Open access peer-reviewed chapter
Abstract
The shoulder joint and clavicle are innervated by the brachial plexus, the cervical plexus, and nerves to muscles around the joint and clavicle. Regional anesthesia is aimed at producing optimal surgical conditions, prolonging postoperative analgesia, being free of complications, reducing costs, and minimizing hospital stay. Regional upper extremity anesthesia can be achieved by blocking the brachial plexus at different stages along the course of the trunks, divisions, cords, and terminal branches. The gold standard of regional anesthesia for shoulder surgery is interscalene brachial plexus block plus cervical plexus block, but it is associated with a high rate of neurological complications and phrenic nerve block. The interest of the anesthesiologist has been directed towards regional blocks avoiding these complications; techniques that approach nerves more distally than interscalene block have been described. These approaches include supraclavicular nerves, upper trunk, suprascapular nerve by anterior approach, axillary nerve block in the axillary fossa, clavipectoral fascia block. The objective of this chapter is to describe the anatomy, sonoanatomy, technique, and the clinical utility of these accesses.
Keywords
- regional anesthesia
- shoulder
- clavicle
- upper trunk
- supraclavicular nerves
- suprascapular nerve
- axillary nerve
- clavipectoral fascial
- interscalene block
1. Introduction
Shoulder surgery by arthroscopy or open methods has increased in recent years. The choice of anesthetic technique depends on the patient’s conditions, the preferences of the surgical group, the position the patient is to be placed, and the experience of the anesthesiologist. General anesthesia (GA) has been considered the ideal technique for this type of surgery, but advances in regional anesthesia have gradually changed this statement. The approaches, interscalene (ISBP) block (C5 C6) or the upper trunk (UT) are the most established options; the supraclavicular approach offers optimal coverage, including the proximal arm. Patients with respiratory compromise may not tolerate hemi diaphragmatic paresis (HDP) associated with proximal approaches. Distal approaches are associated with lower rates of HDP, but coverage of the proximal upper extremity may be incomplete. The use of ultrasound guidance (USG) for nerve blocks has increased success and safety and has allowed access to more peripheral brachial plexus blocks to prevent diaphragmatic paralysis. Regional anesthesia is also an excellent supplement to GA to improve postoperative pain management and decrease the need for opioid use.
Clavicle surgery has even more controversy about the choice of the regional block, since the innervation has not been well described. But in recent years, alternative regional block methods to interscalene brachial plexus block have appeared that are suitable as single anesthesia or combined with sedation or GA.
In this chapter, we pretend to describe the innervation of the shoulder and clavicle based on current knowledge and the sonoanatomy of the neck and armpit as a guide for the performance of regional nerve blocks.
2. Regional anesthesia for shoulder and clavicle surgery
Since shoulder surgeries produce severe postoperative pain, regional anesthesia techniques could effectively control pain at rest and in motion, reduce muscle spasm and facilitate early discharge [1].
2.1 Shoulder innervation
2.1.1 The brachial plexus (BP)
The BP is formed by the fusion of the ventral ramus of the spinal nerves C5, C6, C7, C8, and T1, with the variable contribution of C4 (15-62% of cases) and T2 (16-73% of cases). The roots emerge in the groove between the anterior scalenus and middle scalenus muscles [2]. Shoulder and proximal arm innervation are provided by branches of the BP: suprascapular nerve (SSN) (from posterior division of UT), axillary and subscapular nerves (from posterior cord), lateral pectoral nerve, and medial brachial cutaneous nerve (MBCN)) (from lateral cord), and the intercostobrachial nerve (ICBN) (originating directly from proximal intercostal nerves). SSN may be spared by an infraclavicular approach (Figure 1) [3, 4].
Figure 1.
Brachial plexus. Roots – Start in the spinal cord. Arise from anterior rami C5-T1. Landmark: Pass inferolateral between the anterior and middle scalene muscles. Trunks
2.1.2 Articular branches to the shoulder
The most frequently identified innervation pattern comprises three nerve bridges consisting of articular branches from suprascapular, axillary, and lateral pectoral nerves, connecting trigger points (Figures 2 and 3) [5, 6, 7].
Figure 2.
Distribution of shoulder articular branches. Courtesy of MF Rojas.
Figure 3.
Shoulder structures and their related innervation.
2.1.3 Nerves and articular branches
2.1.3.1 Suprascapular nerve
Articular branches classified in relation to the spinoglenoid notch:
Medial branch (MSAb) originates 1.3 cm proximal to the suprascapular notch, giving branches to the coracoclavicular ligaments and the medial pole of the subacromial bursa, clavicular insertion of the acromioclavicular ligament, and motor branches to the supraspinatus muscle.
