I meant to say, sorry, does a brain injury occur only after physical or can it happen after severe pyschological trauma ?

Functional injury: Psychological trauma changes the brain in different ways than physical trauma. I consider this a type of functional trauma. In ptsd different areas of the brain become hyper or hypo active compared to normal such as the hippocampus, amygdala and frontal cortex.

Thanks for clarifica: As we currently define brain injury based on the pathological findings which can include scar (gliosis), atrophy (encephalomalacia), diffuse axonal injury-this is limited to physical injury. Severe psychological trauma does not cause these physical stigmata of brain injury. At this time we do not know the similarities and differences at the biochemical level.