title: Cortical responses to salient nociceptive and not nociceptive stimuli in vegetative and minimal conscious state.
abstract: OBJECTIVE
  Questions regarding perception of pain in non-communicating patients and the management of pain continue to raise controversy both at a clinical and ethical level. The aim of this study was to examine the cortical response to salient visual, acoustic, somatosensory electric non-nociceptive and nociceptive laser stimuli and their correlation with the clinical evaluation.
  
  
  METHODS
  Five Vegetative State (VS), 4 Minimally Conscious State (MCS) patients and 11 age- and sex-matched controls were examined. Evoked responses were obtained by 64 scalp electrodes, while delivering auditory, visual, non-noxious electrical and noxious laser stimulation, which were randomly presented every 10 s. Laser, somatosensory, auditory and visual evoked responses were identified as a negative-positive (N2-P2) vertex complex in the 500 ms post-stimulus time. We used Nociception Coma Scale-Revised (NCS-R) and Coma Recovery Scale (CRS-R) for clinical evaluation of pain perception and consciousness impairment.
  
  
  RESULTS
  The laser evoked potentials (LEPs) were recognizable in all cases. Only one MCS patient showed a reliable cortical response to all the employed stimulus modalities. One VS patient did not present cortical responses to any other stimulus modality. In the remaining participants, auditory, visual and electrical related potentials were inconstantly present. Significant N2 and P2 latency prolongation occurred in both VS and MCS patients. The presence of a reliable cortical response to auditory, visual and electric stimuli was able to correctly classify VS and MCS patients with 90% accuracy. Laser P2 and N2 amplitudes were not correlated with the CRS-R and NCS-R scores, while auditory and electric related potentials amplitude were associated with the motor response to pain and consciousness recovery.
  
  
  CONCLUSIONS
  pain arousal may be a primary function also in vegetative state patients while the relevance of other stimulus modalities may indicate the degree of cognitive and motor behavior recovery. This underlines the importance of considering the potential experience of pain also in patients in vegetative state and to appropriately assess a possible treatment also in those patients.
authors: Basical Medical Science, Neuroscience and Sensory System (SMBNOS) Department, Bari Aldo Moro University Bari, Italy.
authors: Marina
authors: M
authors: de Tommaso
authors: Fondazione San Raffaele-Presidio Ospedaliero di Riabilitazione ad Alta Specialità Brindisi, Italy.
authors: Jorge
authors: J
authors: Navarro
authors: Fondazione San Raffaele-Presidio Ospedaliero di Riabilitazione ad Alta Specialità Brindisi, Italy.
authors: Crocifissa
authors: C
authors: Lanzillotti
authors: Basical Medical Science, Neuroscience and Sensory System (SMBNOS) Department, Bari Aldo Moro University Bari, Italy.
authors: Katia
authors: K
authors: Ricci
authors: Fondazione San Raffaele-Presidio Ospedaliero di Riabilitazione ad Alta Specialità Brindisi, Italy.
authors: Francesca
authors: F
authors: Buonocunto
authors: Basical Medical Science, Neuroscience and Sensory System (SMBNOS) Department, Bari Aldo Moro University Bari, Italy.
authors: Paolo
authors: P
authors: Livrea
authors: Basical Medical Science, Neuroscience and Sensory System (SMBNOS) Department, Bari Aldo Moro University Bari, Italy.
authors: Giulio E
authors: GE
authors: Lancioni
keywords: disorders of consciousness; event related potentials; nociceptive laser stimuli; non-nociceptive salient stimuli; pain