The seemingly never-ending controversy about the validity of QEEG discriminant functions came up again recently, this time in connection with traumatic brain injury. If a TBI discriminant function is to have validity, then the problem of false negatives and false positives better be a small one. But when it comes to traumatic brain injury, how do we ever know whether a case assigned to the bin of false positives is anything of the kind? Perhaps we are dealing with a case where traumatic brain injury occurred but was not registered as such. Birth injury is a case in point.
Then there is the matter of false negatives. Those who have worked with minor traumatic brain injury over the years are aware that symptom severity does not match up well against the apparent severity of the insult. Even apparently minor whiplash in a low-speed fender bender can leave someone dysfunctional. One of my favorite cases along these lines involves an attorney whose job it was to discredit head injury cases before juries on behalf of his employer, an insurance company. While he was out at a restaurant he visited the men’s room just as the light bulb burned out there and left him in the dark. He thought he knew his way around, but ended up hitting his head on a stall partition. He returned to the table, finished his dinner with his guests, and got back home safely. But he never worked again (until he had done some neurofeedback later). He could no longer organize and plan his work. His edge as a trial attorney was gone. He realized that he was suffering all of the symptoms that he had been ridiculing and diminishing in court for all these years. Suddenly head injury was only too real for him.
The cases where symptoms appear much more severe than they ought to be are often referred to as eggshell cases. For some reason these nervous systems are just more fragile. Most likely, given the stealth nature of minor traumatic brain injury, we are dealing here with cases that had experienced prior traumatic brain injury that still left the system functional but with much less margin of stability. Insurance company attorneys will often make this point, blaming the current symptoms on earlier insults that the victim is just not owning up to. We see the same thing now in the military, where soldiers are routinely labeled with a prior condition to account for their present state.
The chances are, of course, that the prior history is indeed relevant to what one is currently presented with. Both in the matter of physical brain injury and psychological trauma, we are most likely dealing with a concatenation of events that encompasses the person’s entire history. “Head injury knocks you over the cliff that you happen to be standing next to.” The prior life experience has put the person physiologically at the edge of the cliff.
This is not something that the discriminant function can be expected to deal with. Given the ambiguous history in all these cases, one should not expect a correspondence between the severity of the insult and the severity of symptoms. In every football game, I see players get up from plays that would have put a normal mortal on a stretcher. For every concussion that Troy Aikman suffered, he might have suffered another, or none.
At some point, given that discriminant functions yield serviceable data for the majority of cases, it seems appropriate to take the discriminant function data as the best, most definitive data around with respect to a particular case. Even better would be to get these kinds of tests out of the legal arena. Science and the law do not mix; they live by different rulebooks. The law ultimately must come down on one side of a controversy or another. The discriminant function, however, gives soft rather than hard answers. It deals in probabilities. And it cannot unravel the event at issue from its precursor history. The discriminant function is at its best as a descriptor, not as a diagnosis.
The real answer, of course, is to offer a remedy for traumatic brain injury, so that these cases are resolved before they ever end up in court. And for that we have EEG feedback.
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