Evaluation of myelographic contrast-medium tolerance with psychometric testing.

Clinical tolerance to the myelographic contrast media metrizamide and iopamidol was evaluated in 26 and 30 patients, respectively, with a battery of neuropsychologic tests before and after myelography in a randomized, double-blind prospective study. Twenty hospitalized patients with chronic back pain were also studied before and after computed tomography to serve as controls relative to the groups administered contrast agents. Measures of conceptual reasoning and affect were sensitive tests of adverse reactions. These paralleled the incidence of somatic reactions and correlated with the dose of contrast medium. Methodologic problems included varying intervals between myelography and psychometric evaluation among subjects and use of a less-than-ideal control group. Neuropsychologic tests appear to be sensitive for detection of subtle adverse reactions and possibly predictive of their occurrence. Iopamidol was tolerated better than metrizamide, with somatic side effects occurring in 38% of patients receiving metrizamide and in 17% of patients receiving iopamidol.