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An Anatomical Basis for Blocking of the DeepCervical Plexus and Cervical Sympathetic Tract Usingan Ultrasound-Guided TechniqueYosuke Usui, MD,*†‡ Toshiya Kobayashi, MD, PhD,‡ Hiroyuki Kakinuma, MD,‡Keisuke Watanabe, MD, PhD,‡ Toshimitsu Kitajima, MD, PhD,† and Kenjiro Matsuno, MD, PhD*

BACKGROUND: A selective blocking method for the cervical plexus and the cervical sympathetictrunk has not yet been established.METHODS: We performed a detailed examination of the neck anatomy using 28 cadavers. Thepattern of local anesthetic distribution after injection in 2 healthy volunteers was imaged usingcomputed tomographic scan.RESULTS: The deep cervical plexus was located in the groove between the longus capitis andscalenus medius muscles. The cervical sympathetic trunk was located on the anteromedialsurface of the longus capitis. Although anesthetic injected into the longus capitis was confinedto the muscle, it infiltrated into neighboring structures including the C2 to C5 roots andsympathetic trunk.CONCLUSIONS: The longus capitis muscle is a suitable landmark for blocking the cervical plexusand trunk. (Anesth Analg 2010;110:964–8)

Cervical plexus block is indicated to aid in surgery,providing anesthesia and/or analgesia for thyroidoperations1 and carotid endarterectomy,2 and to

relieve neck pain caused by herniation of the C2 to C4disks. Blocking the cervical sympathetic trunk may relievepain in the head and neck by reversing vascular spasms3 orpossibly by removing pain-producing substances in thelesion by increased vascular perfusion. Because the locationof the cervical sympathetic trunk is very close to the deep partof the cervical plexus, blockade of the deep cervical plexusmay also block the trunk. The objective of this study was toprovide the anatomical basis for ultrasound-guided block ofthe deep cervical plexus and the cervical sympathetic trunk.After anatomical examination in cadavers, we performed aninjection in healthy volunteers. The pattern of distribution ofinjected anesthetic in the volunteers was imaged using com-puted tomographic (CT) scan, and the effect of the block wastested.

METHODSTopographic AnatomyUsing 28 Japanese cadavers (18 males and 10 females) thathad been used for gross anatomy practice in DokkyoMedical University, we made a detailed examination of theneck anatomy. We examined the following structures: theuppermost origin of the scalenus medius and the scalenusanterior muscles, the lowermost origin of the longus capitismuscle, the relationship between the longus capitis and the

scalenus anterior at the C6 and C4 levels, the spatialrelationship between these muscles and nerve systems, andthe entrance level of the vertebral artery into the cervicaltransverse foramen.

Ultrasound-Guided Local Anesthetic InjectionBased on the anatomical findings, we devised a protocol todeliver anesthetic to the C2 to C5 roots and the sympathetictrunk and performed a healthy volunteer study. The studywas approved by the IRB, and written informed consent wasprovided. We used an ultrasound system with an 11-MHzlinear-type transducer (LogiQ Book Xp ENHANCED, GEHealthcare, Tokyo, Japan). The volunteer was positionedlaterally. The transducer was shifted laterally until thescalenus anterior and the longus capitis became visible atthe C6 level (Fig. 1, A–C) and moved cranially along thelongus capitis until the scalenus anterior tapered off ateither the C4 (Fig. 1, D–F) or C3 level. A 40-mm, 22-gaugeneedle was inserted into the longus capitis mediodorsallyin a sagittal plane (Fig. 2, A and B). After a negative test, themixture containing iohexol (1 mL) and 1% mepivacainehydrochloride (5 mL) was injected into the longus capitis(Fig. 2, C and D). A CT scan with a 3-dimensional volume-rendering technique (3D-CT) was performed to examinethe spread of the contrast medium. Clinical effects ofinjected anesthetic were examined briefly.

RESULTSTopographic AnatomyThe scalenus anterior was almost absent cranially above theC4 or C3 level in most cases (Figs. 3 and 4). However, thelongus capitis became larger as it ascended above the C6level. In the fourth cervical vertebra, the scalenus mediuswas attached not only to the posterior tubercle but also tothe anterior tubercle. The cervical plexus was situated in agroove between the longus capitis and the scalenus mediusbut not in the interscalene groove. The cervical sympathetictrunk was located on the anteromedial surface of thelongus capitis. Both were situated beneath the prevertebral

From the *Departments of Anatomy (Macro), and †Anesthesiology, DokkyoMedical University; and ‡Department of Anesthesiology, Sanokousei Gen-eral Hospital, Tochigi, Japan.

Accepted for publication October 22, 2009.

Supported by intramural departmental sources.

Reprints will not be available from the author.

Address correspondence to Kenjiro Matsuno, MD, PhD, Department ofAnatomy (Macro), Dokkyo Medical University, 880 Kitakobayashi, Mibu,Tochigi 321-0293, Japan. Address e-mail to kenjiro@dokkyomed.ac.jp.

Copyright © 2010 International Anesthesia Research SocietyDOI: 10.1213/ANE.0b013e3181c91ea0

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fascia. Notable variations were observed in the entrancelevel of the vertebral artery into the cervical transverseprocesses (52 cases [92.9%] at C6 level, 3 cases [5.4%] at C5,and 1 case [1.7%] at C4).

Ultrasound-Guided Local Anesthetic InjectionsIn 3D-CT, the contrast medium was confined to the longuscapitis (Fig. 5). Both volunteers showed sensory blockwithin cutaneous segments of the lesser occipital, thegreater auricular, the transverse cervical, and the supracla-vicular nerves and a relaxation of the ipsilateral neckmuscles. Ipsilateral ptosis, hyperemic conjunctiva withwarm sensation of the face, and nasal obstruction were alsoobserved. These clinical effects suggested that injectedanesthetic infiltrated into neighboring structures, whichincluded the C2 to C5 roots and the sympathetic trunk.

