TAPPING-TIME INFLUENCES CONCENTRATIONS OF 5-HIAA IN THE CSF

Lumbar puncture was performed on 12 healthy male volunteers at the L 4 -5 level to investigate the influence of tapping-time on CSF levels of transmitter metabolites. Applying a backward multiple regression mode l to the data, height, age and tapping-time was found to influence 5-H IAA while HVA correlated only with height. Also HMPG was influenced by height, but the distance from the external occipital protuberance to the site of puncture made a contribution. The present results indicate that tapping-time might be a factor of importance when using CSF conc entrations of 5-HIAA as a measure of serotonin turnover.