Lateral branch (LSAb) originates at the level of the suprascapular notch, giving sensory branches to the lateral subacromial pole and acromial insertion of the acromioclavicular ligament. Two subacromial branches provide medial and lateral sensory innervation (bipolar) to the subacromial bursa.
The posterior glenohumeral branch (PGHb) originates at 3 cm from the suprascapular notch, and posterior to the spinoglenoid ligament, course inferomedial towards the posterior capsule of the shoulder [8].
2.1.3.2 Axillary nerve (AN)
One or two articular branches of the main trunk travel with the anterior humeral circumflex artery between the tendons of the subscapular and latissimus dorsi muscles branching into medial branch to scapular aspect of the anteroinferior capsule and portions of the axillary recess; lateral branch to humeral portion of the anterior capsule [6]. The posterior division (after leaving the quadrangular space) gives a branch for the teres minor muscle, from which emerge 1 to 4 articular branches, to innervate the posteroinferior capsule. The branch innervating the deltoid muscle gives small multiple articular branches towards the lateral aspect of the humeral head the posterior and lateral supra-lying fascia of the shoulder capsule [6, 9, 10].
2.1.3.3 Lateral pectoral nerve (LPN)
The LPN arises from two branches of the anterior divisions of the upper and middle trunks (33.8% of cases), or as a single root of the lateral cord (23.4%). It receives fibers from C5 to C7. Cross the superomedial side of the coracoid process and sends small branches to the coracoclavicular and coracoacromial ligaments, anterior acromioclavicular joint, subacromial bursa and anterosuperior portion of the glenohumeral capsule. It gives branches to the periosteum of the clavicle. Therefore, its blockade produces analgesia for distal clavicle surgery [6, 11]. The muscular branch originates from the articular branch of the LPN and innervates the deltoid muscle and skin over the subacromial region (Figure 4) [7, 11].
Figure 4.
Lateral pectoral nerve.
2.1.3.4 Inferior subscapular nerve
A glenohumeral articular branch anastomosis with branches of the AN to innervate the long head of the biceps tendon (LHBT) and anterior capsule. The superior subscapular nerve gives 1 or 2 articular branches to innervate the anterosuperior quadrant of the glenohumeral joint [12]. Receives fibers for C5-C6.
The
Mechanoreceptors are more concentrated in the medial and lateral insertions of the anterior capsule. Nociceptors are identified primarily in the upper quadrant of the shoulder, including the subacromial bursa (SAB), glenohumeral ligaments (GHL), coracoacromial (CAL), coracoclavicular ligaments (CCL), the proximal portion of the LHBT, and the transverse humeral ligament (THL). The SAB is the area of densest and tripolar nociceptive innervation. These three nociceptive poles may correspond to the location of the lateral/medial subacromial branches of the SSN (i.e., lateral and middle poles) and the articular branch of the lateral pectoral nerve LPN (anterior pole); Thin articular branches of the AN may also participate in the innervation of the lateral pole of SAB [6].
2.2 Clavicle innervation
The most painful structures in clavicle surgery include the skin over the incision area and the highly innervated periosteum. The supraclavicular nerve originates as a single trunk from the anterior ramus of cervical nerves C3-C4. It divides into medial (suprasternal), intermediate (supraclavicular), and lateral (supra-acromial) branches. The medial branch supplements the skin over the anterior aspect of the thorax, as far below as the second rib, and the sternoclavicular joint. The intermediate branch pierces the deep cervical fascia just above the clavicle and runs over the pectoralis major and deltoid muscle; supply cutaneous innervation to the skin above these muscles, as far below as the second rib. The lateral branch pierces the deep cervical fascia just above the clavicle, passes over the acromial process, to innervate skin of the upper and posterior shoulder regions (Figure 5) [13, 14].
Figure 5.
Nerves involved in clavicular innervation.
Innervation of the clavicle itself is less well described. Different authors attribute contributions from SSN, long thoracic, nerve for the subclavian muscle, and LPN [15].
2.2.1 Fascias related to the clavicle
2.2.1.1 Clavipectoral fascia
Situated posterior to the clavicular part of the pectoralis major muscle. It extends from the clavicle, costochondral joints, and coracoid process. It converges in the axilla and acts as a protective structure over the neurovascular package. The clavicular fascia splits to enclose the subclavius muscle before attaching to the clavicle, the posterior layer fuses with the deep cervical fascia which connects the omohyoid muscle to the clavicle. Medially, it is attached to the first rib before coming together with the fascia over the first two intercostal spaces. Laterally, it is attached to the coracoid process before blending with the coracoclavicular ligament. The fascia often thickens to form the costocoracoid ligament, between the first rib and coracoid process. Inferiorly, the fascia becomes thin, splits around pectoralis minor, and descends to blend with the axillary fascia and laterally with the fascia over the short head of the biceps. It is pierced by CALL [cephalic vein, artery (thoracoacromial), lateral pectoral nerve, lymphatics]. The clavipectoral fascia surrounds the clavicle, and the nerve endings of the clavicle penetrate this fascia (Figure 6) [16].
