Fatigue is one of the most common complaints after even the mildest of brain injuries. However, it can be difficult to assess and diagnose because it is often hidden by other common brain injury symptoms such as sleep problems, depression, or hypothyroidism.
A recent study of sport-related concussion found that complaints of fatigue not only correlated with increased errors on an attention test, it was also associated with changes in EEG activity. Increases in delta and theta rhythms on the EEG suggest decreased alertness and drowsiness. Athletes who complained of fatigue after a concussion also showed increased delta and theta rhythms on their EEG.
Fatigue is a very real and disabling problem for people a traumatic brain injury. It should be considered not only during the assessment of a concussed athlete's return-to-sport, but also for anyone who suffers any severity of brain injury.
Barwick F, Arnett P, & Slobounov S. EEG correlates of fatigue during administration of a neuropsychological test battery. Clinical Neurophysiology. (September 2011).