Articles Posted in Brain & Spinal Cord Injuries

The long-term consequences of traumatic brain injuries are always difficult to ascertain for clients as their rehabilitation progresses. One of our concerns has always been the future risk that a client suffering from TBI would later develop Alzheimer’s or other dementias. The medical literature has not established this association to a certainty. Recent data published by the Journal of Neuroscience, however, has significantly moved forward our understanding about this significant medical risk.

Using mice and post-mortem samples from human brains, scientists from Tufts University School of Medicine have found that even a single event of moderate to severe TBI can disrupt the proteins that protect the brain from the enzymes that cause Alzheimer’s disease. Serious TBI can lead to a dysfunction in the regulation of the enzyme BACE1, and elevation of that enzyme causes elevation of amyloid-beta, the key component of brain plaques associated with senility and Alzheimer’s disease. It is hoped that these findings will guide future research, as well as assist in the development of future drug targets to aid in the prevention of Alzheimer’s.

Moderate to severe TBI is often caused by the significant forces found in blunt force trauma, falls, and motor vehicle accidents. The CDC has reported that over 1.7 million people suffer such injury annually, although the majority suffer a milder form of TBI called a concussion. Even concussions and repeated but lesser head trauma is suspected to lead to Alzheimer’s, however. Alzheimer’s disease is reported to affect over 5 million Americans, and is the most common cause of dementia in those over the age of 65.

Although neuroscience has progressed in establishing the role various brain structures play in the executive functioning of the brain, there has not been solid evidence of the brain networks that support high-level cognition and general intelligence. In a new study released in the journal Brain, a fascinating picture is emerging that could support new understanding of the brain’s critical functions. Scientists gathered 182 volunteers with very localized brain injuries from penetrating head wounds, and subjected them to CT scans and an extensive battery of cognitive tests. What they found was that general intelligence was derived from a particularly circumscribed neural system. Several brain regions working in connection were found to be most important for general intelligence. These structures were primarily found behind the forehead (left prefrontal cortex), behind the ear (left temporal cortex), and the top rear of the head (left parietal cortex). The data also disclosed that brain regions for planning, self-control and other key elements of executive functioning overlapped those structures found important for general intelligence. This new evidence suggests that intelligence does’t derive from one brain region or the brain as a whole, but specific brain areas working together in a coordinated way.

Source:A. K. Barbey, R. Colom, J. Solomon, F. Krueger, C. Forbes, J. Grafman. An integrative architecture for general intelligence and executive function revealed by lesion mapping. Brain, 2012; DOI: 10.1093/brain/aws021

A new and powerful imaging technique has been developed that will allow doctors to clearly see the brain’s neural connections that have been broken by traumatic brain injury and other neurological disorders. High Definition Fiber Tracking may now give doctors a means of objectively determining how brain tissue has been injured. Conventional CT or MRI scans often miss brain injuries because they show no brain changes, even though the patient continues to struggle with the devastating consequences of brain injury. HDFT is apparently able to reveal the brain’s wiring in such vivid detail that pinpoint breaks in fiber tracts that contain the brain’s critical neuronal connections can be found, thereby allowing doctors to identify any part of the brain that has lost its connectivity. HDFT is not widely available to patients, but may soon provide promising help in the diagnosis and treatment of those suffering from traumatic brain injury.

Source:

High-definition fiber tracking for assessment of neurological deficit in a case of traumatic brain injury: finding, visualizing, and interpreting small sites of damage.

One of the difficulties faced by our clients who have suffered “mild” traumatic brain injury (TBI) is that there has been no objective means of establishing that brain injury exists even though the clinical signs of dysfunction are present. This has often resulted in clients not getting the medical care that would help them with their rehabilitation, or they have suffered the undeserved claims by defense practioners that they were “malingering” or “magnifying” their symptoms.

Two new studies support the early data on the efficacy of a new MRI tool–diffusion tensor imaging–in the diagnosis of traumatic brain injury (TBI). Diffusion tensor imaging allows the care provider to visualize the brain’s white matter, which contains the fibers that connect nerve cells. Conventional MRI would commonly not reveal any differences between the patients with mild TBI and controls. DTI, however, is finding objective evidence on imaging that is consistent with a positive finding on neuropsychological testing.

One study at the University of New Mexico has found that diffusion tensor imaging can be used to reliably detect and track brain abnormalites in patients with mild TBI. The study compared patients with known mild TBI and found that conventional MRI did not reveal any differences between those with TBI and control subjects. The diffusion tensor imaging, however, demonstrated white matter abnormalities in the subjects known to have TBI. Thus, the technique was successful in finding objective evidence of injury when conventional MRI failed to do so. Another important finding was that, when the patients found to have such abnormalities were evaluted with diffusion tensor imaging 3-5 months later, a period by which recovery is expected, the diffusion tensor imaging was able to track these white matter changes, as well. The study concluded that diffusion tensor imaging can provide an objective biomarker that can assist in the classification and tracking of mild TBI injuries and their effects.

There has long been a debate in medicine, and consequently one in the law, about whether a concussion caused by trauma can lead to structural brain tissue damage and functional deficits. While many recover from such injuries without lasting deficits, it is estimated that over 30 percent suffer from the traditional hallmarks of traumatic brain injury, such as personality changes, deficits in short-term memory, or deficits in executive functions involved in the ability to make decisions, organize, or plan.

As recently reported in the journal Radiology, researchers at the Albert Einstein College of Medicine have now demonstrated objectively the areas of the brain injured when concussion occurs. The study subjected patients who had sustained concussions to tradition MRI and CT scans, which routinely demonstrated that no structural injury had occurred. When neuropsychological testing showed effects upon their executive functions, however, the patients were then given a more sophisticated type of MRI scan known as diffusion tensor imaging (DTI). DTI can detect subtle changes in the brain by measuring the diffusion of water in the brain’s white matter. The DTI studies in these patients showed the presence of major areas of structural damage located mainly in the brain’s prefrontal cortex, a part of the brain essential for normal executive function. It is this area of the brain that is susceptible to injury in concussion, and such structures are involved in the cognitive processes that cause the functional deficits the patients were experiencing.

It is unfortunately the case that many people suffering mild traumatic brain injury are not properly advised about the possibility of functional deficit by either their medical or legal practioners. It is often the case that problems do not disclose themselves until a patient returns to more full function after orthopedic injuries have healed. It is when they try to reengage life at their former level of function that deficits begin to take shape. Using DTI as an adjunct to clinical evaluation will likely help identify those patients who should receive rehabilitation earlier when it is more useful to the patient.