The cascade of Neurobiological events following a concussion:
What actually happens to the brain's biology?
The Meninges are layers of tissue that surround the brain and spinal cord. They function to protect the nervous system, hold it in place, produce cerebrospinal fluid, and provide a passageway for fluids, nerves, and vessels.
Astrocytes are capable of producing a robust antioxidant response to protect themselves and also neurons, through the release of glutathione precursors to neurons. Their role in scar formation allows astrocytes to regulate and contain the immune responses in a manner that controls neuroinflammation.
The blood-brain barrier is a tightly packed layer of cells that line the blood vessels in the brain and spinal cord. This barrier prevents large molecules, immune cells, and disease-causing organisms such as bacteria and viruses from passing from the bloodstream into the central nervous system (CNS).
Microglia are the primary innate immune effector cells of the CNS
Cytokines are small proteins that are crucial in controlling the growth and activity of other immune system cells and blood cells. When released, they signal the immune system to do its job. Cytokines affect the growth of all blood cells and other cells that help the body's immune and inflammation responses.
Proteases are any of a group of enzymes that break the long chain like molecules of proteins into shorter fragments (peptides) and eventually into their components, amino acids.
Brain tissue tares leaving the brain exposed
The brains natural protection is compromised
Lack of oxygen and lactate build up
The brain reacts with its immune response
Excess release of glutamate
The brain will heal
With major brain trauma, the connective tissue of the meninges tear.
The damaged meninges tissues release reactive oxygen species ROS in massive amounts which causes Astrocytes cells to die
The brains blood-brain barrier (BBB) becomes weakened and the metabolic cascade continues Potassium, Chloride and Sodium can now leak through the compromised BBB and cause inflammation in the brain
Astrocytes normally produce energy through a process called glycolysis. During this process, Astrocytes break down glucose and make lactate as a by-product. When lactate combines with oxygen it creates energy the neurons can use, but in the absence of oxygen the lactate level builds up causing more cell death
Now your brain's immune response swings into action, and microglia try to clean up the dead cell debris and fix weaknesses in the BBB. This is the same reactive process in any other injury when Proteases and Cytokines are sent in for tissue repair and it results in the four classic signs of injury redness, heat, swelling and tenderness.
The excitatory neurotransmitter Glutamate is released in excess which creates more toxicity and more cell death
With consistent rest the brain will usually heal itself via brain-derived neurotrophic factor (BDNF). If you do not allow the brain to heal eg: repeat injury the immunological described above gets stuck in action mode and the neuronal damage mounts.
To find out more on repeat injury and the basic science behind repeated head knocks leading to early dementia or C.T.E