title: White matter microstructure in chronic moderate-to-severe traumatic brain injury: Impact of acute-phase injury-related variables and associations with outcome measures.
abstract: This study examines how injury mechanisms and early neuroimaging and clinical measures impact white matter (WM) fractional anisotropy (FA), mean diffusivity (MD), and tract volumes in the chronic phase of traumatic brain injury (TBI) and how WM integrity in the chronic phase is associated with different outcome measures obtained at the same time. Diffusion tensor imaging (DTI) at 3 T was acquired more than 1 year after TBI in 49 moderate-to-severe-TBI survivors and 50 matched controls. DTI data were analyzed with tract-based spatial statistics and automated tractography. Moderate-to-severe TBI led to widespread FA decreases, MD increases, and tract volume reductions. In severe TBI and in acceleration/deceleration injuries, a specific FA loss was detected. A particular loss of FA was also present in the thalamus and the brainstem in all grades of diffuse axonal injury. Acute-phase Glasgow Coma Scale scores, number of microhemorrhages on T2*, lesion volume on fluid-attenuated inversion recovery, and duration of posttraumatic amnesia were associated with more widespread FA loss and MD increases in chronic TBI. Episodes of cerebral perfusion pressure <70 mmHg were specifically associated with reduced MD. Neither episodes of intracranial pressure >20 mmHg nor acute-phase Rotterdam CT scores were associated with WM changes. Glasgow Outcome Scale Extended scores and performance-based cognitive control functioning were associated with FA and MD changes, but self-reported cognitive control functioning was not. In conclusion, FA loss specifically reflects the primary injury severity and mechanism, whereas FA and MD changes are associated with objective measures of general and cognitive control functioning.
authors: Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Medical Imaging, St. Olav's Hospital, Trondheim University Hospital, Trondheim, Norway.
authors: A K
authors: AK
authors: Håberg
authors: Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Physical Medicine and Rehabilitation, St. Olav's Hospital, Trondheim University Hospital, Trondheim, Norway.
authors: A
authors: A
authors: Olsen
authors: Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Neurosurgery, St. Olav's Hospital, Trondheim University Hospital, Trondheim, Norway.
authors: K G
authors: KG
authors: Moen
authors: Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Anaesthesia and Intensive Care, St. Olav's Hospital, Trondheim University Hospital, Trondheim, Norway.
authors: K
authors: K
authors: Schirmer-Mikalsen
authors: FMRIB Centre, University of Oxford, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, United Kingdom.
authors: E
authors: E
authors: Visser
authors: Regional Centre for Child and Youth Mental Health and Child Welfare-Central Norway, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.|Division of Mental Healthcare, Department of Child and Adolescent Psychiatry, St. Olav's Hospital, Trondheim University Hospital, Trondheim, Norway.
authors: T G
authors: TG
authors: Finnanger
authors: Department of Public Health and General Practice, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Laboratory Medicine, Children's and Women's Health, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Physiotherapy, Trondheim Municipality, Trondheim, Norway.
authors: K A I
authors: KA
authors: Evensen
authors: Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Physical Medicine and Rehabilitation, St. Olav's Hospital, Trondheim University Hospital, Trondheim, Norway.
authors: T
authors: T
authors: Skandsen
authors: Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Neurosurgery, St. Olav's Hospital, Trondheim University Hospital, Trondheim, Norway.
authors: A
authors: A
authors: Vik
authors: Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
authors: L
authors: L
authors: Eikenes
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016880:Anisotropy; D001930:Brain Injuries / Q000150:complications / Q000473:pathology*; D016022:Case-Control Studies; D002908:Chronic Disease; D003072:Cognition Disorders / Q000209:etiology; D056324:Diffusion Tensor Imaging; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D012189:Retrospective Studies; D057566:Self Report; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D066127:White Matter / Q000473:pathology*; D055815:Young Adult
keywords: BRIEF; MRI; executive function; head injury; intensive care unit