Neurobiology of Concussion - Part 4


 

Where do symptoms really come from?

To finish up our grand tour of concussion neurobiology, we’ll now look at potential the causes of typical concussion symptoms.  If it’s not obvious from the past 3 parts in this series, concussions are complex injuries.  It’s tough to pin down exactly what is causing particular issues, but research into injury mechanisms suggests that many symptoms are related to particular biological changes in the brain.  

We’ve done our best to outline some of these things below. Keep in mind that there's a lot of overlap between issues, and not all things are experienced by every person.  All changes are temporary, reversible, and can get better over time.

Symptom Potential cause
Memory issues Network disruptions (especially involving connections to the hippocampus)
Misfiring neurons
Mitochondrial and metabolic dysfunction
Executive issues Network disruptions (especially involving connections to the prefrontal cortex)
Misfiring neurons
Mitochondrial and metabolic dysfunction
Reduced processing speed Diffuse axonal injury
Misfiring neurons
Depolarization of neurons
Mitochondrial and metabolic dysfunction
Attention issues Diffuse axonal injury
Reduced brain activation
Interruptions of the default mode network
Fatigue Decreased blood flow
Mitochondrial and metabolic dysfunction
Energy crisis
Depolarization
Deconditioning
Headache Blood flow changes
Blood pressure changes
Mitochondrial and metabolic dysfunction
Ionic flux
Neck injury
Sensitization of neurons
Depression Inflammation
Oxidative stress
Reduced neurogenesis
Neurotransmitter differences
Deconditioning
Discontinued Activity
Injury to limbic system
Delayed symptoms Mitochondrial dysfunction
Delayed neuron injury
Vulnerability to repeat injury Energy crisis
Vascular changes
Inflammation
Light/sound sensitivity Ionic flux
Sensitization of neurons
Vision disfunction
Prolonged symptoms Network disruptions
Enzyme and metabolism changes
Genetic expression changes
Loss of neurons
Sleep Disruption Pain
Endocrine issues
Changes in melatonin and other neurotransmitters
Network disruption affecting Sleep/wake cycle
Anxiety Changes in the behavioral inhibition system
Network disruption
Hypersensitivity
Injury to limbic system
Neurotransmitter differences
Exercise intolerance Energy crisis
Mitochondrial and metabolic dysfunction
Blood flow and blood pressure changes
Dizziness / Balance Issues Neck injury
Vestibular injury
Blood pressure changes
Visual disfunction
Tinittus Injury to hearing structures (due to acoustic trauma)
Vascular changes / fistulas
Injury to the cochlea, the auditory nerve or the brain pathways involved in auditory sensation
bone fractures,
labyrinthine concussions
Loss of consciousness Network disruption
Blood flow changes
Energy crisis and ion imbalances
Amnesia Network disruption
Default mode network issues

 


 

REFERENCES

  1. Barkhoudarian, G., Hovda, D. A., & Giza, C. C. (2016). The Molecular Pathophysiology of Concussive Brain Injury–an Update. Physical medicine and rehabilitation clinics of North America, 27(2), 373-393.
  2. Chen, J. K., Johnston, K. M., Petrides, M., & Ptito, A. (2008). Neural substrates of symptoms of depression following concussion in male athletes with persisting postconcussion symptoms. Archives of General Psychiatry, 65(1), 81-89.
  3. Elder, G. A., Gama Sosa, M. A., De Gasperi, R., Stone, J. R., Dickstein, D. L., Haghighi, F., ... & Ahlers, S. T. (2015). Vascular and inflammatory factors in the pathophysiology of blast-induced brain injury. Frontiers in neurology, 6, 48.
  4. Fischer, T. D., Hylin, M. J., Zhao, J., Moore, A. N., Waxham, M. N., & Dash, P. K. (2016). Altered mitochondrial dynamics and TBI pathophysiology. Frontiers in systems neuroscience, 10.
  5. Giza, C. C., & Hovda, D. A. (2014). The new neurometabolic cascade of concussion. Neurosurgery, 75(0 4), S24.
  6. Kelly, J. P. (2001). Loss of consciousness: Pathophysiology and implications in grading safe return to play. Journal of Athletic Training, 36(3), 249.
  7. Leddy, J. J., Kozlowski, K., Fung, M., Pendergast, D. R., & Willer, B. (2007). Regulatory and autoregulatory physiological dysfunction as a primary characteristic of post concussion syndrome: implications for treatment. NeuroRehabilitation, 22(3), 199-205.
  8. Moore, E. L., Terryberry-Spohr, L., & Hope, D. A. (2006). Mild traumatic brain injury and anxiety sequelae: a review of the literature. Brain Injury, 20(2), 117-132.
  9. Szczupak, M., & Hoffer, M. E. Lead Artilcle of BIP: Current Theories of Post-Traumatic Tinnitus.
  10. Watson, W. D., Buonora, J., Yarnell, A., Lucky, J. J., D'Acchille, M. I., McMullen, D. C., ... & Grunberg, N. E. (2014). Impaired cortical mitochondrial function following TBI precedes behavioral changes. Frontiers in neuroenergetics, 5, 12.
  11. Wickwire, E. M., Williams, S. G., Roth, T., Capaldi, V. F., Jaffe, M., Moline, M., ... & Pazdan, R. M. (2016). Sleep, sleep disorders, and mild traumatic brain injury. What we know and what we need to know: findings from a national working group. Neurotherapeutics, 13(2), 403-417.
  12. Wolf, J. A., & Koch, P. F. (2016). Disruption of Network Synchrony and Cognitive Dysfunction After Traumatic Brain Injury. Frontiers in systems neuroscience, 10.
  13. Zhu, D. C., Covassin, T., Nogle, S., Doyle, S., Russell, D., Pearson, R. L., ... & Kaufman, D. I. (2015). A potential biomarker in sports-related concussion: brain functional connectivity alteration of the default-mode network measured with longitudinal resting-state fMRI over thirty days. Journal of neurotrauma, 32(5), 327-341.