sign in sign up
<<
Home , Erector spinae muscles, Levator scapulae muscle, Splenius capitis muscle

Reg Anesth Pain Med: first published as 10.1136/rapm-2019-101154 on 21 April 2020. Downloaded from Brief technical report Cervical erector spinae plane block: a cadaver study Hesham Elsharkawy,1 Ilker Ince,2 Hassan Hamadnalla,3 Richard L Drake,4 Ban C H Tsui ‍ ‍ 5

1Department of Anesthesiology, Abstract column (including the deep cervical muscles of the Cleveland Clinic, Cleveland, Background Cervical erector spinae plane (ESP) block erector spinae muscle group posteriorly) to form a Ohio, USA 5 2 prevertebral compartment. As a result, a LA in the Department of Anesthesiology has been described to anesthetize the and Reanimation, Ataturk (BP), however, the mechanism of its clinical effect cervical ESP can potentially spread throughout and University, Medical School, remains unknown. As the prevertebral encloses the within the prevertebral compartment to reach the Erzurum, Turkey roots of the brachial plexus. 3 phrenic , BP and to form a Department of Outcomes prevertebral compartment, a local anesthetic injected in In fact, direct cervical ESP block has been recently Research, Anesthesiology Institute, Cleveland Clinic, the cervical ESP could potentially spread throughout the performed successfully for postoperative 6 Cleveland, Ohio, USA prevertebral compartment. This study utilizes cadaveric pain relief . We hypothesized that the clinical anal- 4Department of Anatomy models to evaluate the spread of ESP injections at the gesia of direct cervical ESP injection resulted from and Department of Surgery, C6 and C7 levels to determine whether the injection can LA spreading to the roots of the brachial plexus Cleveland Clinic Lerner College (figure 1). In a cadaveric model, the objective of this of Medicine of Case Western reach the BP and its surrounding structures. Reserve University, Cleveland Methods For each of the five cadavers, an ESP study was to investigate this hypothesis by exam- Clinic, Cleveland, Ohio, USA injection posterior to the transverse process of C6 was ining the spread of dye after a single-shot­ ESP injec- 5Department of Anesthesiology, performed on one side, and an ESP injection posterior tion posterior to either the C6 or C7 TP. Perioperative and Pain Medicine, to the transverse process of C7 was performed on the Stanford University, Palo Alto, California, USA contralateral side. Injections were performed under Methods Avenue NA30. Protected by copyright. ultrasound guidance and consisted of a 20 mL mixture of The study protocol was approved by the director of Correspondence to 18 mL water and 2 mL India ink. After cadaver dissection, the cadaveric laboratory and waived by the institu- Dr Ban C H Tsui, Anesthesiology, craniocaudal and medial-later­ al extent of the dye spread tional review board. Five non-­embalmed fresh adult Perioperative and Pain Medicine, in relation to musculoskeletal anatomy as well as direct cadavers were selected (table 1) and maintained at Stanford University, Palo Alto, staining relevant nerves was recorded. The degree of dye CA 94305, USA; room temperature for 4 hours before injections. bantsui@​ ​stanford.edu​ staining was categorized as “deep,” “faint,” or “no.” Cadavers with evidence of