It is difficult to get an objective readout of mTBI pathology and symptoms. There are technologies and tests available, each with its own shortfalls.
Detection of soluble molecules in fluids
Some molecules found in the blood indicate damage to the brain. One of the most well studied markers is a protein called S100B which is enriched in glial cells in the brain and is released into the blood if they get damaged following trauma1. Associated costs for detection are a third of CT scans, estimated at around $2000/scan2. S100B serum analysis is highly effective in significantly decreasing the number of CT scans particularly if done within three hours of the head trauma2
Computerized tomography (CT)
CT is one of the most common methods of imaging bleeding and bruises in the brain. X rays from several angles are used to visualize a pattern of brain densities. There are several limitations associated with CT including sedating the patient, allergy to iodine (contrast material that is injected), and exposure to radiation. Most importantly, the CT scan can only evaluate structural but not functional abnormalities, so it often shows up as negative for mTBI patients3. Costs can range from $ 270-50004.
Magnetic resonance imaging (MRI)
MRI relies on artificial magnetic fields that influence protons in brain tissues to produce signals that can be computationally analyzed into 3D images. MRI is often incapable of detecting bleeding and damage to white matter. The cost of an MRI can range from $1300 – 21005.
Functional MRI (fMRI)
fMRI measures changes in the regional brain blood flow or oxygen level which reflect changes in brain activity in response to an external stimulus. fMRI is non-invasive and allows clinicians to use a variety of tasks including verbal and auditory tasks and measure responses of the patient in real time. The limitations include limited sensitivity and resolution, which may necessitate repeated readings. Factors such as diet, age and hormonal fluctuations may also affect the results6.
Cognitive Testing
There is a need for a rapid test to diagnose minor injury that does not rely on injecting sedatives for imaging, subjectivity with regards to visual or auditory stimuli and can identify minute changes to brain structure resulting from mTBIs. The Brain Gauge test is the ultimate neurocognitive test that fulfills these criteria.
Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT)
Neurocognitive tests are often used in conjunction with imaging data and physical symptoms exhibited by concussion patients to evaluate deficits in brain function. ImPACT is a neurocognitive test that consists of four modules, approximately a 30-minute test that can measure verbal memory and physical response to a visual stimulus7. It is administered via computers and a keyboard input method and replaces classic pen and paper tests. The tests include word/design memory, matching symbols/colors and three letters. Composite scores are reported for five criteria: verbal memory, visual memory, visual motor speed, reaction time and impulse time8. Currently, it is the most popular computer based neurocognitive test across the US and Canada9. Typically, the test is administered pre-season in athletes (typically every 2 years) and a baseline score is recorded and compared with scores taken post-concussion. It is imperative to have a complete health history of the patient prior to the concussion so as to take pre-existing learning impairments and neuropsychiatric conditions in mind. The overall sensitivity for this test is between 80-90%9. While false positives have been reported previously10, the test has inbuilt features that can recognize any or insufficient effort on the patients’ part11. Prices range from $ 5.75 to 30 per test12.
Brain Gauge
The brain gauge is a battery of computerized tests that measures your ability to tell apart very subtle differences in sensory inputs to measure how well your neurons are working with each other. Two-button device where pulses or vibrations are delivered to the index and middle fingers, delivering neuronal signals that are processed by the somatosensory cortex. The test measures reaction time with 0.3 ms precision, which makes it possible to calculate reaction time variability. In addition, it tests for the subject’s ability to distinguish subtle differences in vibration intensity, duration, and order of pulses. The test takes a total of 15 minute and quantifies many different aspects of brain function.
The brain gauge has already been shown to be reliable in tracking both concussion recovery13 and treatment efficacy with pulsed electromagnetic therapy for traumatic brain injury14. Potential applications of brain gauge goes beyond diagnosing just brain injury. For e.g. the ability to differentiate between two different stimuli is regulated by the interactions between the cerebellum that controls balance and the parietal lobe. Both Parkinson’s patients and individuals afflicted with migraine show defects in these circuits albeit to different extents15-17.
