Abstract
Some patients may develop an altered state of consciousness (coma, vegetative state, minimal consciousness state) following traumatic and other brain injuries. While the cause of their altered consciousness may be well documented in most cases, the precise underlying mechanisms mediating the altered consciousness and its treatment are yet to be discovered. Several hypotheses have been put forward on how the level of consciousness can be improved; all are based on the principle that an injured brain needs to reconnect its disrupted areas. To address this need, several neuromodulation therapies (using invasive and noninvasive stimulation) may serve this purpose. Invasive therapies use chronic electrodes for stimulation, while non-invasive therapies employ transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS) and somato-sensitive stimulation (SSS). The purpose of this chapter is to critically analyze the progress of these therapeutic methods and to review what is still needed to improve the impaired conscious states.