Here's a story you may want to pass on to colleagues in the radiology department. The Institute for Safe Medication Practices recently reported on a patient who received an intrathecal injection of the wrong contrast medium prior to undergoing myelography and died as a result.

A 31-year-old man died after being injected with the wrong contrast media during an outpatient myelogram (spinal radiography). Myelography is safely performed using nonionic water-soluble radiographic contrast media intended for this route of administration. However, misadministration of ionic contrast media intrathecally can result in a syndrome of spasms and convulsions, often leading to death. In this case, it was clear within an hour after the patient received the intrathecal injection of contrast media that something was terribly wrong. The patient was transferred to the Emergency Department, where a neurologist was consulted to diagnose and treat the patient. After visiting the radiology department to investigate, the neurologist discovered that an ionic contrast media, contraindicated for intrathecal use, had been administered in error. The patient was quickly transferred to another hospital for treatment, but he died.

Many radiological contrast agents are neurotoxic and should not be administered intrathecally (1). Oil-based agents (e.g., iophendylate) were introduced many years ago for intrathecal use, but lack of fine image detail (due to cohesiveness) and the need to remove the dye (to prevent arachnoiditis and post-spinal headaches) made these agents suboptimal. Later, ionic water-soluble media (e.g., iothalamate meglumine) were developed. However, they are unsuitable for direct contact with neural tissue, as such contact could lead to severe muscle spasms, seizures, cerebral edema and hemorrhage, coma, paralysis, hypotension, hyperthermia, rhabdomylolysis, multi-system organ failure, and death. An intact blood-brain barrier appears to protect the nervous system when ionic agents are given intravenously. Even then, these agents may cause limited disruption of the blood-brain barrier, particularly when given in high concentrations, which may account for the occasional neurologic complications associated with intravenous use. Over the last 2 decades, nonionic water-soluble agents have been developed (e.g., metrizamide, iohexol), which are significantly less neurotoxic than the ionic water-soluble agents. Some of these agents are suitable for both intravenous and intrathecal administration.

Errors similar to the one cited above have been reported in the literature (2-5) and, like the case above, most patients have died from the neurotoxic effects of ionic contrast media. However, the authors of one error reported in the literature suggest that immediate recognition of a mistake and prompt aggressive treatment may lessen the likelihood of harm or death (5). A 65-year-old man in surgery for a laminectomy had an intra-operative myelogram to confirm complete spinal decompression. The surgeon mistakenly used an ionic agent instead of a nonionic agent. Three hours later (symptoms are often delayed 1 to 6 hours after administration), the patient began experiencing painful clonic spasms in his lower extremities. The spasms increased in frequency and quickly involved his trunk, upper extremities, and face. The patient became obtunded and was intubated. These symptoms, along with hyperthermia and a significantly elevated creatine kinase, led to the quick recognition of the error and prompt, aggressive treatment. Fortunately, the patient recovered with no long-term sequelae.

ISMP points out that only certain products can be safely used intrathecally. In fact, FDA requires the manufacturers of contrast media that are not intended for this use to mark the packages "not for intrathecal use" or "not for myelography."

But these warnings can still be overlooked, and so ISMP has several suggestions to minimize the possibility of error. For example, the pharmacy might consider placing auxiliary warning labels on media that should not be used for myelography.

Various types of contrast media could be stored separately, based on their use. ISMP mentions one facility where media for myelograms are stored in a locked box in an exam room that's used exclusively for intrathecal procedures. No other contrast medium is stored there. Another hospital packages special myelogram kits that include the proper contrast medium. Of course pharmacists should visit these areas periodically to be sure that the right media are in the right places.

And when a contrast medium is to be administered intrathecally, clinical staff should perform an independent double check to be sure the product they're using is the right one for that purpose.

It's also important for the clinical staff to be able to promptly recognize an error and begin treatment, because this may prevent a fatal outcome.

Additional Information:

ISMP Medication Safety Alert. November 27, 2003. "Intrathecal injection of ionic contrast media may be fatal" http://www.ismp.org/MSAarticles/fatal.htm

References: (1) Karl HW, Talbott GA, Roberts TS. Intraoperative administration of radiologic contrast agents: potential neurotoxicity. Anesthesiology 1994;81(4):1068-71. (2) Rosati G, Leto di Priolo S, Tirone P. Serious or fatal complications after inadvertent administration of ionic water-soluble contrast media in myelography. Eur J Radiol 1992;15:95-100. (3) Hilz MJ, Huk W, Schellmann B, et al. Fatal complications after myelography with meglumine diatrizoate. Neuroradiology 1990; 32:70-73. (4) Bohn HP, Reich L, Suljaga-Petchel K. Inadvertent intrathecal use of ionic contrast media for myelography. Am J Neuroradiology 1992;3:1515-19. (5) Killeffer JA, Kaufman HH. Inadvertent intraoperative myelography with Hypaque: case report and discussion. Surg Neurol 1997;48:70-73. (6) Manual on contrast media. Edition 4.1 (2003). American College of Radiology.