This is the name given to an often observed consequence of injury to the frontal lobe(s) of the brain. The frontal lobes in man are important for higher cerebral functioning affecting personal attributes such as insight, judgment, specific rational processes, as well as emotional regulation, motivation, drive and personality.
The injury to frontal lobe can be due to a space occupying lesion such as a meningioma occupying the frontal lobe, or after a forceful impact injury to either the front or back of the head (such as a fall backwards resulting in contra coup).
There are many other causes of a frontal lobe syndrome (FLS) e.g. frontal lobe epilepsy, MS affecting frontal lobe, infection, haemorrhage, early onset dementia, HIV, etc.
There is considerable clinical expertise needed to manage the problems of FLS, usually involving complex psychopharmacology. An expert neuropsychiatrist is essential.