A CT guided (facet joint/nerve root) injection is an injection of local anaesthetic and steroid under CT guidance, into the area where the nerve leaves the spine.
Use of the CT scan for the injection is to guide the radiologist precisely to the area that needs to be treated to ensure accuracy. The procedure involves an injection either directly into the joint or to the small nerve near the joint. The injection consists of a mixture of local anaesthetic (to numb the area) and a corticosteroid (reduces inflammation at the site). Together this reduces pain and other symptoms caused by inflammation.