cervical spine deformi- Results The phrenic was deeply stained in 1 ties or previous surgery were excluded. All Received 17 November 2019 injection and faintly stained in 2 injections. Caudally, procedures were performed by one investigator Revised 29 February 2020 variable staining of C8 (100%) and T1 (50%) roots were Accepted 4 March 2020 (HE). Published Online First seen. Faintly staining at C4 root was only seen in one 21 April 2020 sample (10%). There was variable staining of the anterior http://rapm.bmj.com/ (40%) anterior to the BP and the Block injection technique rhomboid intercostal plane caudally (30%). All procedures were done with a 6 cm, 18 G echo- Conclusions Ultrasound-­guided cervical (C6 and C7) genic Tuohy needle (Pajunk, Geisingen, Germany), ESP injections consistently stain the roots of the BP and the injectate consisted of a 20 mL mixture of and dorsal rami. This study supports the notion that the 18 mL water and 2 mL India ink. The cadavers were cervical ESP block has the potential to provide analgesia placed in the prone position, then a high-­frequency for patients undergoing shoulder and cervical spine (12–15 MHz) linear-­array transducer (X-­Porte, on September 20, 2020 at Cleveland Clinic Library 9500 Euclid surgeries. SonoSite, Bothell, Massachusetts, USA) was placed in a transverse orientation lateral to the posterior midline (figure 1). For the first cadaver, the left side was injected with dye at the C6 level and the right Introduction side was injected at the C7 level. The injection sites Erector spinae plane (ESP) block at the thoracic were then alternating with the next cadavers as and lumbar levels has been utilized for many types shown in table 1. of surgeries at various anatomic locations.1 2 Local For the C6 injection, the ultrasound probe was anesthetic (LA) injected in the ESP at the upper placed in transverse orientation at the C6 TP level, thoracic level extends to the cervical level and which was identified by its sharp anterior tubercle provides postoperative analgesia for shoulder (Chassaignac tubercle). The ESP between the tip of surgery.3 4 Anatomical components of the erector the posterior tubercle of the C6 TP and the overlying spinae muscle group at the cervical area include erector spinae muscle was identified (figure 1). For © American Society of Regional Anesthesia & Pain Medicine semispinalis cervicis, cervicis, and ilio- the C7 injection, the ultrasound probe was placed 2020. No commercial re-use­ . costalis cervicis, which arise from attached in transverse orientation at the C7 TP, which was See rights and permissions. to the posterior tubercles of the C2–C6 transverse identified by the prominent posterior tubercle and Published by BMJ. processes (TPs) and descend into the thoracic absent anterior tubercle. The ESP located between 1 To cite: Elsharkawy H, region. Hence, the erector spinae muscles, in fact, the tip of the C7 TP and the overlying erector Ince I, Hamadnalla H, et al. extend anatomically from the cervical spine to spinae muscle was also identified. Reg Anesth Pain Med the lumbar spine. The prevertebral fascia encloses The needle was then inserted in-­plane medial 2020;45:552–556. the phrenic nerves, brachial plexus, and vertebral to the ultrasound probe through the

