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Invisible Injury: What Really Happens to the Brain During a Concussion

This episode of the Neurocollective Podcast’s Concussion Conversations explains why concussions are often called the invisible injury and what actually happens inside the skull when the brain is impacted. The conversation with Dr. Bagnell & May Bagnell focuses on how concussion is defined, why symptoms can show up later, and why a normal scan does not necessarily mean normal function. They also cover the brain-gut connection, why energy levels in the brain can drop after injury, and how functional testing can reveal problems that CT and MRI scans miss. The takeaway is practical and hopeful: there are ways to evaluate and support recovery even when symptoms linger.

Key topics

• In this episode, concussion and mild traumatic brain injury are treated as equivalent terms, and “mild” does not mean minor or easy to recover from.
• Doc Bagnell explains that a head impact can count as a concussive force even if the person does not lose consciousness or vomit.
• A concussion becomes more likely when symptoms like dizziness, headache, or eye tracking problems appear within minutes to hours after impact and persist for days.
• The brain is described as soft and gelatinous, not rigid, which helps explain how it moves inside the skull during acceleration and deceleration.
• Using a jello model, Doc Bagnell explains shearing, where nerve fibers are stretched or torn during impact.
• Inflammation after concussion can affect cognition, mood, and movement, creating symptoms across multiple domains.
• The brain may enter a low energy state after injury, similar to a phone switching into power-saving mode, in order to conserve resources for healing.
• The conversation highlights gut disruption after concussion and the brain gut connection, including the shared embryologic origin of the gut and brain.
• Symptoms can appear later because compensation hides deficits at first, especially when a person returns to walking, thinking, school, or work.
• CT and MRI scans can show bleeds or masses, but they do not measure functional issues like balance, eye tracking, vestibular function, or brain energy.
• Functional testing such as QEEG, balance testing, vestibular testing, and autonomic evaluation can help explain lingering symptoms when imaging looks normal.
• The episode closes with a reminder that age does not rule out improvement, and that functional optimization can still be pursued at any stage of life.

Timestamps

(00:00) Introducing Concussion Conversations and the invisible injury
(01:47) What makes an injury a concussion
(02:51) Head impacts that may still count even without obvious trauma
(03:20) When symptoms make concussion more likely
(05:58) Why loss of consciousness is not required
(06:45) What happens inside the skull during impact
(07:21) Brain dissection and the difference between fixed and unfixed brains
(09:24) The jello model of brain movement and shearing
(11:21) How nerve fibers get torn and inflammation begins
(12:40) Why concussion severity depends on force, age, and recovery
(14:16) Gut disruption and the brain gut connection after injury
(17:24) Low brain power on QEEG and why the brain slows down
(20:13) Why the brain conserves energy like a phone in low power mode
(21:00) Why symptoms may show up later at home, school, or work
(24:40) Everyday tasks that become harder after concussion
(25:58) What CT and MRI can and cannot tell you
(27:20) Hope after a normal scan and persistent symptoms
(28:47) Why brain health and balance matter at every age
(30:08) Brain localization map and patient resources
(31:12) Closing thoughts and encouragement to heal

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