Cortical Blindness and Retrograde Amnesia Following Cerebral Angiography Studied by Early Diffusion Weighted MR imaging. A Case Report

Neuroradiological features of contrast-induced neurotoxicity: A systematic review and pooled analysis

BACKGROUND

Contrast-induced neurotoxicity (CIN), is an increasingly recognised complication of endovascular procedures, presenting as a spectrum of neurological symptoms that mimic ischaemic stroke. The diagnosis of CIN remains a clinical challenge, and stereotypical imaging findings are not established. This study was conducted to characterise the neuroimaging findings in patients with CIN, to raise diagnostic awareness and improve decision making.

METHODS

We performed a systematic review of PubMed and Embase databases from inception (1946/1947) to June 2023 for reports of CIN following administration of iodinated contrast media. Studies with a final diagnosis of CIN, which provided details of neuroimaging were included. All included cases were pooled and descriptive analysis was conducted.

RESULTS

A total of 84 patients were included, with a median age of 64 years. A large proportion of patients had normal imaging (CT 40.8 %, MRI 53.1 %). CT abnormalities included cortical/subarachnoid hyperattenuation (42.1 %), cerebral oedema/sulcal effacement (26.3 %), and loss of grey-white differentiation (7.9 %). Frequently reported MRI abnormalities included brain parenchymal MRI signal change (40.8 %) and cerebral oedema (12.2 %), most commonly observed on FLAIR sequences (26.5 %). Characterisation of imaging findings according to anatomical location and clinical symptoms has been conducted.

CONCLUSIONS

Neuroimaging is an essential part of the diagnostic workup of CIN. Analysis of the anatomical location and laterality of imaging abnormalities may suggest relationship between radiological features and actual clinical symptoms, although this remains to be confirmed with dedicated study. Radiological abnormalities, particularly CT, appear to be transient and reversible in most patients.

Contrast Medium-Induced Transient Cortical Blindness: A Systematic Review of the Literature

PURPOSE

To summarize identified risk factors, the most common clinical presentations, radiological and neurophysiological features, and proposed pathophysiological mechanisms of contrast medium-induced transient cortical blindness (TCB).

METHODS

A systematic search of PubMed, Cochrane Central Register of Controlled Trials, and clinicaltrials.gov was performed. A total of 115 patients from 2 retrospective cohort studies, 10 case series, and 52 case reports were included.

RESULTS

The available evidence suggests that TCB can manifest after both invasive and noninvasive contrast-enhanced procedures. The pathophysiology of TCB is unclear; however, the primary mechanism suggested involves the direct neurotoxic effect of the contrast medium. Ionic, nonionic, hyperosmolar, isoosmolar, and even ethiodized oil have been implicated. Imaging findings are nonspecific, and absent in about half of patients. Onset is within 30 minutes in about half of patients and resolves within 1 day in about half of patients, but delayed onset after a day and delayed resolution after a week may occur. Higher contrast medium dosage and its injection solely into the posterior circulation were the only risk factors identified in association with TCB.

CONCLUSIONS

TCB is a rare, idiopathic, and typically self-limited condition associated with direct posterior cerebral neurotoxicity of iodinated contrast media, and appears to be dose-dependent.

Rare Cases of Contrast-Induced Encephalopathies

Cortical blindness (CB) due to contrast-induced encephalopathy is a rare complication in endovascular procedure. Although exact mechanism is not known, disruption of blood–brain barrier (BBB) by contrast agent is supposed to be caused. We report two cases of contrast-induced encephalopathies after coil embolization of unruptured aneurysm. A 68-year-old woman with unruptured basilar artery aneurysm was treated with endovascular stent-assisted coil embolization. The procedure was successfully accomplished within 172 min using about 160 ml of contrast medium (iopamidol). However, she manifested with CB 3 h after the procedure and seizure on the next day. Immediate computed tomography revealed the cortical enhancement in both occipital lobes. Diffusion-weighted imaging–magnetic resonance imaging and fluid-attenuated inversion recovery sequence 1 day after the procedure revealed edema in both occipital lobes with no findings of ischemia or hyperperfusion. Electroencephalography showed sharp and slow waves in both occipital lobes. She required endotracheal intubation on day 2 to maintain airways and breathing. Her sensorium improved 4 days after the procedure with administration of steroid and anticonvulsant. She was extubated on day 4 after the procedure. She was discharged with persisting CB as a sequel.

[A case of posterior reversible encephalopathy syndrome associated with coil embolization of a basilar apex aneurysm]

About three weeks after successful coil embolization of a basilar apex aneurysm, a 66-year-old woman developed occipital headaches. T2 and FLAIR MRI brain images demonstrated multiple new hyperintense lesions in the posterior circulation territory including cerebellum, right superior cerebellar peduncle, left thalamus and bilateral temporo-occipital lobes and she was subsequently hospitalized. Findings suggestive of other underlying disease were not observed, although an increased protein level was noted in cerebrospinal fluid (69 mg/dl). Headache and clinical findings improved approximately 12 weeks after coil embolization. MRI findings also showed improvement. These clinical and radiological findings made this patient a distinctive case of posterior reversible encephalopathy syndrome (PRES) associated with coil embolization suggesting that clinicians should be aware that PRES can present as comparatively mild symptoms several weeks after coil embolization.