Cerebrospinal fluid response following metrizamide myelography in normal dogs: effects of routine myelography and postmyelographic removal of contrast medium

The effect of metrizamide myelography on 90-minute postmyelographic cerebrospinal fluid (CSF) samples was evaluated in a paired crossover study in 16 normal dogs. Each dog received a routine cervical myelogram (nonwithdrawal myelography) and a myelogram followed by contrast medium removal via aspiration from the subarachnoid space (withdrawal myelogram). Following nonwithdrawal myelography, the CSF was characterized by mild inflammation with a mixed pleocytosis and increased protein concentration. Compared with the nonwithdrawal CSF samples, the postmyelographic CSF of the withdrawal dogs had a more severe inflammatory response with significant increases (p < 0.05) in absolute numbers of neutrophils, monocytoid cells, eosinophils, lymphocytes, and protein concentration. The withdrawal procedure may have contributed an additional mechanical effect on the leptomeninges producing the more severe inflammatory response in the withdrawal dogs. Although seizure data are not reported here, postmyelographic seizures were more frequent following non-withdrawal myelography as compared with withdrawal myelography (p < 0.05), suggesting a decrease in metrizamide-induced neurotoxicity for the withdrawal dogs.