Olfactory dysfunction in Parkinson's disease.

An olfactory function test in 18 patients with Parkinson's disease (PD) and 10 age-matched control subjects was performed. Both detection and recognition thresholds were measured with five kinds of synthesized odorants (T & T olfactometry). Before each test, rhinoscopic inspections were performed to exclude subjects who could have respiratory hyposmia. Both detection and recognition thresholds in patients with PD were significantly elevated in comparison with those of control subjects. Auditory acuity of PD patients, however, was well preserved and there was no significant correlation between auditory and olfactory threshold. On the basis of the present study, the authors conclude that olfactory dysfunction is one of the characteristic symptoms of PD and it may be attributed to lesions in the olfactory neural pathway including olfactory neuroepithelium.