Effect of Lidocaine on Olfactory Perception in Humans

The effect of local anesthesia to the nasal mucosa on olfactory acuity is the subject of some debate. This study was aimed to investigate the effect of local anesthesia on olfactory perception.

Six healthy participants, five males and one female, were chosen from the academic population of Cardiff University. Olfactory perception was monitored at intervals following administration of 4% lidocaine to the nasal mucosa in the volunteers. Lidocaine was administered using a nasal spray as used in routine otolaryngological investigations. The olfactory stimulus (amyl acetate) was delivered directly to the nostril using an olfactometer. Olfactory perception was determined by the use of a 13 trial, forced choice scoring task.

Lidocaine caused a small, transient reduction in olfactory perception. The maximum reduction in olfactory perception (35%) was achieved by 60 mg lidocaine 15 min following administration, but perception could be increased to almost normal levels by increasing the odor stimulus dose. Detection of the lowest stimulus strength returned to normal levels after 30 min.

Intranasal application of lidocaine, caused a reduction in olfactory perception, however, did not abolish the olfactory function 15 min following administration. Physiological/psychometric olfactory testing would not be precluded under these circumstances, and the effects of anesthesia could be overcome by increasing the stimulus strength.