Thoracic nerve block techniques

INTRODUCTION — Peripheral nerve blocks of the thoracic region include intercostal blocks, thoracic paravertebral blocks (TPVB), and the thoracic fascial plane blocks. These nerve blocks are used are used for operative anesthesia and/or postoperative analgesia for a variety of surgeries of the chest and upper abdomen. This topic will discuss the relevant anatomy, clinical applications, techniques and drugs used for these blocks, and complications specific to each block. Equipment used, contraindications, and complications common to all nerve blocks are discussed separately. Abdominal nerve blocks are also discussed separately. (See "Overview of peripheral nerve blocks" and "Abdominal nerve block techniques".)

INTERCOSTAL NERVE BLOCK — Intercostal nerves can be blocked individually to provide anesthesia and/or analgesia for thoracic surgical procedures (eg, thoracotomy, video-assisted thoracoscopy), chest tube placement, breast surgery, rib fractures, and upper abdominal procedures [1,2]. Each intercostal block achieves a band-like segment of anesthesia at the chosen level. This block is easy to perform, though multiple blocks are often required.

When used to manage acute pain with multiple traumatic rib fractures, intercostal nerve blocks have been shown to decrease opioid requirements and to improve pulmonary mechanics [2-4]. Intercostal nerve block may also be effective for management of pain after breast or thoracic surgery [5-7].

Anatomy — The intercostal nerves arise from the ventral rami of the thoracic spinal nerves from T1 to T11 (figure 1) [1,8]. The corresponding nerve associated with T12 is the subcostal nerve. The first six intercostal nerves are called the thoracic intercostal nerves. The remaining nerves (T7 to T11) supply the thorax and abdomen and comprise the thoracoabdominal intercostal nerves [1,8].

The thoracic spinal nerve roots emerge from the intervertebral foramina and divide into ventral and dorsal rami (figure 2). The ventral rami travel within the paravertebral space, and enter the groove on the underside of each rib, becoming the intercostal nerves. The intercostal nerves run between the innermost intercostal muscles and the internal intercostal muscles, in association with the intercostal vessels, at the lower margin of each rib [3]. The nerve is the most inferior structure in the neurovascular bundle. The thoracic intercostal nerves supply the parietal pleura; their lateral and anterior branches provide sensory innervation of the skin of the lateral and anterior thorax (figure 3) [3].

Intercostal nerve block technique — Intercostal block can be performed using anatomic landmarks or with ultrasound guidance. We perform intercostal block with ultrasound guidance to minimize the chance of intravascular injection and pneumothorax and to increase the reliability of dermatomal coverage. The injection can be made closer to the vertebral column (and more proximal in the course of the nerve) with ultrasound guidance because palpation of the rib is less important than with an anatomic landmark approach. Therefore, with ultrasound, the injection more reliably blocks the nerve prior to its division into the lateral and anterior branches, increasing the likelihood of full dermatomal anesthesia (figure 2).

The patient is placed in the lateral, prone, or sitting position.

●Ultrasound guidance – When possible, the patient is positioned prone, with the arms resting above the head (to rotate the scapula) and a pillow under the abdomen (picture 1). If necessary for patient comfort, sitting or lateral decubitus positioning can also be used.

•Place the ultrasound transducer 4 cm lateral to the spinous process in a parasagittal plane (picture 1). The rib is visualized as a dark shadow; the pleura and lung are visualized below the intercostal space, deep to the rib. The rib can be confirmed by sliding the transducer toward the midline to visualize the transition point where rib can no longer be visualized on ultrasound and is replaced by the transverse process of the spine (image 1).

•Insert the needle either in plane or out of plane to the transducer (picture 2 and picture 3) and advance to place the needle tip just below the inferior border of the rib.

•After negative aspiration, inject 3 to 5 mL of local anesthetic (LA); as the drug is injected, the pleura can be seen moving away, as it is pushed deeper by the LA.

●Anatomic approach – Palpate the rib in the midposterior axillary line, usually 6 to 8 cm from the midline. Insert a 22- to 25-gauge needle at the inferior border of the rib, oriented approximately 20 degrees cephalad, and advance 0.5 cm underneath the rib. After negative aspiration, inject 3 to 5 mL of LA (figure 2). If the needle comes into contact with bone, "walk" the needle off the bone inferiorly. The block can be repeated at each of the levels appropriate for the surgical procedure.