Figure 6.
Clavipectoral fascia.
3. Peripheral nerve block for shoulder surgery
Interscalene or supraclavicular block of the BP are considered the standard technique for anesthesia and analgesia in this type of surgery. The most common adverse effect is HDP due to ipsilateral PN block in 100% of patients and a 27% decrease in forced vital capacity and forced expiratory volume at the first second [17]. At the level of the cricoid cartilage (C6 transverse process (TP)) the PN is 0.18 cm prior to the BP, but it diverges at a rate of 3 mm for each centimeter below the cricoid cartilage.
USG has allowed to decrease the anesthetic minimum volume required in 50% of patients (5-7 mL vs. 30-40 mL) using ropivacaine 0.75% or bupivacaine 0.5%, and a decrease of 50% in the incidence of paralysis of the diaphragm when the injection is performed laterally to the C5-C6 roots. If the concentration of the anesthetic is also diluted to a half or third, the HDP rate is reduced to 20% (it is still a contraindication in patients with decreased lung reserve) but carries the risk of not achieving surgical anesthesia and decreasing the duration of the blockade. According to Renes et al., if the injection is done at the C7 root level, the minimum volume required to block C5-C6 in 50% of patients was 2.9 mL (maximum volume of 6 mL), with no PN block (although there is a substantial risk of vascular lesions from punctures at this level). Renes et al. avoided PN block by administering the anesthetic in the “cornet pocket “ (intersection of the first rib with the subclavian artery and posterolateral aspect of the BP) and a volume less than 20 ml [18]. Aliste et al. compared ISB with supraclavicular block following the Renes technique, finding equal pain control, but with HDP rate of 9% [19]. Cornish found a 1% of HDP rate by advancing a catheter from the supraclavicular level and locating the tip at the infraclavicular level, inferomedial to the coracoid process [20, 21].
A combination that could be effective would be the association of a SSN block with a BP block at infraclavicular level [22] (addresses the axillary, lateral pectoral, subscapular nerves), although Petrar et al. [23] reported a 3% incidence of HDP during infraclavicular BP block (30 mL ropivacaine 0.5%).
The following paragraphs describe different techniques to achieve a selective block of the nerves supplying the shoulder.
3.1 Upper trunk (UT) approach
It focuses on the anesthetic deposit near the UT, before the take of the SSN. At this level, the phrenic nerve (PN) has diverged from the BP. Compoy et al. [24] found that 5 mL of methylene blue injected around UT stains SSN, lateral pectoral nerve, and roots of C5 and C6, but not of the PN [25]. Kim et al. found analgesic equivalence between UT block and ISB, achieving equivalent surgical anesthesia and HDP incidence of 5% vs. 71% using 15 mL of injectate [26]. Ultrasound (US) examination reveals the plexus in the groove between the anterior and middle scalene muscles, deep to the prevertebral fascia. The sternocleidomastoid muscle (SCM) lies superficially, and the PN can be seen on the anterior surface of the anterior scalene muscle (ASM), crossing it towards the medial side, after the last contribution originating in the C5 root. Sonoanatomy of the transverse processes can be used to identify spinal roots. Serial images reveal the process of confirmation of the UT [27].
The blocking needle is advanced from lateral to medial, under the deep cervical fascia until its tip reaches the UT lateral edge, proximal to the exit of the SSN (it is identified as a rounded hypoechoic structure that separates laterally from the UT and runs deep to the omohyoid muscle). The needle does not pass through the middle scalene muscle (MSM), where the dorsal scapular nerve (DSN) and long thoracic nerve (LTN) are located. The injectate volume is 7 to 12 mL of local anesthetic (LA) (one-half or one-third strength). Here the nerves have a greater amount of perineural tissue, protecting against neurological dysfunction, which has been reported in about 14% of ISBP blocks and can last for up to 10 days (Figure 7).
Figure 7.
Upper trunk and supraclavicular nerves blockade. A. C5 and C6 (bifid) roots at interscalene space, near to PN. C7 TP view. B. UT formation (inferior to C7 TP). C. Origin of supraescapular nerve (SSN). D. Back to UT - needle at its posterior surface. Local anesthetic (LA) injection at posterior surface of UT. E. Retreated needle to space between SCM-MSM. LA injected around supraclavicular nerves.
