It is well documented that workers who use heavy vibratory equipment can develope a syndrome of nerve damage. This is often seen, for example, in men who use jack- hammers in thier jobs. The mechanical trauma of the vibration damages the fragile nerve fibers. It makes sense to me that if a person is predisposed to nerve damage, has PN, or has some underlying condition that weakens the nerves to begin with, they will be unable to tolerate the mechanical trauma of vibration. The nerves will succomb to much milder stimuli than a jackhammer because they are already weakened.