Lumbar myelography with metrizamide-a new non-ionic contrast medium.

In contradistinction to all currently available water-soluble contrast media, metrizamide (Amipaque) is not a salt, but a substituted amide and therefore does not dissociate in solution. This unique property results in solutions of high iodine content yet with low osmolality. Metrizamide probably has a lower neurotoxicity than any other known water-soluble contrast agent. A clinical trial of metrizamide lumbar myelography in 201 patients in three clinical centres represents the first clinical assessment of this new contrast medium in the United Kingdom. The technique of the radiological procedure and the adverse reactions encountered are presented and discussed. There were no serious adverse effects: no muscle spasm or epilepsy. Minor adverse reactions--headache, vomiting and nausea occur with approximately the same frequency as with meglumine iocarmate: 43 percent of patients complained of headache. In 118 patients, the lower dorsal subarachnoid space was also examined with no increase in toxic reactions. It is concluded that metrizamide is a safe contrast medium for lumbar and lower dorsal myelography. Water-soluble media will probably largely replace oil products for these investigations. Further clinical trials are being extended to include examination of the upper dorsal and cervical subarachnoid space.