Side effects after ambulatory lumbar iohexol myelography.

Side effect incidences after ambulatory (22G needle and two h bed rest) and after non-ambulatory (22 and 20G needles and 20 h bed rest) lumbar iohexol myelography have been estimated and compared. Headache incidence was significantly greater in ambulatory (50%, n = 107) as compared to non-ambulatory myelography (26%, n = 58). Headaches in the ambulatory group tended to be of shorter duration and the difference between severe headaches in ambulatory and non-ambulatory groups was not significant. Serious adverse reactions did not occur and none of the ambulatory patients required readmission because of side effects. The headache was predominantly postural and occurred significantly earlier in the ambulatory group. Headache incidence was significantly greater after 20G needle myelography (44%, n = 97) as compared to 22G needle iohexol myelography (26%, n = 58). The results supports the hypothesis that CSF leakage is a major cause of headache after lumbar iohexol myelography.