Brain stimulation in patients with disorders of consciousness

Abstract

Background and Aim : There is a long history of brain stimulation in medical science, and it was tested for years trying to treat several neurological diseases. On the other hand, the treatment choices for patients with severe brain injury resulting in disorders of consciousness (DOC) are still limited and research in this field remains challenging. In the current literature, only a few techniques of brain stimulation were studied in this population of patients. This review describes noninvasive techniques, namely transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), which permit to stimulate the brain through the scalp, as well as the current status of deep brain stimulation (DBS) as treatment for patients with DOC. For each technique (i.e. TMS, tDCS and DBS) a systematic search on Pubmed was performed including the term “vegetative state” or “minimally conscious state” or “disorders of consciousness” and 16 articles matched the criteria.

Conclusion : Currently, repetitive TMS (rTMS) and tDCS studies have shown encouraging results, with transient improvements of behavioral signs of consciousness in patients in minimally conscious state (MCS). DBS showed more impressive and extensive behavioral improvement after the implantation of an electrical stimulator in the thalamus. However, this procedure is riskier and the number of patients who can benefit from this intervention is limited. All these therapeutic approaches are still in their infancy. In the years to follow, controlled clinical studies on potential treatments for patients with DOC should multiply and therapeutic measures should be more accessible, controlled and effective.

Key-words: disorders of consciousness; unresponsive wakefulness syndrome/vegetative state; minimally conscious state, transcranial magnetic stimulation; transcranial direct current stimulation; deep brain stimulation, mesocircuit model.