Headache after lumbar iohexol myelography: the influence of a history of headaches and early ambulation.

Whether a history of headache or "early" versus "late" ambulation (no bed rest or bed rest for 24 h) influence the occurrence of headache after lumbar iohexol myelography was studied by blinded interviews in 158 consecutive patients referred for elective lumbar myelography (LM) because of suspected lumbar disc prolapse or spinal stenosis. Headache after LM occurred more often in patients with a history of headache (57%) than in patients without such a history (29%), P < 0.001. Patients with normal myelographic findings complained of headache after LM more often (55%) than patients with abnormal myelograms (31%), P < 0.008. No difference in the incidence of headache after LM was demonstrated in early versus late ambulation.