Getting insurance to cover SGB was a pain. Basically you have to make a compelling case that the treatment is medically necessary. I cited some case studies showing initial promise of the treatment (I listed them below - but there are likely more up-to-date ones now). I explained how there are no FDA approved treatments for long-COVID, so everything is experimental at this point (my initial denial was due to it being experimental).

In your case, I would include your testimony plus that of your physician's on how the treatment has helped. Generally when used for chronic conditions, you need SGBs every so often (my provider said you had to wait a minimum of 3 months; I tend to go 5 to 6 months in between before needing it for my lungs). So try to find some evidence about that, whether for long-COVID or not, and include that too.

Finally, I worked with a health advocacy non-profit to help with my appeal to insurance. You should be able to call your local United Way to see if such a service exists in your area.

Hope this advice helps...best of luck!

Here are the studies I cited in my insurance appeal (but that was 2+ years ago so these are somewhat out of date):

1. “ Know Your Treatment Options for COVID-19”. https://www.fda.gov/consumers/consumer-updates/know-your-treatment-options-covid-19
2. “Stellate Ganglion Block”. https://my.clevelandclinic.org/health/treatments/17507-stellate-ganglion-block
3. “Stellate Ganglion Block Successfully Treats Long COVID/PASC: A Case Series”. https://assets.researchsquare.com/files/rs-873830/v1/80a84314-a831-4ee8-bd3e-cc6501beda46.pdf?c=1631889297
4. “A Review of Stellate Ganglion Block as an Adjunctive Treatment Modality”. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10029323/
5. “Stellate Ganglion Block for Long COVID Symptom Management: A Case Report”. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9822527/
6. “Stellate ganglion block reduces symptoms of Long COVID: A case series”. https://www.sciencedirect.com/science/article/pii/S0165572821003118

The only direct diagnosis was this text "sympathetically maintained pain" for the information associated with this procedure.
I also have the following on my chart. It only shows text, not the codes.
Weakness
Other fatigue
Primary hypertension (started with Long COVID).
Post-COVID chronic fatigue
Procedure codes as follows:
HB INJ CERVICAL SYMP NERVE BK [64510 CPT(R)]
HB PAIN INJECTION PROC TRAY [80008268 Custom]
HB US GUIDE NEEDLE PLACE BIOPSY ASP/INJ/LOC S&I [76942 CPT(R)]

Good luck. At this point, probably not related to any medical procedures but simply time, my remaining issue continues to be fatigue.