The importance of detecting the barely detectible...

Following a mild concussion, individuals typically begin to perceive a sense of normalcy within 1-2 weeks. Symptoms gradually subside, and if undergoing professional assessment, patients often exhibit a return to their initial scores on standard evaluations like SCAT and ImPACT during this post-concussion period. However, the question arises: is their brain genuinely fully recovered?
Unlike a fracture that can be directly observed through an X-ray, head injuries are evaluated indirectly by gauging brain function. This comparison is akin to assessing a broken arm's condition by assessing the arm's mobility – a significant break would be evident, but a minor fracture might be more challenging to diagnose. Similarly, in head injuries, an individual with a mild concussion might seem to have recovered within a week or two, with brain function seemingly unaffected. However, this doesn't necessarily indicate complete healing.
A fascinating method for evaluating persisting imperceptible symptoms involves subjecting patients to more demanding conditions during a concussion test, specifically exposing them to low oxygen levels. Studies by Ewing et al. (1980) and Temme et al. (2013) exemplify this approach. In these studies, subjects who had experienced concussions 1-3 years (Ewing et al. 1980) or 0.6-9.7 years (Temme et al. 2013) earlier displayed no symptoms under normal oxygen conditions. Yet, when subjected to hypoxic conditions, the "recovered" concussion patients exhibited notable deficiencies in comparison to a healthy control group, particularly concerning memory and judgment tasks. Upon returning to normoxic air, all subjects returned to their regular functioning state. This implies that under normal, low-stress circumstances, the brain can compensate for deficits even if damage endures for years following the initial injury.
Temme et al. (2013) theorized that even if an individual can function normally after a concussion, their brain expends significantly more energy to complete tasks. By introducing added complexity (low oxygen conditions), the brain's ability to mask the injury diminishes. Drawing a parallel with the broken arm analogy, you might be able to lift a light object with a fractured arm and assume it's healed, but attempting to lift something heavier would reveal an issue.
This prompts the question: How can you definitively ascertain if a head injury has healed? Regan et al. (2017) suggest conducting standard concussion tests under hypoxic conditions. While this approach seems theoretically valid, its practical implementation can be complex and costly, particularly in settings like athletic training rooms or smaller medical offices. We might be partial, but we consider the Brain Gauge as a more accessible and cost-effective alternative. While a direct comparison hasn't been made between standard concussion tests under hypoxia and Brain Gauge testing under normoxic conditions, based on the Brain Gauge's principles and its focus on fundamental pathway functionality, it's hypothesized that results should be comparable. Brain Gauge tests are rooted in measuring basic pathway performance – mental exertion doesn't influence perception. Thus, even minor damage not detectable on other concussion tests can still be identified by the Brain Gauge (Tommerdahl, et al, 2022).
Irrespective of the evaluation methods employed to assess brain damage, it's essential to recognize that symptom-free status doesn't equate to a fully healed brain. Just as a broken arm is immobilized until it's healed, your brain necessitates protection from further damage until complete recovery. Employing the right tools to evaluate and quantify recovery is pivotal in safely restoring your brain to full functionality.


  1. Ewing R, McCarthy D, Gronwall D, Wrightson P. Persisting effects of minor head injury observable during hypoxic stress. Journal of Clinical and Experimental Neuropsychology. 1980 Oct 1;2(2):147-55.
  2. Regan PM, Bleiberg J, Onge PS, Temme L. Feasibility of using normobaric hypoxic stress in mTBI research. Concussion. 2017 Aug 22;2(3):CNC44.
  3. Temme L, Bleiberg J, Reeves D, Still DL, Levinson D, Browning R. Uncovering latent deficits due to mild traumatic brain injury by using normobaric hypoxia stress. Frontiers in neurology. 2013 Apr 30;4:41.
  4. Tommerdahl, Mark, Oleg Favarov, Christina D. Wagner, Timothy J. Walilko, Laila Zai, and Timothy B. Bentley. "Evaluation of a field-ready neurofunctional assessment tool for use in a military environment." Military Medicine 187, no. 11-12 (2022): e1363-e1369.
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