With the increasing accessibility of information these days, individuals are becoming more aware of the fragility of the brain. From an athlete’s risk of concussions during a football game to the possibility of a brain contusion from a car accident, there is more concern around brain injuries than ever before.
As a result of this increased awareness, the demands on the field of neurology and its subspecialties have grown. This growth has also raised more questions. One common recurring question is, how do doctors determine the chronicity and severity of a neurological injury.
Doctors often rely on brain imaging to determine diagnosis, treatment and prognosis. MRIs are the most accurate type of brain scan science has to offer (at the moment) and they are effective in identifying hematomas, hemorrhages, and cerebral edemas, but not so effective at identifying other types of brain injuries. For example, MRIs usually cannot detect any abnormalities in a patient with traumatic brain injury. It isn’t until much later that an MRI or a CT scan is able to detect brain atrophy from a TBI (results when dead or injured brain tissue is reabsorbed following the injury). At that time, it is much too late to implement any reversable treatments. Since brain scans are often unremarkable in these cases, we must rely on other clinical tools to properly diagnose and treat these injuries.
Since microscopic injuries to the brain cause long term problems, it is key to detect them early in order to adequately treat them. One of the methods employed to do so is through baseline cognitive testing. Baseline cognitive tests are measures that neuropsychologists administer to assess brain function during a healthy state. Following a concussion, neuropsychologists can use a post-injury test (and compare against your baseline cognitive test) to help determine the severity of the injury and the treatment you’ll need.
In my practice, I work a lot with professional athletes and especially football players. Since concussion protocols have been put into place, the National Football League has implemented a baseline cognitive test for all incoming athletes called the ImPact. This allows team doctors to re-examine the athlete when a head injury occurs and compare test results at the time of injury to their baseline. From the results, the doctors are able to identify a) if an injury occurred, b) the severity of the injury, and c) the treatment required.
But what happens when there’s been a neurological insult, and we have no baseline tests? What then can we compare the post-injury test to in order to determine if there has been an injury? And its level of chronicity and severity? This is where the importance of premorbid testing comes in!
A test of premorbid functioning estimates an individual's pre-morbid (pre-injury) cognitive functioning. Similar to that of baseline testing, a pre-morbid test allows us to determine a) if an injury occurred, b) the severity of the injury, and c) the treatment that is needed. The difference is that in this case, the test takes place after the injury, and we are estimating the pre-morbid level of functioning using empirically based measures and collateral information.
Empirically based measures are standardized assessment procedures that assess for crystallized intelligence. Crystallized intelligence is information that relies on accumulated knowledge, such as vocabulary and reading. Generally speaking, these are not vulnerable to brain damage, with the exception of patients with aphasias (communication disorders) due to damage to the Wernicke’s or Broca’s areas in the brain. In patients with aphasia, the LOFT (Lexical-Orthographic Familiarity Test) can be used. This is a forced-choice recognition task based on lexical familiarity judgments. In studies on aphasic patients, it was found that when compared to non-brain damaged individuals, their scores on the LOFT were statistically insignificant, meaning aphasic patients were not affected in their ability to perform on this test.
Combining the results from empirically based measures with clinical impressions derived from socioeconomic variables such as the patient's level of academic, occupational, social and interpersonal relation areas, neuropsychologists can confidently generate a premorbid estimate of cognitive functioning. This is particularly important in the medical-legal field when doctors are asked to consider pre-existing conditions and apportion when there are pre-existing factors.
More often than not, we do not have a brain MRI or CT scan from before a neurological insult. Individuals typically are not getting a brain scan when they are healthy. Similarly, individuals are not getting a neurocognitive evaluation or baseline cognitive test when they are healthy. This means doctors are typically not provided baseline studies. It is therefore important that we always include premorbid testing to help us determine the individual’s premorbid level of cognitive functioning. This is the only way in which we can effectively determine whether there was truly an injury and the chronicity and the severity of the injury.
Without understanding what the starting point is, doctors cannot truly appreciate what, if any, change has occurred.
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