Head injuries result in widespread brain tissue loss one year later



    May provide important clue to why patients are left with
    behavioural handicaps

    TORONTO, March 3 /CNW/ - In a rare, large-scale study of traumatic brain
injury (TBI) patients who span the full range of severity from mild to
moderate and severe, Canadian researchers have found that the more severe the
injury, the greater the loss of brain tissue - particularly white matter.
    "This is an important finding as TBI is one of the most common forms of
disability," said Dr. Brian Levine, Senior Scientist at Baycrest's Rotman
Research Institute and lead author of the study, published in the March 4,
2008 issue of Neurology, the medical journal of the American Academy of
Neurology.
    TBI causes both localized damage through bruises or bleeds, as well as
more diffuse damage through disconnection of brain cells, which ultimately
causes cell death. Both kinds of damage contribute to difficulties with
concentration, working memory, organizing and planning (vital skills for
holding a job), and mood changes.
    In the study, 69 TBI patients were recruited from Sunnybrook Health
Sciences Centre, Canada's largest trauma centre, one year after injury.
Eighty percent of the patients sustained their injury from a motor vehicle
accident. Injury severity was determined by the depth of coma or consciousness
alteration at the time of the initial hospitalization. Twelve healthy,
non-injured participants were recruited as the comparison group.
    Subjects' brains were scanned with high resolution magnetic resonance
imaging (MRI) which provides the most sensitive picture of volume changes in
the brain. The computerized analysis revealed widespread brain tissue loss
that was closely related to the severity of the TBI sustained one year
earlier.
    "We were surprised at the extent of volume loss, which encompassed both
frontal and posterior brain regions," said Dr. Levine. Brain tissue loss was
greatest in the white matter (containing axons which can be compared to
telephone wire interconnectivity), but also involved grey matter (containing
the cell bodies important for information processing).
    Investigators were surprised to find that volume loss was widespread even
in TBI patients who had no obvious lesions on their MRI scans. "A significant
blow to the head causing loss of consciousness can cause extensive reduction
of brain tissue volume that may evade detection by traditional qualitative
radiological examination," Dr. Levine noted.
    He is leading follow-up studies on the same group of TBI patients to
examine more closely the significance of localized white and grey matter
volume loss on behaviour.
    The research team for the Neurology paper included Dr. Sandra Black,
Neurosciences Program Research Director at Sunnybrook Health Sciences Centre,
Brill Professor of Neurology, Department of Medicine, at Sunnybrook and
University of Toronto, and Senior Scientist at Sunnybrook and the Rotman
Institute at Baycrest. Both Baycrest and Sunnybrook are fully affiliated with
the University of Toronto.
    The study was supported by grants from the Canadian Institutes of Health
Research and the National Institutes of Health.





For further information:

For further information: Kelly Connelly, Senior Media Officer, Rotman
Research Institute, Baycrest, kconnelly@baycrest.org, P. (416) 785-2432,
www.baycrest.org


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