Quick answer
Because many head injury symptoms are not visible on scans,[1] evidence from daily life often fills the gap: statements from family, friends and co-workers about changes they noticed; a journal of symptoms; and work or school records that show changes in performance or attendance. The CDC’s symptom list includes changes others may notice, such as irritability, feeling more emotional and memory problems.[2]
Before-and-after witnesses
People who knew the injured person before and after the injury can describe concrete changes: forgetting conversations, losing their temper, avoiding noise, needing to nap or struggling with tasks that were once routine. These observations map onto CDC symptom categories, including thinking and remembering, social or emotional, and sleep.[2]
Symptom journals
A dated journal can record headaches, dizziness, sleep, missed work and activities the person could no longer do. HEADS UP notes that symptoms “may change during recovery,”[3] and a journal can show that change over time. Anything written may be requested by the other side in litigation, since discovery covers any nonprivileged relevant matter.[4]
Work records
Attendance
Missed days, leave requests and reduced hours.
Performance
Reviews, warnings or changes in output after the injury.
Accommodations
Requests for reduced screen time, quieter space or modified duties.
Pay records
Lost wages and lost overtime or bonuses.
School records
For students, grades, attendance, teacher comments and any academic adjustments can show changes after an injury. NINDS notes that some athletes complete baseline cognitive testing before a season,[1] and those baseline results can provide a pre-injury comparison. See sports concussions.
Phone and digital records
Calendars, reminders, messages and fitness or sleep data can corroborate changes in routine. The same records can be used by the other side, so their full content matters. See social media and surveillance.
This page provides general information from the sources listed below. It is not legal or medical advice, and reading it does not create an attorney-client or provider-patient relationship. Laws vary by state and change over time. See our legal disclaimer.
Sources
- National Institute of Neurological Disorders and Stroke. “Traumatic Brain Injury (TBI).” https://www.ninds.nih.gov/health-information/disorders/traumatic-brain-injury-tbi
- Centers for Disease Control and Prevention. “Symptoms of Mild TBI and Concussion.” https://www.cdc.gov/traumatic-brain-injury/signs-symptoms/index.html
- Centers for Disease Control and Prevention, HEADS UP. “Signs and Symptoms.” https://www.cdc.gov/heads-up/signs-symptoms/index.html
- Federal Rules of Civil Procedure, Rule 26. Legal Information Institute. https://www.law.cornell.edu/rules/frcp/rule_26
Sources last checked: October 11, 2026