DISCUSSIONOur anatomical results demonstrated that the cervicalplexus was located in the groove between the longus capitisand the scalenus medius. This differs from the report byWinne et al.4 stating that both the cervical and brachialplexuses are located in the interscalene groove. In this

respect, for a high interscalene brachial plexus block, Roes-sel et al.5 injected 20 mL of local anesthetics into the mostcephalic point of what they believed was the interscalenegroove in 14 patients. However, all patients showed evi-dence of mostly a cervical plexus block, and the authorsstated that by shifting the transducer cephalically, thediameter of the scalenus anterior became smaller accordingto its insertion at the third to sixth vertebra.5 Our studysuggests that their injection site was actually the groovebetween the longus capitis and the scalenus medius wherethe anesthetics selectively blocked the cervical plexus.

The volunteer study has suggested that anesthetic canbe efficiently delivered to the deeper part of the cervicalplexus and the sympathetic trunk when injected into thelongus capitis. In addition, we report that the longus capitisis a suitable landmark, where the deep cervical plexus waslocated dorsolaterally, in the groove between the longuscapitis and the scalenus medius, and the cervical sympa-thetic trunk was located anteromedially on the surface ofthe longus capitis. Accordingly, we consider that anestheticinjection into the longus capitis muscle could block bothnerves, whereas injection into the groove between thelongus capitis and scalenus medius muscles might blockonly the deep cervical plexus.

Figure 1. Ultrasound images and sche-matic drawings of a transverse section ofthe neck at the C6 (A–C) and C4 (D–F)levels. (1) Subcutaneous tissue, (2) in-vesting fascia (2a, sternocleidomastoidmuscle; 2b, trapezius muscle), (3) pre-tracheal fascia, (4) buccopharyngeal fas-cia, (5) carotid sheath, (6) prevertebralfascia, (a) scalenus anterior muscle, (b)scalenus medius muscle, (c) longus ca-pitis muscle, (d) longus colli muscle, (e)brachial plexus (e1, C5 root; e2, C6root), (f) cervical plexus (f1, C3 root; f2,C4 root), (g) cervical sympathetic trunk.

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Figure 2. Ultrasound images and sche-matic drawings of the transverse sectionof the neck at the C4 level before (A and B)and after (C and D) injection of a mixture ofiohexol and mepivacaine. (1) Subcutane-ous tissue, (2) investing fascia (2a, ster-nocleidomastoid; 2b, trapezius), (3) pre-tracheal fascia, (4) buccopharyngealfascia, (5) carotid sheath, (6) preverte-bral fascia, (a) scalenus anterior, (b)scalenus medius, (c) longus capitis, (d)longus colli, (f) cervical plexus (f1, C3root; f2, C4 root), (g) cervical sympa-thetic trunk.

Figure 3. Anatomy of the right side of acadaver neck (A and B) and the rightlateral view (C and D). In C and D, theprevertebral fascia is cut and pulled backwith forceps to show that the sympa-thetic trunk is underneath this fascia.Arrows in A through D indicate the scale-nus medius attached to the anterior tu-bercle at the fourth cervical vertebra. (a)Scalenus anterior, (b) scalenus medius, (c)longus capitis, (d) longus colli, (e) brachialplexus, (f) cervical plexus, (g) cervical sym-pathetic trunk, (h) subclavian artery, (i)subclavian vein.

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Figure 4. A schematic summary concern-ing the origin and insertion of the scale-nus anterior, scalenus medius, and lon-gus capitis muscles. The numbers insquares indicate number of cases thateither the uppermost or lowermost originattached to the transverse process atthe C2 to C6 level.

Figure 5. A scanographic reconstructionof the neck by 3-dimensional computedtomography after injection of a mixture ofiohexol and mepivacaine into the rightlongus capitis of a healthy volunteer.

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In conclusion, this study has revealed that the longuscapitis is a good landmark for locating both the deepcervical plexus and the cervical sympathetic trunk.

AUTHOR CONTRIBUTIONSYU helped to conduct the study, analyze the data, and writethe manuscript. TK helped in data analysis and discussionand management of volunteer study. HK, KW, and TKhelped in data analysis and discussion. KM helped in studydesign and supervision.

ACKNOWLEDGMENTSThe authors thank Drs. Jin Mizushima and Hideo Takahashiand Professor Yasuhisa Okuda for their critical reading of themanuscript. The authors also thank Dr. Atsushi Shinto forreceiving the ultrasound-guided local anesthetic injection as a

volunteer and Ms. Junko Tanaka and Mr. Kazuhide Ichikawafor undergoing helicoidal scans of the head, neck, and upperlimb.

REFERENCES1. Pandit JJ, Satya-Krishna R, Gration P. Superficial or deep

cervical plexus block for carotid endarterectomy: a systematicreview of complications. Br J Anaesth 2007;99:159–69

2. Goldberg ME, Schwartzman RJ, Domsky R. Deep cervicalplexus block for the treatment of cervicogenic headache. PainPhysician 2008;11:849–54

3. Moore DC. Stellate ganglion block—therapy for cerebral vascu-lar accidents. Br J Anaesth 2006;96:666–7

4. Winne AP, Ramamurthy S, Durrani Z, Radonjic R. Interscalenecervical plexus block: a single-injection technique. Anesth Analg1975;54:370–5

5. Roessel T, Wiessner D, Heller AR, Zimmermann T. High-resolution ultrasound-guided high interscalene plexus block forcarotid endarterectomy. Reg Anesth Pain Med 2007;32:247–53

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