552 Elsharkawy H, et al. Reg Anesth Pain Med 2020;45:552–556. doi:10.1136/rapm-2019-101154 Reg Anesth Pain Med: first published as 10.1136/rapm-2019-101154 on 21 April 2020. Downloaded from Brief technical report

Figure 1 The schematic anatomical relationship of the injection sites of cervical ESP plane blocks at C6 level. ESP, erector spinae plane. Avenue NA30. Protected by copyright. and levator scapulae muscles until it came into contact with After a complete examination of the posterior compart- the posterior tip of the TP. The correct needle tip position was ment, the cadaver was then turned to the supine position. A confirmed by hydrodissection using 2–3 mL of water to sepa- skin incision was made in the lateral portion of the sternoclei- rate the erector spinae muscles from the TP. With the needle tip domastoid muscle to above the at the mid-­clavicular maintained posterior to the TP of C6 or C7, a total of 20 mL of line. The incision was thereafter extended towards the deltoid the dye mixture was injected. groove, and the clavicle was removed. The long thoracic and suprascapular nerves were assessed for staining. The subscap- Cadaver dissection and examination ular, thoracodorsal, medial pectoral, lateral pectoral, medial

With the cadaver in the prone position, a midline skin incision brachial cutaneous, and medial antebrachial cutaneous nerves http://rapm.bmj.com/ was made, and the skin was resected laterally. The following were not investigated. Blunt dissection on the anterior aspect muscles were identified: superior aspect of the trapezius muscle of the sternocleidomastoid and scalene muscles was conducted in the lower neck, sternocleidomastoid muscle, semispinalis craniocaudally until the ribs were exposed. The cervical nerve capitis muscle, and . The medial edge of roots of C4–T1 and the distal trunks, divisions, and cords of the trapezius was cut from the spinous processes and retracted the brachial plexus were located. Identification of the supras- laterally. The was released from the capular, phrenic, long thoracic, and dorsal scapular nerves was medial border of the . The following nerves were identi- also attempted. on September 20, 2020 at Cleveland Clinic Library 9500 Euclid fied: lesser occipital, great auricular, spinal accessory, and supra- clavicular. Identification of the prevertebral fascial layer and the brachial plexus sheath was attempted. The area caudal and deep Injectate spread evaluation to the rhomboid intercostal plane was also examined. After careful cadaver dissection, craniocaudal and medial-­lateral extent of the dye spread in relation to musculoskeletal anatomy and direct staining of the brachial plexus and other relevant nerves were recorded. The cervical epidural space was not Table 1 Cadaver specimen details examined. The steps of the dissection were photographed, docu- Cadaver mented, reviewed, recorded by two investigators (HE, RLD). number Age (years) Gender BMI Injection site The dye staining of the nerves and tissue planes were catego- 7 8 1 66 Male 28 Left (C6) rized by consensus between an anatomist (RLD) and an anes- Right (C7) thesiologist (HE) as: “deep” (ie, heavily stained throughout), 2 74 Female 19 Right (C6) “faint” (ie, faintly or only partly stained); or “no” (ie, absent of Left (C7) any stain). 3 77 Female 31 Left (C6) Right (C7) 4 67 Male 22 Right (C6) Results Left (C7) Five non-embalmed­ fresh adult cadavers were studied (table 1). 5 71 Female 28 Left (C6) The extend of dye staining with its most relevant nerves is Right (C7) summarized in table 2. Figure 2A–E shows the examples of the BMI, body mass index. spread of injectate after cadaveric dissection.

Elsharkawy H, et al. Reg Anesth Pain Med 2020;45:552–556. doi:10.1136/rapm-2019-101154 553 Reg Anesth Pain Med: first published as 10.1136/rapm-2019-101154 on 21 April 2020. Downloaded from Brief technical report

Table 2 Spread of injectate following cervical ESP injections at the level of C6 and C7 transverse processes Cadaver Cephalad Caudad Anterior Nerves # Injection site C4 C5 C6 C7 C8 T1 ASMPN LTN DSN SCN RI 1 Left (C6) F √ √ √ F – √ F √ √ √ – 1 Right (C7)– √ √ √ √ ––– √ √ √ – 2 Right(C6)– √ √ √ F – √ √ √ √ √ – 2 Left(C7)– √ √ √ √ F √ – √ √ √ – 3 Left(C6)– √ √ √ F F –– √ √ √ √ 3 Right(C7)– √√√√√FF√√√√ 4 RightC6)– √ √ √ √ ––– √ √ √ – 4 Left(C7)– √ √ √ F F –– √ √ √ – 5 Left(C6)– √ √ √ √ F –– √ √ √ √ 5 Right(C7)– √ √ √ F ––– √ √ √ – Percentage (%) No 90 0 0 0 0 50 60 70 0 0 0 70 Faint 10 0 0 0 50 40 10 20 0 0 0 0 Deep 0 100 100 100 50 10 30 10 100 100 100 30 Faintly stained samples are denoted as F and deep stained samples are denoted as a check mark in the table. ASM, anterior scalene muscle; DSN, ; ESP, erector spinae plane; LTN, long thoracic; PN, Phrenic nerve; RI, rhomboid intercostal plane; SCN, suprascapular nerve.

