[Detection rates of chemosensory evoked Potenzials with healthy and anosmic subjects].

Background: The detection rate of olfactory chemosensory event-related EEG Potentials (oCSERP) and trigeminal chemosensory event-related EEG Potentials (tCSERP) is also dependent on the stimulants and the evaluator of the averaged EEG curves.

Methods: In 45 subjects with age-appropriate normal olfactory capacity (NP) and 20 anosmics (AN), oCSERP (stimulation by hydrogen sulphide, HS 6 ppm and phenylethyl alcohol, PEA 30 % v/v,) and tCSERP (irritation with CO 20-60 % v/v, intensity standardized) were derived by default. Two investigators categorized the averaged EEG curves in: CSERP recognizable, no CSERP recognizable and artefact. Investigator 1 knew whether the subject was a NP or an AN, and which stimulants was used, whereas investigator 2 lacked this information.

Results: AN needed higher trigeminal stimulus concentrations but showed same intensity ratings compared to NP. The attention (tracking game) did not deteriorate in the course of test. The detection rate of HS-CSERP was higher than that of PEA-CSERP. The match of HS-CSERP detection rates between the two investigators was higher than that of PEA-CSERP and CO-CSERP.

Conclusion: For the standard derivation of oCSERP, stimulation with HS is usually sufficient. Stimulation with PEA and CO as well as a blinded investigator is not necessary.