No I don't think and MRI, I curently am having a shoulder problem my self it will be 5 years sense my accident.. getting back on the subject lol... U would Have to go for a EMG i they sick these tiny needles in the affected area and give you a tiny shock. or whatever. i HAVE gone for 2, I have what they consider a normal amount of nerve damage for my injury and 3 surgies i under went.
Hope it was helpful.
Auntteta
Radiation to the area of the axilla can cause damage to the nerves which may be delayed - I'n not sure how long there is between the radiation and the appearance of your symptoms. If a nerve was damaged at surgery the symptoms from that should have been present straight away.
An MRI may not be sensitive enough to pick the damage up, however an EMG exam will, and you should ask your neurologist about scheduling one. An EMG should be performed at least 3 weeks after the onset of the symptoms, for it to be of most use.