Case Presentation: Patient is a 73-year-old female with history of hypertension, chronic back pain on gabapentin, prior intravenous drug use, peripheral artery disease status post bilateral femoral endarterectomies with stenting on dual anti-platelet therapy who presented to the emergency department with right lower extremity pain. Patient was hemodynamically stable, alert and oriented. Shortly after undergoing CT angiogram with IV iodinated contrast to evaluate the right lower extremity, she developed altered mental status and hypoxic respiratory failure requiring intubation, sedation and ICU admission, Computed tomography (CT) of the head and magnetic resonance imaging (MRI) brain were without acute intracranial process and infectious workup was negative. She received levetiracetam 500 mg 12 days due to concern for seizure, but this was discontinued without issue. Her clinical status gradually improved, and she was downgraded to the floor at neurologic baseline. Patient developed right flank pain with right hydroureteronephrosis requiring evaluation with CT urogram with IV iodinated contrast. Shortly after contrast administration, she again developed acute altered mental status, myotonic jerks, eye fluttering and leukocytosis. Staff noted significant lip smacking and repetitive upper extremity posturing. Stat Head CT without contrast was unremarkable. Levetiracetam was restarted and neurology was consulted for abnormal movements. However, continuous EEG was only notable for moderate diffuse encephalopathy and showed no seizure activity over 48 hours. She returned to baseline mental status after 3 days with no intervention. One week later, she required percutaneous nephrostomy tube placement (with iodinated contrast) by interventional radiology due to persistent right flank pain and hydroureteronephrosis. Although this procedure involves injecting contrast into the collecting system, intravenous and intra-arterial contamination does occur with high frequency (1). She was pre-medicated with prednisone and diphenhydramine prior to receiving iodinated contrast and tolerated the contrast well. She had no further episodes of altered mental status and was discharged on levetiracetam and outpatient neurology follow-up.
Discussion: Iodinated contrast media (ICM) is commonly used in a range of imaging modalities. While ICM is generally safe, its use does not come without risk. Adverse reactions to ICM are classified as allergic-like and physiologic. Allergic-like reactions include anaphylactic symptoms while physiologic reactions include nephropathy and, rarely, neurotoxicity. Contrast-induced neurotoxicity (CIN) is a rare side effect that has a reported incidence of < 0.1%. It is associated with symptoms such as altered mental status, seizures, and focal neurological deficits. Dystonic reactions, as seen in this patient, are not commonly reported in the literature. CIN is believed to be caused by blood-brain barrier disruption by the hyperosmolarity and chemotoxicity of ICM.
Conclusions: Contrast-induced neurotoxicity should be on the differential diagnosis of in patients with new altered mental status or neurological deficits after receiving ICM. Pre-treatment with allergic protocols may be an effective strategy in patients with adverse neurologic reaction to CT contrast.