It's maddening Pat as I can't remember where it comes from I'm very careful where I research so I know it's not just something I've picked up on the Internet and I'm pretty sure one of the neurologists [poss Clare Rusbridge?] quoted it too.
I've done quite a bit of research into pain and know that in Fibromyalgia one of the reasons for the patient experiencing high levels of pain is low serotonin levels. It is recognised in pain management - but I can't quote any studies unfortunately.
Thank you for sharing those links - I didn't have those so they will be useful to read. I hadn't appreciated the link with MVD.