A concussion is a type of mild traumatic brain injury that occurs when rapid movement of the head or an impact to the head causes the brain to move within the skull, potentially stretching axons and damaging cell membranes of neurons. In this video, I discuss the biochemical and structural changes in the brain that are associated with the symptoms of a concussion.

TRANSCRIPT:

Welcome to 2-minute neuroscience, where I explain neuroscience topics in 2 minutes or less. In this installment I will discuss concussions.

A concussion is a type of mild traumatic brain injury that occurs when rapid movement of the head or an impact to the head causes the brain to move within the skull, potentially stretching axons and damaging cell membranes of neurons.

When neuronal membranes are disrupted, it can cause the dysregulated flow of ions into and out of the cell, as well as the increased release of excitatory neurotransmitters like glutamate, which leads to further disruptions in ionic balance and a general inhibition of neuronal activity. Sodium-Potassium pumps work frantically to restore balance, but this causes depletion of energy stores and an energy crisis that’s compounded by lower than normal levels of blood flow. Additionally, the increased glutamate activity prompts excess calcium to enter cells; the high calcium levels can disrupt the function of mitochondria, amplifying the energy crisis. The decreased energy availability may last for days to a week or more and impact cognition. The trauma and subsequent effects can also damage the structural integrity of neurons and glia, further disrupting brain function.

These structural and biochemical changes are associated with the symptoms of a concussion, which include (but aren’t limited to) headaches, confusion, memory loss, and dizziness. After a concussion, patients may also experience an increased susceptibility to another injury, and repeated concussions have been linked to longer-lasting effects on brain function. In some cases, patients who have experienced repeated concussions may begin, often years after the repetitive trauma, to display symptoms of early-onset dementia, mood disturbances, and Parkinsonian symptoms. The resultant condition, known as chronic traumatic encephalopathy, has also been linked to the appearance of neurofibrillary tangles and amyloid plaques, which are typically seen in neurodegenerative diseases like alzheimer’s disease.

References:

Barkhoudarian G, Hovda DA, Giza CC. The molecular pathophysiology of concussive brain injury. Clin Sports Med. 2011; 30(1):33-48.

Giza CC, Hovda DA. The new neurometabolic cascade of concussion. Neurosurgery. 2014; 75 Suppl 4:S24-33.

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