A friend on another forum has posted this picture of a roe buck recently shot. From what I know the buck is old, no upper teeth and few lower but according to my friend was in fairly good nick. (Seems a bit strange as obvioulsy this buck would have problems eating)
There are signs that the head/antlers may have been caught up in wire or something similar perhaps stopping or reducing blood flow but any further thoughts on the head appreciated. I would think a combination of old age and possibly parasites.