Pharmacological and electrical stimulation in chronic disorders of consciousness: new insights and future directions

Chronic disorders of consciousness are costly and challenging conditions to treat. Although recent studies that have tested pharmacological and electrical stimulation for these conditions are promising, the optimal intervention, mechanisms of action and side effects of these experimental therapies are unclear.

To systematically review the clinical results of treatments for vegetative state (VS) and minimally conscious state (MCS) from the last 10 years.

MEDLINE, LILACS and SCOPUS were searched as data sources. Because the potential bias when search is limited to databases of peer-reviewed journals, reference lists were examined and experts in the field were contacted for other relevant or unpublished articles (i.e. negative studies). No negative unpublished studies were found. Studies were included related to therapeutic interventions in adult MCS or VS patients at least 3 and 12 months after non-traumatic and traumatic injuries, respectively. Eight studies met the inclusion criteria. The following interventions were reviewed: levodopa, amantadine, zolpidem, baclofen, dorsal column stimulation and deep brain stimulation.

The adverse effects that were associated with these treatments were typically mild. Most of the studies demonstrated considerable improvements with the interventions, but their low strength of evidence limit the generalizability of the findings.