Rare pitfall in the magnetic resonance imaging of status epilepticus

Area of Science:

• Neurology
• Radiology
• Neuroimaging

Background:

• Brain Magnetic Resonance Imaging (MRI) is crucial for diagnosing and localizing seizure foci in Status Epilepticus (SE).
• Typical MRI findings in SE include ipsilateral diffusion-weighted imaging (DWI) abnormalities in the hippocampus and pulvinar, potentially extending to other brain regions.
• These changes are attributed to transient edema resulting from blood-brain barrier disruption, influenced by seizure frequency and duration.

Observation:

• This case highlights a transient FLAIR hyperintensity in cerebrospinal fluid (CSF) observed on a follow-up brain MRI in a patient with focal SE.
• This unusual finding initially caused diagnostic confusion, raising suspicion for subarachnoid hemorrhage.
• Subsequent investigations, including lumbar puncture, CT, and repeat MRI, excluded other CSF pathologies.

Findings:

• The transient FLAIR hyperintensity was ultimately identified as a rare imaging artifact.
• This artifact, termed hyperintense acute reperfusion marker (HARM), results from Gadolinium enhancement of CSF on FLAIR sequences.
• HARM can mimic serious pathologies, necessitating careful interpretation of MRI findings in SE.

Implications:

• Recognizing HARM is essential to avoid misdiagnosis of conditions like subarachnoid hemorrhage in SE patients.
• Understanding this imaging pitfall improves the accuracy of neuroimaging interpretation in epilepsy.
• This case underscores the importance of correlating imaging findings with clinical presentation and diagnostic tests.