Iopamidol and metrizamide for myelography: prospective double-blind clinical trial

In a comparative randomized double-blind study, 73 patients underwent myelography using iopamidol (36 patients) or metrizamide (37 patients) as contrast medium. The overall diagnostic adequacy of iopamidol myelography was found to be comparable to that of metrizamide myelography. The incidence of examinations graded as superior (64%) or adequate (36%) with iopamidol was equivalent to that with metrizamide (57% superior, 43% adequate). Adverse reactions after iopamidol myelography were fewer, less severe, and generally of shorter duration than those associated with metrizamide. In the iopamidol group, adverse reactions occurred in nine (25%) patients, all of whom experienced mild or moderate headache, one with nausea, vomiting, and fatigue. In the metrizamide group, adverse reactions occurred in 17 (46%) patients, all of whom experienced mild or moderate headache, six with nausea and vomiting and four with back and leg pain. Of nine individuals who underwent myelography using 300 mg 1/ml metrizamide injected via lateral C1-C2 puncture, three experienced a toxic encephalopathy with confusion, dysphasia, headache, nausea, and vomiting, and a fourth individual suffered severe nausea, vomiting, fever, and irregular pulse. Encephalopathy was not observed in any of the 11 patients in whom myelography was performed via lateral C1-C2 puncture with a similar concentration of iopamidol. No seizures were encountered, and no clinically significant changes in laboratory studies were observed with either contrast medium.     

Risk of seizures after myelography: comparison of iohexol and metrizamide

A parallel, double-blind, randomized study comparing iohexol and metrizamide--both 180 mg l/ml--in lumbar myelography was carried out in 60 consecutive patients. Eight to 15 ml of contrast medium were administered with the upper level at the middle thoracic column. A detailed neurologic examination was performed before and 24 hr after myelography. EEG recordings--evaluated visually and with fast Fourier transformation analysis--and somatosensory evoked responses were registered before, 6 hr after, and 24 hr after myelography. All patients were observed for adverse reactions for 24-48 hr. Iohexol did not produce any epileptiform activity but epileptiform activity was detected in five patients receiving metrizamide. Iohexol produced significantly less frequent and less severe EEG changes than did metrizamide both at visual evaluation (p less than .0025) and at fast Fourier transformation analysis (p less than .04). No significant changes occurred in the early components of the somatosensory evoked potentials after either contrast medium. Iohexol caused significantly (p less than .002) less frequent and less severe adverse reactions than did metrizamide. The neurologic examination revealed no changes of clinical importance with either contrast agent.     

Iohexol lumbar myelography: clinical study

Forty-three patients underwent lumbar myelography with the new, nonionic contrast medium iohexol. Multiple laboratory examinations, neurologic examinations, and electrocardiograms showed no significant alterations after intrathecal injection of the contrast agent. Mild electroencephalographic changes were seen in one patient. Nineteen adverse reactions occurred in 13 patients; only one of them was considered severe. No patient experienced a seizure, auditory or visual hallucination, or similar neuropsychologic reaction. This is a distinct improvement over the side effects described for previous water-soluble contrast agents. The adverse reactions occurring with iohexol myelography are fewer in number and less severe than with metrizamide myelography, and radiographic visualization obtained with iohexol is equal to that obtained with metrizamide. With iohexol, it appears that the most disturbing and disabling neuropsychologic reactions have been reduced to an acceptable minimum.     

Iohexol vs. metrizamide: study of efficacy and morbidity in cervical myelography

A double-blind study was conducted in 60 patients undergoing either cervical or more complete myelography via C1-C2 puncture. Patients received either iohexol or metrizamide at a 300 mg l/ml concentration. The contrast media were equally efficacious in the production of high-quality radiographs and CT scans. However, the incidence of adverse reactions differed markedly. Of patients receiving metrizamide, 68% had some type of adverse reaction, whereas only 26% receiving iohexol had symptoms. The incidence of headache (metrizamide, 34%; iohexol, 26%) was not statistically different, but the quality of the headache differed: half of the metrizamide headaches were moderate or severe, whereas all iohexol headaches were mild. Nausea (31%) and vomiting (28%) were common with metrizamide but unusual (3% nausea) with iohexol. Of the metrizamide patients, 21% had overt psychologic changes that did not occur in the iohexol group.     