Nerves stained a cervical ESP block may provide analgesia for patients under- Avenue NA30. Protected by copyright. Anterior to the TP, deep staining of the brachial plexus roots going major shoulder surgery and cervical spine surgery.6 9 The of C5, C6, and C7 (n=10/10) was noted. Caudally, variable observations in this study were consistent with previous imaging staining of the C8 (100%) and T1 (50%) roots was seen. Faintly studies of T2 ESP blocks using 20 mL of injectate, which demon- staining of the C4 root was seen only in one sample side (10%). strated the spread of injectate from the thoracic level up to the The anatomical area of the dorsal rami (DR) was stained bilater- C3 level.10 11 ally in all cadavers from C4 to T1 level. The phrenic nerve was Anatomically, fascia is an important connective tissue that deeply stained in 1 injection out of 10 and faintly stained in 2 forms bands or sheaths that surround and enclose muscles, injections out of 10. vessels, and nerves in different regions of the body. In the neck, Transverse cervical and supraclavicular nerves were only iden- cervical fasciae are not only complex in their physiology but also tified in four samples (two cadavers). The transverse cervical in the notable disagreements in their nomenclature found in the nerves were stained in all four samples and the supraclavicular literature.5 This makes studies performed in the neck region http://rapm.bmj.com/ nerves were not stained. The greater auricular and lesser occip- more challenging and confusing. Nevertheless, there are two key ital nerves were identified in one sample and were not stained. fasciae in the neck which are well defined and accepted—the The spinal was identified in three samples and superficial cervical fascia and the . The super- was not stained in any sample. The suprascapular, long thoracic, ficial cervical fascia is a subcutaneous layer of the skin in the and dorsal scapular nerves were stained in all cadavers bilaterally. neck and contains the platysma muscle, cutaneous nerves from Dye injectate also spread to the anterior aspect of the brachial the , and superficial vessels and lymph nodes. plexus in 3 out of 10 with deep staining and 1 with faint staining. In contrast, the deep cervical fascia consists of three layers (figure 3) “investing,” “pretracheal,” and “prevertebral” layers, on September 20, 2020 at Cleveland Clinic Library 9500 Euclid Extent of dye spread which are also known as the superficial, middle, and deep layers, The identification of the prevertebral fascial layer and spread respectively. The investing (superficial) layer surrounds the ster- of dye inside the posterior compartment were positive in all nocleidomastoid muscle anteriorly and the trapezius muscle samples, as illustrated in figure 2A–C. Cranially, dye injectate posteriorly. Laterally, it forms the roof of the posterior triangle spread up to the origin of the trapezius and sternocleidomastoid. and attaches to the posterior aspects of the spinous processes Caudally, dye injectate reached the rhomboid intercostal tissue at the midline. The pretracheal (middle) layer of fascia is situ- plane in 2 injections at C6 and in 1 injection after C7 injection. ated in the anterior neck and covers the hyoid bone superiorly Posteriorly, there was staining of the entire middle scalene and the inferiorly. The prevertebral (deep) layer is one of muscle, posterior aspect of anterior scalene muscle and posterior the major clinically relevant structures in the cervical ESP block. side of the brachial plexus (figure 2C). This layer attaches to the ligamentum nuchae and fully encircles the vertebrae, scalene, erector spinae and associated vertebrae Discussion muscles, as well as neurological structures such as the cervical This is the first cadaveric study examining the spread of dye after portion of the sympathetic trunk ganglia, phrenic nerve, brachial ESP injection at the C6 and C7 levels that demonstrates consis- plexus, and the nerves to the rhomboids and serratus anterior. tent spread to the roots of the brachial plexus anteriorly as well Thus, any injections under the prevertebral layer may allow the as to relevant nerves, including the long thoracic, dorsal scap- potential spread to its enclosed structures. ular, and suprascapular nerves. The craniocaudal spread of injec- Clinically, the approach and needle trajectory of the ESP block tate suggests that injection at both the C6 and C7 levels spreads described here is similar to the commonly described cervical in a similar manner to cover the target sensory level of C5–C8. paravertebral block using a posterior approach.12 Instead of Thus, this report provides anatomical evidence to explain how the needle being “walked off ” the bony cervical TP to reach

554 Elsharkawy H, et al. Reg Anesth Pain Med 2020;45:552–556. doi:10.1136/rapm-2019-101154 Reg Anesth Pain Med: first published as 10.1136/rapm-2019-101154 on 21 April 2020. Downloaded from Brief technical report

Figure 3 The schematic anatomical relationship of fasciae and their interfascial planes at the C7 level in the neck.

