Study of Chronic Post-Comatose States: On the Way to Understanding the Phenomenon of Consciousness

Chronic disorders of consciousness (DOC; i.e., vegetative state and minimally consciousness state) develop in patients surviving coma after severe brain damage. Characteristic clinical feature of these syndromes is the dissociation between preserved wakefulness and complete or almost complete absence of awareness. Advanced diagnostic technologies provide us with valuable insights into the pathophysiology of chronic DOC, and structural and/or functional disconnection of elements of brain networks that are essential for information processing is believed to be its major underlying cause. Depending on the study modality, findings may include global or more localized decrease of cortical metabolism on PET scanning, or abnormal structural or functional connectivity on DTI or fMRI, as well as low-differentiated/disintegrated TMS-EEG responses, etc. Understanding the mechanisms of chronic DOC leads us to deeper knowledge about the phenomenon of human consciousness.