The Prognostic Value of Pupil Near Response in UWS Patients

Overview

Previous studies suggest that the stimulus of pupil near response (PNR) may be a conscious perception of a blurred image. Moreover, PNR is a reflex that can be objectively observed and with no motor output, suggesting it might be a more convenient index for consciousness evaluation and consciousness recovery in patients with disorders of consciousness (DOC). We thus hypothesized that PNR+ patients (patients show PNR during the assessment) would have better prognosis than PNR- patients (patients fail to show PNR during the assessment).Based on this hypotheis, researchers will assess pupil near response in patients with unresponsive wakefulness syndrome (UWS) and compare the prognosis difference between PNR+ patients and PNR- patients to assess its prognosis value.

PNR assessments will be conducted in patients with Unresponsive Wakefulness Syndrome (UWS) diagnosed by the Coma recovery scale-revised (CRS-R).An objective index,the ratio of pupillary constriction (pupil diameter change after a stimulus presentation divided by the resting state pupil diameter) will be used as the measure of PNR's presence (positive results indicate the presence of PNR,whereas negative results indicate the absence of PNR).According to the presence of PNR,patients will be divided into 2 groups,one includes patients who show PNR during the PNR assessment (PNR+),the other includes patients who fail to show PNR during the PNR assessment(PNR-).3 months later,a follow-up will be conducted to obtain their prognosis in the form of another CRS-R assessment.Patients diagnosed as Minimally Conscious State (MCS) will be considered as favourable prognosis,patients diagnosed as UWS will be considered as unfavourable prognosis.Their prognosis difference will then be compared to see PNR's effect on their prognosis (consciousness recovery). And for they couldn't show conscious visual behaviors (visual behaviors in CRS-R which indicate MCS) in the first CRS-R,their difference between visual prognosis (difference between each group's proportion of patients showing conscious visual behavior diagnosed by CRS-R in the follow up) will be compared to see PNR's capability to predict prognosis in patients without voluntary eye movements (conscious visual behaviors in CRS-R require voluntary eye movements). Researchers expect to see the PNR+ group have better prognosis in both comparison.