Nasal obstruction is a common symptom which is most frequently associated with an increased nasal airway resistance. However it is important to appreciate that the objective measurement of nasal airway resistance does not always correlate with the subjective perception of the degree of nasal obstruction. Damage to trigeminal sensory nerve endings can cause a sensation of nasal stuffiness without any change in nasal airway resistance and similarly inhalation of menthol can cause a subjective improvement in nasal sensation of airflow without any change in nasal resistance.