Characteristic appearance of the oropharynx in patients with postnasal drip (PND)-induced cough

Post-nasal drip (PND)-induced cough is a common cause of chronic cough. However, there is little known about the characteristic physical findings of this condition.

We investigated views of the pharyngeal wall in patients with PND-induced cough using a handy endoscopic images.

The subjects were 135 consecutive patients referred to our hospital with a sensation of something "dripping down the throat" as one of their symptoms. Physical findings for the oropharynx were examined using Wi-Fi endoscope camera. The difference in probability of symptoms in patients with acute cough and those with subacute/chronic cough was assessed using a Bayesian Fisher exact test on a 2 × 2 table.

Among the patients, 105 (78%) complained of cough, 78 (58%) of acute cough, 20 (15%) of subacute cough, and 7 (5%) of chronic cough; and 71 (53%) had coexisting asthma. Using Bayesian inference, a sore or scratchy throat and fever were more common in patients with acute cough than in those with subacute/chronic cough. In endoscopic images of the oropharynx, a reddish curtain sign on the posterior pharyngeal wall behind the palatopharyngeal arch was found in 121 patients (90%).

Patients with acute PND-induced cough have a component of acute upper respiratory infection, because of high probability of a sore or scratchy throat and fever as symptom. A reddish curtain sign may be a useful finding for identifying PND-induced cough in these cases.