Behavioural and electrophysiological effects of tDCS to prefrontal cortex in patients with disorders of consciousness

Cavinato, Marianna; Genna, Clara; Formaggio, Emanuela; Gregorio, Caterina; Storti, Silvia Francesca; Manganotti, Paolo; Casanova, Emanuela; Piperno, Roberto; Piccione, Francesco

doi:10.1016/j.clinph.2018.10.018

Cited by 46 publications

(73 citation statements)

References 39 publications

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“…The other 37 patients (80% of the sample) did not gain nor lose a sign of consciousness following a- or s-tDCS (i.e., tDCS = ) and, unsurprisingly, all of the UWS patients were in that group. This is in line with previous studies showing that patients in UWS exhibit less clinically relevant behavioral changes after tDCS than those in MCS ( Thibaut et al, 2014 , Angelakis et al, 2014 , Cavinato et al, 2019 ); as they also have a farther path to recovery.…”

Section: Discussionsupporting

confidence: 92%

Behavioral and electrophysiological effects of network-based frontoparietal tDCS in patients with severe brain injury: A randomized controlled trial

Martens

Kroupi

Bodien

et al. 2020

NeuroImage: Clinical

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Section: Discussionsupporting

confidence: 92%

Behavioral and electrophysiological effects of network-based frontoparietal tDCS in patients with severe brain injury: A randomized controlled trial

Martens

Kroupi

Bodien

et al. 2020

NeuroImage: Clinical

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“…A sham-controlled, randomized, double-blind study showed a significant clinical improvement in MCS patients (n = 8) following ten sessions of active tDCS targeting the lDLPFC, along with an increase in P300 amplitude [14]. After two weeks of active tDCS over the lDLPFC, Cavinato et al found an increase in the power and coherence of the frontal and parietal alpha and beta frequency bands, along with clinical improvements in MCS patients (n = 12), whereas UWS (n = 12) only showed some local changes in the slow frequencies over frontal electrodes [15]. Finally, Hermann et al recently reported increased power and connectivity in the theta-alpha band after one session of lDLPFC tDCS in responders (12/60-20%; 7/32 MCS-21.9%) in a prospective open-label study with DOC patients [16].…”

Section: Introductionmentioning

confidence: 99%

Neurophysiological Correlates of a Single Session of Prefrontal tDCS in Patients with Prolonged Disorders of Consciousness: A Pilot Double-Blind Randomized Controlled Study

et al. 2020

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Background. Transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (lDLPFC) was reported to promote the recovery of signs of consciousness in some patients in a minimally conscious state (MCS), but its electrophysiological effects on brain activity remain poorly understood. Objective. We aimed to assess behavioral (using the Coma Recovery Scale—Revised; CRS-R) and neurophysiological effects (using high density electroencephalography; hdEEG) of lDLPFC-tDCS in patients with prolonged disorders of consciousness (DOC). Methods. In a double-blind, sham-controlled, crossover design, one active and one sham tDCS (2 mA, 20 min) were delivered in a randomized order. Directly before and after tDCS, 10 min of hdEEG were recorded and the CRS-R was administered. Results. Thirteen patients with severe brain injury were enrolled in the study. We found higher relative power at the group level after the active tDCS session in the alpha band in central regions and in the theta band over the frontal and posterior regions (uncorrected results). Higher weighted symbolic mutual information (wSMI) connectivity was found between left and right parietal regions, and higher fronto-parietal weighted phase lag index (wPLI) connectivity was found, both in the alpha band (uncorrected results). At the group level, no significant treatment effect was observed. Three patients showed behavioral improvement after the active session and one patient improved after the sham. Conclusion. We provide preliminary indications that neurophysiological changes can be observed after a single session of tDCS in patients with prolonged DOC, although they are not necessarily paralleled with significant behavioral improvements.

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“…In the same line, a recent EEG study reported decreases in the delta band when assessing coherence in patients with DOC after tDCS over the precuneus (Guo et al, 2019). Other EEG studies showed increased frontoparietal coherence in the alpha, beta, and/or theta frequency bands (Bai et al, 2018;Cavinato et al, 2019), along with an increase in P300 amplitude (Zhang et al, 2017) after tDCS over the DLPFC in MCS patients. Comparing tDCS responders to non-responders, increased EEG power, network centrality, and functional connectivity were found in the theta and theta-alpha bands, with larger P300 responses after tDCS (Thibaut et al, 2018b;Hermann et al, 2020).…”

Section: Discussionmentioning

confidence: 81%

“…This technique of passing a small electric current through two electrodes attached to the scalp has been well established to modulate the neural activity of the underlying networks ( Nitsche and Paulus, 2000 ). One stimulation site in particular, the left dorsolateral prefrontal cortex (DLPFC, with the cathode over the right supraorbital area), has been shown to be effective in a number of studies ( Angelakis et al, 2014 ; Thibaut et al, 2014 , 2017 , 2018a ; Naro et al, 2015 ; Estraneo et al, 2017 ; Martens et al, 2018 ; Cavinato et al, 2019 ; Wu et al, 2019 ; Hermann et al, 2020 ). For instance, of 30 MCS patients undergoing just a single session of tDCS, 13 showed new signs of conscious behavior following the intervention ( Thibaut et al, 2014 ).…”

Section: Introductionmentioning

confidence: 99%

Decreased Evoked Slow-Activity After tDCS in Disorders of Consciousness

Mensen

Bodart

Thibaut

et al. 2020

Front. Syst. Neurosci.

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Due to life-saving medical advances, the diagnosis and treatment of disorders of consciousness (DOC) has become a more commonly occurring clinical issue. One recently developed intervention option has been non-invasive transcranial direct current stimulation. This dichotomy of patient responders may be better understood by investigating the mechanism behind the transcranial direct current stimulation (tDCS) intervention. The combination of transcranial magnetic stimulation and electroencephalography (TMS-EEG) has been an important diagnostic tool in DOC patients. We therefore examined the neural response using TMS-EEG both before and after tDCS in seven DOC patients (four diagnosed as in a minimally conscious state and three with unresponsive wakefulness syndrome). tDCS was applied over the dorsolateral prefrontal cortex, while TMS pulses were applied to the premotor cortex. None of the seven patients showed relevant behavioral change after tDCS. We did, however, find that the overall evoked slow activity was reduced following tDCS intervention. We also found a positive correlation between the strength of the slow activity and the amount of high-frequency suppression. However, there was no significant pre-post tDCS difference in high frequencies. In the resting-state EEG, we observed that both the incidence of slow waves and the positive slope of the wave were affected by tDCS. Taken together, these results suggest that the tDCS intervention can reduce the slow-wave activity component of bistability, but this may not directly affect high-frequency activity. We hypothesize that while reduced slow activity may be necessary for the recovery of neural function, especially consciousness, this alone is insufficient.

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Behavioural and electrophysiological effects of tDCS to prefrontal cortex in patients with disorders of consciousness

Cited by 46 publications

References 39 publications

Behavioral and electrophysiological effects of network-based frontoparietal tDCS in patients with severe brain injury: A randomized controlled trial

Behavioral and electrophysiological effects of network-based frontoparietal tDCS in patients with severe brain injury: A randomized controlled trial

Neurophysiological Correlates of a Single Session of Prefrontal tDCS in Patients with Prolonged Disorders of Consciousness: A Pilot Double-Blind Randomized Controlled Study

Decreased Evoked Slow-Activity After tDCS in Disorders of Consciousness

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