I have sciatica, will manipulation under anesthesia help?

Probably not. Manipulation under anesthesia is good for frozen shoulder, knee joints or hip joints that have reduced mobility. Generally not done for spine issues.
Jury is out. The use of manipulation under anesthesia is done by chiropractors. The scientific utility of this has not been proven by independent studies. I wold make sure that the MRI or ct used to make tis decision reviewed by a physician before proceeding.
MUA. Mua is done by chiropractors. Make sure that a full evaluation is done by an md with a revies of the MRI before you think of an mua.