A time-saving method for recording chemosensory event-related potentials

The objective of this study was to reduce the recording duration of chemosensory event-related potentials (CSERP) and thereby to make the method more suitable for routine clinical use. Measurements were performed in the Department of Otorhinolaryngology of the university hospital of Cologne. Two protocols with different sequences [inter-stimulus intervals (ISI)-standard sequence: 30 s; PRS-15: pseudo-randomized sequence, mean ISI of 15 s] were applied to 40 volunteers to record CSERPs. To compare CSERP recordings under optimal and adverse test conditions, 20 younger/normosmic adults and 20 older/hyposmic participants were included in this study. Olfactory function was gauged using the “Sniffin’Sticks” test. For CSERP recordings, phenylethyl alcohol, hydrogen sulfide and carbon dioxide were used for olfactory or trigeminal stimulation, respectively. Both ISI protocols allowed recording CSERPs under optimal and adverse test conditions and distinguishing both groups by latencies (p ≤ 0.015). The time requirement for the recording of CSERPs with the PRS-15 sequence was less than 30 min. The pseudo-randomized sequence allowed the recording of diagnostically conclusive CSERPs in both groups and saved approximately 40% of the measuring time. This seems to be especially useful in cases where a yes/no answer (e.g., medical reports, exclusion of anosmia) is required. Shortening the time requirement significantly allows applying CSERPs to larger populations of patients with olfactory impairment.