title: The importance of polysomnography in the evaluation of prolonged disorders of consciousness: sleep recordings more adequately correlate than stimulus-related evoked potentials with patients' clinical status.
abstract: OBJECTIVE
  The aim of our study was to evaluate the importance of sleep recordings and stimulus-related evoked potentials (EPs) in patients with prolonged disorders of consciousness (DOCs) by correlating neurophysiologic variables with clinical evaluation obtained using specific standardized scales.
  
  
  METHODS
  There were 27 vegetative state (VS) and 5 minimally conscious state (MCS) patients who were evaluated from a clinical and neurophysiologic perspective. Clinical evaluation included the Coma Recovery Scale-Revised (CRS-R), Disability Rating Scale (DRS), and Glasgow Coma Scale (GCS). Neurophysiologic evaluation included 24-h polysomnography (PSG), somatosensory EPs (SEPs), brainstem auditory EPs (BAEPs), and visual EPs (VEPs).
  
  
  RESULTS
  Patients with preservation of each single sleep element (sleep-wake cycle, sleep spindles, K-complexes, and rapid eye movement [REM] sleep) always showed better clinical scores compared to those who did not have preservation. Statistical significance was only achieved for REM sleep. In 7 patients PSG showed the presence of all considered sleep elements, and they had a CRS-R score of 8.29±1.38. In contrast, 25 patients who lacked one or more of the sleep elements had a CRS-R score of 4.84±1.46 (P<.05). Our multivariate analysis clarified that concurrent presence of sleep spindles and REM sleep were associated with a much higher CRS-R score (positive interaction, P<.0001). On the other hand, no significant associations were found between EPs and CRS-R scores.
  
  
  CONCLUSIONS
  PSG recordings have proved to be a reliable tool in the neurophysiologic assessment of patients with prolonged DOCs, correlating more adequately than EPs with the clinical evaluation and the level of consciousness. The main contribution to higher clinical scores was determined by the concomitant presence of REM sleep and sleep spindles. PSG recordings may be considered inexpensive, noninvasive, and easy-to-perform examinations to provide supplementary information in patients with prolonged DOCs.
authors: Neurology Unit, Department of Experimental and Clinical Medical Sciences, University of Udine Medical School, Italy.
authors: Stefano
authors: S
authors: de Biase
authors: Neurology Unit, Department of Experimental and Clinical Medical Sciences, University of Udine Medical School, Italy; Department of Neurosciences, "S. Maria della Misericordia" University Hospital, Udine, Italy. Electronic address: gigli@uniud.it.
authors: Gian Luigi
authors: GL
authors: Gigli
authors: Neurology Unit, Department of Experimental and Clinical Medical Sciences, University of Udine Medical School, Italy.
authors: Simone
authors: S
authors: Lorenzut
authors: Department of Neurology, "Sacro Cuore Don Calabria" Hospital, Negrar, Verona, Italy.
authors: Claudio
authors: C
authors: Bianconi
authors: Private Hospital "Pineta del Carso", Aurisina, Trieste, Italy.
authors: Patrizia
authors: P
authors: Sfreddo
authors: Department of Neurology, "Sacro Cuore Don Calabria" Hospital, Negrar, Verona, Italy.
authors: Gianluca
authors: G
authors: Rossato
authors: Neurology Unit, Department of Experimental and Clinical Medical Sciences, University of Udine Medical School, Italy.
authors: Federica
authors: F
authors: Basaldella
authors: Neurology Unit, Department of Experimental and Clinical Medical Sciences, University of Udine Medical School, Italy.
authors: Matteo
authors: M
authors: Fuccaro
authors: Department of Neurology, "Sacro Cuore Don Calabria" Hospital, Negrar, Verona, Italy.
authors: Antonio
authors: A
authors: Corica
authors: Department of Neurology, "Sacro Cuore Don Calabria" Hospital, Negrar, Verona, Italy.
authors: Davide
authors: D
authors: Tonon
authors: Institute of Hygiene and Clinical Epidemiology, Department of Medical and Biological Sciences, University of Udine, Italy.
authors: Fabio
authors: F
authors: Barbone
authors: Neurology Unit, Department of Experimental and Clinical Medical Sciences, University of Udine Medical School, Italy; Department of Neurosciences, "S. Maria della Misericordia" University Hospital, Udine, Italy.
authors: Mariarosaria
authors: M
authors: Valente
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001930:Brain Injuries / Q000175:diagnosis / Q000503:physiopathology; D001933:Brain Stem / Q000503:physiopathology; D002540:Cerebral Cortex / Q000503:physiopathology; D003951:Diagnostic Errors; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005074:Evoked Potentials, Visual / Q000502:physiology; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018458:Persistent Vegetative State / Q000175:diagnosis* / Q000503:physiopathology*; D017286:Polysomnography; D011237:Predictive Value of Tests; D011379:Prognosis; D012131:Respiratory Insufficiency / Q000175:diagnosis / Q000503:physiopathology; D012895:Sleep, REM / Q000502:physiology; D013223:Statistics as Topic; D020521:Stroke / Q000175:diagnosis / Q000503:physiopathology; D055815:Young Adult
keywords: Coma Recovery Scale-Revised (CRS-R); Evoked potentials; Minimally conscious state; Polysomnography; REM sleep; Vegetative state