Human Imaging: Adult

Abstract

Abstract 1 Bassel W. Abou-Khalil, 1 Christine Dong, 1 Muhammad Al-Kaylani, 1 Amir Arain, 1 Pradumna Singh, 1 Michael J. McLean, and 1 Subramaniam Sriram ( 1 Neurology, Vanderbilt University, Nashville, TN ) Rationale: A confident diagnosis of nonconvulsive status epilepticus confirmed with EEG is essential for appropriate patient management. However, EEG may not be diagnostic in some patients, particularly when the seizure activity is focal or deep. We encountered five patients with ictal aphasia (4) or ictal amnesia (1), in whom the diagnosis of nonconvulsive status epilepticus could not be made on EEG, but was demonstrated with focal hypermetabolism on positron emission tomography with fluorodeoxyglucose (FDG PET). Methods: We obtained FDG PET scans in 5 patients with suspected ictal aphasia or ictal amnesia who did not have demonstration of ictal activity on EEG. Positive scans were repeated after resolution of symptoms in 3 patients. We reviewed clinical, EEG and imaging data, as well as outcome with treatment. Results: Four patients presented with subacute onset of aphasia and one with amnesia, without structural abnormalities on MRI. The EEG showed left temporal irregular delta activity but no clear ictal pattern in three patients with aphasia, and other nonspecific abnormalities in the two remaining patients. All patients had a focus of hypermetabolism on FDG PET. This was left frontotemporal in the patients with ictal aphasia and bilateral hippocampal in the patient with amnesia. Intravenous benzodiazepines in three patients produced transient response. Symptoms and PET hypermetabolism gradually resolved with anti-epileptic drug therapy. Conclusions: FDG PET scan should be considered as a diagnostic tool in patients with suspected focal nonconvulsive status epilepticus who fail to show clear evidence of ictal activity on EEG.