Olfactory event-related potentials in psychosis-prone subjects

Previous studies in schizophrenic patients have suggested that there are changes in olfactory sensitivity. In order to externally validate a psychometrical assessment of the psychosis-risk indicated by schizotypic factors, this study was carried out to determine whether changes in olfactory perception could be determined even for persons merely at risk of developing schizophrenia. These 'psychosis-prone' subjects consistently scored high in either the scale for 'physical anhedonia' (PA) or the scale for 'perceptual aberration' (PAB). Thus, three groups were investigated (control, n = 11; PA, n = 12; PAB, n = 12). Each subject participated in one testing session where the two odorants, vanillin (pleasant) and hydrogen sulphide (unpleasant), were applied by means of a specially designed delivery apparatus. Subjects rated both the intensity and the hedonic quality of the stimuli. In addition, olfactory event-related potentials (OERP) were recorded after dichotomous stimulation. In general, there were only few significant differences between the three groups investigated. Contrary to expectations, ratings for pleasantness of vanillin were highest in PA subjects compared to PAB subjects and controls (p < 0.05). Correspondingly, OERP amplitudes in response to vanillin were largest within the PA group (p < 0.05). For hydrogen sulphide, PAB subjects showed the smallest OERP amplitudes (p < 0.05). In addition, it was observed that female subjects had significantly larger OERP amplitudes when compared to male subjects (p < 0.05), which possibly indicates gender differences in olfactory sensitivity.

Pain in extracorporeal shock-wave lithotripsy: a comparison of different lithotripters in volunteers

The aim of the present study was to investigate pain sensations experienced during extracorporeal shock-wave application, comparing an electrohydraulic (MPL 9000; Dornier Medizintechnik, Germering, Germany), an electromagnetic (Lithostar Plus; Siemens, Erlangen, Germany), and a piezoelectric (Piezolith 2300; Wolf, Knittlingen, Germany) shock-wave system. In nine healty volunteers, three therapeutically used intensities were applied in a randomized order with each lithotripter (MPL 9000: 16, 20, and 24 kV; Lithostar Plus: settings 5, 7, and 9; and Piezolith 2300: settings 2, 3, and 4). The subjects received nine series of 20 shock waves amounting to a total of 180 shock waves per session. The treatment was performed under clinical conditions, and no premedication was given. A visual analog scale and the McGill Pain Questionnaire were used for assessment of pain. In addition, somatosensory evoked potentials caused by shock-wave stimulation were recorded. Some of the volunteers were unable to bear the pain caused by the highest shock-wave intensity of the electrohydraulic (n = 3) and the electromagnetic system (n = 4). Estimates using the visual analogue scale showed increased pain sensations with increasing energy settings for each lithotripter. The amplitudes of the somatosensory evoked potentials became larger, and latencies shortened with increasing stimulus intensities (P less than 0.05). Subjective estimates by means of the visual analogue scale (P less than 0.01) as well as the McGill Pain Questionnaire (NS) and the somatosensory evoked potentials (P less than 0.05) showed that stimulation by the piezoelectric lithotripter was less painful than stimulation by the two other generators.

Dose-related analgesic effects of flupirtine

1. Flupirtine is a novel and, in all probability, centrally acting, analgesic. The present investigation was conducted in order to investigate dose-related effects of perorally administered flupirtine in man, with special regard to specifically analgesic actions, employing a model based on pain-related chemosomatosensory evoked potentials and subjective intensity estimates of painful stimuli. 2. Plasma concentrations of flupirtine measured 2 h after dosing linearly increased as a function of the administered dose. 3. It was possible to reproduce our own previously obtained results, which established the analgesic action of 200 mg flupirtine administered perorally. 4. Intensity estimates linearly decreased as a function of the administered dose, whereas chemosomatosensory evoked potential amplitudes non-linearly changed in relation to the administered dose. 5. In the spontaneous EEG, a dose-dependent increment in the power-spectra was observed, and this mainly in the alpha- and beta-range.