Focal seizure with transient asymmetrical cortical and subarachnoid enhancement on computed tomography following iodinated contrast administration

Abstract

ObjectivesTo report an uncommon seizure precipitant with associated neuroimaging findings.CaseA 79 years old female underwent bronchial artery embolisation for the treatment of haemoptysis associated with a cavitating lung lesion from previous Mycobacterium avium complex infection. Her medical history included colorectal adenocarcinoma without known metastases. Approximately 90 min into the procedure she developed rhythmic right-sided limb twitching followed by right hemiparesis. Urgent CT brain, with residual contrast from the procedure, demonstrated strongly asymmetrical, predominantly left hemisphere, cortical and subarachnoid enhancement and cortical swelling. No thrombus was identified on CT angiography. The impression was focal seizure with post-ictal (Todd’s) paresis. Intravenous thrombolysis was not administered. Two hours later she had further right-sided twitching, evolving to a bilateral tonic–clonic seizure. She was given IV midazolam and levetiracetam 500 mg bd. EEG performed shortly thereafter showed generalised slowing and sharply-contoured delta waves with a left-sided predominance but no epileptiform features. There was no personal or family history of epilepsy, although a similar episode had occurred following the previous attempt at this procedure approximately 9 months prior, with unilateral gyral swelling on CT. She was not known to our service at the time. The hemiparesis and CT changes resolved within 24 hours of onset. Contrast MRI brain on day 6 was normal. She was discharged home on day 12 with no further seizures and no residual neurological deficits.ConclusionsIodinated contrast is a rare precipitant of seizures, with an incidence of 0.19% in one series.1 The risk was higher in patients with pre-existing epilepsy and/or intracranial pathology. Transient asymmetrical cortical swelling, cortical enhancement and sulcal enhancement on contrast CT have been reported to occur acutely following focal seizures.2,3 Such changes are thought to reflect seizure-associated regional hyperperfusion and blood–brain barrier breakdown.