Local anesthetic choice — Rapid uptake of LA from the intercostal space may reduce the duration of anesthesia and analgesia and increase the risk of LA toxicity. The addition of epinephrine can reduce uptake, allowing the use of lower-concentration LA, and can achieve longer duration of block. We typically use 0.2% ropivacaine or 0.25% bupivacaine with epinephrine (1:200,000 or 5 mcg/mL) to achieve analgesia. Patients are also monitored in the post-anesthesia care unit or intensive care unit for 30 minutes to detect delayed absorption of LA (table 1). (See "Overview of peripheral nerve blocks", section on 'Drugs'.)

Complications — Pneumothorax is a risk of intercostal block and may be less likely with ultrasound-guided block as compared with a landmark-based approach. The incidences of asymptomatic and symptomatic pneumothorax are less than 0.1 percent and 0.5 percent, respectively [9]. Symptomatic pneumothorax can usually be treated with needle decompression; the need for chest tubes is extremely rare. LA toxicity is possible, especially when multiple blocks are performed. Rarely, case reports have described subarachnoid spread of LA occurring with intercostal blocks if the needle tip enters a dural sleeve [10]. (See "Overview of peripheral nerve blocks", section on 'Complications'.)

THORACIC PARAVERTEBRAL BLOCK — Thoracic paravertebral block (TPVB) is a compartment block; success relies on spread of injected local anesthetic (LA) within the paravertebral space. This block anesthetizes spinal nerves as they emerge from intervertebral foramina and run through the paravertebral space.

TPVB results in somatic and sympathetic nerve block, similar to that which would be achieved with epidural blockade. Paravertebral block is used most commonly to provide anesthesia and/or analgesia for mastectomy, cosmetic and other breast surgeries, thoracic surgery, nephrectomy, and rib fractures.

Single-injection TPVB at T4 level is an alternative to general anesthesia for breast surgery [11,12] and has been described as a sole method of anesthesia for video-assisted thoracoscopic surgery [13]. Numerous studies have reported improved postoperative pain scores and reduced analgesic consumption after paravertebral block for breast surgery [14]. Several studies, though not all, have also reported a reduction in the incidence or severity of chronic pain after breast surgery [15-17]. A retrospective study reported a reduction in cancer recurrence with paravertebral block for breast cancer surgery, compared with opioid analgesia [18]. However, this effect has not been confirmed in prospective trials [19].

Compared with epidural blockade, TPVB offers the advantage of unilateral block and is associated with a lower incidence of hypotension, urinary retention, respiratory problems, and postoperative nausea and vomiting [20-22].

The relevant anatomy and techniques for thoracic paravertebral blocks are discussed separately. (See "Thoracic paravertebral block procedure guide".)

FASCIAL PLANE BLOCKS OF THE CHEST WALL — The pectoral nerve blocks, serratus plane (SP) block, transversus thoracic muscle plane (TTMP) block, and erector spinae plane (ESP) block are peripheral nerve blocks that rely on injection of local anesthetic (LA) between the muscles of the chest wall to anesthetize nerves that run in the fascial planes.

Terminology — Pectoral nerve blocks were originally described as Pecs I (single injection between pectoralis major and minor muscles) and Pecs II (injection used for the Pecs I block plus a second deeper injection as described below). A multi-society consensus statement in 2021 recommended that these blocks be renamed in anatomic terms, with the term interpectoral block replacing Pecs I and pectoserratus block the name for the deep component of Pecs II [23]. We will use the terms interpectoral and pectoserratus.

Applications for fascial plane blocks of the chest wall — Combinations of these chest wall blocks can be used for surgical anesthesia and postoperative analgesia for procedures of the pectoral region of the chest as alternatives to the more invasive paravertebral and epidural blocks [24-26].

●Interpectoral plane (Pecs I) block – The interpectoral plane block can be used as a supplemental block in combination with other pectoral chest wall blocks (serratus anterior plane block, transthoracic muscle plane block, and ESP block) for surgeries of the chest wall. This block specifically targets motor branches of the medial and lateral pectoral nerves that originate in the brachial plexus. This block is beneficial for procedures that involve dissection of the pectoralis major and/or minor muscles, such as tissue expander placement. The Pecs I block is part of the Pecs II block. (See 'Interpectoral plane plus pectoserratus (Pecs II) block' below.)

