Why do some babies recover from erb palsy while others do not?
Erb's palsy is an injury to the nerves of the neck/shoulder that results in weakness of certain muscles of the arm and shoulder. Why 75-90% spontaneously recover without lasting problems while others have prolonged impairment is not well understood.
There is, therefore, no consensus regarding the timing or utility of various therapies (particularly surgery) in those for whom it persists.
ERB DUCHENNE PARALYSIS