Why shoulder weakness after discetomy?

this may not answer your question but it may be of interest to you.before i a fusion done at c6/7 , that was my problem. i could not lift my arm to pour a cup of coffee.I was told that if i didn't have it fixed that it could permanently damage the nerve and it would be like that till death do us part . so i git it fixed .2 - 3 weeks after the sugery ,that problem was gone but i gained another one. i had a severe pain between my shoulder blades.after mri , discovered another blown disc at c4/5.doctor said it was very common to blow out another disc right after a fusion , but it was uncommon to skip a set.both the limited arm use and the pain in shoulder blade area were due to a nerve being pinched in my neck.i will say that i had a little bit of trouble convincing the doctor that the pain i had developed after my fusion was real.i got the feeling that he thought i was faking it to get more pain pills.he kept telling me that it was bursitus.i've talked to several people that have had this procedure done and they all have different stories.but they all had different doctors. my wife had it done with no complications at all.her sister had it done but did not make the problem completly go away.my family doctor had it done twice but is better now .my best suggetion would be to check in to finding another doctor if the one you have is not getting you fixed.i dont know if any of this was of help to you , but good luck with it