Abstracts

Rationale: Children with perinatal arterial ischemic stroke (PAIS) have a potential risk for infantile spasms (IS) in addition to focal epilepsy. IS secondary to PAIS, however, present hypsarrhythmia despite the focal/regional stroke. A subset of IS children secondary to PAIS may have a benefit from hemsipherotomy despite the generalized EEG discharges. Synchronization likelihood (SL) can measure the degree of generalized synchronization between each pair of signals in time-series of dynamical systems. Modulation index (MI) measures the strength of phase-amplitude coupling between the amplitude of high frequency oscillations (HFOs) and the phase of slow waves. We hypothesize that IS secondary to perinatal MCA ischemic stroke (P-MCAIS) establish a pathological network connection to present hypsarrhythmia. This is a preliminary report to expertise SL and MI for the hypsyarrythmia in IS patients secondary to P-MCAIS. Methods: We selected 4 patients with IS secondary to P-MCAIS and 3 age-matched controls.We selected 10 x 2-minutes epochs (total 20 minutes) of interictal EEG without artefacts during non-REM sleep. SLs between all pairs of electrodes were analyzed in the following 8 frequency bands: delta (0.5-1 Hz; 1-2 Hz; 2-3 Hz; 3-4 Hz), theta (4-8Hz), alpha (8-13Hz), beta (13-30Hz) and gamma (30-70Hz). The SL matrix was divided to two connectivity groups; A, inter-hemispheric connectivity; B, intra-hemispheric connectivity. We investigated SL values in 8 frequency bands, and compared mean SL of each electrode among affected side, non-affected side and controls. Two MI of coupling between gamma oscillation amplitude and A, 3-4 Hz; B, 0.5-1Hz were calculated in all electrodes. We compared MIs in affected hemisphere to those in non-affected hemisphere. Results: We collected 4 IS patients with histories of perinatal strokes (Left, 3; Right,1). Infantile spasms occurred at 5 to 8 months (mean 6.4). EEG (6 to 10 months; mean8.3) showed hypsarrythmia (bilateral, 3; unilateral, 1). Intra-hemispheric SL index of beta and gamma band of affected hemisphere were higher than those of non-affected hemisphere and controls. In affected hemisphere, MI (gamma&3-4Hz) index were higher than MI (gamma&0.5-1Hz) index. In non-affected hemisphere, MI (gamma&0.5-1Hz) index were higher than MI (gamma&3-4Hz) index.Inter-hemispheric SL index of beta and gamma band in P-MCAIS were higher than those of controls. Conclusions: We found that the phase coupling of gamma and delta slow waves, and functional connectivity at beta and gamma bands might be valuable to differentiate the affected hemisphere from the non-affected hemispheres in hypsarrhythmia of patients with IS secondary to P-MCAIS. MI (gamma&3-4Hz) was stronger in the affected hemisphere. Beta and gamma band functional connectivity were higher in patients with P-MCAIS than those of control. Funding: No funding