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The Neurophysiologic Action of Contrast Media

The contrast media employed in cerebral angiography are not biologically inert and produce effects that are often underrated and associated with clinical complications in 1.5 to 3 per cent of patients. Some accidents are due to faulty techniques and therefore independent of the contrast medium. The intramural injection is fairly common and is dangerous as it is responsible for nearly one per cent of the serious sequelae (PERRET). An examination performed with a perfectly correct technique may however also produce complications, especially if the vascular condition of the patient is precarious. Severe cerebral arteriosclerosis, arterial occlusion with or without hemodiversion or vascular spasm following the rupture of an aneurysm may accentuate the risks. Apart from any vascular weakness or faulty technique a certain number of complications directly connected with the contrast medium remain. BROMAN & OLSSON stated twenty-five years ago that a contrast medium may alter the cerebral vascular physiology by injuring the blood-brain barrier, i.e. by increasing the permeability of the cerebral capillaries. This produces cerebral oedema and aggravation of the neurologic signs. On the other hand labelled contrast media have recently proved that if the capillary permeability is increased, say by infarcts or tumours, some may enter the cerebral parenchyma. The contrast