of epidural spread. It was difficult to accurately localize blood vessels in this study, including the vertebral vessels, as well as many individual small nerves. We did not dissect the cranial, nerves; glossopharyngeal, vagus and its branches (recurrent and

superior laryngeal nerves), hypoglossal, and accessory nerves. Avenue NA30. Protected by copyright. Thus, there was a potential that we missed dye spreading to the upper cranial nerves, as there are neural anastomoses between the cranial nerves and the cervical roots. In addition, we did not address the percentage of staining for nerves that we could not consistently identify in all cadavers. Repositioning the cadaver from prone to supine may have caused further spread of the dye Figure 2 Illustration of injected dye spread with cadaver dissection and exaggerated the staining of the tissues’ planes and nerves. from selected posterior views (A, B, C: prone) and anterior views In this study, we evaluated and graded the degree of the staining (D, E: supine). (A) superficial posterior view with trapezius muscle as “deep” stain, “faint” stain, or “no” stain. Similar to other retracted and overturned. (B) posterior views with splenius capitis regional anesthesia cadaver studies’ reporting,7 8 it is important and levator scapulae muscles retracted medially and laterally. (C) to point out that this kind of stain evaluation is not only prone http://rapm.bmj.com/ deep posterior dissection view with the middle scalene muscle to subjectivity but also the degree of staining may not reflect retracted and overturned. (D) Superficial anterior dissection view with accurately the clinical effect from the injection. sternocleidomastoid muscle retracted medially. (E) Deep anterior Another limitation that often arises in any cadaver study is dissection view with anterior scalene muscle retracted and overturned. the anatomical and physiological differences between living and ASM, anterior scalene muscle; BP, brachial plexus; DSN, dorsal scapular deceased tissues. Even though this body of research has the unde- nerve; IF investing fascia; ES, erector spinae muscles, LSM, levator niable merit of offering valuable insights for hypothesis gener- scapulae muscle; LTN, long thoracic nerve; MSM, middle scalene muscle; ation and preliminary evidence, it has limitations in assuming PF, prevertebral fascia; PN, phrenic nerve; RM, rhomboid; SCM, splenius equivalent mechanisms of action to living subjects. For validating on September 20, 2020 at Cleveland Clinic Library 9500 Euclid capitis muscle; SSN, suprascapular nerve; TM, trapezius muscle. any new therapeutic treatment, most experts consider cadav- eric studies as the lowest supportive form of evidence. Other threats to generalizability are due to the variation of the injectate the roots of the brachial plexus, the ESP injection is performed composition and its viscosity, the bevel and size of the needle, posterior to the cervical TP. Although it is not our primary focus and differential pressure generated during the injection. Such or the intended scope of this study to evaluate the risks and discrepancies could potentially impact fluid dynamics, leading benefits of the cervical ESP, it is important to point out that, due to different patterns of dye spread. For interfascial blocks such to the location of needle placement for this particular ESP block, as ESP blocks, these are particularly important factors as the there is a theoretical risk of adverse events related to phrenic success of the block relies heavily on the pattern of LA spread. nerve paresis and vertebral injury. However, we would Nevertheless, ultrasound-guided­ cervical (C6 and C7) ESP injec- also note that this needle placement is further away from the tions consistently stain the roots of the brachial plexus and DR. phrenic nerve in comparison with the interscalene block, and the This study may support the concept that the cervical ESP block bony TP anterior to the needle tip can guard the vertebral artery. has the potential to provide analgesia for patients undergoing Cadaveric studies, such as one described here, typically have shoulder and cervical spine surgeries.3 6 9 limited sample sizes and can be technically challenging in the In summary, this study illustrates that cervical ESP injections dissection and identification of all the relevant anatomical struc- at both the C6 and C7 levels resulted in universal staining of tures, such as the epidural space, without inadvertent disrup- the ventral of C5 to C7 (ie, brachial plexus), but with much less tion of the dye injectate spread. Without epidural dissection incidence and staining of the phrenic nerve in cadaveric subjects. as in this study, the interpretation of these studies is subject to Dye injectate also consistently spread to the posterior aspect of high instinct bias risk without ruling out clinically significant the erector spinae muscles and the DR area in all cadavers.

