Diagnosis of Traumatic Brain Injury

Typically, traumatic brain injury involves injury to the brain from external forces.  These injuries are typically referred to as acquired brain injuries.  Diseases of the brain; tumors, lesions or the like, can result in what is defined as organic brain injuries.  My office handles acquired brain injuries from accidents, most of which are traffic accidents involving motor vehicles, trucks, or motorcycles.  Often, these injuries can occur without any fracture to the skull, and are referred as closed-head injuries.  Not every closed-head injury will result in a traumatic brain injury.  Some will resolve over time without any permanent features.  Often, these encompass what is referred to generally as post-concussion injuries.  Post concussion injuries are a more minor sub-set of closed-head injuries.

The typical mechanism for this type of injury is a blow to the head, resulting from the head striking some object which creates a bruising to the brain.  Traumatic brain injuries are typically classified as “mild”, “moderate”, or “severe.”

The most significant issue with respect to establishing or proving a brain injury is the lack of an emergency room diagnosis.  This is because unless there is a clear indication of trauma to the head, or a clear loss of consciousness (disorientation, confusion, etc.) that is reported, most of these types of head injuries go undiagnosed.  At times, this un-reporting or misreporting occurs because the emergency room personnel will either fail to inquire about a loss of consciousness or the injured person may not even know they were unconscious and report none if asked.  Therefore, it is very important for the injured patient to attempt to determine any cut or bruise to the head, and report it to the ER personnel.  If unknown, it is always better to advise the ER staff that any loss of conscious is unknown to the patient.

If there is some report of potential head injury, ER staff will often order some type of brain scanning.  There are several types of brain scanning technologies.  Each may have particular uses, depending on the circumstances presented or the availability of the scanner.   Computed tomography, or CT, uses a picture developed from the differential absorption of x-rays and is commonly used in ER for initial diagnosis.  However, it is typically useless for traumatic brain injury diagnosis unless the brain is hemorrhaging in a more obvious way.  It can be  contrasted (with radioisotope tracers) or non-contrasted (more often).  Thus, due to it’s limitations, a negative CT scan in the ER can be fairly common in traumatic brain injury cases.

Often, Magnetic Resonance Imaging (MRI) testing can be used, typically post ER visit.  MRI can be contrasted (with radioisotope tracing) or non-contrasted. However, standard MRI sequencing typically fails to show any abnormalities of the brain (other than intracranial bleeding of more than 2 mm).  High resolution MRI with specifically tailored scanning protocols may show microstructural abnormalities, which relate to neurofilaments causing traumatic axonal injuries.  A newer subset of MRI, called functional MRI (fMRI), uses blood flow (in place of injection of a signal boosting compound or radioactive tracer) to measure neuron activity and thus define problem areas of the brain attributable to injury because of a disruption in blood flow.  Specifically, fMRI measures oxygen carried in blood by hemoglobin.  However there is a mix of consensus on whether these changes can accurately identify areas of actual brain deficiency.  This type of testing is nearly always used later in treatment, where the suspicion of a traumatic brain injury continues to be present.

Other diagnostic testing for traumatic brain injury includes Positron Emission Tomography (PET), which uses trace radioisotopes to map various functions in brain tissue.  PET continues to offer potential diagnosis for Alzheimer’s or Parkinson’s disease.

Magnetoencephalography (MEG) scanning is used to measure magnetic fields produced by electrical activity from highly sensitive devices such as superconductive quantum interference devices (SQUIDs). It is a direct electrical measurement of brain activity, but this type of scanning is currently primarily used for epilepsy evaluation and has much more limited in use for traumatic brain injury. See, e.g., Integrated Imaging Approach with MEG and DTI to Detect Mild Traumatic Brain Injury in Military and Civilian Patients, Huang MX, Theilmann RJ, Robb A, Angeles A, Nichols S, Drake A, D’Andrea J, Levy M, Holland M, Song T, Ge S, Hwang E, Yoo K, Cui L, Baker DG, Trauner D, Coimbra R, Lee RR. J Neurotrauma. Aug 26, 2009:1213-26.

Therefore, it is important to complete tailored studies using specifically defined imaging.  An example would be a contrasted SPECT (single photon emission computed tomography) image, using both pre- and post- specific mental activities.  For example, scanning under static brain function vs. active brain function.  Another method is the use of diffusion tensor imaging (DTI), which basically uses directional orientation of diffusion images:

“The last family of parameters that can be extracted from the DTI concept relates to the mapping of the orientation in space of tissue structure. The assumption is that the direction of the fibers is colinear with the direction of the eigen-vector associated with the largest eigen diffusivity. This approach opens a completely new way to gain direct and in vivo information on the organization in space of oriented tissues, such as muscle, myocardium, and brain or spine white matter, which is of considerable interest, clinically and functionally.”  Diffusion Tensor Imaging: Concepts and Applications, Denis Le Bihan, MD, PhD, Jean-Franc¸ois Mangin, PhD, Cyril Poupon, PhD, Chris A. Clark, PhD, Sabina Pappata, MD, PhD, Nicolas Molko, MD, and Hughes Chabriat, MD, Journal of Magnetic Resonance Imaging, 13:534–546 (2001), pg. 538.

“An important potential application of DTI is the visualization of anatomic connections between different parts of the brain on an individual basis. Studies of neuronal connectivity are tremendously important for interpreting functional MRI data and establishing how activated foci are linked together through networks.”  Id., pg. 543.

Often, these scanning techniques are used in conjunction with more common and acceptable forms of traumatic brain injury measurement offered through neuropsychological testing to afford correlation to those results.  Today, neuropsychological testing is considered the major predictor of traumatic brain injury assessment.  More extensive study is needed however, as to the use of various scanning techniques in assessing traumatic brain injury, which can be particularly helpful in a trial setting, as juries often react more favorably to actual scanning test results than anything else.  At this point, there still exists some argument in the legal setting as to whether there is sufficient scientific approval to merit some of the above scanning technique’s reliability in proving traumatic brain injury.

Traumatic brain injured patients (or those who suspect they may be), should discuss these technologies with their neurologist to determine whether they should be administered.


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