●Combined interpectoral and pectoserratus (Pecs II) block – This block is a dual injection technique that includes the interpectoral plane injection and a deeper injection in the pectoserratus plane. The pectoserratus component targets the lateral branches of the intercostal nerves (therefore adding superficial coverage of the skin, subcutaneous tissues, and upper/lateral/inferior quadrants of the breast) as well as the long thoracic and thoracodorsal nerves (adding further coverage of the deep chest wall [serratus anterior and latissimus dorsi muscle]) in addition to the intercostobrachial nerve for axillary coverage. This block provides analgesia for both superficial and deeper or more extensive procedures in the anterolateral chest and axilla (eg, simple mastectomy, placement of breast tissue expanders, pectoral muscle dissection, pacemaker placement, and Port-A-Cath placement, mastectomy, tumor excision, and axillary node dissection) [25,27]. The combined interpectoral and pectoserratus block has also been used along with supraclavicular brachial plexus block for upper arm arteriovenous fistula creation [28-30]. It is important to note that both pectoral nerve blocks (as well as SP block below) spare the anterior branches of the intercostal nerves and therefore will miss the medial half of the breast, as well as the overlying skin and subcutaneous tissues in the parasternal areas of the chest wall.

●Serratus plane block – Similar to the superficial component of the Pecs II block, the SP block can provide analgesia for deep structures in the anterolateral chest and axilla. SP block can also provide analgesia after rib fractures [31], thoracotomy [32], and breast surgery [33].

●Transversus thoracic muscle plane block – The TTMP block is intended to supplement other pectoral and chest wall blocks (SP and Pecs) to provide medial coverage to the breast as well as parasternal skin and subcutaneous tissue [34]. The block targets the anterior cutaneous branches of the intercostal nerves that terminate in the fascial plane between the internal intercostal and the transversus thoracic muscle (TTM) in the parasternal area between the third and fourth ribs.

●Erector spinae plane block – The ESP block targets structures in the fascial plane between the erector spinae muscle and the vertebral transverse process. ESP block may share similar block characteristics and complications as the thoracic paravertebral blocks (TPVB). ESP blocks placed at T3-4 level have been used for breast procedures [35], thoracic procedures [36], cardiac procedures [37], and trauma, while ESP blocks placed at T7 or lower have been used for upper abdominal procedures such as epigastric and ventral hernia procedures [38] and bariatric surgery [39], laparoscopic cholecystectomy (at T9 level) [40,41], and lumbar spine fusion (L3) [38,42,43]. ESP block has also been used for analgesia for neuropathic rib pain [44].

Anatomy — The pectoral nerves (lateral and medial) arise from the cords of the brachial plexus (lateral and medial, respectively) and innervate the pectoral major and minor muscles (figure 4). The lateral pectoral nerve (C5 to C7) courses along the undersurface of the pectoralis major muscle, in the fascial plane between the pectoralis major and minor muscles, and is consistently located lateral to the thoracoacromial artery. The medial pectoral nerve (C8 to T1) also runs between the pectoralis major and minor muscles [25,45]. These are small nerves that are not usually visualized using ultrasound.

The intercostobrachial nerve (thoracic nerve, T2), the lateral cutaneous branches of the thoracic intercostal nerves (T2-9), the long thoracic nerve, and the thoracodorsal nerve run in variable anatomic courses, piercing the fascial plane between the serratus anterior muscle, ribs, and pectoralis minor muscle. The structures innervated by these nerves are as follows [45]:

●The long thoracic nerve innervates the serratus anterior muscle

●The intercostobrachial nerve innervates structures in the axilla

●The lateral cutaneous branches of the thoracic intercostal nerves innervate the lateral breast tissue, superficial tissue in the upper abdomen, and overlying skin

●The thoracodorsal nerve innervates the latissimus dorsi muscle

The anterior cutaneous terminal branches of the intercostal nerves pierce and run in the fascial plane between the internal intercostal and the TTM in the parasternal area to supply the overlying skin and subcutaneous tissues of the medial and parasternal chest wall.

