Causes

The causes of Alien Hand Syndrome vary and are somewhat unknown. Although stroke is one of the causes, AHS is not considered to be a characteristic of vascular stroke syndrome. Lesions to certain parts of the brain can be a contributing factor to AHS, such lesions to corpus callosum, motor cortex, caused by trauma or cancer. Some exhibit symptoms of AHS after a neurological procedure especially where the corpus callosum (which integrates motor and cognitive function) is effected.  The majority of recorded cases are a side effect of a brain operation called a corpus callosotomy; a surgery which helps to relieve extreme cases of epilepsy by severing the bundle of nerve fibers that carry information between the two hemispheres of the brain. With fMRI scans scientists have found that the "alien hand" is being led only by the motor strip of the brain. So there is no relay to the frontal lobe.