@borders74 Welcome to Connect. What you're describing of not being able to turn your head, lightheadedness, pain in arms and shoulders sounds like symptoms from thoracic outlet syndrome. I see that you did have ulnar nerve compression, and TOS also compresses the ulnar nerve in a different location perhaps where it passes through scalene muscles at the side of the neck or between the collar bone and rib cage in the upper chest. There is also scar tissue from surgeries that can make things tight.

You might want to consider myofascial release which is physical therapy by a specially trained therapist that will stretch out scar tissue, release tight fascia, and get your body moving better again. A lot of doctors don't think about fascia getting stuck and these are not problems that would show up on imaging. I have done a lot of this MFR work, and I do have TOS in addition to a C5/C6 spinal fusion. You should be able to turn your head if that is the only fused level. It sounds like you have muscular spasms or restrictions or perhaps scar tissue interfering.

Here is a discussion where you can learn mote.

Neuropathy - "Myofascial Release Therapy (MFR) for treating compression and pain"
https://connect.mayoclinic.org/discussion/myofascial-release-therapy-mfr-for-treating-compression-and-pain/
The nice thing about MFR is it's just PT, and not surgery. It doesn't cause pain unless something is really stuck and it is gentle.

Have you heard of MFR before?