Diagnosis of Brain Injury – In Search of the Footprints
Diagnosis of Brain Injury – the Footprints of Pathology
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Diagnosis of brain injury is like the religious story called the “Footprints in the Sand”. Footprints in the Sand is a wonderful allegory about believing in what cannot be seen, without looking for secondary evidence. The story begins with two sets of footprints. One set is for the narrator, one for Jesus who is walking beside him. But at times of crisis, there is only one set of footprints. The narrator blames Jesus for abandoning him in times of crisis. Jesus explains that he never abandoned him. The reason there is only one set of footprints is that Jesus was carrying the narrator on his shoulders through the crisis.
Any diagnosis of brain injury must be based largely upon what can be called the “footprints of pathology.” Just because imaging studies are negative, does not mean that there is no “objective evidence” of brain injury. Footprints of pathology are objective evidence upon which a diagnosis of brain injury can be made. The continuing challenge in the diagnosis of brain injury is to heighten our search for the fingerprints of brain injury. The fingerprints of pathology are harder to find than the footprints – but as diagnostically significant.
I use a term I heard first heard 20 years ago called thingomometers[1]. A thingomometer is one of the alphabet soup of shiny metal tubes and other technological devices used by modern medicine to diagnose pathology. MRI, EEG, CT and PET are thingomometers. But it is a mistake to think technological breakthroughs will guide us out of the dark ages of the diagnosis of brain injury. The quest for the holy grail of objective evidence from a machine, is abandoning the art of being a physician.
More on the state of the art of thingomometers later. But for now, the critical thing to understand about brain imaging is that normal studies do not rule out brain injury. There is only one way to conclusively “see” brain pathology: autopsy. Brain cells are microscopic. Autopsy studies, which utilize the microscope, can see brain damage. Even our best imaging studies would need to improve their resolution thousandfold, to see dead brain cells.
What our imaging studies are getting better at doing is seeing conditions which will cause cell death: hemorrhage and hematoma. We can also the see effect of the “big stuff” – large clusters of dead cells. But when the primary cause of brain damage is diffuse damage (meaning spread widely throughout the brain) to brain cells, there is a great likelihood of normal scans. Scans can even be normal for conditions that result in coma and death.
Diagnosis of Brain Injury is Based Upon Observation and Listening
Diagnosis of brain injury must start with the physicians greatest tool: observation. It must also include a true lost art: listening not just to the patient but also to those who know the patient. Observation and listening can find the fingerprints of pathology, which are far larger and far brighter than anything seen on a post-acute scan. Finally, what is learned about the patient from observation and listening, must be measured against the clinical judgment of the experienced physician.
The problem is that today, fewer and fewer physicians know what a brain injury looks or sounds like. What is worse is that physicians are no longer being taught to look for the footprints in the sand. The doctor’s focus instead is on the breaking waves of technology.
Imaging studies are not the only objective findings in medicine. Neurological science has developed based upon the premise that a “footprint of pathology” is objective evidence of injury. When a person cannot see, even if we cannot pinpoint the cause of the blindness, this “footprint of pathology” tells us that there is damage. When a person cannot hear, likewise this “footprint of pathology” tells us that there is injury. When a neurological exam shows focal neurological deficits, this is a “footprint of pathology”. A focal neurological deficits is a finding upon which the diagnosis of brain injury should be made.
Neuropsychological testing is essentially a “footprint of pathology”. Neuropsychology can provide the objective evidence upon which the diagnosis of brain injury can be made. Neuropsychological testing is based upon the theory that by measuring and assessing how the brain is functioning, we can determine if there is a pathology. Neuropsychological testing can objectively determine the brain’s current capacities at specific, localized tasks. (By localized, I mean focused on a particular function of the brain.) The next step is comparing the pattern of localized results with the patients pre-morbid capabilities. Then the neuropsychologist must correlate the identified changes with the nature of the trauma suffered by the patient. Through such process, neuropsychologists should be able to make a diagnosis of brain injury.
Unfortunately, neuropsychology was developed for diagnosing severe brain injury deficits. It does not have the same capacity to diagnose the type of deficits that arise from Mild Traumatic Brain Injury. Traditional neuropsychology developed measures that could can measure cognitive “declines in the seconds”. Measuring the “seconds” is sensitive enough to measure severe brain injury deficits. Most cognitive deficits post concussion are “deficits of the milliseconds”. The eye of the neuropsychological camera doesn’t open and close fast enough for “milliseconds.”
There are other “footprints of pathology” which establish objective evidence of brain pathology. These would include blood pressure variations, neurological exams, performance based functional capacity exams and brain stem and vestibular testing. A clear footprint of pathology in mild brain injury diagnosis is amnesia. If documented when occurring, it shows the fingerprints of the brain injury diagnosis as clearly as if the patient’s hand were covered with blood.
The more difficult to quantify is the change in the person before and after the brain injury. The survivor will feel it, may be able to share specific examples. But the best way to corroborate the change is through listening to those who know the survivor. It is not enough for the doctor to listen to the patient. The doctor must also inquire of those who have observed the changed behavior in the real world laboratory, life.
Next – the Enlightened Neurological Exam
[1] The origin of the term thingomometer is unknown. I first heard it in a talk by William Merrick, Ph.D., a neuropsychologist in Madison, Wisconsin.