A double-blind clinical trial of iopamidol versus metrizamide for lumbosacral 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.

Outpatient Myelography: A Prospective Trial Comparing Complications after Myelography between Outpatients and Inpatients in Japan

STUDY DESIGN

Prospective comparative study.

PURPOSE

To compare the incidence and severity of adverse reactions associated with myelography performed in outpatients vs. in inpatients and report the safety and usefulness of outpatient myelography in Japanese patients.

OVERVIEW OF LITERATURE

Myelography is normally performed as an inpatient procedure in most hospitals in Japan. No studies have reported the usefulness and adverse effects of outpatient myelography in Japanese patients.

METHODS

We performed 221 myelography procedures. Eighty-five of the 221 patients underwent outpatient myelography using our new protocol. The incidence and severity of adverse reactions were compared with the other 136 patients, who underwent conventional inpatient myelography. We further compared the cost of outpatient and inpatient myelography.

RESULTS

The overall rate of adverse effects was 9.4% in outpatients, as compared with 7.4% in inpatients. Overall, 1.2% of outpatients and 0.74% inpatients experienced "severe" adverse effects (requiring hospitalization). There were no significant differences between the 2 groups in either the overall rate of adverse effects or the rate of "severe" adverse effects. Moreover, the average outpatient procedure cost was only one-third to one-half that of the inpatient procedure.

CONCLUSIONS

This was the first study to address the safety and usefulness of outpatient myelography in Japanese patients. If selected according to proper inclusion criteria for outpatient procedure, no significant differences were observed in the adverse effects between inpatients and outpatients. The outpatient procedure is more economical and has the added benefit of being more convenient and time-efficient for the patient.

Complications of fluoroscopically guided transforaminal lumbar epidural injections

OBJECTIVES

To assess the incidence of complications of fluoroscopically guided lumbar transforaminal epidural injections.

DESIGN

A retrospective cohort design study. Patients presenting with radiculopathy, caused by either lumbar spinal stenosis or herniated nucleus pulposus confirmed by magnetic resonance imaging or computed tomography scanning, received transforaminal epidural steroid injections as part of a conservative care treatment plan.

SETTING

A multidisciplinary spine care center.

INTERVENTION

All injections were performed consecutively over a 4-month period by five physiatrists. An independent observer reviewed medical charts, which included a 24-hour postprocedure telephone call by an ambulatory surgery center nurse who had asked a standardized questionnaire about complications following the injections. Physician follow-up office notes 1 to 3 weeks after the injection, along with epiduragrams, were also reviewed.

RESULTS

Two hundred seven patients who received 322 injections were reviewed. Complications per injection seen included 10 transient nonpositional headaches that resolved within 24 hours (3.1%), 8 increased back pain (2.4%), 2 increased leg pain (0.6%), 4 facial flushing (1.2%), 1 vasovagal reaction (0.3%), 1 increased blood sugar (258 mg/dL) in an insulin-dependent diabetic (0.3%), and 1 intraoperative hypertension (0.3%). No dural punctures occurred.

CONCLUSIONS

There were no major complications. The incidence of minor complications was 9.6% per injection. All reactions resolved without morbidity, and no patient required hospitalization.

Seizures after myelography with lopamidol

A 32-year-old man presented to the emergency department (ED) with seizures 6 hours after a lumbar myelogram with iopamidol (Isovue-M 200, Squibb, Princeton, NJ). Seizures are a rare complication after myelography with the current nonionic contrast agents and have not been previously reported in the emergency medicine literature. Emergency physicians should be aware of this potential complication because outpatient myelograms are frequently performed, and these patients may present to the ED after seizures.

Iopamidol myelography: morbidity in patients with previous intolerance to iodine derivatives

The records of 1005 patients who underwent iopamidol myelography between January and September, 1988, were reviewed. In this group, 50 patients had histories suggestive of untoward sequelae associated with iodine intake, contact, or administration. The charts of these patients were carefully reviewed, and none of them had any reactions or sequelae suggestive of toxicity or an allergic response after iopamidol myelography. It is concluded that, even in patients with a previous history suggestive of intolerance to iodine administration, iopamidol myelography is generally a safe procedure.

