IMHO, rare, it's a particular manifestation of weakness with low potassium. Maybe there's another defect involving the diaphragm or phrenic nerve.
Phrenic Nerve.....in the 4th or 5th vertebrae ? Hmmmmmm bad back can be cause of this as well then if it’s damaged or pinched ????
Here is a cool pic BTW if ya haven’t seen it !!
http://cliptank.com/PeopleofInfluencePainting.htm