Can I ask what part of your brain was injured? I only started experiencing dyshporic hypomania & depression after a simple partial seizure (& later a complex partial) & they found a lesion in my left temporal lobe, maybe caused by a clot. I believe I have experienced euphoric hypomania prior to this though, but because I never entered full blown mania i was able to function at a high level & I had no insight into this at the time, only in hindsight can I identify it. I can identify with the low moods to homicidal rage part.