There are medical conditions, such as diabetes, hypertension, or asthma, that almost all of us will have heard of. But what about those that are so rare that very few of us will know about? Here are some of them.

This dangerous syndrome involves losing control over one of the hands which acts and manipulates objects without the person even knowing about it.

AHS differs from other conditions of involuntary limb movement in that the actions of the affected limb have purpose and are goal-oriented. The affected hand will pick up an object and attempt to use it, or will perform a simple task, such as buttoning and unbuttoning a shirt. Patients retain all sense of feeling in the alien hand, but they often describe feelings of disassociation. Patients may also exhibit strange behaviors, such as speaking to the hand, claiming demonic possession or referring to it in the third person.

This mental illness has patients believing that they are already dead and possibly rotting and have lost their vital organs. It usually occurs with severe depression and some psychotic disorders. It can accompany other mental illnesses and neurological conditions.