Convulsion contrast agents

Cerebral effects can complicate thoracic aortography when excessive doses of concentrated agent are injected, particularly if the catheter is sited so that the major dose of contrast agent is directed into the cerebral circulation. In one case, 10 ml of sodium iotalamate 70% was injected into the carotid artery, being mistaken for methylgluca-mine iotalamate 60% this was followed by an immediate convulsion, with loss of consciousness for 2 minutes. The patient at first appeared to have recovered completely, but hemiparesis followed and persisted for some 24 hours. Such changes are presumably due to cerebral edema after transient damage to the blood-brain barrier. 

Fatal cases of accidental overdosage have been reported in infants the complications leading to death were either pulmonary edema or convulsions. The latter can be due to hyperosmolarity (leading to hypertonic dehydration) or to the chemical toxicity of the contrast agent. 

In contrast to either the G-series or V-series agents, the observable signs and symptoms of exposure to the GV-series agents are more insidious and tend to be very mild and transient. Even convulsions occurring just prior to death are usually milder than with G-series or V-series agents. 

Great care must be taken when performing contrast injection into the subarachnoid space. Improper technique could lead to a dcva.stating infection or spinal injury, and the use of the wntng contra.st agent can also have devastating results such us convulsions and subsequent, seven arachnoid in-riummution. 

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