Localizing the seizure onset zone by comparing patient postictal hypoperfusion to healthy controls

Abstract

Arterial spin labeling (ASL) MRI can provide seizure onset zone (SOZ) localizing information in up to 80% of patients. Clinical implementation of this technique is limited by the need to obtain two scans per patient: a postictal scan that is subtracted from an interictal scan. We aimed to determine whether it is possible to limit the number of ASL scans to one per patient by comparing patient postictal ASL scans to baseline scans of 100 healthy controls. Eighteen patients aged 20–55 years underwent ASL MRI <90 min after a seizure and during the interictal period. Each postictal cerebral blood flow (CBF) map was statistically compared to average baseline CBF maps from 100 healthy controls (pvcASL; patient postictal CBF vs. control baseline CBF). The pvcASL maps were compared to subtraction ASL maps (sASL; patient baseline CBF minus patient postictal CBF). Postictal CBF reductions from pvcASL and sASL maps were seen in 17 of 18 (94.4%) and 14 of 18 (77.8%) patients, respectively. Maximal postictal hypoperfusion seen in pvcASL and sASL maps was concordant with the SOZ in 10 of 17 (59%) and 12 of 14 (86%) patients, respectively. In seven patients, both pvcASL and sASL maps showed similar results. In two patients, sASL showed no significant hypoperfusion, while pvcASL showed significant hypoperfusion concordant with the SOZ. We conclude that pvcASL is clinically useful and although it may have a lower overall concordance rate than sASL, pvcASL does provide localizing or lateralizing information for specific cases that would be otherwise missed through sASL.

Sudden unexpected death in epilepsy is prevented by blocking postictal hypoxia

“…Consistent with findings found in animal studies, human neuroimaging studies have clearly delineated postictal hypoperfusion in the vicinity of the seizure onset zone and up to 90 minutes after seizure termination by means of two different imaging methodologies: arterial spin labeling (ASL)–perfusion MRI and computed tomography-perfusion (CTP) (Gaxiola-Valdez et al, 2017; Li et al, 2019; Perera et al, 2020). Moreover, Liu and colleagues studied patients with forebrain focal epilepsies using ASL MRI and found postictal hypoperfusion of medullary brainstem respiratory centres following generalized seizures providing evidence for the increased risk of SUDEP seen in bilateral tonic clonic seizures over other seizure types (Liu et al, 2020).…”

Arterial spin labeling for presurgical localization of refractory frontal lobe epilepsy in children

“…Nevertheless, at present, the actual application of ASL for the presurgical evaluation of epilepsy is still rare. Several studies have reported the localization value of ASL, such as in MRI-negative children with new onset seizures, mesial temporal lobe epilepsy, nonlesional focal impaired awareness seizures, intractable epilepsy, partial epilepsy status, and localizing the seizure onset zone [ 6 – 12 ].…”

Ictal Focal Hyperperfusion Demonstrated by Arterial Spin Labeling in Child With Refractory Frontal Lobe Epilepsy: A Case Report

“…Nevertheless, at present the actual application of ASL in the presurgical evaluation of epilepsy is still rare. Several studies have reported that the localization value of ASL, such as in MRI negative children with new onset seizures, mesial temporal lobe epilepsy, non-lesional focal impaired awareness seizures, intractable epilepsy, partial epilepsy status, and localizing the seizure onset zone [13][14][15][16][17][18][19] . Epilepsy can induce cortical hyperperfusion during seizures, especially following repeated seizures or status epilepticus.…”