Specificities of arterial spin labeling (ASL) abnormalities in acute seizure

Arterial spin labeling (ASL) is a non-invasive tool measuring cerebral blood flow (CBF) and is useful to assess acute neurological deficit. While acute stroke presents as hypoperfused vascular territory, epileptic activity causes cortical hyperperfusion. Other neurological conditions exhibit hyperperfusion, like migraine or secondary "luxury perfusion" in strokes. Our objectives were to evaluate the usefulness and potential specificities of ASL in acute seizure and correlate it with electroencephalogram.

Amongst a cohort of patients with neurological deficit, addressed for suspicion of stroke, we retrospectively reviewed 25 consecutive patients with seizures who underwent magnetic resonance imaging (MRI) with ASL and electroencephalography (EEG). We compared them with a control group of patients with migraine and stroke secondary re-perfusion, exhibiting ASL hyperperfusion.

Lateralized cortical hyperperfusion (high relative CBF) was observed in all patients. Good topographic correlation with EEG was found in 18 patients (72%). Eight (32%) had hyperperfusion of ipsilateral pulvinar, 5 (20%) had hyperperfused contralateral cerebellar hemisphere, 16 (64%) presented diffusion abnormalities and 20 (80%) had underlying epileptogenic lesions. Pulvinar hyperperfusion was not observed in the control group, nor were diffusion abnormalities in migrainous patients. Contralateral cerebellar hyperperfusion was observed in two migrainous patient, without associated pulvinar activation, whereas all patients with cerebellar hyperperfusion in the study group had associated pulvinar activation.

Elevated CBF can be observed in the epileptogenic zone, ipsilateral pulvinar and contralateral cerebellum (diaschisis) in seizure. These abnormalities seem specific when compared with other causes of hyperperfusion. Arterial spin labeling can be highly effective in the differential diagnosis of strokes.