A recently published study conducted by scientists at the National Institutes of Health Clinical Center in Bethesda, Maryland has significant implications for detecting, classifying, and treating traumatic brain injury, at all severity levels. Published July 8, 2020 in the American Academy of Neurology’s journal, Neurology[1], the study sought to determine whether serum neurofilament light, as a blood biomarker, can detect traumatic brain injury diagnosis, injury severity and likely recovery outcome. It was already known that a neurofilament light chain, a protein, breaks away from neurons in the brain following traumatic brain injury and collects in the cerebral spinal fluid (CSF). Scientists in this study confirmed that the neurofilament light chain protein also collects in the blood in levels that correlate with the levels in the CSF. The study demonstrated that this blood biomarker appears to confirm a traumatic brain injury diagnosis, provide insights into severity and potential recovery outcomes.
The study took place over 8 years between 2011 and 2019. Participants to the study included 45 Swedish hockey players with acute concussion, sampled at 6 days, 31 with repetitive concussion with persistent post concussive symptoms, assessed with paired CSF and serum, 28 pre-season controls and 14 nonathletic controls. A second cohort involved 230 clinic-based participants in the US. This group consisted of 162 participants with TBI and 68 controls, who underwent serum, functional outcome, and imaging assessments at various time frames, up to 5 years post-injury.
In athletes paired with specimens, CSF neurofilament light and serum neurofilament light were correlated and could distinguish players with post concussive symptoms for greater than one year from those with symptoms for less than one year. The clinic-based participants with neurofilament light distinguished patients with mild traumatic brain injuries from those with moderate and severe traumatic brain injuries. The serum decreased over the course of 5 years but remained significantly elevated compared to the control participants. The serum also correlated with measures of functional outcome, MRI brain atrophy and diffuse tensor imaging estimates of traumatic axonal injury.
Researchers conclude that the serum neurofilament light shows promise as a blood biomarker for acute and repetitive sports-related concussion and in patients with subacute and chronic traumatic brain injury. The study’s promise is potentially significant, as there are currently no validated blood-based biomarkers that provide an objective diagnosis for mild traumatic brain injury. This study creates an exciting path forward to include a diagnostic test to help clinicians determine when concussed athletes can safely return to play, or to help determine when injured patients can safely return to work or other activities of daily living.
Each year in the United States, well over 1 million people sustain a traumatic brain injury (TBI) and seek treatment at an emergency room in the United States, approximately 80% of which are “mild”[2] TBIs (mTBI). A mTBI involves a traumatically induced physiological disruption of brain function, as manifested by at least one of the following:
(1) any period of loss of consciousness;
(2) any loss of memory for events immediately before or after the event;
(3) any alteration in mental state at the time of the injury (i.e., feeling dazed, disoriented, or confused); and
(4) focal neurological deficits that may or may not be transient; but where the severity of the injury does not exceed
(a) loss of consciousness of approximately 30 minutes or less;
(b) after 30 minutes at Glasgow Coma Scale of 13/15; and
(c) post traumatic amnesia not greater than 24 hours.[3]
A mTBI is not diagnosed well with conventional computed tomography (CT) and magnetic resonance imaging (MRI) scans as those scans are not sensitive enough to detect microscopic diffuse axonal injuries (DAI), also called traumatic axonal injuries (TAI), commonly found with a mTBI. For those unfortunate victims of mTBI whose cognitive, physical and/or behavioral symptoms cannot be correlated with radiological evidence to confirm a brain injury, some opine that the injury is not real and is more psychological in nature. Advances in the use of blood-based biomarkers has great promise not only in diagnosing and mapping a recovery path for individuals with mTBI, but the evidence can also assist individuals in legal claims.
Adler Giersch remains committed to monitoring advances in research and science to ensure that our clients have access to the best care possible, and to assist with accessing justice for victims of traumatic brain injury.
[1] Pashtun Shahim, Adam Politis, Andre van der Merwe, Brian Moore, Yi-Yu Chou, Dzung L. Pham, John A. Butman, Ramon Diaz-Arrastia, Jessica M. Gill, David L. Brody, Henrik Zetterberg, Kaj Blennow, Leighton Chan Neurology Aug 2020, 95 (6) e610-e622; DOI: 10.1212/WNL.0000000000009983
[2] A label of “mild” suggests that the injury is minor or trivial. However, the word “mild” describes only the initial insult relative to the degree of neurological severity. The term “mild” usually does not relate to the degree of short or long term functional difficulties or disability.
[3] Mild Traumatic Brain Injury Committee of the American Congress of Rehabilitation Medicine.