Elsharkawy H, et al. Reg Anesth Pain Med 2020;45:552–556. doi:10.1136/rapm-2019-101154 555 Reg Anesth Pain Med: first published as 10.1136/rapm-2019-101154 on 21 April 2020. Downloaded from Brief technical report

Correction notice This article has been corrected since it published Online First. 2 Tsui BCH, Fonseca A, Munshey F, et al. The erector spinae plane (ESP) block: a pooled Data within the article abstract and content has been corrected. review of 242 cases. J Clin Anesth 2019;53:29–34. 3 Tsui BCH, Mohler D, Caruso TJ, et al. Cervical erector spinae plane block catheter Twitter Hesham Elsharkawy @kaohesham using a thoracic approach: an alternative to brachial plexus blockade for forequarter Acknowledgements Permission to use images was obtained from the Cleveland amputation. Can J Anaesth 2019;66:119–20. Clinic Department of Art Photography. 4 Ma W, Sun L, Ngai L, et al. Motor-sparing­ high-thor­ acic erector spinae plane block for Contributors HE: conceived, planned, supervised, contributed, collected data, proximal humerus surgery and total shoulder arthroplasty surgery: clinical evidence revised, approved, and is accountable for the final manuscript. RLD: collected for differential peripheral nerve block? Can J Anaesth 2019;66:1274–5. data, contributed, revised, approved, and is accountable for the final manuscript. 5 Feigl G, Hammer GP, Litz R, et al. The intercarotid or alar fascia, other cervical , II and HH: collected data, contributed, approved, and is accountable for the final and their adjacent spaces – a plea for clarification of cervical fascia and spaces manuscript. BCHT: conceived, data analyses, revised, approved, and is accountable terminology. J Anat 2020:joa.13175. for the final manuscript. 6 Hamadnalla H, Elsharkawy H, Shimada T, et al. Cervical erector spinae plane block catheter for shoulder disarticulation surgery. Can J Anaesth 2019;66:1129–31. Funding The authors have not declared a specific grant for this research from any 7 Yang H-­M, Park SJ, Yoon KB, et al. Cadaveric evaluation of different approaches for funding agency in the public, commercial or not-­for-­profit sectors. quadratus lumborum blocks. Pain Res Manag 2018;2018:1–7. Competing interests HE has received unrestricted educational funding from 8 Elsharkawy H, Maniker R, Bolash R, et al. Rhomboid intercostal and Subserratus PAJUNK (GA, USA), and consultant for PACIRA (Troy Hills, NJ, USA). Those companies plane block: a cadaveric and clinical evaluation. Reg Anesth Pain Med had no input into any aspect of the present project design or manuscript preparation. 2018;43:745–51. Patient consent for publication Not required. 9 Ueshima H, Otake H. Blocking of multiple posterior branches of cervical nerves using an erector spinae plane block. J Clin Anesth 2018;46:44. Provenance and peer review Not commissioned; externally peer reviewed. 10 Forero M, Rajarathinam M, Adhikary SD, et al. Erector spinae plane block for the management of chronic shoulder pain: a case report. Can J Anaesth ORCID iD 2018;65:288–93. Ban C H Tsui http://orcid.​ ​org/0000-​ ​0002-6984-​ ​5998 11 Adhikary SD, Bernard S, Lopez H, et al. Erector spinae plane block versus Retrolaminar block: a magnetic resonance imaging and anatomical study. Reg Anesth Pain Med References 2018;43:756–62. 1 Forero M, Adhikary SD, Lopez H, et al. The erector spinae plane block: a novel 12 Borene SC, Rosenquist RW, Koorn R, et al. An indication for continuous cervical analgesic technique in thoracic neuropathic pain. Reg Anesth Pain Med paravertebral block (posterior approach to the interscalene space). Anesth Analg 2016;41:621–7. 2003;97:898–900. Avenue NA30. Protected by copyright. http://rapm.bmj.com/ on September 20, 2020 at Cleveland Clinic Library 9500 Euclid

556 Elsharkawy H, et al. Reg Anesth Pain Med 2020;45:552–556. doi:10.1136/rapm-2019-101154