Nociception Coma Scale Revised allows to identify patients with preserved neural basis for pain experience.

The Nociception Coma Scale-Revised (NCS-R) was developed to help assessing pain in non-communicative patients with disorders of consciousness (DOC). Several studies have shown its sensitivity in assessing responses to acute noxious stimuli. However, they failed to determine a reliable cut-off score that could be used to infer pain processing in these patients.
This retrospective cross-sectional study aimed to determine an NCS-R cut-off score supporting preserved neural basis for pain experience, based on brain metabolism as measured by fluorodeoxyglucose positron emission tomography (FDG-PET).
We included FDG-PET confirmed patient with unresponsive wakefulness syndrome (UWS) (n=13) and looked at their highest NCS-R total scores. As the highest score was 4, we determined the cut-off of 5 and compared the brain metabolism of these patients with matched DOC patients with a cut-off score ≥ 5 (i.e., potential pain) and healthy controls.
We found a higher global cerebral metabolism in healthy subjects compared with both patients’ groups and also in patients with potential pain compared with FDG-PET confirmed UWS. We observed a preserved metabolism in the left insula in patients with potential pain when compared with FDG-PET confirmed UWS. We also found a preservation of the connectivity between the left insula and the medial frontal gyrus in patients with potential pain compared with FDG-PET confirmed UWS. Our data suggest that using the cut-off score of 5 can be helpful to improve pain management in DOC patients. Future studies should focus on patients showing scores below this cut-off to better characterize their profile and improve cares.