From healthline.com

Perineural cysts, which are also known as Tarlov cysts, are fluid-filled sacs that form on nerves at the base of the spine. A person with such cysts would likely never know it. They almost never cause symptoms. When they do cause symptoms, however, the most common is pain in the lower back, buttocks, and legs

If a C-7 T-1 cyst is causing problems, it would likely be to your stomach or esophagus or digestive system. Look up TOS, Thoracic Outlet Syndrome.

In my experience, the muscle spasms needed gentle treatment. My PT used myofascial release to release the spasms. Over a year of treatment and my good discipline with posture, especially during sleep or napping, my neck is much better.

My neck interrupted blood flow to my brain during sleep causing me to have stressful dreams and a bad day the next day.