Arachnoid response to contrast media: a comparison of iophendylate and metrizamide in experimental animals

Arachnoiditis resulting from administration of intrathecal iophendylate (Pantopaque) was compared with that from metrizamide (Amipaque) in 16 monkeys. Four animals initially underwent metrizamide myelography, eight underwent iophendylate myelography, and four control animals received only cerebrospinal fluid. Twelve weeks later, all 16 animals underwent metrizamide myelography and then histologic studies. Animals receiving iophendylate for the first myelogram differed significantly from the other two groups on inflammation, fibrosis, and myelographic evidence of arachnoiditis. The arachnoiditis produced by iophendylate was more severe than that produced by metrizamide; the iophendylate also produced a more cellular reaction that was qualitatively different from the reaction to metrizamide. This more severe reaction to iophendylate has clinical implications for patients undergoing myelography if the contrast medium is not completely removed from the system after myelography.     

Evaluation of myelographic contrast-medium tolerance with psychometric testing

Clinical tolerance to the myelographic contrast media metrizamide and iopamidol was evaluated in 26 and 30 patients, respectively, with a battery of neuropsychologic tests before and after myelography in a randomized, double-blind prospective study. Twenty hospitalized patients with chronic back pain were also studied before and after computed tomography to serve as controls relative to the groups administered contrast agents. Measures of conceptual reasoning and affect were sensitive tests of adverse reactions. These paralleled the incidence of somatic reactions and correlated with the dose of contrast medium. Methodologic problems included varying intervals between myelography and psychometric evaluation among subjects and use of a less-than-ideal control group. Neuropsychologic tests appear to be sensitive for detection of subtle adverse reactions and possibly predictive of their occurrence. Iopamidol was tolerated better than metrizamide, with somatic side effects occurring in 38% of patients receiving metrizamide and in 17% of patients receiving iopamidol.     

Clinical trial of iotrol for lumbar myelography

Iotrol, a new nonionic, water-soluble, hexiodinated dimeric contrast medium for myelography, was used in clinical trials in 29 patients. The purpose of the study was to acquire information on local and general tolerance, distribution and excretion, and image quality. Preliminary results show that iotrol is well suited for lumbar and thoracolumbar myelography. Side effects observed with the use of iotrol were fewer and less severe than those reported with metrizamide. Iotrol is cleared from the cerebrospinal fluid and excreted by glomerular filtration within the same time range as other water-soluble contrast media.     

Cognitive and affective changes after myelography: a comparison of metrizamide and iohexol

A battery of brief cognitive tests and a mood scale were administered to 42 patients before and after cervical myelography with either metrizamide (20 patients) or iohexol (22 patients). The patients receiving metrizamide experienced a deterioration in mood after myelography and a relatively greater decline in cognitive test performance than did those receiving iohexol. These two side effects tended to occur together in the metrizamide group, suggesting a common underlying cause; but there was no correlation between changes in mood and cognitive function after myelography with iohexol. These results suggest that metrizamide has a greater neurotoxic effect than iohexol.     

Lumbar myelography with iohexol and metrizamide: a comparative multicenter prospective study

Diagnostic quality of radiographs and adverse reactions associated with the use of metrizamide and iohexol as contrast agents in lumbar myelography were compared in a prospective randomized double blind study in 350 patients at seven centers. The contrast media were administered in comparable volumes at a concentration of 180 mg I per ml. Overall quality of radiographic visualization was graded good or excellent in 95% of 175 metrizamide studies and in 98% of 175 iohexol studies. Ninety-three patients examined using metrizamide (53%) and 130 patients examined using iohexol (74%) experienced no discomfort during or after myelography. Postmyelographic headache was associated with 38% of metrizamide examinations and 21% of iohexol examinations. Nausea and vomiting were also more common with metrizamide. Five patients examined using metrizamide (3%) experienced transient confusion and disorientation following lumbar myelography. No such reactions were observed following iohexol myelography.     

Risk factors in complications of aqueous myelography.

