Sequence of Actions in the Cough Reflex Pathway Resulting in Cough
The chronic cougher tends to have an increased urge to cough. It can be described as a tickle in the back of the throat. Sometimes it can be a feeling that something is stuck there. Often, there is a feeling of post nasal drip, but rarely any is produced. A hypersensitive or heightened cough reflex requires less stimuli, such as nasal secretions, airborne irritants, acid or gastroesophageal reflux, to trigger a chronic cough. What creates these feelings?
- Cough receptors in the upper airway (nose), larynx (voice box), lung, and esophagus are activated by direct irritation such as throat infection, post nasal drip or gastric acid (which has contact with the receptors in the larynx/voice box)
- The receptors send a signal to the cough center in the lower brain area
- The cough center then decides if there is enough stimulus to set off a cough
- The cough center becomes hyperactive by repeated stimulation from the peripheral cough receptors
- The cough center is also influenced by higher brain function which can result in a voluntary and habit cough
- Stimulation of the upper airway, esophagus, and lung can heighten or sensitize the cough reflex without actually triggering off a cough. For example, acid or even food entering the esophagus from the stomach can send signals to the cough center to become more sensitive or irritable. Allergic nasal symptoms also send signals to the cough center and increase sensitivity.