Effect of additional cations on the twitching reaction to intracarotid, nonionic contrast media in rabbits.

Previous investigations in this laboratory have confirmed the observation of facial muscle twitching during intracarotid injections of nonionic contrast media (CM) in rabbits. The reaction appears to be a locally mediated effect. To further investigate this reaction, cortical electroencephalogram (EEG) and facial electromyogram (EMG) recordings were made from rabbits receiving selective internal carotid artery (ICA) and external carotid artery (ECA) injections of CM. The effects of iopromide and iohexol were compared with and without the addition of sodium (Na) and calcium (Ca) ions at different concentrations. External carotid injections of iopromide also were performed in some animals paralyzed with D-tubocurarine to exclude the possibility that the reaction is due to an effect on peripheral nerves. The addition of between 5 and 20 mM Ca ions to both CM prevented the reaction but while the addition of Na ions (up to 150 mM) to iopromide had some preventative effect, it did not totally abolish the reaction. In those animals paralyzed with D-tubocurarine, the reaction to iopromide, as observed and recorded by EMG, was the same as that occurring in nonparalyzed animals. This finding is consistent with this reaction being independent of the peripheral nervous system.

The effect of intracarotid nonionic contrast media on the blood-brain barrier in acute hypertension.

PURPOSE: To determine whether acute hypertension (HT) is a risk factor for damage to the blood-brain barrier in carotid angiography with nonionic contrast media. METHODS: Anesthetized rats received intravenous injections of technetium-99m-pertechnetate and horseradish peroxidase. Two groups of rats received metaraminol to raise their blood pressure to between 165 and 190 mmHg peak systolic and then received intracarotid injections of saline or iopamidol. Two other groups remained normotensive and received intracarotid injections of saline or iopamidol. Animals were perfused with a fixative solution and their brains removed. Activity of extravasated Tc-99m-pertechnetate was determined to assess blood-brain barrier breakdown. Brains were then sectioned, treated histochemically to visualize extravasated horseradish peroxidase, and ranked visually according to horseradish peroxidase staining. RESULTS: Extravasation of both tracers was significantly greater in the hypertensive group that received contrast media than in the other three groups. CONCLUSIONS: Acute hypertension potentiates the blood-brain barrier-damaging effects of nonionic contrast media during carotid angiography in rats.

Muscular and CNS effects of carotid artery administration of contrast media in rabbits.

Facial muscle twitching during intracarotid injections of nonionic contrast media has been observed in rabbits. To investigate the cause of this reaction, cortical EEG and facial EMG recordings were made from rabbits receiving selective internal and external carotid artery injections of control solutions (normal saline, mannitol), an ionic contrast medium (meglumine iothalamate), and three nonionic contrast media (iohexol, iopromide, and iotrolan). Internal carotid artery injections with all contrast media, both ionic and nonionic, produced ipsilateral EEG changes in 24 of 28 animals; however, ipsilateral EMG changes and visible twitching were observed only in animals injected with nonionic contrast media. Internal carotid artery injections with control ionic and nonionic solutions (physiological saline and mannitol, respectively) produced no EEG changes in any animals. Mannitol produced only ipsilateral EMG changes and visible twitching in most animals. The severity of the reaction to mannitol was generally less than that to the nonionic contrast media, and this difference was statistically significant when comparing mannitol with iohexol and iotrolan but not with iopromide. External carotid artery injections with nonionic solutions (contrast media and mannitol) produced significantly more severe ipsilateral EMG changes and visible twitching than were recorded with the internal carotid artery injections. Ionic solutions (contrast media and saline) had no effect. EEG changes were not observed after external carotid artery injection of any solution, with the exception of two of the seven animals injected with iotrolan. Angiography demonstrated retrograde filling of the external carotid arterial system from internal carotid artery injection via functioning orbital anastamoses. In contrast, internal carotid arterial vessels were not seen angiographically after external carotid artery injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Beckwith-Wiedemann syndrome: antenatal diagnosis.

The Beckwith-Wiedemann syndrome is an unusual complex with variable features. The major findings include abdominal wall defects, macroglossia and visceromegaly. These features should be amenable to antenatal ultrasound detection. Only a few such cases have been reported to date. Antenatal diagnosis allows optimum perinatal care. Hypoglycaemia in the neonatal period is common in these babies and requires early detection and appropriate management to prevent long-term intellectual complications. We present a case where the diagnosis was suggested prior to delivery.