The American Congress of Rehabilitation defines a mild traumatic brain injury (mTBI) as a physiological disruption of brain function as demonstrated by one or more of the following:
- any period of loss of consciousness;
- any loss of memory for events immediately before or after the accident (pre or post-traumatic amnesia);
- any alteration in mental state at the time of the accident (e.g., being dazed, disoriented, or confused); and
- the focal neurological deficit(s) that may or may not be transient;
but where the severity of the injury does not exceed the following:
- loss of consciousness for proximally 30 minutes or less;
- after 30 minutes, and initial Glasgow Coma Scale of 13-15; and
- posttraumatic amnesia (PTA not greater than 24 hours.)
Mild traumatic brain injuries may occur by the head being struck; the head striking an object; and the brain undergoing an acceleration/deceleration movement (i.e., whiplash) without direct external trauma to the head.
Common physical symptoms seen with mild traumatic brain injuries include headaches; sensitivity to light (photophobia); sensitivity to noise (phonophobia); nausea; vomiting; blurry vision; dizziness; fatigue; and sleep disturbances.
Mild traumatic brain injuries also cause cognitive deficits including problems with attention; concentration (e.g., being easily distractible); memory, especially short-term memory; speed of processing information; multi-tasking; speech/language; or executive functioning such as planning, time management, organization, reasoning, and judgment.
Behavioral changes may also be evident after mild traumatic brain injuries including irritability; anxiety; depression; quickness to anger; disinhibition or impulsivity; and emotional lability (e.g., mood swings).Often, people with mild traumatic brain injuries have other physical injuries as well, and do not immediately recognize their mild traumatic brain injury symptoms until they attempt to return to normal functioning and their other physical injuries have begun to resolve.