The UT provides anesthesia to nerves from the spinal cord segments C5 and C6 (originating fiber to SSN and AN, inferior subscapular nerve, and partially, to LPN) [25] and decreases the incidence and severity of PN block. HDP was observed in 97.5% in ISB vs. 76.3% of the UT block groups (P = 0.006); paresis was complete in 72.5% vs. 5.3% of the patients, respectively. The decrease in spirometry values from baseline was significantly greater in the ISB block group. UT block provides non inferior analgesia compared to ISBP block [28].
It can be supplemented with blockade of the supraclavicular nerves to anesthetize the skin over the shoulder. The needle is retracted to the space between prevertebral fascia (over the MSM) and superficial (enveloping) layer of the deep cervical fascia, under the SCM, where the supraclavicular nerves are located. A new injection of 2 to 3 mL of LA blocks nerves supplying skin over collarbone and shoulder cap and their sensitive contribution to the acromioclavicular joint.
3.2 Supraclavicular nerve trunk blockade
The supraclavicular nerve trunk (C3 and C4) emerges at the posterior edge of SCM. The superficial cervical plexus (SCP) is localized by placing a transducer on the posterior edge of the SCM at the level of the upper pole of the thyroid cartilage. It can be difficult to identify the individual nerves. The greater auricular nerve (GAN) is a useful reference reliably identified as a small superficial hypoechoic round structure on SCM (Figure 8) [29].
Figure 8.
Supraclavicular nerve trunk and SCP scan process.
3.3 SSN blockade
The posterior approach in the suprascapular fossa (in the space between the suprascapular notch and the spinoglenoid notch) where the nerve travels through its floor under the supraspinatus muscle fascia, results in adequate flooding of SSN with minimal propagation to the BP [30] but may spare MSAb. This approach is inferior to ISBP block for pain control, at least in the first 4 hours [31, 32, 33]. The UT (C5-C6) is the major contributor to the suprascapular, axillary, and subscapular nerves. Hence, UT blockade can provide adequate control of shoulder pain, but it is still remarkably close to the PN [34, 35].
With ultrasound image, the SSN could be identified as it branches from UT, and runs laterodorsally underneath the omohyoid muscle, in 81% of cases vs. 36% in the supraspinatus fossa, at an average depth of 8 mm vs. 35 mm in the supraspinatus fossa. Peripheral nerve stimulator can help in the identification [35]. Rothe et al. studied twelve healthy volunteers; the SSN was followed into the subclavian triangle under the inferior belly of the omohyoid muscle; injecting 1 mL of lidocaine 2%, 10 blocks were performed, 8 demonstrated a reduced manual muscle-testing scale (MMT) of the supra- and infraspinatus muscles at 15 min and 30 min; increasing the injected volume, produced musculocutaneous and radial nerves blockade due to cephalic diffusion of the anesthetic (Figure 9) [36].
Figure 9.
Scan sequence of the SSN at the supraclavicular fossa. A: Locate the transverse process of C6 vertebral vertebra and C6 and C5 roots. B: Scanning downward, locate the C7 TP and C7 root, which can be seen laterally to vertebral vessels. C: Just below the C7 transverse process, C7 root runs towards the interscalene groove. The PN is diverging from the BP, on the anterior surface ASM. Caudally to the C7 transverse process, UT and MT conformation can be imaged. D: In the supraclavicular fossa. From the UT branches the SSN. E: The SSN travels below the omohyoid muscle. F: The SSN separates from the UT, below omohyoid muscle. The nerve goes along suprascapular artery.
In 14 BP of 7 corpses, the separation between the SSN and the PN was found to be 2.5-6.4 cm, and the injection of 10 mL of solution around the SSN produced staining of the UT of the BP and its branches (SSN, anterior and posterior divisions - 14 cases, 100%), the middle trunk (MT) (13 cases, 93%), the PN (3 cases; 21.4%) [37]. In the cadaveric study by Sehmbi, the SSN and omohyoid muscle were easily identified and, with nerve injections of 5 mL, nerve staining with contrast dye was seen in 90% of dissections. The UT, MT, and LT were stained in 90%, 80% in 20% of dissections, respectively. The PN was mildly stained in 20% of the dissections [38]. Figure 9 shows the scan sequence of the SSN at the supraclavicular fossa.
3.4 Articular branch of lateral pectoral nerve (LPN)
The articular branch or LPN crosses the superomedial side of the coracoid process [6, 11]. The US probe is placed between the inferior border of the clavicle and the superior border of the coracoid process. Below the deltoid muscle, the acromial branch of the thoracoacromial artery and, along with it, the nerve can be found (Figure 10).
Figure 10.
