Incidence of post-lumbar puncture headache is independent of daily fluid intake.

The clinical practice of advising patients to increase their daily fluid intake after lumbar puncture in order to increase CSF production by re-hydration and thus try to prevent post-lumbar puncture headache (PLPH) has not yet been shown to be effective. In 100 patients the different effects of re-hydration on the incidence of PLPH (1.51 compared with 3.01 oral fluid per day over a period of 5 days) were tested prospectively. The incidence of PLPH was independent of the amount of fluid intake in both groups (18, 36%), as was the duration of PLPH. The physiology of CSF production and resorption suggests that PLPH is not a problem of CSF dynamics but a simple mechanical problem of how to close the dural rent and thereby stop the continuous leakage. It is no longer justifiable to advise patients to drink more than usual since there is no physiological or empirical basis for this and it does not seem to have even a placebo effect.