Pubblicazioni

Combined behavioral and electrophysiological evidence for a direct cortical effect of prefrontal tDCS on disorders of consciousness

B, Hermann; F, Raimondo; L, Hirsch; Y, Huang; M, Denis-Valente; P, Pérez; D, Engemann; F, Faugeras; N, Weiss; S, Demeret; B, Rohaut; LC, Parra; JD, Sitt; L, Naccache

Abstract:

Severe brain injuries can lead to long-lasting disorders of consciousness (DoC) such as vegetative state/unresponsive wakefulness syndrome (VS/UWS) or minimally conscious state (MCS). While behavioral assessment remains the gold standard to determine conscious state, EEG has proven to be a promising complementary tool to monitor the effect of new therapeutics. Encouraging results have been obtained with invasive electrical stimulation of the brain, and recent studies identified transcranial direct current stimulation (tDCS) as an effective approach in randomized controlled trials. This non-invasive and inexpensive tool may turn out to be the preferred treatment option. However, its mechanisms of action and physiological effects on brain activity remain unclear and debated. Here, we stimulated 60 DoC patients with the anode placed over left-dorsolateral prefrontal cortex in a prospective open-label study. Clinical behavioral assessment improved in twelve patients (20%) and none deteriorated. This behavioral response after tDCS coincided with an enhancement of putative EEG markers of consciousness: in comparison with non-responders, responders showed increases of power and long-range cortico-cortical functional connectivity in the theta-alpha band, and a larger and more sustained P300 suggesting improved conscious access to auditory novelty. The EEG changes correlated with electric fields strengths in prefrontal cortices, and no correlation was found on the scalp. Taken together, this prospective intervention in a large cohort of DoC patients strengthens the validity of the proposed EEG signatures of consciousness, and is suggestive of a direct causal effect of tDCS on consciousness.

Patologie/Applicazioni:

• Stimolazione elettrica transcranica (TES)

Anno:

2020

Tipo di pubblicazione:

Articolo

Parola chiave:

stimolazione elettrica transcranica; NIBS; tDCS; disorders of consciousness DoC; coma; stato vegetativo; DLPFC-SX; corteccia prefrontale

Testata scientifica:

Scientific Reports

Nota:

Studio dove vengono stimolati con stimolazione elettrica transcranica 60 pazienti DoC, con lo strumento StarStim 8 di Neuroelectrics. Su 69 pazienti con DoC idonei, 66 pazienti sono stati trattati in modo prospettico con una singola sessione tDCS di 20 minuti con l'anodo posizionato sulla corteccia prefrontale dorsolaterale sinistra (DLPFC-SX) e il catodo sopra la corteccia sopraorbitale destra. La valutazione comportamentale clinica è migliorata in dodici pazienti (20%) e nessuno è peggiorato. Questa risposta comportamentale dopo la tDCS ha coinciso con un miglioramento dei marcatori EEG putativi di coscienza.

DOI:

doi.org/10.1038/s41598-020-61180-2