USG to locate the articular branch of LPN.
3.5 US-guided approach to the AN and ICBN in the axillary fossa
The AN provides motor innervation to subscapular, teres major and minor, and deltoids muscles. The nerve branches before entering the quadrangular space. The anterior division of the AN originates the first articular branch, which ends in the anteroinferior capsule; blocking the nerve by the posterior approach can provide incomplete analgesia.
The sensitive skin supply of the medial aspect of the arm is provided by MBCN, ICBN, and variable branches of the intercostal nerves [39].
The AN run into the inferolateral margin of the subscapular muscle and enters the quadrangular space (QS) (limits: upper, teres minor muscle; inferior, teres major muscle; medial, long head of the triceps muscle; lateral, surgical neck of the humerus; anterior, insertion of the subscapular muscle on the minor tuberosity). The subscapular muscle, the upper edge of the teres major muscle, and the humerus are the sonographic marks that lead to the identification of the AN. The ICBN originates mainly from the second intercostal nerve, with variable contributions from intercostal nerves T1, T3, and T4. It is identified in the axillary subfascial space, along.
with fat, lymph nodes, and other cutaneous branches of the upper intercostal nerves. After crossing the axillary subfascial space, it courses on the surface of the latissimus dorse muscle, covered by the superficial axillaryfascia [40].
With the arm abducted 90o, the BP is identified in the armpit (anterior to the teres major and the tendon of the latissimus dorse muscles, seen in short axis) (Position 1, Figure 11). The probe moves slightly in a proximal direction (position 2, Figure 11) towards the QS, which is identified as soon as the upper edge of the teres major muscle deepens. At this point, the AN appears as an oval honeycomb structure, accompanied by the posterior circumflex artery of the humerus (although it has an inconsistent course and presence). The elevation of the arm from 90 o to 180 o brings the nerve closest to the skin by closing the quadrangular space.
Figure 11.
AN US images at axillary fossa. A. Transducer position 1. The US imagen corresponds to D. B. Transducer position 2. The US imagen corresponds to E. C. Anterior view of axilla showing the quadrangular space; AN emerges posterior to brachial plexus and enters the QS divided in anterior and posterior ramus. D. Scanning starts viewing the brachial plexus at the axillary level, observing the fascia of the teres major muscle. E. Moving proximally the transducer (towards the axillary fossa) shows the teres major muscle fascia deepening and the subscapular muscle tendon; the QS is seen. F. with 180° arm extension, the teres major muscle closes the QS. G and H. the axillary nerve is observed above the subscapular muscle as a hyperechoic image next to the circumflex humeral artery.
3.6 USG anterior approach to AN block
With the arm positioned parallel to the thoracic wall with internal rotation and forearm pronated on the abdomen, a US probe is placed below and parallel to the clavicula identifying the coracoid process and lesser tubercle and intertubercular (bicipital) groove; then the arm is externally rotated, pushing the subscapular muscle rostrally and identifiable under the deep lamina of the deltoid fascia; the first portion of the AN is present between the deep lamina of the deltoid fascia and the superficial lamina of the subscapular muscle, where needle tip is placed. Interfacial position is confirmed after injection of 2 mL of normal saline, then 10 mL of 0.25% bupivacaine is injected. Rotating caudally the medial side of the probe and abducting the limb permits to directly visualize the AN and posterior circumflex humeral artery.
The injection is distributed on the anterior surface of the subscapular muscle and around the proximal insertion of the coracobrachialis and biceps brachial muscles. The sensory block is detected in AN area and areas supplied by the branches of the musculocutaneous nerve, lateral pectoral nerve, lateral supraclavicular nerve, and intercostobrachial nerve.
A complete AN blockade could provide anesthesia to the anteroinferior and lateral edges, and to part of the posterior aspect. of the shoulder joint capsule. The remaining shoulder joint areas are innervated by the SSN, which must be blocked if complete anesthesia of the shoulder is to be achieved. The LPN, or its articular branches, can be blocked by PECS I block or at the space between the coracoid process and clavicle (Figure 12) [41, 42].
Figure 12.
US-guided anterior approach to AN blockade. A. Axillary nerve and its relations to subscapular, deltoid, and pectoralis muscles, axillary and circumflex humeral arteries, coracoid process, and humerus bone. B. Sagittal oblique ultrasound anatomy of the anterior axilla. C. Ultrasound scan: Transducer between coracoid process (medial) and the lesser tubercle of the humerus. Arm adducted and internal rotation. D. Transducer parallel to the inferior border of the clavicle, ultrasound mark is lateral. E and F. arm rotated externally/no abduction; subscapular muscle appears over humeral head. G and H. full external rotation and abduction of the arm. The medial side of the transducer is rotated inferiorly to obtain a sagittal oblique view of the axilla. The subscapular muscle is pushed rostrally and is identifiable under the deep lamina of the deltoid fascia. The cephalic vein is seen in the groove between deltoid and pectoralis major muscles. The axillary artery appears in the image and laterally to it, the axillary nerve is located. The needle shows the injection around the axillary nerve, on the surface of the subscapular muscle.
