Usefulness and limitation of addition of 1.5-Tesla arterial spin labeling magnetic resonance perfusion imaging to routine electroencephalography in pathophysiological diagnosis of post-intracerebral hemorrhage epilepsy at neurological emergency

Abstract

Background: We investigated the usefulness and limitations of adding arterial spin labeling (ASL) perfusion imaging to 1.5-Tesla magnetic resonance imaging (MRI) to compensate for the weakness of routine electroen-cephalography (EEG) in the pathophysiological diagnosis of post-intracerebral hemorrhage (ICH) epilepsy (PICHE) at neuroemergency.

Patients & Methods: Five patients who developed PICHE and were immediately admitted to our hospital between August 2023 and January 2024 were studied. Patients 1-3 developed PICHE within 2 years after ICH onset, whereas patients 4 and 5 developed PICHE after more than 12 years. We retrospectively analyzed the performance status and MRI and EEG findings of each patient during the periictal and interictal states.

Results: MRI was performed within 1 h of arrival in all patients. On the other hand, EEG was performed within 1 h in patients 1 and 2, who were transported during weekday hours, but 1-2 days later in patients 3-5, who were transported outside the consultation hours. In patients 1-3, periictal ASL showed focal hyperperfusion related to the site of cortical involvement due to the ICH and corticotomy performed during surgery. EEG revealed paroxysmal discharges almost corresponding to the site of periictal ASL hyperperfusion. However, ASL demonstrated the pathophysiological mechanism of structural focal epilepsy more clearly. In patients 4 and 5, on the contrary, the periictal ASL showed no focal hyperperfusion. MR angiography (MRA) showed markedly poor visualization of the ipsilateral peripheral middle cerebral artery (MCA), and the ipsilateral hemisphere showed a marked decrease in blood flow on the interictal ASL.

Conclusion: Capturing periictal ASL hyperperfusion can improve the diagnosis of PICHE. However, in cases of PICHE occurring long after ICH onset, degeneration and regression of the affected MCA may occur in addition to primary damage to the MCA that supplies periictal hyperperfusion, making the visualization of periictal hyperperfusion difficult. Therefore, evaluations in conjunction with other modalities such as MRA and EEG are necessary.