Superficial Cervical Plexus Block
Two nice articles reviewing the superficial cervical plexus block. Abstracts are listed below.
Spread of injectate with superficial cervical plexus block in humans: an anatomical stud
J. J. Pandit*,1, D. Dutta1 and J. F. Morris21 Nuffield Department of Anaesthetics, John Radcliffe Hospital, Oxford OX3 9DU, UK. 2 Department of Human Anatomy, Parks Road, Oxford OX1 3PT, UK
Corresponding author. E-mail: jaideep.pandit@physiol.ox.ac.uk
Background. This study was undertaken to investigate why the superficial cervical plexus block for carotid endarterectomy is so effective. Initial consideration would suggest that a superficial injection would be unlikely to block all terminal fibres of relevant nerves. One possibility is that the local anaesthetic crosses the deep cervical fascia and blocks the cervical nerves at their roots.
Methods. Superficial cervical plexus blocks (injections just below the investing fascia) were performed using methylene blue (30 ml) in four cadavers. In one additional control cadaver, a deep cervical plexus injection was performed. In a second control cadaver, a subcutaneous injection (superficial to investing fascia) was performed at the posterior border of the sternomastoid muscle.
Results. Anatomical dissection showed that with superficial block there was spread of the dye to structures beneath the deep cervical fascia. In the first control, dye remained in the deep cervical space. In the second control, dye remained subcutaneous.
Conclusions. The superficial cervical space communicates with the deep cervical space and this may explain the efficacy of the superficial block. The method of communication remains unknown. Our findings also indicate that the suitable site of injection for the superficial cervical plexus block is below the investing fascia of the neck, and not just subcutaneous.
Br J Anaesth 2003; 91: 733–5
The Superficial Cervical Plexus Block for Postoperative Pain Therapy in Carotid Artery Surgery. A Prospective Randomised Controlled Trial
M. Messner, S. Albrecht, W. Lang, R. Sittl and M. Dinkel
Eur J Vasc Endovasc Surg 2006;33:49-53..
Available online 8 January 2007.Objectives Rapid and reliable neurological evaluation soon after carotid artery surgery is feasible with modern methods of general anesthesia, but postoperative pain therapy remains a challenge. Use of opioids can mask neurological deficits. We investigated whether superficial cervical plexus block reduced postoperative opioid consumption after carotid endarterectomy.
Design Prospective, randomised, double-blinded, placebo controlled trial.
Methods 46 patients undergoing unilateral carotid endarterectomy under general anesthesia were randomized to either superficial cervical block with ropivacaine (n = 23) or placebo (n = 23). A patient controlled analgesia device (PCA) delivering morphine was provided for all patients. Subjective pain levels (visual analog scale, VAS) were recorded. The primary outcome was total morphine consumption on discharge from the recovery room. Secondary outcomes included arterial pCO2 (as an indicator of central nervous effects of morphine) and patient satisfaction.
Results No adverse effects of the superficial cervical plexus block were reported. Four patients in the placebo group were excluded because of other drug use post-operatively. Per protocol analysis compared 23 patients in ropivacaine group and 19 patients in the placebo group. The ropivacaine group had a significant reduction in morphine consumption (3.8 ± 2.0 versus 12.9 ± 4.0, p < 0.001), lower maximal pain scores (2.6 ± 2.0 versus 5.8 ± 1.6, p < 0.001), and paCO2 levels (39.0 ± 2.6 versus 41.9 ± 3.4, p = 0.008) at discharge from the recovery room. Patient satisfaction (1 = very good to 6 = insufficient) was substantially higher in the ropivacaine group (1.7 ± 0.7 versus 3.1 ± 1.2, p < 00.01).
Conclusion The significant and clinically relevant lower morphine consumption and pain score, as well as the substantially higher patient satisfaction demonstrate that superficial cervical plexus block provides effective pain relief for patients undergoing carotid endarterectomy.
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The investing layer of the deep cervical fascia- difficult to determine whether your needle is actually deep to the fascia when performing a sup.cervical plexus block.There was an article in Anesthesiology in 2005 where they performed an anatomical study on cadavers and found that the investing layer does not encircle the whole neck.The fascia around the SCM was not continuous with the fascia surrounding the strap muscles or the submandibular gland.They postulate that the spread of local anesthetic into the deeper layers with a superficial cervical plexus block was via potential spaces of fatty connective tissue around structures outside the prevertebral fascia ( that is around the SCM, Sub-mandibular gland, strap muscles. This may explain the high success rate of a superficial cervical plexus block for carotid endarterectomy.