title: Preserved cardiac autonomic dynamics during sleep in subjects with spinal cord injuries.
abstract: BACKGROUND
  Spinal cord injuries (SCI) are associated with altered cardiovascular autonomic control (CAC). Sleep is characterized by modifications of autonomic control across sleep stages; however, no data are available in SCI subjects on CAC during sleep. We aim to assess cardiac autonomic modulation during sleep in subjects with SCI.
  
  
  METHODS
  27 participants with a neurological and radiological diagnosis of cervical (Cerv, n = 12, ie, tetraplegic) and thoracic SCI (Thor, n = 15, ie, paraplegic) and healthy subjects (Controls) were enrolled. Overnight polysomnographic (PSG) recordings were obtained in all participants. Electrocardiography and respiration were extracted from PSG, divided into sleep stages [wakefulness (W), non-REM sleep (NREM) and REM] for assessment of CAC, using symbolic analysis (SA) and corrected conditional entropy (CCE). SA identified indices of sympathetic and parasympathetic modulation and CCE evaluated the degree of complexity of the heart period time series.
  
  
  RESULTS
  SA revealed a reduction of sympathetic and predominant parasympathetic control during NREM compared to W and REM in SCI patients, independent of the level of the lesion, similar to the Controls. In all three groups, complexity of autonomic regulation was higher in NREM compared to W and REM.
  
  
  CONCLUSIONS
  In subjects with SCI, cardiac autonomic control changed across sleep stages, with a reduction of sympathetic and an increase of parasympathetic modulation during NREM compared to W and REM, and a parallel increase of complexity during NREM, which was similar to the Controls. Cardiac autonomic dynamics during sleep are maintained in SCI, independent of the level of the lesion.
authors.affiliation: Department of Internal Medicine, Ca' Granda IRCCS Foundation, Ospedale Maggiore Policlinico, Milan, Italy; Cardiovascular Neuroscience Laboratory, Department of Biomedical and Clinical Sciences 'L. Sacco', University of Milan, Milan, Italy; Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, MN, USA.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Tobaldini
authors.affiliation: Department of Neuroscience, "Niguarda Ca' Granda" Hospital, Milan, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Proserpio
authors.affiliation: Department of Neuroscience, "Niguarda Ca' Granda" Hospital, Milan, Italy.
authors.forename: Katrina
authors.initials: K
authors.lastname: Sambusida
authors.affiliation: Department of Neuroscience, "Niguarda Ca' Granda" Hospital, Milan, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Lanza
authors.affiliation: Department of Neuroscience, "Niguarda Ca' Granda" Hospital, Milan, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Redaelli
authors.affiliation: Department of Neuroscience, "Niguarda Ca' Granda" Hospital, Milan, Italy.
authors.forename: Pamela
authors.initials: P
authors.lastname: Frigerio
authors.affiliation: Department of Neuroscience, "Niguarda Ca' Granda" Hospital, Milan, Italy.
authors.forename: Lara
authors.initials: L
authors.lastname: Fratticci
authors.affiliation: Neurology Unit, L. Sacco Hospital, Milan, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Rosa
authors.affiliation: Department of Science and Technology, Science and Technology Institute, Federal University of São Paulo, São José dos Campos, São Paulo, Brazil.
authors.forename: Karina R
authors.initials: KR
authors.lastname: Casali
authors.affiliation: Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, MN, USA.
authors.forename: Virend K
authors.initials: VK
authors.lastname: Somers
authors.affiliation: Department of Neuroscience, "Niguarda Ca' Granda" Hospital, Milan, Italy.
authors.forename: Lino
authors.initials: L
authors.lastname: Nobili
authors.affiliation: Department of Internal Medicine, Ca' Granda IRCCS Foundation, Ospedale Maggiore Policlinico, Milan, Italy; Cardiovascular Neuroscience Laboratory, Department of Biomedical and Clinical Sciences 'L. Sacco', University of Milan, Milan, Italy. Electronic address: nicola.montano@unimi.it.
authors.forename: Nicola
authors.initials: N
authors.lastname: Montano
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D019277:Entropy; D005260:Female; D006321:Heart / Q000294:innervation*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010264:Paraplegia / Q000503:physiopathology; D017286:Polysomnography; D011782:Quadriplegia / Q000503:physiopathology; D012016:Reference Values; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000503:physiopathology; D014630:Vagus Nerve / Q000503:physiopathology
keywords: Autonomic nervous system; Entropy measures; Sleep; Spinal cord injury; Symbolic analysis