BackgroundMagnetic resonance imaging (MRI), including perfusion MRI with arterial spin labeling (ASL) and diffusion-weighted imaging (DWI), are applied in the periictal detection of circulatory and metabolic consequences associated with epilepsy. Although previous report revealed that prolonged ictal hyperperfusion on ASL can be firstly detected and cortical hyperintensity of cytotoxic edema on DWI secondarily obtained from an epileptically activated cortex, the hemodynamic state of the periictal hyperperfusion has not been fully demonstrated.Methods: study-1We retrospectively analyzed the relationship between seizure manifestations and the development of periictal MRI findings, in Case 1 with symptomatic partial epilepsy, who underwent repeated periictal ASL/DWI examination for three epileptic ictuses (one examination for each ictus). Study-2: We evaluated the hemodynamic state of periictal hyperperfusion with the ASL technique using a dual postlabeling delay (PLD) of 1.5 and 2.5 s in nine patients, according to the presence or absence of the localized epileptogenic lesion (EL) on conventional 3 T-MRI, who were divided into Group EL+ (six patients) and Group EL− (three patients).ResultsStudy-1 confirmed that the stratified representation of the periictal MRI findings depends on the time interval between the ictal cessation and MRI examination in addition to the magnitude and duration of the epileptic activity. In Study-2, two types of periictal hyperperfusion were noted. In all six Group EL+ patients, periictal ASL findings showed “fast flow type”. Markedly increased ASL signals were noted at the epileptically activated cortex, having a tight topographical relationship with EL, on ASL with a PLD of 1.5 s, which is decreased on ASL with a PLD of 2.5 s. In all three Group EL− patients, periictal ASL findings showed “gradual flow type”, which is characterized by gradual signal increase of the epileptically activated cortex on ASL with a PLD of 1.5 and 2.5 s.ConclusionWe confirmed that ASL hyperperfusion is superior to DWI in the periictal detection of epileptic events. ASL with dual PLD offers the ability to document two types of hemodynamics of periictal hyperperfusion.
Background: "Onset seizures" are acute symptomatic seizures occurring within 24 h after the onset of ischemic stroke, and their pathophysiological states are unknown. Electroencephalography is commonly used to diagnose epileptic activities; however, it is limited for use with acute stroke. Magnetic resonance imaging, including diffusion-weighted imaging and perfusion imaging with arterial spin labeling, are applied mainly in an emergency. Ictal hyperperfusion on arterial spin labeling and cortical hyperintensity of cytotoxic edema on diffusion-weighted imaging, peri-ictally, can be obtained from an epileptically activated cortex. Aim: We aimed to show pathophysiological states of onset seizures by complementary use of peri-ictal magnetic resonance imaging and electroencephalography. Methods: Four patients diagnosed as onset seizures underwent an initial magnetic resonance imaging and subsequent electroencephalography. Results: In case 1, having persistent non-convulsive status epilepticus after control of onset seizures, ictal magnetic resonance imaging and electroencephalography findings clearly showed the topographical relationship between the acute atherothrombotic infarction and the peri-infarction activated cortex. In case 2, with multiple embolic strokes in the bifrontal lobes, prolonged arterial spin labeling hyper signals were observed in the perirolandic area of the right leg; cortical hyperintensity on diffusion-weighted imaging and paroxysmal activities on electroencephalography were not shown. In cases 3 and 4, postictal hypoperfusion was shown in the large extent involving the multiple embolic infarctions. Because the epileptic cortex was located in the convexity, electroencephalography clearly showed inter-ictal paroxysms in case 3, and localized slow wave in case 4.Conclusion: The present study shows that the complementary use of peri-ictal arterial spin labeling/diffusion-weighted imaging and electroencephalography potentially offers the ability to document the various pathophysiological states of onset seizure.
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