I too have had botox in the scalenes.

I originally recieved botox in my forehead, temples, back of neck and shoulders for migraines. Botox was the first thing to really help my migraines. I went from 13 a month to a couple every 3 months. Now they are much reduced and less intense when I do have a migraine.

I started having problems with my right arm getting very cold when I ran or hiked. Testing showed tos, but no extra rib, etc. More testing indicated that I have cervical dystonia (not sure I spelled that correctl). My muscles are constantly firing. The thought being the scalene was so tight it was closing off the pathway for the nerve and arteries to the arm. One nerve in particular causes the arm problem

The first time I had botox in the scalene they used ultrasound to guide the needle. My scalene was 2 times the size it should be. Now they are very atrophied. I go in every 5-6 months for botox. Even atrophied my neck it tighter than normal.

I do get some relief from the botox . It allows me to do other things like stretching and yoga which gives me more help as well.

I have had odd times where the muscles get too relaxed and for a few weeks I have trouble doing certain movements. Small price to pay for not being drugged all the time