The brain gauge can also be useful for disorders like schizophrenia and Alzheimer’s where neuroplasticity which is defined as the ability of the brain to form or reorganize connections in response to the environment or injury is severely affected.
About the Author
References:
1. Cook, G. A. & Hawley, J. S. A Review of Mild Traumatic Brain Injury Diagnostics: Current Perspectives, Limitations, and Emerging Technology. Mil. Med. 179, 1083–1089 (2014).
2. Norlund A, Marké LA, af Geijerstam JL, et al. Immediate computed tomography or admission for observation after mild head injury: cost comparison in randomised controlled trial. – PubMed – NCBI. https://www.ncbi.nlm.nih.gov/pubmed/16895945.
3. Alex, Y. Limitations of CT in assessment of traumatic brain injury | Deranged Physiology. https://derangedphysiology.com/main/required-reading/neurology-and-neurosurgery/Chapter 1.1.8/limitations-ct-assessment-traumatic-brain-injury.
4. How Much Does a CT Scan Cost? – American Health Imaging. https://www.americanhealthimaging.com/how-much-does-a-ct-scan-cost/.
5. How much does an MRI cost? – HonorHealth. https://www.honorhealth.com/patients-visitors/average-pricing/mri-costs.
6. Gore, J. C. Principles and practice of functional MRI of the human brain. J. Clin. Invest. 112, 4–9 (2003).
7. Dessy, A. M. et al. Review of Assessment Scales for Diagnosing and Monitoring Sports-related Concussion. Cureus 9, e1922 (2017).
8. Libraries, S. U. EZProxy | Syracuse University Libraries. https://login.libezproxy2.syr.edu/login?qurl=https://www.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC1250250%2F.
9. Schatz, P. & Sandel, N. Sensitivity and specificity of the online version of ImPACT in high school and collegiate athletes. Am. J. Sports Med. 41, 321–6 (2013).
10. Broglio, S. P., Macciocchi, S. N. & Ferrara, M. S. Sensitivity of the concussion assessment battery. Neurosurgery 60, 1050–1057 (2007).
11. Allen, B. J. & Gfeller, J. D. The immediate post-concussion assessment and cognitive testing battery and traditional neuropsychological measures: A construct and concurrent validity study. Brain Inj. 25, 179–191 (2011).
12. ImPACT Applications, I. ImPACT Test Cost & Packages | ImPACT Applications. https://impactconcussion.com.
13. King, D. A., Hume, P. A. & Tommerdahl, M. Use of the Brain-Gauge Somatosensory Assessment for Monitoring Recovery from Concussion: A Case Study. J Physiother Res vol. 2 www.corticalmetrics.com (2018).
14. Francisco, E. et al. OPEN ACCESS Tracking the effects of pulsed electro-magnetic field (PEMF) on individuals with a history of traumatic brain injury (TBI) with the Brain Gauge. vol. 1 www.corticalmetrics.com (2017).
15. Nelson, A. J., Hoque, T., Gunraj, C. & Chen, R. Altered somatosensory processing in Parkinson’s disease and modulation by dopaminergic medications. Park. Relat. Disord. 53, 76–81 (2018).
16. Nguyen, R. H. et al. Neurosensory assessments of migraine. Brain Res. 1498, 50–58 (2013).
17. Tommerdahl, M., Lensch, R., Francisco, E., Holden, J. & Favorov, O. The Brain Gauge: a novel tool for assessing brain health. (2018).
Ketan Marballi is a neuroscientist who holds a Ph.D. in Cellular and Structural Biology from the University of Texas, San Antonio. Over the last decade, his research has spanned the areas of different neurodevelopmental and psychiatric disorders such as schizophrenia and alcohol abuse research. He is currently studying the molecular mechanisms of Rett syndrome, a genetic syndrome similar to autism. Ketan has guest lectured at the University of Texas at Austin, teaching epigenetics to nursing students and mentored 7 students including high school, and undergraduate and medical resident trainees for their research projects. His work has been featured in leading publications including PLoS ONE and the Journal of Molecular Medicine. He enjoys playing tennis and singing in his spare time.