What is Mild Traumatic Brain Injury (mTBI)?
Nobody expects to be in an emergency department (ED) with a head injury, but when it does happen we would all expect fast assessment, clear diagnosis and advice on how we should manage any persistent symptoms.
Injury to the head can cause a disruption in cognitive abilities, including learning, thinking, decision making and more. The leading causes of traumatic brain injury in the ED can be attributed to falls, being struck by an object or being involved in a traffic accident. Some of these events result in a loss of consciousness and clinical staff have a challenge in assessing the extent of the suspected brain injury.
Injury to the brain can lead to long-lasting or permanent problems so classifying the injury at the earliest opportunity can lead to improved outcomes for the injured individual. Depending on the severity of the injury, studies have shown that the risk of developing Alzheimer’s or dementia is increased in individuals who have experienced traumatic brain injury.
mTBI, or concussion, is the most common type of traumatic brain injury. Most individuals’ symptoms resolve within 3 months post-injury. A small percentage of individuals will experience persistent post-concussion syndrome.
Assessment of mTBI in the Emergency Department
The Glasgow Coma Scale (GCS) and clinical evaluation are currently used to assess patients who have suspected brain injury. The information is subjective and can lead to requests for CT scans which may not be required. If biomarkers for brain injury could be tested whilst patients are in the emergency department, an improved accuracy of assessment could avoid unnecessary imaging.
An estimated 82% of patients with traumatic brain injury undergo CT, but >90% show no evidence of traumatic abnormality1. As a tool for evaluating suspected mTBI, CT scans have a number of drawbacks such as delays between ordering and reading a CT scan, high radiation doses that could be avoided and difficulties with managing intoxicated or confused patients.
Biomarkers
Following TBI, the blood-brain barrier becomes more permeable so that proteins associated with the brain can leak into the circulation. Deciding which biomarkers to test in the clinical setting is dictated by certain characteristics. To be useful as a rapid tool for mTBI the sample type must be easily accessible such as peripheral blood, minimising the complexity and time to collect the specimen.
The biomarkers tested must be specific to brain injury and sensitive enough to detect mTBI. Two biomarkers of interest are glial fibrillary acidic protein (GFAP) and ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1). GFAP is a structural protein almost exclusively found in astrocytes whilst UCH-L1 is a degradation enzyme exclusively found in neurones. In combination, the two can distinguish mTBI from non-brain injury.
These two biomarkers are combined in a single multiplex test, the Abbott Alinity iSTAT TBI Plasma Test designed to help determine the need for head CT. Both have been shown to complement the other, and are specific for brain injury.
Application of the rapid test
Studies have shown that using the test was able to reduce the number of unnecessary CT scans by up to 40% (see https://www.globalpointofcare.abbott/en/lp/apoc/overcoming-challenges-evaluation-mild-traumatic-brain-injury.html for references). The test utilises plasma from an EDTA sample and results are available within 15 minutes of commencing the assay. The test is not being offered as a point of care solution, rather a rapid testing alternative to referring all suspected cases for CT scanning.
Due to the sample preparation required (EDTA sample centrifugation to obtain plasma) the testing equipment is best situated in a hot lab or the main laboratory with access to a centrifuge. Results obtained by this rapid test will empower clinicians when making decisions to order CT scans.
Additional benefits
Reducing the number of CT scan orders in the emergency department will have the following benefits:
- Improved patient flow through the ED
- Reduction in wait times
- Reduced CT scan lists
- Improved workflow in imaging
- Reduction in costs and waste
- Better resource utilisation
- Improved patient experience
- Timely discharge
These potential benefits can fundamentally change the management of patients presenting with symptoms of brain injury. Although intended for use by healthcare professionals in a laboratory setting, the future application and utility of this test should be explored so that the full benefits can be realised.
References
- Korley FK, Kelen GD, Jones CM, Diaz-Arrastia R. Emergency department evaluation of traumatic brain injury in the United States, 2009-2010. J Head Trauma Rehabil. 2016;31(6):379-387
NICE guidance on the assessment and management of head injury:
https://www.nice.org.uk/guidance/cg176/chapter/Introduction
The long term effects of concussion can be accessed here:
https://pubmed.ncbi.nlm.nih.gov/28399158/
More detail about the Abbott Alinity iSTAT TBI Plasma test can be found here:
https://www.globalpointofcare.abbott/en/product-details/apoc/istat-tbi-plasma.html
Tony Cambridge is the Managing Director of Thornhill Healthcare Events and Consultancy, and former Lead Biomedical Scientist in the Pathology Management team of a busy acute care hospital in England. He frequently speaks at national and international healthcare events, and is a key opinion leader for point of care testing. He is also a member…
The company was set up in 2018 by Tony Cambridge MSc. BSc. Lead Biomedical Scientist, who is the managing director. With over 20 years experience in Blood Sciences and more recently Pathology management, Tony set out to provide affordable training opportunities to healthcare organisations through a number of different ways, from small group seminars to…