Written by Kevin Kennedy, Esq.
Edited by Bill Pfund, Esq.
The long term effects of brain injuries have been increasingly studied in recent years and the corresponding rise in public awareness has changed the focus of many plaintiff’s cases. While headaches and memory loss were previously viewed as difficult injuries to ask a jury to quantify when compared to broken bones, those symptoms now form the basis of a claim for a traumatic brain injury. But plaintiff’s attorneys making these claims often lack objective proof from a traditional CT scan of the plaintiff’s brain to support the subjective testimony put forth to prove a brain injury.
Diffuse Tensor Imaging (DTI) has been increasingly favored by plaintiff’s attorneys and championed as cutting edge technology that is more sensitive and can provide objective evidence of a brain injury when old methods failed to show any abnormality. Are these claims accurate and have plaintiffs found the evidence needed to bridge the gap between unreliable personal testimony and indisputable scientific findings? Understanding the current state of DTI technology and the limits of the science are key in evaluating its admissibility and weight at trial in a brain injury case.
DTI is an MRI based imaging technique that uses water diffusion to measure the brain’s white matter tracts. To strip the technology down to its most basic explanation, when water is dropped on a smooth, uniform surface, it diffuses in a uniform manner. When water is dropped on an uneven surface, it diffuses in an uneven manner. Our brains are not a smooth, uniform surface so when water molecules are dispersed throughout the brain, they run along certain grooves, channels, or folds of the brain. Scientists who have developed the technology of DTI are able to track the path of water molecules throughout the brain and then use that data to develop a higher image quality of the brain than previously obtained through older magnetic based imaging studies. Scientists involved in DTI research are legitimate, credentialed research scientists and are excited about the possibilities it presents for assisting in studying the brain and in diagnosing brain injuries. How then is this information used to support plaintiffs’ claims and what basis exists for challenging such testimony in court?
The main problem with using DTI to support a plaintiff’s claim of a TBI is the lack of sufficient control groups to make the information worthwhile. DTI technology is new so there simply aren’t that many brains that have been mapped using this method. Aggressive plaintiff’s lawyers and experts witnesses have attempted to use the technology by taking the existing DTI brain studies and creating one “average” brain. The plaintiff, post-accident, then undergoes his own DTI study and his results are compared to an average brain. All the areas where his brain are shown to differ from the average brain are then claimed as evidence of brain injury that have been diagnosed thanks to this exciting new technology. The problem with this method and conclusion is that it ignores long-established science about differences in brains. For example, brains look different based on age, gender, and dominant handedness, among other factors. A 30 year-old male’s brain will look different from a 75 year-old female’s brain. Those differences are not the result of brain damage to one party, but are simply the result of normal brain development when factoring in gender and age. So then using a 75 year-old female’s brain as part of a control group to determine if a 30 year-old male plaintiff has suffered brain damage is not helpful data. DTI technology could be helpful if the plaintiff’s brain was being compared apples to apples. In other words, a 45 year-old left-handed male plaintiff’s brain should be compared to a control group or “average” brain of other 40 to 50 year old left-handed men. However, experts attempting to find the appropriate control group for DTI studies have run into a data problem. There aren’t enough similar brains that have undergone imaging with DTI to create accurate control groups. An expert witness is left to either throw out DTI, or just expand the control group to the point that the basis for the opinion is no longer reasonable.
While defense counsel may attempt to exclude the opinion, DTI is widely acclaimed in current academic journals and plaintiff’s attorneys can safely demonstrate to the court that it isn’t junk science. More than likely, courts will allow plaintiff’s experts to offer their conclusions based on DTI and simply invite the defendant to attack the weight of the testimony. Working with an appropriate expert is critical to demonstrate to a jury why DTI may be good science overall, but misapplied in this case. When confronted with an expert who is using DTI, issuing a subpoena to obtain information on the control group used as the basis for the opinion is the first order of business. In virtually all cases, the control group will include so many dissimilar brains, the data is essentially useless. The promised “objective evidence” of a brain injury can quickly dissolve and even be used against a plaintiff to show the flawed reasoning that the plaintiff asked the jury to believe in order to support the claim. In summary, while DTI may be appropriate for diagnosing brain injuries in coming years, the scant data limits its value at this time, and a plaintiff relying on DTI to support a brain injury claim is vulnerable to attack.