Headache following a lumbar puncture （post-lumbar-puncture headache,PLPH）is a common and often debilitating syndrome, which was reported to occur in about 40% patients who received lumbar puncture. Now there lacks of effective approaches in the prophylaxis of PLPH, although some physicians consider bed rest for at least 6 hours to be a useful methods (Some recent meta-analysis found no benefit of bed rest for any hours in the prevention of PLPH). Studies have found that P substances and its receptor (Neurokinin-1 receptor, NK-1R)have played an important role in the pathogenesis of PLPH. Thus, we hypothesize that use of NK-1R inhibitor (aprepitant) 1 hour before lumbar puncture may decrease the incidence of PLPH and lower the severity of PLPH.