The Alaska Personal Injury Law Group often handles cases involving traumatic brain injuries(TBI). With severe brain injuries, the impairments suffered by the client are usually unmistakable to the client’s care providers and neurological experts testifying on their behalf. With “mild” brain injuries-although there is no such thing as a “mild” brain injury when it happens to you-the impairments are more nuanced and difficult to determine with standard neuroimaging or routine neurological and neuropsychological testing. Often clinicians have concluded that no impairments have occurred simply because there was minimal or no loss of consciousness reported when the brain injury was sustained. Now, advances in neurological imaging are establishing what we have already found to be true in our practice-cognitive impairments can occur even with minimal or no loss of consciousness.
In a study published in the October issue of the journal Brain, researchers at the University of Illinois’ Chicago College of Medicine report that diffusion tensor imaging (DTI) can identify structural changes in the brain’s white matter-which is particularly vulnerable to injury-even in patients identified as having minimal or no loss of consciousness. They studied 37 TBI patients with both diffusion tensor imaging and neuropsychological testing to evaluate memory, attention, and executive function. All the patients were at least six months post-injury, and most were highly functioning, i.e., in school or working at the time of evaluation. The structural white matter changes found by DTI correlated to cognitive deficits that were observable.
The researchers were also able to determine axonal damage-a tearing of the axons that allow one neuron to communicate with another-occurring the brain’s white matter. This differs from injury to the myelin, which is the protective sheath around the axons. Injury to the myelin can interrupt the signals between the brain and other parts of the body. The study showed that all severities of brain injury, even those typically viewed as “mild,” caused some degree of axonal damage, while myelin damage was only apparent in moderate to severe TBI.
These findings help us explain why TBI victims can often experience cognitive deficits that one would not expect when their MRI and CT films show no focal lesions. There is now objective evidence that can explain why clients suffer from cognitive impairments even when little or no loss of consciousness has occurred.
Source: White Matter Integrity and Cognition in Chronic Traumatic Brain Injury: A Diffusion Tensor Imaging Study, http://brain.oxfordjournals.org/cgi/content/abstract/awm216v1