Substance P concentration and history of headache in relation to postlumbar puncture headache: towards prevention.

Medical treatment of postlumbar puncture headache (post-LP HA) is often difficult and ineffective. Prevention would be preferable to more invasive procedures, including blood patch. The aim was to determine the incidence of post-LP HA in two suspected high risk groups compared with the general outpatient population. Based on previous research, it was hypothesised that a low substance P concentration, or a history of chronic headache, or both would be associated with a higher risk of post-LP HA. A total of 310 randomly selected patients undergoing diagnostic lumbar puncture in the outpatient neurology clinic over 30 consecutive months were studied. Follow up was by headache questionnaire or phone survey after diagnostic lumbar puncture. Substance P was measured by radioimmunoassay on a subset of 102 samples of CSF. The overall incidence of post-LP HA was 38%. Patients with a measured substance P value < 1.3 pg/ml were three times as likely to have post-LP HA than those with a higher value. A history of chronic or recurrent headache was reported by 57% of those who developed post-LP HA. This group was also three times as likely to experience post-LP HA as those who did not have chronic headaches.