The exact mechanism of injectate and dermatomal spread have not been elucidated for the ESP and TTMP blocks [46-48]. The ESP block may share targets similar to the TPVB. The TTMP block targets the anterior cutaneous branches of the intercostal nerves that terminate in the fascial plane between the internal intercostal and the TTM in the parasternal area between the third and fourth ribs.

Interpectoral plane (Pecs I) block — This block is performed by injection of LA in the plane between the pectoralis major and minor muscles to anesthetize the lateral and medial pectoral nerves. It is performed using ultrasound guidance. This block is performed in combination with the Pecs II block, with separate injections with a single needle pass. The initial images for Pecs I serve as orientation landmarks for the Pecs II block during ultrasound scanning.

●Place a linear, high-frequency ultrasound transducer in the parasagittal plane below the clavicle, just medial to the coracoid process. Identify the pectoralis major and pectoralis minor muscles (image 2). Rotate the probe laterally using color-flow Doppler to identify the pectoral branch of the thoracoacromial artery between the muscles, to avoid puncture, and to more precisely deposit LA near the nerves.

●After negative aspiration, inject 10 mL of LA in 5-mL increments, with gentle aspiration between injections.

Interpectoral plane plus pectoserratus (Pecs II) block — This block aims to block the pectoral nerves, intercostobrachial nerve, the intercostal nerves 3 through 6, the thoracodorsal nerve, and the long thoracic nerve. It involves two injections, one between the pectoralis major and minor muscles (ie, the interpectoral plane [Pecs I] injection), and a deeper injection in the plane between the pectoralis minor muscle and the serratus anterior muscle. This block is performed using ultrasound guidance.

●After locating the Pecs I view described above, slide the transducer caudally to identify the second rib (image 2). Rib shadows are visualized as bright white hyperechoic structures. Tilting of the transducer towards the sternum or lungs may be required to visualize the ribs, intercostal muscles, pleura, and lungs. After identifying the second rib, move the transducer in a lateral and caudal direction while counting the ribs. Slide the ultrasound transducer toward the axilla until the third rib is visualized at the midaxillary line on the lateral chest wall. At the level of the third rib, the pectoralis major and minor muscles and the insertion of the serratus anterior muscle are visualized. The hyperechoic (white) pleura should also be identified, with the lung sliding with respiration beneath the pleura. If identification of the ribs proves difficult, aiming the transducer medially may help.

●Insert the needle in plane (picture 2), past the pectoralis and serratus anterior muscles, until the rib is contacted. Withdraw the needle slightly until it is positioned deep to the serratus anterior, just on top of the rib. If the serratus muscle is not well visualized, LA can be injected just deep to the pectoralis minor muscle. The goal is to pierce the axillary sheath deep to the pectoralis minor muscle, in the axillary compartment. Injection can be made above or below the serratus anterior muscle but must be deep to the pectoralis minor muscle.

●The two injections for this block can be performed with either injection first. The deep injection is typically performed first; after negative aspiration, inject 20 mL of LA in 5-mL increments, aspirating gently between injections. Withdraw the needle to place the tip of the needle in the fascial plane between the pectoralis major and pectoralis minor muscles (as described for interpectoral plane injection above). After negative aspiration, inject 10 mL of LA in 5-ml increments, with gentle aspiration between injections. Visualize injectate spread between the muscles and confirm that pectoralis major is displaced upward and pectoralis minor muscle is displaced downward on ultrasound.

Serratus plane block — The SP block is designed to anesthetize the thoracic intercostal nerves in order to provide analgesia for the lateral chest wall. Intercostal nerves from T2 to T9 are usually blocked [26]. The SP block is a more posterior and lateral modification of the Pecs II block; they are not performed together. However, the Pecs I injection must be added to the SP block for breast reconstruction or surgery that violates the anterior chest wall, to block the medial and lateral pectoral nerves. The SP block is performed using ultrasound guidance.

●Place a linear, high-frequency ultrasound transducer in a parasagittal plane under the mid-clavicle (image 2). Rotate the transducer 45 degrees, such that the caudal end is aimed lateral and move the transducer inferolaterally, counting ribs until the fifth rib is identified in the midaxillary line. Identify the latissimus dorsi superficially and posteriorly, the teres major muscle superiorly, and the serratus muscle deep and inferiorly, overlying the fifth rib.

