“It’s just a concussion.” It’s one of the most common phrases said after a bump to the head — and one of the most misleading. A concussion is a traumatic brain injury, and understanding what’s actually happening in the brain helps explain why these injuries deserve real attention, even when imaging looks normal.
What counts as a mild TBI
A traumatic brain injury (TBI) is any injury that affects how the brain works, caused by a bump, blow, or jolt to the head or a hit to the body that makes the head and brain move rapidly back and forth. When that movement is severe enough, the brain can bounce or twist inside the skull, triggering chemical changes and stretching brain cells — even without any visible bleeding or bruising on a scan (CDC).
“Concussion” is simply the everyday term for mild TBI. Healthcare providers call it “mild” because it’s usually not life-threatening, not because the effects are minor. As Mayo Clinic puts it, a mild brain injury is still a serious injury that requires prompt attention and an accurate diagnosis.
Why it happens more than people realize
Falls, motor vehicle crashes, and assaults are among the most common causes of TBI, and falls alone account for nearly half of all TBI-related hospitalizations (CDC). Sports and recreation add to the numbers, particularly among youth. Older adults and young children are at the highest risk — and in older adults, TBI symptoms are frequently missed because they overlap with conditions like dementia, or because the person is on a blood thinner that raises the risk of bleeding after even a minor hit to the head (CDC).
TBI is also a significant public health issue: there were more than 69,000 TBI-related deaths in the U.S. in 2021, or roughly 190 a day (CDC).
What it looks like
Immediately after a concussion, someone might experience a brief loss of consciousness or simply feel dazed and confused — loss of consciousness isn’t required for a diagnosis. Common symptoms include headache, nausea, dizziness, fatigue, sensitivity to light or sound, blurred vision, and difficulty concentrating. Mood changes, irritability, anxiety, and sleep disruption are also common, and symptoms can shift as recovery progresses: physical symptoms like headache and nausea often dominate early on, while emotional and sleep-related symptoms may show up a week or two later (CDC, Mayo Clinic).
How it’s diagnosed — and why testing matters
A brain scan like a CT is not needed to diagnose a mild TBI and often looks entirely normal even when real injury has occurred. Instead, healthcare providers may use neuropsychological or neurocognitive testing to assess learning, memory, concentration, and problem-solving — tools that can pick up on real effects of the injury that a scan simply can’t show (CDC).
Recovery — and when it doesn’t go as expected
For most people, mild TBI symptoms improve steadily and resolve within weeks to a few months, especially with an early medical check-up and a paced return to normal activities. But recovery isn’t guaranteed to be quick or complete: a history of repeated or prior concussions is associated with longer recovery and more severe symptoms, including ongoing problems with concentration, memory, headache, and balance (CDC). When symptoms persist well beyond the expected window, that’s generally referred to as persistent post-concussive symptoms — a topic worth its own discussion.
The bottom line: any blow to the head that causes concerning symptoms or behavioral changes warrants a visit to a healthcare provider, and danger signs (worsening headache, repeated vomiting, seizures, one pupil larger than the other, increasing confusion) warrant emergency care right away.
Understanding what a concussion actually is — and isn’t — matters for patients, families, and the attorneys and physicians who work with them after an injury. At The Brain Psychologist, Dr. Daniel Fenton conducts neuropsychological evaluations that assess the cognitive and emotional effects of mTBI and concussion, whether for clinical care or as part of a forensic case.
Sources
- Centers for Disease Control and Prevention, “About Mild TBI and Concussion.” https://www.cdc.gov/traumatic-brain-injury/about/index.html
- Centers for Disease Control and Prevention, “Facts About TBI.” https://www.cdc.gov/traumatic-brain-injury/data-research/facts-stats/index.html
- Mayo Clinic, “Traumatic brain injury — Symptoms and causes.” https://www.mayoclinic.org/diseases-conditions/traumatic-brain-injury/symptoms-causes/syc-20378557