Neuroscientist breaks down misconceptions about concussions

By Melissa Brown. This article was initially published in our Concussion Update newsletter; please consider subscribing.

Neuroscientist Richard Sima has written a terrific article for the Washington Post explaining what concussions are–and the serious nature of these mild traumatic brain injuries (mTBI). “The word ‘mild’ is a misnomer,” says John Leddy, a clinical professor of orthopedics and the director of the Concussion Management Clinic at the University at Buffalo. ‘Mild’ refers to the lack of structural damage observable using imaging techniques commonly available in clinics, like CT or standard MRI scans.

However, the more advanced imaging techniques available to researchers reveal damage at the microstructural level. Even mTBI cause the brain’s axons (“thin cable-like neuronal offshoots that connect neurons and brain regions”) to stretch and shear, causing them to release a storm of neurotransmitters into the brain. This neurochemical miscommunication and the subsequent metabolic changes contribute to the short- and long-term effects of mTBI.

Following a concussion, the brain rushes to fix the ionic imbalances caused by neurochemical miscommunication—this healing process demands an increased supply of glucose and adequate blood flow to deliver it. A healthy brain closely regulates cerebral blood flow with a set of vasoconstrictive substances, but mTBI compromises this process. Dysregulation of the baseline cerebral blood flow, combined with the increased demand for glucose, widens an energy gap that could contribute to fatigue symptoms following a concussion. 

Research indicates that mTBIs result in changes to autonomic system functioning. Consequently, blood pressure, heart rate, and other processes regulated by this system may be affected by a concussion. The article goes on to explain the symptoms of a concussion, recovery rates, and how diagnoses are made.