--they they would have been able to document the damage, providing they were testing the correct affected nerve pathways, and provided there was enough damage to leave an observable deficit (which is not always the case--damage can be patchy and incomplete, and not show up definitively).

Nerve conduction studies and EMG's are notoriously difficult to standardize--the placement of the electrodes has a lot to do with documenting the nerve damage--not everyone's pathways are in the same places--and the skill of the doctor or technician is very important. If the compression only happens in certain positions, I do think they may have wanted to try in that position. And other things can enter into this--the test is supposed to take place in a relatively cool room--heat is the enemy of nerve conduction--and several different series of readings are supposed to be taken and averaged.