title: Functional near infrared spectroscopy as a probe of brain function in people with prolonged disorders of consciousness.
abstract: Near infrared spectroscopy (NIRS) is a non-invasive technique which measures changes in brain tissue oxygenation. NIRS has been used for continuous monitoring of brain oxygenation during medical procedures carrying high risk of iatrogenic brain ischemia and also has been adopted by cognitive neuroscience for studies on executive and cognitive functions. Until now, NIRS has not been used to detect residual cognitive functions in patients with prolonged disorders of consciousness (pDOC). In this study we aimed to evaluate the brain function of patients with pDOC by using a motor imagery task while recording NIRS. We also collected data from a group of age and gender matched healthy controls while they carried out both real and imagined motor movements to command. We studied 16 pDOC patients in total, split into two groups: five had a diagnosis of Vegetative state/Unresponsive Wakefulness State, and eleven had a diagnosis of Minimally Conscious State. In the control subjects we found a greater oxy-haemoglobin (oxyHb) response during real movement compared with imagined movement. For the between group comparison, we found a main effect of hemisphere, with greater depression of oxyHb signal in the right > left hemisphere compared with rest period for all three groups. A post-hoc analysis including only the two pDOC patient groups was also significant suggesting that this effect was not just being driven by the control subjects. This study demonstrates for the first time the feasibility of using NIRS for the assessment of brain function in pDOC patients using a motor imagery task.
authors.affiliation: The Institute of Neuro-palliative Rehabilitation, Royal Hospital for Neuro-disability, SW15 3SW London, UK; Department of Brain Repair and Rehabilitation, Institute of Neurology, University College London, Queen Square, WC1N 3BG London, UK.
authors.forename: Agnieszka M
authors.initials: AM
authors.lastname: Kempny
authors.affiliation: The Institute of Neuro-palliative Rehabilitation, Royal Hospital for Neuro-disability, SW15 3SW London, UK.
authors.forename: Leon
authors.initials: L
authors.lastname: James
authors.affiliation: The Institute of Neuro-palliative Rehabilitation, Royal Hospital for Neuro-disability, SW15 3SW London, UK; Department of Brain Repair and Rehabilitation, Institute of Neurology, University College London, Queen Square, WC1N 3BG London, UK.
authors.forename: Kudret
authors.initials: K
authors.lastname: Yelden
authors.affiliation: The Institute of Neuro-palliative Rehabilitation, Royal Hospital for Neuro-disability, SW15 3SW London, UK.
authors.forename: Sophie
authors.initials: S
authors.lastname: Duport
authors.affiliation: The National Hospital for Neurology & Neurosurgery, Queen Square, London WC1N 3 BG, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Farmer
authors.affiliation: The Institute of Neuro-palliative Rehabilitation, Royal Hospital for Neuro-disability, SW15 3SW London, UK; Department of Brain Repair and Rehabilitation, Institute of Neurology, University College London, Queen Square, WC1N 3BG London, UK.
authors.forename: E Diane
authors.initials: ED
authors.lastname: Playford
authors.affiliation: Department of Brain Repair and Rehabilitation, Institute of Neurology, University College London, Queen Square, WC1N 3BG London, UK; Institute of Cognitive Neuroscience, University College London, Queen Square, WC1N 3AR London, UK.
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Leff
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001931:Brain Mapping; D003244:Consciousness Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007092:Imagination; D008297:Male; D008875:Middle Aged; D019265:Spectroscopy, Near-Infrared; D055815:Young Adult
keywords: (Prolonged) disorders of consciousness; Brain function assessment in disorders of consciousness; Functional near infrared spectroscopy; M1, primary motor cortex; MCS, minimally conscious state; MI, motor imagery; MM, motor movement; SMA, supplementary motor area; SMART, Sensory Modality Assessment for Rehabilitation Technique; UWS, unresponsive wakefulness state; VS, vegetative state; fNIRS, functional near infrared spectroscopy; pDOC, prolonged disorders of consciousness