Often, neuropsychological reports will reflect the beliefs of the neuroscience of twenty-five years ago, rather than more current research. As a result, brain injury is often claimed where none exists and patients are kept home from work, when a return to normal activity would be far better for them in the long run. In particular, there are three neuropsychological “myths” that no longer represent the best thinking in the field.
MYTH #1: “The effects of a Post Concussion Syndrome can last for eighteen to twenty-four months and can impair cognitive functioning throughout this period.”
The recently released “Mild Traumatic Brain Injury and Postconcussion Syndrome” from the American Academy of Clinical Neuropsychology”makes it clear that the cognitive effects associated with a Postconcussion Syndrome (PCS) typically last between one and seven days and rarely exceed thirty days. Old knowledge based its conclusions about neuropsychological damage on the mistaken belief that axonal shears were the principal outcome with physical trauma to the head. It was believed that these breaks then led to many of the symptoms reported after the accident had taken place. Fresh evidence tells us that the brain’s post-trauma changes are almost all chemical, not physical, in origin. Within seconds following the head injury, a neurometabolic cascade is underway that critically alters brain metabolism.
Using the research findings from prospective studies of sports-linked concussions and mild traumatic brain injury (MTBI) from a variety of causes, we know that a series of altered states of consciousness and cognitive impairment that are often present during the initial hours post-accident. We also know that more than ninety percent of those with MTBI as the result of a concussion return to normal brain metabolic functioning within days to weeks. Everything but calcium metabolism is back to baseline within 24 hours and normal calcium processing, itself, is almost always restored within seven days.
Nothing having to do with the severity of the MTBI predicts outcome for the five to ten percent of plaintiffs who’s PCS symptoms persist past the first week. In addition, nothing from neural imaging (MRI or CT scans) of those patients seems able to predict the direction of their eventual recovery. Several recent studies suggest that the best predictor of poor recovery long-term is involvement in litigation. The next best predictors of poor outcome (persisting cognitive complaints) are the presence of pre-existing and on-going social and emotional problems. The recovery of impaired cognitive functioning in 90 percent of patients faithfully mimics the path of the metabolic recovery outlined above. The overwhelming majority of patients with MTBI regain their skills within a matter of days to a few weeks following injury.
MYTH #2: Almost all neuropsychologists report their findings as if there was a perfect connection between a poor score on a test and a specific geographic location within the brain.
Neuropsychologists who do this were taught that there is a specific relationship between impaired performance on certain tasks and the likelihood of physical damage or disruption to brain tissue in or on a portion of the brain’s surface or interior. This belief has become even more pronounced with the advent of functional imaging techniques. These have been used to study behaviors like reading, certain kinds of memory functions and problem-solving in the hope of isolating those parts of the cortex that are particularly involved in those cognitive activities. Unfortunately, as in most studies of this kind, the evidence is almost always mixed, with no clear conclusions to be drawn.
In fact, four different research teams ( trying to identify the location in the brain where we process the meaning of words) discovered that, apparently, almost all areas of the brain could be involved in this activity. Based on the efforts of a number of neuroscience labs, it would seem that many areas of the brain act in an interlocking manner when something like visual or auditory memory processing is measured. This kind of interaction is not true for sensory or motor activity, which does appear to utilize specific brain sites.
In fact, it is our inability to accurately and specifically define what we mean by attention, focus, memory, problem-solving and other behaviors that has made this localizing effort and the drive to specifically pin down which lobe does what that comes up empty. So, when you read a neuropsychologist’s report that indicts the frontal or the temporal lobe as the site of the injury (because of a poor cognitive test score) the neuropsychologist may be relying on “scientific facts” that don’t really exist when careful studies are carried out. For example, some neuropsychologists will call a poor score on the California Verbal Learning Test evidence of a poor auditory memory while others will say that the subject failed to “learn” and still others would say that the poor score points to a failure in attention or focus. Each conclusion would blame a different part of the brain.
MYTH #3: Often, neuropsychologists will decide that impairment exists because a plaintiff/patient has scored poorly on a particular neuropsychological test, compared to how they did on so-called “hole functions,” usually verbal tests that are part of an IQ test that was given.
Study after study suggests that the process outlined above is a faulty approach to figuring out a patient’s pre-morbid level of intelligence. A number of efforts, discussed by Stebbins and Wilson in the APA Pocket Handbook of Clinical Neuropsychology have proved that mild traumatic brain injury (MTBI) can affect performance on verbal skills just as often as it impairs performance on nonverbal or visual-motor skills. Whether within test comparisons or between test comparisons, the highest score on someone’s battery should never be used as evidence of their best, pre-morbid levels of functioning. Tulkey and the other authors of the standardization of the WAIS-III and the WMS-III argue persuasively that this common practice is faulty and typically results in the over-diagnosis of cognitive impairment or a false positive finding of MTBI. We are all an assortment of relative strengths and weaknesses. To label anyone’s inability to do well creating a design from multi-colored blocks as an impairment (when compared to their vocabulary skills) would leave more than a third of USA adults with a diagnosis of brain injury. It is a mistake to identify a cognitive weakness as a cognitive failure or brain impairment.
WHAT DOES IT ALL MEAN?
1. We are just now beginning to learn how long the effects of a typical concussion may last. Fifteen years ago no one would have believed that an injured patient could be back to baseline within ten to fifteen days.
2. Neuropsychologists have believed that the use of functional magnetic resonance imaging (fMRI) was going to produce the final proof we would all like to have about where the impact of a head injury is located. Unfortunately, what MRI’s have done is muddy the water when it comes to proving what happens where inside the brain. As many as four different areas of the brain may be involved in what was once believed to be an exclusively “frontal lobe” or “temporal lobe” activity. We do not know as much about where an injury has impacted patient functioning as we thought we did.
3. Finally, standardized high school test scores may provide the best glimpse of pre-morbid IQ, not some contemporaneous measure based on a patient’s best performance on a few of the many tests administered.