The adverse reactions from aqueous myelography in 88 primates were reviewed to determine what factors increase the risk of complications. Seventy-four iocarmate (Dimeray) myelograms were obtained on 41 animals, and 90 metrizamide (Amipaque) myelograms were obtained on 47 animals. The risk of seizures and death from iocarmate myelography was higher than from metrizamide myelography. In animals that had previous myelograms or showed evidence of arachnoiditis, the risk of complications from aqueous myelography was higher. Additional precautions may be indicated if aqueous myelography is performed in patients with arachnoiditis.     

Myelography with lopamidol

Two hundred patients who underwent myelography with iopamidol were independently assessed as to film quality and adverse side effects. Comparison was made with a similarly assessed group of 1,000 patients who underwent myelography with metrizamide. Diagnostic quality was generally excellent with both contrast media. The incidence of side effects, notably vomiting and headache, was significantly less with iopamidol but remains appreciable. More severe side effects may occasionally occur with either contrast medium.     

Conventional and CT metrizamide myelography in Arnold-Chiari I malformation and syringomyelia

Four normal controls and 26 cases of Arnold-Chiari I malformations and/or syringomyelia were reviewed. The pathologic cases included five isolated Arnold-Chiari I malformations, nine communicating syringomyelia, five idiopathic syringomyelia, four posttraumatic syringomyelia, one syringomyelia with hemangioblastoma, and two postshunt syringomyelia. The objectives of this study were to compare the accuracy of conventional metrizamide myelography with CT metrizamide myelography and to study indirectly the hydrodynamics of CSF flow in syringomyelia by comparing the sequential enhancement patterns of the spinal cords and cord cavities in the different groups of patients. Twenty-five patients underwent conventional metrizamide myelography immediately before CT metrizamide myelography, and one patient underwent CT metrizamide myelography only. Scans were obtained 1-2 hr, 4-8 hr, and 12-24 hr after injection of metrizamide, but not all patients were scanned during all three intervals. CT metrizamide myelography was found to be more sensitive than conventional metrizamide myelography in the diagnosis of both Arnold-Chiari I malformation and syringomyelia. Performing just an immediate and a delayed scan was found to be more cost-effective than doing all three scans. Contrary to previous reports, it was found that delayed (12-24 hr) scans demonstrated more syrinx cavities than intermediate ones. In studying the sequential enhancement patterns of the spinal cords and cord cavities, some interesting trends were observed that tend to support the theories of Aboulker and of Ball and Dayan of transneural passage of CSF into cord cavities in syringomyelia.     

Sequelae of metrizamide myelography in 200 examinations.

Twenty pediatric and 180 adult patients underwent myelography using metrizamide (Amipaque). All patients were examined and interviewed before and after the studies. New or exacerbated symptoms attributed to metrizamide myelography were graded according to severity. After the procedure, 51 of 200 patients were unchanged from baseline. Headache was the most common complaint, with an overall incidence of 62%. Nausea and/or vomiting occurred in 38%. Back or leg pain, neck stiffness, temperature elevation, and a variety of less common manifestations were also observed. The incidence of sequelae was higher than in comparable Scandinavian studies with this contrast medium.     

Psychopathometric demonstration and quantification of mental disturbances following myelography with metrizamide and iopamidol

Summary Groups each consisting of ten patients underwent lumbar and cervical myelography with metrizamide and iopamidol, together with a control group of ten patients who underwent lumbar punctures only. These groups were studied with a psychopathometric test procedure in order to demonstrate and quantify mental disturbances. It was shown that in contrast to myelography with iopamidol, mild mental disturbances are common after myelography with metrizamide. The severity of the mental disturbances after myelography with metrizamide was dependent on the quantity of contrast medium which diffused into the intracranial space after myelography, suggesting a dose-related neurotoxic effect of this substance. Such a correlation was not found with iopamidol.     