Effect of injections of contrast media on regional uptake of (14C)-2-deoxyglucose by the rat brain

Mechanisms contributing to the rare but consistent neurotoxicity of contrast media currently in clinical use for the radiological examination of the subarachnoid space remain to be isolated. We assessed, by means of the (14C)-2-deoxy-D-glucose (2-DG) autoradiographic method, the effect of three non-ionic, low-osmolar contrast media, namely metrizamide, iopamidol and iohexol, on the local cerebral glucose utilization in the rat brain after intracisternal application. A significant (-30%) global reduction of the brain's metabolic activity occurred following intracisternal metrizamide injection. When compared with the mock-CSF control group the greater relative changes were observed in the supratentorial grey matter structures. In contrast, no significant changes were observed in metabolic brain activity in rats treated intracisternally with iopamidol and iohexol. These findings were consistent with the hypothesis that metrizamide is a competitive inhibitor of human brain hexokinase. The apparent lack of interference on neural tissue metabolism makes the second generation contrast media less neurotoxic and more suitable for neuroradiological subarachnoid investigations in clinical settings. The present experimental work establishes the 2-DG method as a viable laboratory approach to investigate aspects of neuronal dysfunction induced by contrast media.

Seizures following myelography with iopamidol

Iopamidol, a water-soluble contrast medium, has been rarely associated with seizures. We describe 3 patients (from a series of 785) who had generalized tonic-clonic seizures after iopamidol myelography. Two of the patients underwent lumbar and one cervical myelography. There was a history of seizures in 2 patients, and the dose of iopamidol used in the patients who convulsed was high, ranging from 3,000 to 4,500 mg iodine. Despite the reported low incidence of complications with iopamidol, seizures may occur, especially in patients with previous seizures and also in those receiving higher doses of iopamidol.

Influence of the spread and period of retention of Iotrolan in the subarachnoid space on the side effects rate in myelography

Fifty patients underwent myelography with the newly developed CSF-isotonic, dimeric, non-ionic contrast medium Iotrolan. Repeat spinal and cranial computerised tomographic studies with measurement of the attenuation values were conducted to demonstrate the administered contrast medium in the spinal canal and intracranial subarachnoid space. The patients were examined neurologically, observed clinically and asked about concomitant symptoms. The period of retention and the spread of the contrast medium in the subarachnoid space was not found to have any influence on the side effects rate. In particular, no association was confirmed between intracranially demonstrable contrast medium and the occurrence of side effects.

Tolerance of iohexol, iopamidol, and metrizamide in lumbar myelography

Iohexol and iopamidol, two new nonionic contrast media, have been extensively studied in comparison with metrizamide for lumbar myelography. Review of the literature with statistical analysis indicates both agents are superior to metrizamide in terms of number of patients with adverse reactions (p less than 0.001). Preliminary data suggest, but do not prove, that use of iohexol may result in fewer side effects than iopamidol.

Computed tomographic cisternography with iopamidol in the diagnosis of primary empty sella

Twenty-one patients with primary empty sella were studied with computed tomography iopamidol cisternography. Ten milliliters of iopamidol at a concentration of 200 mg I/mL was administered intrathecally via the lumbar route. Eleven patients had a partial and 10 a complete empty sella. In six cases the third ventricle had prolapsed to the level of the interclinoid plane. There was no relationship between the clinical presentation and the grade of empty sella. The quality of the images obtained was always good or excellent. Cisternographies were performed in all of the patients although in 13 of them the correct diagnosis could have been achieved with a standard contrast-medium-enhanced computed tomography scan. The overall complication rate was 29%. Four patients (19%) had mild headaches and nausea; two patients (10%) had more severe side effects: vomiting, discomfort, and meningism. Computed tomographic cisternography with low-concentration iopamidol is a safe diagnostic procedure that allows a definite visualization of the anatomic alterations that occur in patients with empty sella. We think that this procedure should always be employed in symptomatic patients.

[Transient cortical blindness after cerebral angiography: report of a case]

A case of temporary cortical blindness following cerebral angiography is presented and discussed. The etiology of this rare complication is not completely understood. Probably the blindness is secondary to the direct effect of the contrast medium in the blood-brain-barrier in the striate cortex.