Correlations between the olfacto-respiratory reflex and nasal mucosa blood flow: comparative evaluation through rhinomanometry and laser-Doppler flowmeter testing.

The authors compared the reliability of the olfacto-respiratory test with the vasomotor response evoked by the olfactory stimulation of nasal mucosa, as detected by laser-Doppler flowmetry. The aim was to investigate the possible advantages offered by laser-Doppler flowmeter testing, since this machine has a great capacity for detecting even very small variations in blood flow. The authors, however, can affirm that laser-Doppler flowmetry is only able to detect reflex reactions evoked by stimuli affecting trigeminal innervation. No reaction could be detected following trial with purely olfactory odorants and, in any case, even the reaction to olfacto-trigeminal or gusto-olfacto-trigeminal stimuli could be detected only in response to stimulation that was quantitatively stronger than that necessary to trigger the corresponding respiratory reflex.