4. Surgery involving the collarbone
Clavicle fractures account for 2.6–4% of fractures in adults and 35% of shoulder injuries. The annual incidence is estimated between 29 and 64 per 100,000, and are distributed as follows: diaphysis 69-82%, lateral end 21-28%, and medial end 2-3%. There is often caudal displacement of the lateral fragment under the shoulder weight and elevation of the medial fragment by traction by the SCM. Infrequently, posterior displacement of the medial end can cause compression of the mediastinum and main vessels requiring urgent intervention. Non-displaced fractures are managed without surgery, while surgical management is preferred in cases of displaced fractures in active adults [43].
Innervation of the skin above the second rib is supplied by the supraclavicular nerves of the SCP. Terminal branches of suprascapular, subclavian, lateral pectoral, and long thoracic nerves pass through the plane between the clavipectoral fascia and the clavicle and, theoretically, contribute to collarbone innervation.
Common approaches in anesthesia for clavicle fracture surgery are GA, regional anesthesia techniques such as ISBP block combined with SCP block. The clavipectoral fascial plane (CPB) block (Figure 13) is accomplished by injecting 10 to 15 mL of LA deep to the clavipectoral fascia on the medial and lateral side of the fracture site. A SCP or supraclavicular nerves block should be implemented to provide a sensory block of the skin of the shoulder. This nerve block can potentially involve the PN if the injection is not performed accurately in the proper subcutaneous plane and using low volumes. The block can be used for diaphysis and lateral end interventions, but as isolated block for surgical anesthesia, it only works for diaphysis fractures (Figure 13) [44].
Figure 13.
The peri clavicular fascial plane or clavipectoral planes block (CPB). A: Scan throughout all clavicle surface, identifying the fracture site (proximal segment is displaced upward) B: Initiate the US scan in a sagittal paramedian position C: Tilting the ultrasound probe, is positioned on the upper surface of the clavicle D: Identify the anterior and posterior borders of clavicle E: 25 G needle tip positioned between bony surface and periosteum (if seen: By the fractured site, the periosteum is usually detached F: After 1-2 ml injected, the periosteum is further disengaged G: A second hyperechoic line appears, which correspond to clavipectoral fascia H: Needle tip positioned in the gap between periosteum and clavipectoral fascia I: Initial injection under clavipectoral fascia. Track Injectate spread in caudal and cephalic way along the anterior surface of clavicle I: Alternatively, Clavipectoral fascia scanning and needle in plane insertion from caudal to cephalic over clavipectoral fascia between pectoral major and minor muscles; this plane is the target for injection of local anesthetic.
For lateral fractures, including acromioclavicular and coracoacromial ligaments, articular branch of lateral pectoral nerve should be blocked. Likewise, if the surgery involves the acromioclavicular joint, the SSN should be blocked. Yamak Altinpulluk states that in the description of Ince et al., the LA was injected between the periosteum of the clavicle and the surrounding fascia (assumed as the clavipectoral fascia), but cadaveric dissections show that the spread is between the clavicle and fascia of the pectoralis major muscle in the upper and anterior aspect of the clavicle, with anesthetic spread under the deep layer of superficial cervical fascia and the superficial layer of pectoralis major fascia. The naming of this block as CPB is misleading and suggests that this block should be named as peri clavicular block (PB) [45]. The publication of a series of cases by Kukreja et al., shows the injection of the LA between the clavipectoral fascia and the pectoralis major muscle, resolving the previous objections described by Yamak Altinpulluk et al. [46].
5. Interscalene brachial plexus (ISBP) block
ISBP block targets the roots and trunks of the BP in the interscalene groove between ASM and MSM, and is directed towards C5-C6 nerve roots or UT. With higher volumes, C7 and even C8 nerve roots may be blocked. The block provides analgesia and anesthesia to the shoulder, lateral two-thirds of the clavicle, proximal humerus, and shoulder joint surgeries. Continuous infusion of 0.15% bupivacaine or ropivacaine (vs GA or intravenous anesthesia) provides adequate pain relief, similar side effects, and high patient satisfaction. ISBP block is associated with a high risk of PN blockade and HDP. Persistent PN palsy after ISBP block has recently gained wider recognition (reported incidence of 1:2000). Phrenic nerve palsy could be due to direct needle trauma or intraneural injection during landmark guided ISB but this complication has not been described with USG ISBP block. More peripheral BP nerve blockades are alternatives in scenarios in which avoiding PN palsy is critical, without clinically meaningful analgesic differences compared with ISBP block, except during recovery room stay [47]. Vocal hoarseness and Horner’s syndrome are due to self-limiting temporary blockade of the ipsilateral recurrent laryngeal nerve and stellate ganglion [48]. ISBP block cannot reliably block the C8 and T1 ventral rami [48, 49].
