Perception of pungent, gustatory and olfactory stimuli in patients with congenital insensitivity to pain with anhidrosis

Congenital insensitivity to pain with anhidrosis (CIPA) is a rare disease caused by a mutation in the nerve growth factor (NGF) receptor, which results in an absence of A delta and C fibers. It can be considered that this defect may also lead to deterioration of oral sensations. The aim of the present study was to clarify the ability of CIPA patients to perceive pungent, gustatory, and olfactory stimuli, which is essential for eating function, and the impact of the defect on dietary habits. Sensitivities to capsaicin and the five basic tastes were evaluated by measuring their threshold values, and dietary habits were examined using a questionnaire. Additionally, odor identification ability was evaluated using the odor stick method. The detection threshold for capsaicin and the recognition threshold for sour taste were significantly higher in the patients than in healthy volunteers. The questionnaire responses showed that the patients consumed spicy food more often. All patients were able to identify the tested odors, except those to which they had not been well accustomed. Since the abilities of CIPA patients to perceive taste and smell were not basically impaired, despite their lower sensitivity to capsaicin, it was suggested that their dietary habits were only minimally affected, except for intake of pungent foods.