Galvanic Skin Response e Apprendimento Dello Stimolo Nocicettivo In Pazienti Con Sindrome Da Veglia Aresponsiva: Quali Implicazioni?

Background The correct diagnosis is a challenge and the assessment, by behavioral scales as Coma Recovery Scale (CSR-R) and Nociception Coma Scale (NCS), remains the best and simple way to assess the level of consciousness. The support of the Galvanic Skin Response (GSR) in the assessment of the nociception stimuli could be represent a useful support to evaluate the level of consciousness in patients with DOC.
Materials and Method Where recruited 13 healthy control subject (HC) and 20 UWS patients (hospitalized from no more of 15 days). A protocol of classic conditional learning of the nociceptive stimulus (LNS) was applied and results evaluated by GSR analysis. The consciousness status was assessed in the three successive weeks by CRS-R and NCS. The LNS was composed by three phases of 25 seconds 1) phase A: acoustic stimulus 1 associated to a musical stimulus; 2) phase B: acoustic stimulus 2 associated to the nociceptive stimulus; 3) acoustic stimulus 2 associate to absence of stimuli. After 5 minutes of baseline, the sequence A-B-A-A-B-A-B-C (NL) was applied to evaluate the learning of the nociceptive stimulus and the sequence A*-C-C-A*-C-A*-C-A* (NE) to evaluate the extinction of pain learning in the patients group. The entire protocol was developed in 5 steps, where the patients were assessed by CRS-R and NCS administered with an interval of time of one week from each other: T0) CRS-R and NCS assessment 1 week before of LNS protocol; T1) LNS and CRS-R; T2 to T4) CRS-R and NCS. The patients were compared for presence (PT1) or absence (PT0) of LNS. GSR component prominence and width of the last three phases of the NL (A, B and C) was considered for the analysis. Coherence between waves in C and waves in B and A respectively was also considered. Each group were compared for GRS component in A, B and C by Mann-Whitney’s test and A, B and C phases were compared among them by Wilcoxon’s test. PT1 and PT0 were compared in the different time steps (T0 - T4) by Mann-Whitney’s test.
Results All the HC subjects showed in the phase C a GSR wave compatible with the learning of the nociceptive stimulus. In the phases A, B and C 6 UWS patients showed a GSR response superimposable with HC. No significant difference was found comparing the phases A, B, and C among them in PT0. PT0 was different for prominence with PT1 and HC (p≤0.001).Significant difference was found comparing the wave’s correlation between A and C, and B and C in HC and PT1, while no difference was found for PT0. Comparing PT1 and PT0 for CRS-T and NCS a significant difference was found in III week (p≤0.003).
Conclusion Some patients, diagnosed as UWS patients by the behavioural assessment and clinical
consensus, when underwent to the psychophysiological correlates evaluation, show pattern of (nociceptive) stimulus learning. The association between behavioural assessment methods and psychophysiological correlates should allow reducing the misdiagnosis percentage. This diagnosis accuracy could directly improve the intervention and treatment strategies.