Absence status epilepticus resulting from metrizamide and omnipaque myelography

Critical Assessment of Myelography Practices: A Call for Rational Guideline Revision

BACKGROUND AND PURPOSE

Patient preparation for myelography and postprocedural monitoring varies widely between practices, despite published guidelines. Our aim was to examine the current practice variations in discontinuing reportedly seizure threshold-lowering medications before myelography and to assess the reported incidence of postmyelographic seizures.

MATERIALS AND METHODS

An e-mail survey was sent to American Society of Neuroradiology members concerning the number of postmyelographic seizures experienced in the past 5 years, the presence of an institutional policy for discontinuing seizure threshold-lowering medications, and the type of myelographic contrast used. We compared the postmyelographic seizure frequency in the responses.

RESULTS

Of 700 survey responses, 57% reported that they do not discontinue seizure threshold-lowering medications before myelography. Most (97%) indicated never having a patient experience a seizure following myelography. The number of postmyelographic seizures between those who discontinue seizure threshold-lowering medications and those who do not was not statistically significant (OR = 2.13; 95% CI, 0.91-4.98; P = .08). Most (95%) reported using nonionic hypo-osmolar agents.

CONCLUSIONS

Survey results revealed widely variable practices for patient myelography preparation and postprocedural monitoring. We found no difference in reported seizures between those who discontinued seizure threshold-lowering medications and those who did not. In light of our findings, we propose that discontinuing reportedly seizure threshold-lowering medications is not warranted with the current nonionic water-soluble contrast agents and may be potentially harmful in some instances. This work supports revision of existing recommendations to withhold such medications before myelography.

Postoperative seizure following transforaminal percutaneous endoscopic lumbar discectomy

Endoscopic surgery for lumbar disc herniation has been available for more than 30 years. Transforaminal percutaneous endoscopic lumbar discectomy is a well-known, safe, and effective method used for the treatment of the lumbar disc herniation. The published complications of the transforaminal percutaneous endoscopic lumbar discectomy consist of infections, thrombophlebitis, dysesthesia, dural tear, vascular injury, and death. Seizure after transforaminal percutaneous endoscopic lumbar discectomy is an extremely rare complication. A 20-year-old patient applied at our department who had undergone transforaminal percutaneous endoscopic lumbar. During the procedure, while performing the discography, non-ionic contrast media was administered into the thecal sac inadvertently. Two hours after surgery, the patient developed generalized tonic-clonic seizure of 5-min duration. Diagnosis of iohexol-induced seizure was made and the patient was treated supportively without anti-epileptics. Here we present the first case of seizure after transforaminal percutaneous endoscopic lumbar discectomy, which was caused by inadvertent administration of the contrast media into the thecal sac.

Nonconvulsive status epilepticus

Nonconvulsive status epilepticus (NCSE) refers to a prolonged seizure that manifests primarily as altered mental status as opposed to the dramatic convulsions seen in generalized tonic-clonic status epilepticus. There are 2 main types of NCSE, each of which has a different presentation, cause, and expected outcome. In the first type of NCSE, patients present with confusion or abnormal behavior, suggesting the diagnosis of absence status epilepticus (ASE) or complex partial status epilepticus (CPSE). The second type of NCSE (subtle status epilepticus [SSE]) must be considered in comatose patients who present after a prolonged generalized tonic-clonic seizure and who may have only subtle motor manifestations of a seizure, such as facial or hand twitchings. Whereas the morbidity and mortality in patients with prolonged ASE or CPSE is low, the mortality associated with SSE can exceed 30% if the seizure duration is greater than 60 minutes.

Seizure Potential of Concomitant Medications and Radiographic Contrast Media Agents

OBJECTIVE

To review seizure risk of concomitant medication administration and nonionic, water-soluble radiographic contrast media agents for myelography.

DATA SOURCES

Clinical literature was identified through MEDLINE (1966-May 2003). Key search terms included metrizamide, iohexol, myelogram, myelography, seizure, and contraindications.

DATA SYNTHESIS

Administration of myelography contrast media can produce rare serious adverse events, including meningeal irritation, seizures, or psychological disturbances. An evaluation of case reports and clinical trials concerning seizure risks of nonionic, water-soluble radiographic myelography contrast media and concomitant medications with potential to lower the seizure threshold was performed.

CONCLUSIONS

Available data supporting the incidence of increased seizure risk with nonionic, water-soluble contrast media agents and concomitant medication administration that lowers the seizure threshold are anecdotal. However, because of product labeling and additive potential to decrease the seizure threshold, discontinuation of such medications should be considered to avoid the presumed increased risk of seizures.

Acute psychosis following cervical myelography with iohexol

We report a young man who developed transient acute psychosis following uneventful cervical myelography with iohexol. This complication has not been described previously.

Somatosensory evoked potentials after iohexol myelography

Tibial nerve and S1 dermatome somatosensory evoked potentials (SSEPs) were recorded before and after iohexol lumbar myelography in order to evaluate possible neurotoxic effects of this contrast medium. No significant change in SSEP latencies nor amplitudes was noted after iohexol myelography, supporting the low neurotoxic profile of this contrast agent. Results were compared to those of a control group of patients before and after lumbar puncture (LP), without injection of contrast agent. In this group also no significant change in SSEP components was found, indicating that a preceding LP does not affect this electrophysiological examination.