Contrast-Induced Encephalopathy Following Coronary Angiography with no Radiological Features: A Case Report and Review of the Literature

Aim: To review the pathophysiology, clinical presentation, radiological diagnosis and management of contrast-induced encephalopathy post-cardiac catheterisation.
Materials and Methods: We report a case of contrast-induced encephalopathy with no radiological features. The PubMed database was searched and all cases in the literature were reviewed.
Results: 52 cases of contrast-induced encephalopathy following cardiac catheterisation were found. Transient cortical blindness is the most common clinical manifestation but seizures, encephalopathy, hemiparesis and aphasia have been reported. It is hypothesised that contrast-induced encephalopathy occurs when the blood-brain barrier is disrupted by the direct neurotoxicity of the contrast agent. Symptoms typically manifest within minutes to hours of contrast injection and resolves spontaneously with supportive management. Typical radiological findings on CT head may show cerebral oedema and cortical enhancement. In some cases, imaging is normal. We present a case of contrast-induced encephalopathy in a 76-year old gentleman following a normal diagnostic coronary angiography that involved the iodinated contrast agent Iohexol (Omnipaque 300). Ninety minutes post-procedure he became acutely confused with a normal non-contrast CT head. After 9 days of conservative treatment he recovered spontaneously with no neurological deficits.
Conclusion: Contrast-induced encephalopathy is a rare but important clinical entity to consider in the differential diagnosis of stroke or intracranial haemorrhage following cardiac catheterisation. This case highlights that contrast-induced neurotoxicity may not always present with the typical radiological signs. Given that prognosis is excellent with supportive management only, angiographers and interventionalists should be well aware of this condition.