Concussion & TBI Glossary

Who this is for: Written for patients, families and paralegals reading head-injury records full of unfamiliar terms.

Injury terms

• Concussion: a brain injury caused by a blow or jolt that disrupts how the brain functions, often considered a form of mild TBI. Under ACRM 2023, a concussion can be diagnosed without loss of consciousness and with normal imaging.
• Mild TBI: a classification based on factors at the time of injury. "Mild" describes the classification, not necessarily how mild the symptoms or their impact turn out to be.
• Closed head injury: a head injury where the skull is not penetrated. Most car-crash concussions are closed head injuries.
• Post-concussion or persistent symptoms: symptoms that continue after a concussion, such as headaches, dizziness, fatigue and trouble concentrating, that should be evaluated by a provider.
• Red flags: emergency warning signs after a head injury, such as a worsening headache, repeated vomiting, a seizure, weakness, slurred speech or confusion, that require immediate ER care.

“Mild” describes the classification, not necessarily how mild the symptoms or their impact turn out to be.

Imaging and testing terms

• CT scan: emergency imaging that is very good at finding bleeding, fractures and swelling. It does not measure function.
• MRI: imaging that shows brain structure in more detail than CT, but is still primarily structural.
• Eye-movement (oculomotor) testing: measurement of how the eyes track, shift and coordinate while the patient follows targets on a screen.
• Saccades: quick eye movements from one point to another. Smooth pursuit: the eyes' ability to follow a moving target steadily.
• Neurocognitive testing: computer-based tasks that measure thinking skills against reference data.
• Brain-activity (EEG-based) assessment: a recording of the brain's electrical signals through scalp sensors. It only records, and it is one adjunct part of a physician-interpreted evaluation, not used on its own to diagnose concussion.
• Baseline: a measurement of performance before an injury. Reference data: results from large groups that show typical performance, used for comparison.

Symptom and function terms

• Cognitive: having to do with thinking, including attention, memory, processing speed and problem-solving.
• Executive function: planning, organizing, switching between tasks and controlling impulses.
• Processing speed: how quickly a person takes in and responds to information.
• Vestibular: relating to the balance system, including the inner ear and how the brain processes balance information.
• Photophobia: sensitivity to light. Phonophobia: sensitivity to noise.
• Anticoagulant (blood thinner): a medication that reduces clotting. People taking one who hit their head need prompt emergency evaluation because of bleeding risk.

Related in this series: Mild TBI vs. Concussion: Are They the Same?, Sample Report Walkthrough (Synthetic Example) and Why a CT Scan Can Miss a Concussion. For the full overview, start with our guide, TBI Diagnostics: What Tests and Reports Show.

A concussion can be diagnosed without loss of consciousness and with normal imaging.

Care and report terms

• Treating provider: the chiropractor, physical therapist, physician or other clinician managing a patient's care, who refers for testing and receives a copy of the interpreted report.
• Referral: a treating provider's request for testing, including symptoms and history.
• Physician-reviewed diagnostic report: a report whose test results a neurologist interprets in the context of the patient's history.

Using this glossary

Patients can use it to understand their records, providers to explain terms and attorneys as a plain-language reference. Clinical meanings can vary by context, so ask your provider about your own situation.