The Prognostic Value of Pupil Near Response in UWS Patients
Condition: Vegetative State
MeSH terms: Persistent Vegetative State
Study type: Observational

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): pupil near response
Intervention type(s): Behavioral
Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        patients who has been diagnosed as unresponsive wakefulness syndrome by CRS-R before this
        study.
      
Keywords: disorders of consciousness; unresponsive wakefulness syndrome; pupil near response; prognosis of consciousness recovery