Evaluating the Extent of Ultrasound-Guided Cervical Selective Nerve Root Block in the Lower Cervical Spine: Evidence Based on Computed Tomography Images.

Objective: To verify the injectate dispersal patterns (IDP) and therapeutic outcome of ultrasound-guided cervical selective nerve root block (UG-SCNRB) in treating cervical radiculopathy (CR). Methods: Overall, 18 CR patients were recruited to undergo UG-SCNRB in the CT room. Following placement of the puncture needle tip between the target nerve root and posterior tubercle, 3 mL of the drug was administered per root (0.33% lidocaine 0.5 mL + Compound betamethasone injection 0.5mL + methylcobalamin injection 1mL + iohexol 1mL). Subsequently, the IDP was assessed on postintervention CT scan images. Results: In all, 18 participants were analyzed. We injected 21 target cervical nerve roots, namely, 1 C4 nerve, 9 C5 nerves, and 11 C6 nerves. Among the IDPs on postintervention CT scan images, two IDPs were most prevalent, namely, the contrast spread into the extraforaminal spaces (Zone I, the interscalene) in 100% (21/21) of cases, and the foraminal space spread (Zone II) in 61.90% (13/21) of cases. The injectate spread into the epidural spaces (Zone III) in only 2 out of 21 cases (9.52%). The pain relief was significantly improved two hours after surgery, compared to the preoperative VAS pain scores (2 hours, 1.39±0.50 vs VAS at baseline, P<0.01). The VAS pain scores during follow-up were significantly lower than preoperation (1 weeks, 1.94±0.54 vs VAS at baseline; 2 weeks, 2.61±0.70, P<0.01 vs VAS at baseline; 4 weeks, 2.67±0.59, P<0.01 vs VAS at baseline). Conclusion: We verified, via CT imaging, that the UG-SCNRB drug diffusion was within safe range (the injectate mainly spread to the extraforaminal spaces), and without any serious complications, such as, intravascular drug injection, extensive diffusion of the epidural space, and general spinal anesthesia.