Arterial spin labeling MR perfusion image in differentiating metabolic encephalopathy from non-convulsive status epilepticus in a patient with generalized periodic discharges with triphasic morphology

Abstract

Introduction: Arterial spin labeling (ASL) magnetic resonance (MR) perfusion imaging is useful for diagnosing non-convulsive status epilepticus (NCSE) as it visualizes ictal hyperperfusion in epileptically activated areas.

Case report: A 94-year-old woman presented with inability to communicate. An electroencephalogram revealed generalized periodic discharges with triphasic morphology. However, as her liver and kidney function were normal, it was difficult to distinguish metabolic encephalopathy from NCSE. ASL showed not only diffuse hypoperfusion in the cerebral parenchyma, instead of ictal hyperperfusion, but also marked appearance of arterial transit artifact in the major arteries, probably due to stagnant flow. The patient was therefore diagnosed with hyperammonemic encephalopathy (ammonia level 128 mg/dL) induced by constipation. Along with normalization of the ammonia level, the mental status and ASL findings improved.

Conclusion: In this case, ASL helped visualize the decreased blood flow and velocity secondary to hypometabolism. The addition of ASL to conventional MR images may be useful in differentiating metabolic encephalopathy from NCSE, particularly in neuroemergency situations.