ISBP Blockade relies on the visualization of the relevant anatomy, needle-tip position and LA spread using USG plus peripheral nerve stimulation with or without injection pressure monitoring. USG allows fewer needle passes, lower volumes of LA, and better postoperative analgesia [1].
Figure 14 shows the scan process of interscalene space: At cricoid cartilage level, with transverse scan, identify the carotid artery and move the transducer laterally to locate the sonographic image of C5 and C6 TP; C5-C6 nerve roots are seen between the anterior and posterior tubercles and are traced in the groove between ASM and MSM, deep to the prevertebral fascia. The SCM lies superficially, and the PN runs medially over the ASM, away from the C5 root. Below the C6 TP and nerve root, C7 TP appears and the C7 nerve root can be seen anteriorly as hypoechoic round structure, lateral to vertebral vessels (identified by doppler color scan); meanwhile C5 and C6 nerve trunk are merging to conform to the UT; inferiorly to C7 transverse process, C7 nerve root conforms the MT. The dorsal scapular nerve (DSN) arises from the C5 nerve root and is imaged as a hyperechoic structure traversing the MSM, accompanied by LTN. Both must be avoided not needling through MSM. The block is performed positioning the tip deep to the C6 nerve root or UT and seeking the spread of LA anterior and posterior to the nerves, within the interscalene groove, and then repositioning of the needle superficial to the C5 nerve root or UT to obtain a satisfactory spread of LA. Do not needle between C5 and C6. 10-15 mL of LA (ropivacaine 0.75%) produce surgical anesthesia. Supraclavicular nerves blockade is added aimed to provide complete anesthesia to the shoulder cap.
Figure 14.
Interscalene brachial plexus block.
The PN diverges at a rate of 0.3 mm per cm below the cricoid cartilage. Its blockade is reported in as 100% with a traditional landmark-based approach using volumes greater than 20 mL, and between 25 and 50% with lower volumes. Forced expiratory volume in 1 s (FEV1) may be reduced by up to 40%, and patients with comorbidities (obesity and respiratory disease) may develop troublesome dyspnea. ISBP block has been associated with an incidence of temporary neurological dysfunction in up to 14% at 10 days. Hypotension and bradycardic events occur in up to 20% during shoulder surgery, typically in the sitting position, and at around 30 min after the placement of an ISBP block. High circulating catecholamine concentrations and an underfilled, hyper contractile ventricle (induced by venous pooling) stimulates intramyocardial mechanoreceptors resulting in an abrupt reduction in sympathetic tone together with increased vagal tone. Prompt treatment with an antimuscarinic (ideally atropine) with or without sympathomimetic drugs is indicated [1].
Selective trunk block (SeTB) targets injection around individual trunks, with small volumes of LA. Produces anesthesia of the entire upper extremity (C5-T1) except the ICBN innervated area (T2). Is performed as one injection targeting UT and MT at interscalene and another one targeting LT at the corner pocket of the supraclavicular fossa (Up to 25 ml of LA are used). Produces HDP similar to UT approach [49, 50].
6. Diaphragm-sparing BP blocks
Shoulder surgery is accompanied by severe acute postoperative pain that continues to be an unresolved problem. The gold standard for analgesia after this surgery is the ISBP. Unfortunately, this block is associated with a high incidence of ipsilateral phrenic nerve block and the consequent HDP, which restricts its use in patients with pre-existing pulmonary involvement, so it is prudent to consider the practical options to avoid or reduce the incidence of this complication. Nerve block techniques without diaphragmatic involvement such as supraclavicular blocks, upper trunk blocks, anterior suprascapular nerve blocks, costoclavicular blocks, and combined infraclavicular-suprascapular blocks are some of the possible alternatives. It has been suggested that costoclavicular blocks could provide postoperative analgesia similar to ISBP along with a 0% incidence of HDP. It is not clear whether costoclavicular blocks could achieve surgical anesthesia for shoulder surgery. The anterior suprascapular nerve blocks have been shown to provide surgical anesthesia and analgesia similar to ISBP. However, the risk of HDP has not been adequately quantified. Of the remaining nerve blocks that preserve diaphragm function, supraclavicular blocks (with injection of posterolateral local anesthetic to the brachial plexus), upper trunk blocks, and combined anterior and infraclavicular suprascapular blocks achieve analgesia similar to ISBP, along with an incidence of HDP <10% [17, 25, 51].
