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
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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 brachial plexus 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 fascia encloses the within the prevertebral compartment to reach the Erzurum, Turkey roots of the brachial plexus. 3 phrenic nerves, BP and erector spinae muscles 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 shoulder 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 nerve was deeply stained in 1 ties or previous neck 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/ scalene muscles (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, longissimus cervicis, and ilio- the C7 injection, the ultrasound probe was placed 2020. No commercial re-use . costalis cervicis, which arise from tendons 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 trapezius 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 clavicle 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 splenius capitis muscle. 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 levator scapulae muscle was released from the capular, phrenic, long thoracic, and dorsal scapular nerves was medial border of the scapula. 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).