Addition of 1.5-Tesla arterial spin labeling magnetic resonance perfusion imaging to routine electroencephalography in pathophysiological diagnosis of first-onset generalized convulsive seizures in patients with dementia at neurological emergency

Abstract

Background: We investigated the usefulness of the addition of arterial spin labeling (ASL) perfusion imaging to 1.5-Tesla magnetic resonance imaging (MRI) during the periictal period for the pathophysiological diagnosis of focal to bilateral tonic-clonic seizures (FBTCS) in dementia patients presenting at neurological emergency, to compensate for the weaknesses of electroencephalography (EEG).Patients & Methods: We retrospectively examined the performance status and findings of EEG and MRI in eight dementia patients who were transported to our hospital immediately after first-onset generalized convulsive seizures. Results: Five of the eight patients were transported outside of consultation hours, while three were transported within consultation hours. MRI was performed 1 to 7 h (mean, 2.8 h) after arrival, while EEG 2 h to 2 days (mean, 15.1 h). In addition, MRI was performed first in seven patients, and EEG was done first in only one patient. ASL demonstrated focal hyperperfusion in all patients. In Patients 1 and 2, periictal hyperperfusion was observed around the organic lesions, indicating the pathophysiology of structural focal epilepsy and acute symptomatic seizure, respectively. In Patients 3-8, periictal hyperperfusion was noted in one cerebral hemisphere or the apex of bilateral frontotemporal lobes unrelated to the organic lesions, which led to a suspicion of dementia-related epilepsy. In contrast, paroxysmal discharges were observed on EEG in only three patients, and their locations were consistent with the hyperperfusion identified on ASL. Focal slow waves, the location of which matched the ASL findings, were observed in one patient. However, a pathophysiological diagnosis could not be made from the EEG findings alone in the other patients. Conclusion: At our hospital, ASL was almost always performed prior to EEG. Capturing periictal ASL hyperperfusion first may improve the ability to make a prompt pathophysiological diagnosis of FBTCS associated with dementia.