TGN Block?

Does anyone know what this stands for? I had a call from the Pain Clinic and they said they wanted me to see a doctor with them for consult for a TGN Block? I had already previously seen a neurosurgeon regarding a glycerol injection and he said I wasn't a candidate for it. I had gamma knife last year, the actual surgery over 20+ years ago. but I don't know anything about a TGN block? And the lady on the phone didn't know either. I'm scheduled to see him on 12/16 and I guess go from there. All I know is I would like to be out of pain and though I've taken and am on plenty of medicines, nothing helps at this point.

Thanks!
Rachel