High-dose iohexol myelography

Lumbar myelography was performed with high volumes of iohexol (15-24 ml) at a concentration of 180 mgI/ml (average dose, 20 ml) in 48 patients. In 44 patients receiving more than the currently recommended upper dose limit of 17 ml, the frequency of headache (41%), nausea (14%), and vomiting (9%) was comparable to results for routine-dose lumbar metrizamide myelography. Overall, adverse reactions were more frequent, particularly at the highest dose levels, than reported for conventional-dose iohexol myelography. However, there were no occurrences of neuropsychiatric disorder, encephalopathy, or seizure. High-dose technique allows superior visualization of upper lumbar and conus detail and may be advantageous in patients with large subarachnoid spaces and in multi-level examinations. This study supports the results of previous trials that suggested the relative safety of iohexol as a contrast agent and extends those observations to a higher dose range. Because of the increased rate of adverse reactions at the highest dose levels (despite the absence of major adverse reactions), iohexol should continue to be used conservatively, with doses carefully tailored to each examination.     

CT myelography for outpatients. An inpatient/outpatient pilot study to assess methodology

The diagnostic usefulness, limitations, and adverse reactions associated with computed tomographic myelography using metrizamide were assessed for broad outpatient application. The initial approach was to examine inpatients (n = 38) with low-dose metrizamide (100 mgI/ml). This low dose was believed less likely to be associated with side effects. They were then treated as if they were outpatients, with the liberties this entailed. The consequences of needle puncture were minimized by using a 25-gauge disposable needle. Thirty-four (89%) patients remained free of side effects after the procedure. Subsequently, this technique was extended to 42 outpatients, 38 (90.5%) of whom remained asymptomatic. For comparison, 170 mgI/ml was used in another 25 outpatients, who evidenced more symptoms. The potential medical, economic, and therapeutic benefits of obviating hospitalization by safer outpatient CT myelography seem clear.     

The effect of dehydration on the side effects of metrizamide myelography.

The effect of dehydration on the incidence of side effects from metrizamide myelography was studied. One hundred consecutive patients scheduled for myelography fasted overnight and were then randomly divided into two groups. Group I received 2 liters of fluid intravenously just prior to myelography; Group II did not. Both groups were studied in the standard manner, using 170 mg l/ml of metrizamide. Side effects were recorded 24 and 48 hours after the procedure. Headaches, vomiting, and some other side effects were less common and less severe in the hydrated group. Clear liquids given orally or intravenous fluids are recommended prior to myelography to minimize side effects.     

Clinical experience with iopamidol for myelography

Within 20 months 145 ascending thoracocervical myelographies and 155 lumbar myelographies with the nonionic water-soluble contrast medium iopamidol were performed. The iodine concentration given was 250 mg I/ml or 200 mg I/ml respectively. The total iodine never exceeded 2.5 g (8-10 ml). Image quality was assessed in terms of diagnostic value having experience of more than 1,000 myelographies using metrizamide. Picture quality was similar to metrizamide of equal iodine concentration. In 35 patients electroencephalography (EEG) was recorded before and after myelography with iopamidol 250. No changes that could be referred to the contrast medium were seen. There were no adverse reactions to lumbar myelography other than those following the lumbar puncture. In thoracocervical myelography mild and transient side effects occurred in 41 (28.3%). The most common were headache (41 cases), nausea (12), radicular pain (10), and dizziness (five). General seizures and psychopathologic symptoms were not observed.     

Lumbar myelography with omnipaque (iohexol)

Summary Lumbar myelography with iohexol (Omnipaque) was performed in 103 consecutive adult patients with low back pain or sciatica. The patients were observed for 48 h with registration of possible adverse reactions. Mild or moderate transient side effects were recorded in 24 patients. No serious adverse reactions were noted, and EEG recorded in 25 patients showed no changes.     

Metrizamide compared with iohexol for cervical myelography: a double-blind study

A double-blind comparative study of iohexol and metrizamide for use in cervical myelography through lumbar puncture was carried out in a group of 30 patients. No difference was found in the quality of radiographic examinations of the cervical or lumbar regions nor in the postmyelographic computed tomographic examinations of the cervical spine. The overall incidence of side effects was significantly higher in the metrizamide group (93.4%) than in the iohexol group (40%) (p = 0.002). The differences in incidence of nausea (53% in the metrizamide group compared with 13% in the iohexol group) and vomiting (46.6% with metrizamide, 6.6% with iohexol) were also significant (p = 0.02). Pyramidal signs and seizures occurred only after metrizamide myelography.