Infraslow scalp electroencephalogram is closely linked to transient neurological events in Moyamoya disease

Transient neurological events (TNEs) commonly occur following direct revascularization for moyamoya disease (MMD). Although changes in the cerebral blood flow (CBF) may be linked to TNEs, the underlying mechanism remains unclear. Herein, we investigated the relationship between TNEs and EEG to elucidate the underlying mechanisms and pursue the clinical utility of EEG as a TNE biomarker.

Twenty-six hemispheres in 22 patients with MMD aged ≥15 years who underwent revascularization were analyzed. Scalp electroencephalography (EEG) and single-photon emission computed tomography (SPECT) performed within 7 days postoperatively were analyzed using the clinical information.

Sixteen of 26 hemispheres developed TNEs, of which 12 demonstrated an increased frequency of delta waves (> 0.5, < 4 Hz) on postoperative EEG (P = 0.0002), which was located in an area consistent with each symptom. Infraslow activity (ISA, < 0.33 Hz) was observed in all 4 hemispheres on the day of TNE development. More frequent occurrence of delta wave on postoperative EEG preceded onset in 2 hemispheres. CBF did not differ between the patients with and without TNEs.

ISA may be associated with the pathophysiology of TNEs. Delta waves can be used as clinical biomarkers to predict TNEs.

Slow waves on scalp EEG have the potential can predict and elucidate TNEs. Non-standard Abbreviations and Acronyms. TNEs, transient neurological events; MMD, Moyamoya disease; ISA, infraslow activity; SD, spreading depolarization; TC, time constant.