As stated in a previous post, Alien-Hand-Syndrome is: "A disorder in which a person’s hand or limb acts as if it has autonomous, voluntary activity independent of the individual." -- Medical Dictionary
While the cause of Alien-Hand-Syndrome is not quite understood, scientists have agreed, more or less, that it is rooted in a neurological disorder or trauma. And while I certainly understand that it is a neurological phenomenon and not the limbs themselves, I am wondering if there have been any studies on alien-hand-syndrome and individuals born with extra limbs and phalanges? I know that it's not the number of limbs that causes alien-hand-syndrome, but brain trauma or neuro-degenerative disease such as a stroke, but is it more likely to occur in those with more limbs and dactyls (when these head traumas and diseases strikes)? -- or is to rare and specific that research hasn't been conducted?
In cases of "parasitic twins," the individual is born with the set of limbs (sometimes complete set of limbs!) of the "parasitic" twin that wasn't viable. See: CNN: Risky surgery separates 10-month-old from parasitic twin. However, it seems that the extra limbs in these cases are removed because it is too much for a tiny heart to sustain all the limbs. Nevertheless, in polymelia and dysmelia, birth-defects born with an extra or partial extra limbs (whether functioning or malformed), where the limbs are not surgically removed -- has there been studies on alien-hand-syndrome and their limbs?
While I certainly know that Alien Hand Syndrome is related to movement in the limbs (and not the phalanges/dactyls) -- Can alien hand syndrome include "involuntary movement of the phalanges or dactyls?" What is this called? How frequent is it among polydactyls?