Traumatic brain injury (TBI) is a complex clinical phenomenon. (Raji) The classic designations of mild, moderate, or severe TBI are based on the acute clinical presentation and do not necessarily predict the long-term outcome. The long held assumption that the mild forms of this condition recover rapidly and without consequence is not supported by more recent literature. The effects of several mechanisms for TBI lead to neurophysiological changes, cellular depolarization, and apoptosis that occur on a continuum and can progress over a protracted period of time. Mild TBI (mTBI), particularly repetitive mild TBI, can create neuropathology that contributes to long-term increases in morbidity and mortality. People with TBI have an increased risk of death by suicide (3-4 times greater), higher suicide attempts and suicide ideation. (Simpson) Repetitive mild TBI, also known as ‘‘repetitive concussion,’’ can lead to a progressive deposition of tau protein in neural tissues (tauopathy), now known as chronic traumatic encephalopathy (CTE). At this point this is an irreversible and deadly condition.
The diagnosis of TBI, particularly mild TBI (mTBI), remains a challenge clinically. There is overlap between the symptoms of mild TBI and posttraumatic stress disorder (PTSD). Symptoms can include headache, dizziness, irritability, sleep disturbances, sensitivity to light and noise, impulsivity, judgment problems, visual disturbances, emotional outbursts, depression, and anxiety.
Imaging using MRI, neuroimaging, is one focus to identify changes in brain function. Changes in brain structure are a late change in most neurological disorders, such as dementia. Structural changes able to be seen on MRI are frequently insensitive to the earliest changes seen in disease progression.
In TBI, a recent study showed that changes in cerebral blood flow (CBF) preceded changes in MRI diffusion tensor imaging (DTI). CBF abnormalities persist even in chronic TBI. Single Photon Emission Computed Tomography (SPECT) can identify early changes in neurological diseases through regional CBF. This may be predictive of damage. But, SPECT is not widely available, expensive and not covered by insurance.
It’s actually likely, given the limitations of every technology, that multiple approaches are necessary to produce a complete picture.
Pawluk, William. “The role of pulsed magnetic fields in the management of concussion and traumatic brain injury.” The Journal of Science and Medicine vol. 1, 2 (2019)