<s>[INST] Hi, I am having difficulty with my shoulder. I was involved in an explosion in Afghanistan, and now I can t lift my arm to the side past 90 degrees and have no strength in it. This lack of ability isnt caused by pain but rather I just cant. Its kinda like when you try to bend your leg past straight your knee just doesnt let you. I have had MRI s and they show nothing really abnormal. I was wondering if this could be caused by a tbi. The doctors are running out of ideas [/INST] Hi, You said that the MRIs do not show anything. I assume these are shoulder MRIs. This is muscle weakness caused in turn from a nerve injury from the level of the neck or brain. A cervical spine and brain MRI is needed along with EMG studies with help to pinpoint the level of injury which mostly will be at the level of the neck. A neurological assessment and intensive physiotherapy will be required </s>