CT fluoroscopy-guided transforaminal and intra-articular facet steroid injections for the treatment of cervical radiculopathy: injectate distribution patterns and association with clinical outcome

Objectives: To investigate injectate dispersal patterns and their association with therapeutic efficacy during a transforaminal (TFSI) or an intra-articular facet steroid injection (IFSI) to treat cervical radiculopathy.

Methods: This retrospective study examined the post-intervention cervical spine CT of 56 patients randomized to receive one CT fluoroscopy-guided IFSI (29 patients; 10 (34.5%) males; mean age 45.0 years; SD 8.8 years; range 26-61 years) or TFSI (27 patients; 13 (48.2%) males; mean age 51.1 years; SD 11.2 years; range 29-72 years) (December 2010 to August 2013). The presence of contrast within the intra-articular facet, juxta-articular facet, retrodural, epidural, and foraminal and extraforaminal spaces during IFSI, and within the extraforaminal, foraminal, and epidural spaces during TFSI was assessed. Descriptive data are presented as frequencies. The association between injectate dispersal patterns and therapeutic efficacy, 4-week post-intervention, was assessed with ANCOVA models.

Results: During IFSI, the injectate predominantly spread to the retrodural (62%; 18/29) or juxta-articular (21%; 6/29) space. During TFSI, the injectate predominantly spread to the extraforaminal/foraminal spaces (41%; 11/27) or to the extraforaminal/foraminal/epidural spaces (33%; 9/27). Injectate presence in the juxta-articular (p = .007) or extraforaminal (p < .001) space was a predictor of therapeutic efficacy but not in the foraminal (p = .54), epidural (p = .89), or retrodural (p = .75) space.

Conclusions: TFSI and IFSI led to preferential extraforaminal and retrodural injectate spread, respectively. Targeting the extraforaminal or juxta-articular facet space improved the clinical efficacy of steroid injections when treating cervical radiculopathy.

Key points: • During intra-articular facet injection, the injectate spreads from the facet joint to the retrodural space and rarely reaches the epidural and/or foraminal spaces. • Epidural spread of the injectate during an anterolateral transforaminal steroid injection is the least effective for pain relief in patients with cervical radiculopathy. • Injection techniques targeting the extraforaminal or juxta-articular facet space are safer than transforaminal injections and effectively relieve pain in patients with cervical radiculopathy.