Contrast-induced encephalopathy
General description
Contrast-induced encephalopathy is a rare complication that can occur after the injection of non-ionic contrast agents, particularly during neurovascular procedures. It is characterized by neurological symptoms such as seizures, hemiparesis, and transient cortical blindness or homonymous hemianopia, often associated with posterior circulation disturbances.
The condition is believed to result from disruption of the blood-brain barrier (BBB), allowing the contrast agent to leak into the cerebral cortex or subarachnoid space, where it exerts neurotoxic effects. Factors contributing to BBB breakdown include repeated contrast injection into the same vessel, high osmotic pressure, and chemical toxicity. The occipital lobe, which is particularly susceptible due to its incomplete BBB and unique sympathetic innervation, is frequently affected. This vulnerability is exacerbated by factors such as elevated blood pressure, cerebral edema, diuresis, or eclampsia, leading to impaired autoregulation. However, the precise mechanisms underlying contrast-induced encephalopathy remain unclear.
Subarachnoid hyperintensity
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Subarachnoid space
On CT scans, contrast agent leakage into the subarachnoid space appears as areas of high attenuation, which may mimic subarachnoid hemorrhage. Dual-energy CT is a valuable tool for distinguishing between the two.
PRES-like lesion
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CerebrumParietal lobe
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CerebrumOccipital lobe
On MRI, findings similar to those seen in Posterior reversible encephalopathy syndrome (PRES) have been reported. These include:
- Bilateral involvement, predominantly in the parietal and occipital lobes.
- Hyperintense signals on T2-weighted and FLAIR images, with increased ADC values, suggesting vasogenic edema.
- Contrast enhancement.
- Occasional evidence of microbleeds.