Treating prolonged disorders of consciousness (pDoC) is challenging. Thus, accurate assessment of residual consciousness in patients with pDoC is important for the management and recovery of patients. Functional near-infrared spectroscopy (fNIRS) can be used to detect brain activity through changes of oxygenated hemoglobin/deoxygenated hemoglobin (HbO/HbR) concentrations changes and has recently gained increasing attention for its potential applications in assessing residual consciousness. However, the number of fNIRS studies assessing residual awareness in patients with pDoC is still limited. In this study, fNIRS was used to evaluate the brain function in 18 patients with pDoC, including 14 vegetative states (VS) and 4 minimally conscious states (MCS), and 15 healthy controls (HC). All participants accepted two types of external stimuli, i.e., active stimulation (motor imagery, MI) and passive stimulation (subject\'s own name, SON). The results showed that the mean concentrations of HbO/HbR in the prefrontal cortex of the HC during the passive stimulation were significantly lower than those of the active stimulation, and the fitting slope was high. However, the hemodynamic responses of the patients with pDoC were opposite to those of the HC. Additionally, the mean concentrations of HbO/HbR increased as the level of consciousness decreased during passive stimulation. Our findings suggest that the residual level of consciousness in pDoC patients can be assessed by measuring brain responses to different stimulations using fNIRS. The present study further demonstrates the feasibility and reliability of fNIRS in assessing residual consciousness in patients with pDoC, providing a basis for its expanded clinical application.

BACKGROUND: Epidemiological data on prolonged disorders of consciousness (pDOC) are not available due to lack of research in this field. The objective of this pioneering prospective cohort study in the Russian Federation was to collect the data on the survival and the level of consciousness of patients with pDOC, as well as to search for prognostic markers of survival and improvement of the level of consciousness on longterms outcomes (up to 24 months).
METHODS: All patients (n=184) had pDOC and were admitted to the Federal Research and Clinical Center of Intensive Care Medicine and Rehabilitology. We assessed the neurological status and acquired followup diagnosis as well. Out of total patients: anoxic brain injury (ABI) (n=52), vascular lesions (VL) (n=50), traumatic brain injury (TBI) (n=74), and other causes (n=8). Changes in patients\' vital and conscious status were recorded in four-time slices: 3, 6, 12, and 24 months after the event that led to pDOC.
RESULTS: The survival rate is less than 30%, and the rate of recovery in terms of consiousness is 21%, which are both low, though do not differ significantly from existing data for this category of patients. Unprofessional home care may have a role to play in the declined long-term survival rate. We still do not have reliable prognostic markers among demographical and clinical indices; however, younger age can be considered the only significant predictor of survival and positive dynamics in the level of consciousness.
CONCLUSIONS: We expect that our research will help to personalize and help the patient and families with the appropriate clinical as well as social measures.

Pain perception in individuals with prolonged disorders of consciousness (PDOC) is still a matter of debate. Advanced neuroimaging studies suggest some cortical activations even in patients with unresponsive wakefulness syndrome (UWS) compared to those with a minimally conscious state (MCS). Therefore, pain perception has to be considered even in individuals with UWS. However, advanced neuroimaging assessment can be challenging to conduct, and its findings are sometimes difficult to be interpreted. Conversely, multichannel electroencephalography (EEG) and laser-evoked potentials (LEPs) can be carried out quickly and are more adaptable to the clinical needs. In this scoping review, we dealt with the neurophysiological basis underpinning pain in PDOC, pointing out how pain perception assessment in these individuals might help in reducing the misdiagnosis rate. The available literature data suggest that patients with UWS show a more severe functional connectivity breakdown among the pain-related brain areas compared to individuals in MCS, pointing out that pain perception increases with the level of consciousness. However, there are noteworthy exceptions, because some UWS patients show pain-related cortical activations that partially overlap those observed in MCS individuals. This suggests that some patients with UWS may have residual brain functional connectivity supporting the somatosensory, affective, and cognitive aspects of pain processing (i.e., a conscious experience of the unpleasantness of pain), rather than only being able to show autonomic responses to potentially harmful stimuli. Therefore, the significance of the neurophysiological approach to pain perception in PDOC seems to be clear, and despite some methodological caveats (including intensity of stimulation, multimodal paradigms, and active vs. passive stimulation protocols), remain to be solved. To summarize, an accurate clinical and neurophysiological assessment should always be performed for a better understanding of pain perception neurophysiological underpinnings, a more precise differential diagnosis at the level of individual cases as well as group comparisons, and patient-tailored management.

Patients with brain injury are at high risk for infections. Although infection and cognitive deterioration are established for people with dementia, this has not been shown for patients with a prolonged disorder of consciousness (PDOC). This study determines whether regular Wessex Head Injury Matrix (WHIM) assessments can identify early signs of infections in patients with PDOC.
Retrospective and prospective approaches were used to assess the WHIM scores of patients with a PDOC (N = 21 in the retrospective study and 22 in the prospective study).
The WHIM total scores decreased due to infections in 17 of the 21 cases of infection (p < 0.001) in the retrospective study and 15 (p = 0.001) of the 22 prospective cases of infection. Patients in a minimally conscious state (MCS) showed a bigger proportion of change between their baseline score and the scores taken in the pre-infection stage in both the retrospective and prospective studies when compared to patients in a vegetative state (VS).
The findings suggest the importance of serial WHIM assessments throughout the period of recovery, not only to measure cognitive changes but also to highlight underlying physical changes such as infections that will impact the response to rehabilitation and recovery.