Actually, it was different from a brain tumor, it was actually a late developing "twin". I've never heard of this, and will be grilling my sister, who is in the medical field about this:
http://www.dprp.net/specials/pagansmind/index.html
Andy: From the album notes I see you used to have a rhythm guitarist, Thorstein Aaby, but there was just one guitarist on stage today. Has Thorstein left the band or was he just unable to make this long trip?
Nils: No that's a difficult story... you tell it better than I do Jørn...
Jørn: It started last year with him fainting a lot for no apparent reason. No-one knew what was happening, so he went to the doctor and they discovered a kind of object inside his forehead. First of all they thought it was cancer and everyone was obviously very worried. Anyway he had to undergo major surgery to have it removed and they found there was no cancer in the object. What they found, was that it was actually his twin that had started growing inside of him.
Nils: There were hairs, hands, even fingernails. It was a real person in his forehead between his skull and his brain.'
Andy: Oh, that it sounds like something out of the Stephen King novel, The Dark Half. It must have been a shocking experience for everyone who knew Thorstein?
Jørn: Apparently it happens in small number of people. It's from cell structures that were intended to be a second baby. In a small number of people it starts growing again when they're older. It's usually in relatively harmless places such as on the arm, but for Thorstein it was a dangerous operation and it left a scar on his brain surface which will take a long time to heal. A common problem is that you get a lot of epileptic fits, which he does get. Thankfully he's getting better but needs to relax and take its easy. As a lot of things are happening for the band now, he said: 'Look guys, because of my health I've got to take it easy.' So we've not got a rhythm guitarist. We've got no plans to replace him at present - you never know what will happen in the future.
RIP.
