Functional Near-infrared Spectroscopy in Unconscious Patients

Inclusion Criteria - experimental group: * Patients of either sex with severe hemorrhagic, ischemic stroke or hypoxic brain injury after cardiac arrest and cardiopulmonary resuscitation treated at the Institute of Intensive Care Medicine, University Hospital Zurich * Unconsciousness (GCS \< 9) or sedated to the severity of the disease (for the subgroup of patients included in the fNIRS-EEG measurement unconscious patients are defined as not responding to verbal stimuli. The motor response to pain should be one of the following: no response to pain / extensor response / flexor response / localize to pain) * Age ≥ 18 years * Signed informed consent obtained from legal representative * Measurement logistically and technical possible within the first 7 days after admission Inclusion Criteria - control group: * Subjects of either sex * Conscious (GCS = 15) * Age ≥ 18 years * Signed informed consent Exclusion Criteria - experimental group: * Patients age \< 18 years * Positive pregnancy test for any female of childbearing potential or breast feeding female * Previous auditory complaints or any ear diseases * No response detectable at Erb's point in SSEP (e.g. due to peripheral nerve lesions, edema etc.) * Any history of previous cerebral or brainstem disease * Concomitant instable critical illness (e.g. sepsis, multi-organ failure, hemodynamic or respiratory instability) * Acute status epilepticus * Clinical recovery (GCS ≥ 9) or death before enrolment of the study Exclusion Criteria - control group: * Subjects age \< 18 years * Positive pregnancy test for any female of childbearing potential or breast feeding female * Previous auditory complaints or any ear diseases * No response detectable at Erb's point in SSEP (e.g. due to peripheral nerve lesions, edema etc.) * Any history of previous cerebral or brainstem disease