CHEMOSENSORY EVENT-RELATED POTENTIALS IN RESPONSE TO TRIGEMINAL AND OLFACTORY STIMULATION IN IDIOPATHIC PARKINSONS-DISEASE

Decrease of olfactory function in patients with Parkinson's disease (P D) has been reported by several authors. The current study investigate d olfaction in PD patients using olfactory event-related potentials (O ERPs) as an electrophysiologic correlate of olfactory function in comb ination with psychophysical testing. A specific focus was the influenc e of antiparkinsonian drugs. We investigated PD patients treated with antiparkinsonian drugs (n = 13) and PD patients who received no pharma cologic treatment (n = 18). They were compared to age-and sex-matched control subjects (n = 38). To obtain OERPs, stimulants were chosen to stimulate specifically the olfactory nerve (2.1 ppm vanillin, 0.8 ppm H2S). In addition, chemosomatosensory event-related potentials were re corded after trigeminal stimulation with 52% v/v CO2. Moreover, the su bjects' ability to identify and to discriminate odorants was tested by means of a ''squeeze bottle'' technique. The study yielded the follow ing major results: (1) Odor identification was impaired in PD patients . It was not influenced by treatment with antiparkinsonian drugs. (2) The OERP latencies were prolonged in both PD patients taking and not t aking antiparkinsonian drugs; however, this effect was mare pronounced in PT) patients taking antiparkinsonian drugs. (3) The intranasal che mosensory trigeminal system seemingly was neither affected by the neur onal degeneration seen in PD nor by treatment with antiparkinsonian dr ugs.