Myelography with Omnipaque (Iohexol) using basic radiographic facilities: the main adverse effects

Documentation of main adverse effects, their magnitudes and relationship to contrast concentrations in patients subjected to myelography under basic radiographic facilities. Use of the acquired data for better patient management in the future.

In a prospective double blind study consecutive admitted neurological patients of age range seven to 77 years were subjected to myelography with different concentrations of Omnipaque (300* cervical, 240* thoracic and 180* lumbar) under limited radiographic facilities by radiologists (cases). Thirty admitted patients of about the same age range with justified medical problems were subjected to diagnostic lumbar puncture by different physicians (controls). The main adverse effects were assessed in both groups (subjects) by a neuro-physician unaware of subject status. Patients primarily admitted to the hospital with headache, dizziness, nausea, vomiting and convulsions and subjected to lumbar puncture were excluded from the study.

Cases and controls were derived from patients referred from variable regional hospitals scattered throughout the country.

110 consecutive neurological cases referred to the Radiology Department for myelography between December 1989 and January 1991. Thirty consecutive qualifying diagnostic lumbar puncture patients managed at the same period.

Development of symptoms including headache, dizziness, nausea, vomiting and convulsions and evaluation of their magnitude subjectively quantitated from mild (+) and moderate (+2) (tolerable) to severe (+3), (intolerable) among the cases and controls.

Overall, symptoms in all magnitudes (mild to severe) occurred in 63.6pc of cases compared to 36.7pc of controls (p < 0.05). Concentrations of 300 and 180 were more associated with the effects (p = 0.017 and 0.016 respectively) while the 240 concentration was relatively safe causing no more adverse effects than a diagnostic lumbar puncture (p = 0.137). In severe magnitudes (intolerable) the same effects occurred in 20.9pc of cases compared to 6.7pc of controls (p < 0.05); differences in contrast concentrations did not significantly feature (p = 0.59: Omnipaque 300; p = 0.063: Omnipaque 240 and p = 0.061; Omnipaque 180).

Even with limited radiographic facilities, myelography with Omnipaque 240 is relatively safe; being associated with no more adverse effects than a medical diagnostic lumbar puncture; thus the contrast concentration of choice for myelography under sub-optical radiographic set up. With the 180 and 300 concentrations, the procedure is associated with tolerable adverse effects not significantly differing from those arising from the same procedure performed under ideal radiodiagnostic establishments.