7. Discussion
Orthopedic surgeries are well known to be very painful. General anesthesia or regional anesthesia, or a combination of both, are optimal options for shoulder surgery. Regional nerve blocks are essential for postoperative analgesia and can be used alone or as a complement to GA, therefore the postoperative analgesia could be prolonged for 24 hours or more [49]. Regional anesthesia in the setting of GA has a relative contraindication but, with the use of USG, this statement has been challenged [52].
ISBP blockade is the most common approach and a highly effective technique, but with a high incidence of HDP, that contraindicates it in patients with lung disease or contralateral PN paralysis [25, 51]. Supraclavicular blocks vs. ISBP, result in similar pain control and patient satisfaction, but with an incidence of HDP exceeding 60%, when LA is injected intracluster, vs. 9% depositing LA posterolateral to neural cluster (in this setting, cluster refers to the confluence of trunks and divisions of BP) [25, 28].
UT block targets C5-C6 nerve fibers traveling with SSN and AN, producing analgesia not inferior to ISBP block and a 75% incidence reduction of PN involvement [21, 22, 23, 24]. The HDP occurs with an incidence of 5% [25].
AN block (posterior access) plus SSN block (sub supraspinous muscle access) produces a good analgesic effect in minor surgeries, compared to ISBP block, but spares the AN anterior articular branches, the lateral pectoral nerve articular branch, and subscapular nerve [25, 41, 45] and is inferior in terms of analgesia when compared to ISB in major surgeries. SSN block at sub omohyoid level extends to the UT almost always and occasionally to the middle trunk, with almost no PN block [33, 34, 35, 37]. It provides surgical anesthesia and similar analgesia to ISB [25]. It remains necessary to formally quantify the incidence of HDP. Both blocks should be accompanied by a supraclavicular nerve block at the lateral edge of the SCM to give analgesia to the skin over the shoulder and its contribution to the acromioclavicular joint [29].
AN block may be performed at the axillary fossa, producing anesthesia/analgesia that includes the anterior and posterior branches, with the advantage that intercostobrachial nerve block may be performed with the same puncture [38]. Access to the AN by anterior route is easy to perform and has the possibility of extending to the musculocutaneous nerve, superior subscapular nerve, lateral pectoral nerve and through the clavipectoral fascia, to the lateral supraclavicular nerve [41]. Clavipectoral fascia and peri clavicular block can provide anesthesia and analgesia for fractures of the middle third of the clavicle, without PN paralysis [44, 45, 46].
To date, the strategy that achieves analgesic equivalence with ISB with a 0%-incidence of HDP is the costoclavicular block. In 2019, Aliste et al. [53] compared ISB and costoclavicular block in 44 patients undergoing arthroscopic surgery, finding equivalent analgesia in both groups. Moreover, there is no evidence that this block results in surgical anesthesia [25]. Supraclavicular blocks (with LA injection posterolateral to the BP), UT blocks, and combined infraclavicular-anterior suprascapular blocks have been shown to achieve similar analgesia to ISB [54], coupled with an HDP incidence <10%. Decreasing LA injectate volume could avoid HDP altogether and should also be investigated for the provision of surgical anesthesia [25].
8. Conclusions
The anesthetic challenge imposed by shoulder surgery is considerable. This chapter reviews current options for regional anesthesia in this type of surgery. A regional technique, GA, or a combination of both can be appropriately used. Performing nerve blocks distally to the ISBP approach, PN paralysis can be reduced considerably, although not eliminated, taking care when performing them in patients with lung disease or contralateral HDP.
Acknowledgments
We thank MF Rojas for Figure 2. The authors also thank Dr. Victor Whizar-Lugo for his valuable support with this chapter.
Acronyms
axillary nerve anterior scalene muscle brachial plexus clavipectoral plane block dorsal scapular nerve general analgesia great auricular nerve hemi diaphragmatic paresis intercostobrachial nerve interscalene brachial plexus intravenous analgesia Local anesthetic Long head biceps tendon lateral pectoral nerve lateral suprascapular articular branch Levator scapulae muscle lower trunk long thoracic nerve medial brachial cutaneous nerve medial pectoral nerve medial suprascapular articular Branch middle scalene muscle middle trunk peri clavicular block phrenic nerve Quadrangular space sternocleidomastoid muscle superficial cervical plexus suprascapular nerve Selective trunk block transverse process ultrasound ultrasound guidance ultrasound image upper trunk
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