Upper Cervical Plexus Block, New Compartmental Approach: Primary CT Study, Fresh Frozen Cadaver Study

Abstract

Background: Upper cervical plexus (C1 to C4 spinal nerves) are clinically very important, especially to pain clinicians. Until now, no satisfactory block method existed for both the muscular and cutaneous branches. Herein, a new compartmental approach for blockade of the upper cervical plexus was developed. Methods: Two fresh frozen cadavers were prepared in the prone position. Under CT guidance, 10 or 30 ml of a natural liquid rubber and barium hydroxide mixture (2 : 1) was injected through the inferior medial mastoid point, between the longissimus capitis and splenius capitis, and just below, but within, the superior obliquus longissimus capitis, skull base triangle. A CT study was performed 1 hour later. After waiting 2 weeks for the natural rubber to harden, anatomic dissections were performed. Three-dimensional reconstruction and morphometry of the new upper cervical plexus block were also carried out using the V - (version 4.0) program. Results: In both cases the new method showed good spread of the natural liquid rubber and barium hydroxide mixture below the splenius capitis and spinalis capitis muscle covering over the cutaneous branches of the upper cervical plexus i.e. the lesser occipital nerve (C2 and C3), great auricular nerve (C2 and C3), transverse cervical nerve (C2 and C3), supraclavicular nerves (C3 and C4), great auricular to the XI branch for the sternocleidomastoid muscle or the proximal main XI nerve. Conclusions: With this new approach, it was possible to confirm a compartmental space, which can be used for the administration of some local anesthetics and block the upper cervical plexus (C1, 2, 3 & 4).