Lumbar leptomeningeal and radicular reactions after the subarachnoid injection of water-soluble contrast media, meglumine iocarmate (dimer-Xr) and metrizamide (amipaquer) . An experimental study in the pig
Punto, L.
Acta Veterinaria Scandinavica. Supplementum 1980(73): 1-47
1980
ISSN/ISBN: 0065-1699 PMID: 6930154 Document Number: 154715
Fifty-two growing pigs, divided into 4 groups of 12 according to the contrast media used, were studied. The remaining 4 pigs were used as controls. Meglumine iocarmate in an I concentration of 175 mg I/ml and 280 mg I/ml and metrizamide in an I concentration of 170 mg I/mg and 300 mg I/ml were injected into the subarachnoid space via a lumbar puncture with a repeat injection after 5-8 wk. The controls were injected with saline solution 0.9%. The study was completed with 8 adult pigs using meglumine iocarmate in an I concentration of 175 mg I/ml. In addition to radiographic examinations, the CSF cell count, protein concentration and the electrophoretic pattern of the CSF proteins were determined before the 1st injection of the myelographic contrast medium, 24 h later and after 5-8 wk. At 2-5 days after the 2nd myelography the animals were killed and the lumbar spinal cord with its nerves and leptomeninges was studied macroscopically and microscopically. The pig's CSF normal cell count and protein concentration were identical to those in man. At 24 h after the 1st injection of the contrast medium used the cell count was elevated in all groups, but there was no remarkable difference between the groups. The increase of the protein concentration 24 h after the injection was also observed in all groups. The increase was significantly higher in the pigs examined with meglumine iocarmate than those examined with metrizamide. From 5-8 wk later both the cell count and the protein concentration was normal. The electrophoretic pattern of the CSF protein fractions showed that the .gamma.-globulin/albumin ratio normally is somewhat higher in the pig than in man. The ratio in the pig was 0.26, whereas in man it is under 0.20. A significant increase of the .gamma.-globulin/albumin ratio was found 24 h after the injection of meglumine iocarmate, but not after the injection of metrizamide. The 2nd myelography revealed adhesive arachnoiditis 8 of 24 (8/24) cases (33%) examined with meglumine iocarmate, and in 3/24 cases (13%) examined with metrizamide. The macroscopic inspection revealed 4 cases of constricted dural sac and 22 cases of congested blood vessels. Leptomeningeal fibrosis seen in the microscopic specimen (van Gieson staining) verified the diagnosis of adhesive arachnoiditis in all cases observed in the 2nd myelography. Leptomeningeal fibrosis was seen in 5/48 cases (10%), though the 2nd myelography was normal. One (1/24) of these was from the metrizamide group and 3/24 from that of meglumine iocarmate. Myelography alone cannot explain the incidence of adhesive arachnoiditis. The microscopic examination revealed leptomeningeal inflammatory reaction in 12/24 cases (50%) examined with meglumine iocarmate and in 6/24 cases (25%) of the metrizamide group. The myelin staining (Kluever-Barrera method) revealed demyelination of the axon sheaths and glial proliferation in the lumbo-sacral nerves. These changes occurred in 8/24 pigs (33%) examined with meglumine iocarmate. After metrizamide myelography, no demyelination was found. The results from a complementary study made on 8 adult pigs injected twice with meglumine iocarmate in I concentration of 175 mg I/ml at 5-8 wk intervals were produced to compare the reactions before the growing and adult animals. The results of the CSF examinations made before the injection of meglumine iocarmate, 24 h and 8 wk later did not remarkably differ from those in the growing pigs. In the adult group also, the CSF IgG and IgG/albumin ratio was estimated at the above-mentioned times. At 24 h after the injection, a significant increase both in the total IgG concentration and IgG/albumin ratio was found. Eight weeks later these values were decreased compared with those found 24 h after the injection, but were still higher than normal. The microscopic specimens revealed inflammatory reaction, fibrosis and demyelination, which were more common than those in the growing pig. Leptomeningeal side effects are more common after the injection of meglumine iocarmate than those after metr.