They are conditions that one would be hard-pressed to find in medical literature. Bring them up in front of a physician and in some cases you may get little more than a blank stare. But they exist, often as an extreme form of a normal bodily function that most people experience every day.
And while the thought of uncontrollable hiccups or never feeling pain sensations are cocktail-party fodder for some, they can be a source of difficulty and shame for those who experience them firsthand.
People with these strange conditions can be so uncomfortable, physically, socially and emotionally, that their lives can grind to a halt as they struggle to find a cure.
The following pages feature some of the more unusual medical conditions that have received recent media attention.