was determined according to the following criteria:
latent time (LT), the time following a bolus injection of distilled
water at the suprapharynx to the onset of swallowing;
inspiratory suppression time (IST), the time from the termination of
swallowing to the next onset of inspiration; and threshold volume, the
minimum volume of water (range, 0.4 to 2 mL) that could evoke the
Results: Whereas the LT
values in patients with OSAS were larger than the LT values in the
control subjects, the IST values (which may reflect the switching
mechanism from deglutition apnea to breathing) were actually shorter.
In addition, a greater bolus volume was necessary to elicit swallowing
in patients with OSAS than was necessary in the control subjects.
Conclusion: Patients with OSAS are likely to exhibit an
impaired swallowing reflex, probably due to the perturbed neural and
muscular function of the upper airways.