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Although it does not happen often, there have several cases that I have evaluated over the years in which a mild traumatic brain injury (MTBI) is misdiagnosed as a severe TBI. I have heard the same story from some of my colleagues, alerting me that this is a problem occurring across the country. On the surface, such a misdiagnosis would seem impossible. After all, mild and severe traumatic brain injuries should be fairly easy to tell apart by using the Glasgow Coma Scale (GCS; Teasdale and Jennett, 1974), a measure which assesses level of consciousness in the acute injury phase to infer brain injury severity. The scale ranges from 3 to 15 points and provides a way to rate patients on their eye movements, motor responses, and verbal responses. The TBI classification scheme based on the GCS is as follows: 13-15 (mild), 9-12 (moderate), and 3-8 (severe). At the extreme ends of the spectrum, a patient with a GCS score of 15 is alert, oriented, moving all extremities purposely, and has his/her eyes open. By contrast, a patient with a GCS score of 3 is in a coma and non-responsive (no sounds, movements, or eye opening). Patients with mild TBIs generally have no evidence of brain injury on structural neuroimaging whereas brain damage is generally readily apparent in a severe TBI case.
Since there are so many ways
in which mild TBI and severe TBI differ, you might wonder how a physician would not be able to distinguish the two? As it turns out, I have never seen this diagnostic error made in the acute setting. When I see this mistake made, the situation often goes something like this: The patient suffered a mild traumatic brain injury between 10 and 40 years ago when all operational definitional criteria are applied to the case. All neuroimaging (e.g., brain CT/MRI) and EEG results are normal. The physician, nurse practitioner, or other health care provider who evaluates the patient for the first time a decade or more later either does not have the original medical records, does not request the records, or has the records but does not bother to review them in detail because there are too many.
The health care provider hears the patient say that ever since the injury that he/she has not been the same and experiences severe symptoms in numerous areas, such as rage episodes or memory problems. The provider, perhaps partly due to limited time, does not elicit a thorough enough history to evaluate the degree of brain injury that actually occurred and instead equates the severity of symptom reporting with the severity of brain injury. This is a significant error in reasoning, particularly since patients with mild TBI tend to report more severe symptoms than patients with severe TBI. For example, this has been thoroughly documented with memory and other cognitive complaints by Dr. Paul Green, who developed a normative database of memory and cognitive complaints for the Memory Complaints Inventory (2004). As another example, the severity of headache complaints are inversely related to brain injury severity, with more severe complaints associated with milder injuries.
The error in reasoning described above has serious implications besides misdiagnosis. To begin with, perfectly logical competing explanations for the severe symptom presentation besides TBI tend to be ignored, dismissed, or minimized. This means that patients are not referred for specialized evaluations and appropriate treatments that can lead to improved functioning. Instead, the patients are often referred to incorrect forms of treatment, such as brain injury rehabilitation a decade or more post-injury. The other problem is that the patient now believes that he/she is severely brain injured when this is not the case. This can increase resistance to getting help for a psychiatric problem that may be the cause of the severe symptoms because the patient (understandably) views the symptoms to be all caused by brain-damage based on what he/she was told by the health care provider.
In one case I evaluated, a physician completely overlooked the contribution of severe PTSD, panic attacks, and bipolar disorder to the patient’s severe symptoms. All evidence showing normal brain CT, MRI, and EEG was not considered in the case conceptualization. Evidence showing a GCS score of 15 prior to arrival at the hospital was also not considered. Neither was the patient’s and spouse’s description of the injury, which all indicated the presence of a mild injury. Solely based on severe subjective complaints, the injury was retrospectively diagnosed as severe. This does not represent evidence-based practice.
The type of diagnostic error described in this article can easily be avoided if health care providers take the step of requesting and evaluating any and all medical records pertaining to the head injury. Readers would be stunned to know how often this is not done. The most important records to review are those from where the patient was first medically evaluated after injury. Conducting a thorough interview about the acute injury characteristics, cross-checking the information with that in the medical records, assessing the course of symptom progression, comparing the information obtained to empirically-based data on symptom course after brain injury, integrating objective data, and exploring differential diagnostic possibilities in the psychiatric and non-psychiatric medical realm are also very important. At the end of the evaluation, if the health care provider is unclear what is causing the severe symptoms, further diagnostic tests can be ordered and the patient can be referred for a neuropsychological evaluation to obtain diagnostic clarity.
REFERENCES
Green, P. (2004). Memory Complaints Inventory. Edmonton, Canada: Green’s Publishing.
McCrea, M. (2008). Mild traumatic brain injury and postconcussion syndrome. The new evidence base for diagnosis and treatment. New York: Oxford University Press.
Solomon, S. (2001). Postraumatic headache. Medical Clinics of North America, 85, 987-996.
Teasdale, G, Jennett, B. (1974). Assessment of coma and impaired consciousness. A practical scale. Lancet, 2:81–84.
Dr. Carone offers paid lectures on MTBI, “post concussion syndrome,” and symptom validity testing upon request. He can be contacted at info@mtbifacts.com.
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