Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts.
Department of Neurology, SUNY Downstate Medical Center, Brooklyn, New York.
Epilepsia. 2020 Aug;61(8):1606-1616. doi: 10.1111/epi.16590. Epub 2020 Jul 11.
Photoplethysmography (PPG) is an optical technique measuring variations of blood perfusion in peripheral tissues. We evaluated alterations in PPG signals in relationship to the occurrence of generalized tonic-clonic seizures (GTCSs) in patients with epilepsy to evaluate the feasibility of seizure detection.
During electroencephalographic (EEG) long-term monitoring, patients wore portable wristband sensor(s) on their wrists or ankles recording PPG signals. We analyzed PPG signals during three time periods, which were defined with respect to seizures detected on EEG: (1) baseline (>30 minutes prior to seizure), (2) preseizure period, and (3) postseizure period. Furthermore, we selected five random control segments during seizure-free periods. PPG features, including frequency, amplitude, duration, slope, smoothness, and area under the curve, were automatically calculated. We used a linear mixed-effect model to evaluate changes in PPG features between different time periods in an attempt to identify signal changes that detect seizures.
We prospectively enrolled 174 patients from the epilepsy monitoring unit at Boston Children's Hospital. Twenty-five GTCSs were recorded from 13 patients. Data from the first recorded GTCS of each patient were included in the analysis. We observed an increase in PPG frequency during pre- and postseizure periods that was higher than the changes during seizure-free periods (frequency increase: preseizure = 0.22 Hz, postseizure = 0.58 Hz vs changes during seizure-free period = 0.05 Hz). The PPG slope decreased significantly by 56.71 nW/s during preseizure periods compared to seizure-free periods. Additionally, the smoothness increased significantly by 0.22 nW/s during the postseizure period compared to seizure-free periods.
Monitoring of PPG signals may assist in the detection of GTCSs in patients with epilepsy. PPG may serve as a promising biomarker for future seizure detection systems and may contribute to future seizure prediction systems.
光体积描记术（PPG）是一种测量外周组织血液灌注变化的光学技术。我们评估了 PPG 信号的变化与癫痫患者全身性强直阵挛发作（GTCS）发生的关系，以评估发作检测的可行性。
在脑电图（EEG）长期监测期间，患者将腕带或踝带式传感器佩戴在手腕或脚踝上，以记录 PPG 信号。我们分析了 PPG 信号在三个时间段内的变化，这三个时间段是根据 EEG 上检测到的癫痫发作定义的：（1）基线（发作前>30 分钟），（2）发作前期，和（3）发作后期。此外，我们在无发作期间选择了五个随机对照段。自动计算 PPG 特征，包括频率、幅度、持续时间、斜率、平滑度和曲线下面积。我们使用线性混合效应模型来评估不同时间段之间 PPG 特征的变化，试图识别检测发作的信号变化。
我们前瞻性地从波士顿儿童医院癫痫监测单元招募了 174 名患者。从 13 名患者中记录到 25 次 GTCS。每位患者首次记录的 GTCS 数据均包含在分析中。我们观察到发作前期和发作后期 PPG 频率增加，高于无发作期的变化（频率增加：发作前期=0.22Hz，发作后期=0.58Hz，无发作期=0.05Hz）。与无发作期相比，发作前期 PPG 斜率下降了 56.71nW/s。此外，与无发作期相比，发作后期 PPG 平滑度增加了 0.22nW/s。
PPG 信号的监测可能有助于癫痫患者 GTCS 的检测。PPG 可以作为未来癫痫检测系统的有前途的生物标志物，并可能为未来的癫痫预测系统做出贡献。
