Anatomy of the nasal cavity determines intranasal trigeminal sensitivity.

BACKGROUND

Aim of this study was to investigate whether intranasal anatomy plays a role in intranasal trigeminal sensitivity.

MATERIAL AND METHODS

A total of 65 healthy subjects (30 female, 35 male) participated in this study (age range 18-35 years). Nasal cavities were assessed using magnetic resonance imaging (MRI). The area of the nasal cavity was measured in 5 coronal sections distributed across the length of the nasal cavity. Trigeminal function was assessed by determining thresholds for CO2, and responses to suprathreshold stimulation with CO2 and menthol (intensity ratings; event-related potentials). In addition, rhino-manometric measures were obtained.

RESULTS

A positive correlation was found between the size of the nasal cavity and trigeminal event-related potentials in response to suprathreshold CO2 and menthol stimuli. By contrast, no such correlations were found between nasal cavity size and CO2 thresholds. Results from rhino-manometry correlated only with the size of the nasal cavity in the nasal valve area.

CONCLUSIONS

These data suggest that, at least at a suprathreshold level, nasal anatomy plays a significant role in determining interindividual differences in the sensitivity to trigeminal stimuli.