Developing an Asymmetry Method for Detecting Postictal Hyperperfusion in Poststroke Epilepsy

Kazuki Fukuma; Tomotaka Tanaka; Shigetoshi Takaya; Maya Tojima; Katsuya Kobayashi; Akihiro Shimotake; Yoshiaki Morita; Kunihiro Nishimura; Masatoshi Koga; Kazunori Toyoda; Riki Matsumoto; Ryosuke Takahashi; Akio Ikeda; Masafumi Ihara

doi:10.3389/fneur.2022.877386

Developing an Asymmetry Method for Detecting Postictal Hyperperfusion in Poststroke Epilepsy

Front Neurol. 2022 Jul 13:13:877386. doi: 10.3389/fneur.2022.877386. eCollection 2022.

Authors

Kazuki Fukuma¹, Tomotaka Tanaka¹, Shigetoshi Takaya^{2

3}, Maya Tojima⁴, Katsuya Kobayashi⁴, Akihiro Shimotake⁴, Yoshiaki Morita⁵, Kunihiro Nishimura⁶, Masatoshi Koga⁷, Kazunori Toyoda⁷, Riki Matsumoto^{4

8}, Ryosuke Takahashi⁴, Akio Ikeda⁹, Masafumi Ihara¹

Affiliations

¹ Department of Neurology, National Cerebral and Cardiovascular Center, Osaka, Japan.
² Department of Neurology, Senri Rehabilitation Hospital, Osaka, Japan.
³ Department of Rehabilitation Medicine, Senri Rehabilitation Hospital, Osaka, Japan.
⁴ Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
⁵ Department of Radiology, National Cerebral and Cardiovascular Center, Osaka, Japan.
⁶ Departments of Preventive Medicine and Epidemiology, National Cerebral and Cardiovascular Center, Osaka, Japan.
⁷ Department of Cerebrovascular Medicine, National Cerebral and Cardiovascular Center, Osaka, Japan.
⁸ Division of Neurology, Kobe University Graduate School of Medicine, Kobe, Japan.
⁹ Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Kyoto, Japan.

Abstract

Using dual single-photon emission computed tomography (SPECT) scanning, we recently found the postictal-interictal (P-I) subtraction method frequently detects prolonged postictal hyperperfusion in poststroke epilepsy (PSE) and thus may be valuable for auxiliary diagnosis. This study aimed to determine if the asymmetry method can localize hyperperfusion to reflect epileptic activity in PSE using a single postictal SPECT scan. Sixty-four patients with PSE who had undergone perfusion SPECT two times (postictal and interictal) were enrolled. We formulated a novel asymmetry method (subtraction analysis of reversed postictal SPECT from postictal SPECT, co-registered to magnetic resonance imaging) to identify paradoxical asymmetric increase, defined as a higher perfusion area adjacent to stroke lesions compared to the contralateral side. The postictal hyperperfusion area and detection rates were determined by the asymmetry and P-I subtraction methods independently. We subsequently calculated the sensitivity and specificity of the asymmetry method, compared to the gold standard P-I subtraction method. We also evaluated lateralization concordance between the asymmetry method and other clinical findings. Among 64 patients (median age, 75 years), prolonged postictal hyperperfusion was detected in 43 (67%) by the asymmetry, and 54 (84%) the P-I, method. The asymmetry method had high sensitivity (80%) and specificity (100%) in detecting postictal hyperperfusion, showing high lateralization concordance with seizure semiology (97%) and epileptiform electroencephalography findings (interictal/ictal epileptiform discharges or periodic discharges) (100%). The present study demonstrated the advantages of the objective asymmetry method for detecting prolonged hyperperfusion through using one postictal SPECT scan in PSE.

Keywords: asymmetry; epilepsy; hyperperfusion; poststroke epilepsy; single photon emission computed tomography (SPECT); stroke.