Comparative Study between Conventional Accessory Nerve Block Method and New Compartmental Approach: CT Study, Fresh Frozen Cadaver Study

Abstract

Background: In a clinical situation, such as in the interventional treatment for spasmodic torticollis patients, a conventional approach for accessory nerve blockade can not assure blockade of the accessory nerve (XI) branch supplying the sternocleidomastoid muscle (SCM). Therefore, a new approach, which can block the XI branch to the SCM or main XI nerve, is required. Methods: Two fresh frozen cadavers were prepared in the prone position, and then slightly rotated to the blockaded side. Thereafter, 10 ml of a natural liquid rubber and barium hydroxide mixture (2 : 1) was injected underneath the SCM, through the entry point at the posterior border junction of the upper and middle thirds (conventional method) successively in each cadaver. The inferior mastoidal, just lateral to the styloid process approach to the compartment, in which the accessory nerve, internal jugular vein, hypoglossal nerve, vagus nerve, glossopharyngeal nerve, sympathetic trunk and internal carotid artery stay, was threaded with a block needle and 10 ml of the natural liquid rubber and barium hydroxide mixture (2 : 1) (new method) successively injected in each cadaver. Computed tomography (CT) was performed on all specimens. Three-dimensional reconstruction and morphometry of the new and conventional approach were also performed using the V-workstm (version 4.0) program. Results: In both cadavers, the conventional method show no spread of the natural liquid rubber and barium hydroxide mixture (2 : 1) to the XI branch for the SCM or proximal main XI nerve. However, the new method show good spread of the natural liquid rubber and barium hydroxide mixture (2 : 1) to the XI branch for the SCM or proximal main XI nerve in both cadavers. Conclusions: With this new approach, it is possible to confirm a compartmental space, which can then be used for the administration of local anesthetics, which can then block the XI branch for the SCM or main XI nerve.