Neurotherapeutics (Jul 2024)
High-definition transcranial direct current stimulation desynchronizes refractory status epilepticus
Abstract
Recently, we showed that high-definition transcranial direct current stimulation (hd-tDCS) can acutely reduce epileptic spike rates during and after stimulation in refractory status epilepticus (RSE), with a greater likelihood of patient discharge from the intensive care unit compared to historical controls. We investigate whether electroencephalographic (EEG) desynchronization during hd-tDCS can help account for observed anti-epileptic effects. Defining desynchronization as greater power in higher frequencies such as above 30 Hz (“gamma”) and lesser power in frequency bands lower than 30 Hz, we analyzed 27 EEG sessions from 10 RSE patients who had received 20-minute session(s) of 2-milliamperes of transcranial direct current custom-targeted at the epileptic focus as previously determined by a clinical EEGer monitoring the EEG in real-time. During hd-tDCS, median relative power change over the EEG electrode chains in which power changes were maximal was +4.84%, −5.25%, −1.88%, −1.94%, and +4.99% for respective delta, theta, alpha, beta, and gamma frequency bands in the bipolar longitudinal montage (p = 0.0001); and +4.13%, −5.44%, −1.81%, −3.23%, and +5.41% in the referential Laplacian montage (p = 0.0012). After hd-tDCS, median relative power changes reversed over the EEG electrode chains in which power changes were maximal: −2.74%, +4.20%, +1.74%, +1.75%, and −4.68% for the respective delta, theta, alpha, beta, and gamma frequency bands in the bipolar longitudinal montage (p = 0.0001); and +1.59%, +5.07%, +1.74%, +2.40%, and −5.12% in the referential Laplacian montage (p = 0.0004). These findings are consistent with EEG desynchronization through theta-alpha-beta-gamma bands during hd-tDCS, helping account for the efficacy of hd-tDCS as an emerging novel anti-epileptic therapy against RSE.
