Deep brain stimulation, neuroethics, and the minimally conscious state: Moving beyond proof of principle

We briefly review the motivation, ethical framing, and results of a recent single-subject study of central thalamic deep brain stimulation (DBS) in a patient remaining in the chronic minimally conscious state (MCS). In the study, a severely brain-injured human subject showed behavioral improvements in attentive responsiveness, limb control, recovery of oral feeding, and spoken language following central thalamic DBS.1 These findings are placed into the context of, and contrasted with, prior efforts applying thalamic brain stimulation to patients in the vegetative state (VS). Efforts to develop DBS for recovery of function in the setting of disorders of consciousness must meet several challenges presented by the expected wide variance of underlying brain injuries and need to carefully identify potential goals of therapeutic intervention. Although the study involved only a single subject, the results demonstrate a causal relationship between brain stimulation and cognitive recovery. The generalizability of these findings is completely unknown and the complexity of the problem will require careful and systematic research to move forward.