Cervical foraminal steroid injections under CT guidance: retrospective study of in situ contrast aspects in a serial of 248 cases

To describe all the CT findings after in situ contrast injection just before steroid injection and to recognize the abnormal aspects associated with intravascular contamination. We retrospectively evaluated 248 cervical transforaminal steroid injections done at the university hospital in Dijon, France, in 2008-2012, to treat cervicobrachial neuralgia inadequately improved by optimal medical treatment for at least 3 weeks. Features describing the opacification patterns were recorded. Five main nonvascular opacification patterns were identified: clumps of contrast agent outside the foramen (16 %), a crab claw pattern surrounding the ganglion (13 %), a ``French'' circumflex accent pattern (15 %), reflux along the needle (7 %), and facet joint capsule opacification (22 %). Concerning the situations requiring a change in needle position, intravenous injection occurred in 26 % of the patients, with a crab claw pattern in half the cases and a clump pattern in half the cases. Intraarteriolar injection was noted in two patients. CT after in situ contrast injection ensures proper needle positioning outside the blood vessels before steroid injection. Penetration of the needle tip into a vein is very common, whereas arteriolar puncture is extremely rare.