Tadokoro Award 2021 Best clinical poster presentation

Kozue Hayashi

Abstract #404
Slow and infraslow of scalp EEG is associated with transient neurological events in Moyamoya disease
HAYASHI K1, USAMI K2, TOGO M3, KOBAYASHI K1, YAMAO Y4, SHIMOTAKE A5, FUNAKI T4, HITOMI T6, KIKUCHI T4, MATSUHASHI M2, YOSHIDA K4, MIYAMOTO S4, TAKAHASHI R1, IKEDA A2
1Kyoto University Graduate School of Medicine, Neurology, Kyoto, Japan, 2Kyoto University Graduate School of Medicine, Epilepsy, Movement Disorders and Physiology, Kyoto, Japan, 3Kobe University Graduate School of Medicine, Neurology, Kobe, Japan, 4Kyoto University Graduate School of Medicine, Neurosurgery, Kyoto, Japan, 5Kyoto University Graduate School of Medicine, Neurology, Kobe, Japan, 6Kyoto University Graduate School of Medicine, Clinical Laboratory, Kyoto, Japan

Purpose

Transient neurological event (TNE) is a common phenomenon occurring after direct revascularization for moyamoya disease. It appears gradually and lasts for about 15-30 minutes. Cerebral blood flow (CBF) change may be associated with TNE, but EEG in TNE has not been researched. Previously, slow activities were observed in ECoG when neurological symptom occurred with CBF change. Our objective is to clarify the relationship between TNE and the slow wave of scalp EEG.

Method

We recruited 15 moyamoya disease patients over 15 years old who underwent revascularization. Scalp-EEG and SPECT taken within 7 days after surgery were analyzed. We examined EEG about the frequency of δ slow with TC 0.3 sec and infraslow activity (ISA) with TC 2.0 sec. The operational definition of ISA was 1) duration >3 sec, 2) amplitude >100 µV. We calculated CBF ratio (post/pre-operation) using quantitative value of SPECT.

Results

9 of 15 patients developed TNE. All of them showed increased frequency of δ wave in EEG. ISA was observed in 3 of 4 patients who underwent EEG while TNE was present. Analysis of CBF revealed a trend of higher CBF ratio among the patients with TNE (p=0.07).

Conclusion

Our results suggest that TNE is associated with slow waves (δ and ISA) and CBF increase. These slow and infraslow waves could be sensitive biomarkers of TNE with CBF change. Besides, the scalp slow waves may have common generator mechanism to ECoG slow activities, which are called cortical spreading depolarization caused by neuron and glia, since both of them are observed in patients with neurological symptoms with CBF change.