C5 ventral ramus block for clavicle surgery: How low concerning the volume can we go?

Abstract

Background and aims: Clinical case reports mention 3-5 ml of local anesthetic (LA) at the cervical root 5 (C5) for surgical anesthesia essential for clavicle surgeries with reasonable success. A volume of 5 ml LA has been shown to cause hemidiaphragmatic paresis.

Material and methods: We implement the 3-5 ml LA for awake clavicle surgeries along with a supraclavicular nerve (SCN) block with another 2 ml. To understand the spread of injectate, we conducted anatomic macroscopic dissection on Theil based cadavers. Post ultrasound injection of 3 ml of blue latex in one cadaver and green latex in the other, we dissected one cadaver and the other cadaver underwent a cross-section.

Results: Dissection confirmed a vertical spread of dye more caudad than cephalad. There was no neuraxial spread visualized in the cross-section. The phrenic nerve (PN) was not stained in both cadavers, but a possibility exists depending on its course.

Conclusion: Based on this limited study we recommend a volume of LA of 3 ml at the level of C5 and another 2 ml at the level SCN of LA for clavicle surgeries.

Keywords: Cadaver; cervical root; clavicle; phrenic nerve; regional anesthesia; supraclavicular nerve; ultrasonography.

Figure 1

Left neck dissection demonstrating the bluish discolouration below the prevertebral fascia. (SCM -sternocleidomastoid; SCN - supraclavicular nerve; MCF-middle cervical fascia; Black arrows – Bluish stain below prevertebral fascia)

Figure 2

The left side of the neck shows the blue latex spreading in the interscalene gap, along the superior trunk. The phrenic nerve is not coloured. (SCM - sternocleidomastoid; SuTr- Superior Trunk; MSM – middle scalene muscle; ASM - anterior scalene muscle; PN-phrenic nerve; MCF-middle cervical fascia; SCN-supraclavicular nerve)

Figure 3

The latex reaches the area of the intervertebral foramen. The phrenic nerve is not stained by the latex although the close relationship. (SCM -sternocleidomastoid; ST- Superior Trunk; MSM – middle scalene muscle; ASM - anterior scalene muscle; PN-phrenic nerve (green arrows) SCN-supraclavicular nerve; MT-middle trunk; aST – anterior division superior trunk; suprascapular nerve; TCA- transverse cervical artery)

Figure 4

Latex visualized on the superior aspect of the C5 ventral branch. A small spread in the front of the vertebral artery. The superficial cervical plexus is below the sternocleidomastoid and posterior. (VrC5-Ventral ramus C5; SC - spinal cord; VA- vertebral artery; CA- carotid artery; SCM- sternocleidomastoid)