Ultrasound-Guided Cervical Nerve Root Block: Does Volume Affect the Spreading Pattern?

OBJECTIVE: Ultrasound-guided cervical nerve root block (US-CRB) is considered a safe and effective method for the treatment of radicular pain. However, previous studies on the spreading pattern of injected solution in US-CRB have reported conflicting results. The aim of this study was to investigate the spreading pattern in relation to injection volume.

DESIGN: An institutional, prospective case series.

SETTING: A university hospital.

SUBJECTS: Fifty-three patients diagnosed with mono-radiculopathy in C5, 6, or 7.

METHODS: US-CRB with fluoroscopic confirmation was performed. After the cervical roots were identified in ultrasound imaging, a needle was gently introduced toward the posterior edge of the root using an in-plane approach. The spread of 1 mL and 4 mL contrast medium, each injected in the same needle position, was examined with anteroposterior and lateral fluoroscopic views. After contrast injection, a mixture of local anesthetic and corticosteroid was injected. Clinical outcome was assessed using a numeric rating scale before and 2 weeks after the procedure.

RESULTS: Contrast medium did not spread into the epidural space in any patients with 1 mL contrast medium injection, but it did spread into the intraforaminal epidural space in 13 patients (24.5%) with 4 mL. Pain improved in all patients. There was no significant difference in pain relief according to the spreading pattern.

CONCLUSION: The spreading pattern of injected solution in US-CRB could be partially affected by the injectant volume. However, further studies are needed to assess the importance of other factors, such as needle position and physiological effects.