Why does duglutition apnea occur during swallowing?

Answer 1

There is a fleshy flap-like structure called epiglottis that is situated in the throat, behind the tongue, at the entrance to the larynx, that is, at the point where the larynx and trachea (conduct leading to the lungs) and the esophagus (conduct leading to the stomach) meet. The epiglottis works as a valve that covers the entrance to the lungs while food is passing down the pharynx and into the digestive system; it's a safety mechanism to ensure that food particles don't damage the delicate respiratory organs.
So while we swallow (deglutition is the technical name for swallowing), we cannot breathe (=we're in apnea), because the entrance to the trachea is closed.

This is a diagram showing the position of the epiglottis:
http://www.emedicinehealth.com/images/4453/4453-4468-10013-23657.jpg
and here's an animation showing the right path for food (green) and the wrong path that can make one choke (red):
http://people.eku.edu/ritchisong/epiglottis.gif

Answer 2

I'm not sure if you wanted a treatment or a symptom. Try hitting this liknk that tells about both...
http://www.wrongdiagnosis.com/medical/deglutition_apnea.htm