●Insert the needle in plane to the transducer (picture 2) from the medial side, and position the needle tip above the serratus muscle. Injection can be performed either superficial or deep to the serratus anterior muscle, and there is little evidence to support either choice. The superficial injection is preferred by the authors.

●After negative aspiration, inject 20 mL of LA in 5-mL increments, aspirating between injections.

Transversus thoracic muscle plane block — The TTMP block is intended to anesthetize the anterior cutaneous terminal branches of the intercostal nerves that supply the medial and parasternal areas of the chest wall (T2 to T7). It can be performed bilaterally using ultrasound guidance.

●Place a linear, high-frequency ultrasound transducer in a parasagittal plane in the midsternal area at the level of third and fourth ribs.

●Visualize the ribs, intercostal muscles, pleura, and identify lung sliding. The intercostal muscle lies in between the ribs. If the transducer is moved medially to contact the sternum, all muscles and pleural structures will disappear and will be replaced with this hyperechoic structure. From the sternum, slowly slide the transducer laterally until structures reappear and keep scanning laterally until a dark, black, hypoechoic, and linear structure appear below and deep to the intercostal muscle. This thin band is the TTM.

●Before needle placement, the surrounding area should be scanned carefully to identify the internal thoracic artery (previously known as the internal mammary). Doppler can be used to identify arterial flow. This artery must be avoided during injections.

●Insert the needle in-plane to the transducer in a cephalad to caudad direction (caudad to cephalad is also acceptable) and place the tip of needle between the intercostal muscle and the TTM between the ribs and above the pleura. The TTM serves as a buffer between needle and pleura but cautious use of hydrodissection should be used to avoid deeper penetration to the pleura.

●After negative aspiration, inject 10 mL of LA in 5-mL increments, aspirating between injections.

Erector spinae plane block — The ESP block involves injection of LA in the plane between the erector spinae muscle and the transversus vertebral process in the posterior chest wall. It can be performed bilaterally under ultrasound guidance in the sitting, lateral decubitus, or prone position. The relevant anatomy and technique for ESP block are discussed in detail separately. (See "Erector spinae plane block procedure guide".)

Local anesthetic choice — A long-acting LA (eg, 0.25% bupivacaine or 0.2% ropivacaine) is typically administered for each of the chest wall blocks (table 1). (See "Overview of peripheral nerve blocks", section on 'Drugs'.)

Complications — To date, there are few published complications of chest wall blocks. Theoretical concerns include the possibility of pneumothorax; local anesthetic systemic toxicity; injury to the long thoracic nerve (which would result in a winged scapula), the thoracodorsal nerve, or the pectoral nerve; or epidural spread of LA during ESP with possible complications similar to TPVB.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Local and regional anesthesia" and "Society guideline links: Local anesthetic systemic toxicity".)

SUMMARY AND RECOMMENDATIONS

●Intercostal nerve blocks – Thoracic and thoracoabdominal intercostal nerves can be blocked to provide anesthesia and/or analgesia for thoracic and upper abdominal surgical procedures and neuropathic pain treatment (figure 2). Each intercostal block achieves a band-like segment of anesthesia at the chosen level (figure 3). This block is easy to perform, though multiple blocks are often required. (See 'Intercostal nerve block' above.)

●Thoracic paravertebral block – Thoracic paravertebral block (TPVB) is a compartment block used most commonly to provide anesthesia and/or analgesia for mastectomy and cosmetic breast surgery, thoracic surgery, nephrectomy, and rib fractures. Compared with epidural blockade, TPVB offers the possibility of unilateral block. (See 'Thoracic paravertebral block' above and "Thoracic paravertebral block procedure guide".)

●Thoracic fascial plane blocks – Thoracic fascial plane blocks include the Pecs I (interpectoral plane), Pecs II (interpectoral plane plus pectoserratus), serratus plane (SP), transversus thoracic muscle plane (TTMP), and erector spinae (ESP) blocks (figure 4 and image 2). These blocks can be used for superficial and deep surgery of the chest wall, axillary regions, upper abdominal regions, and posterior back and spine regions. (See 'Fascial plane blocks of the chest wall' above.)

●Ultrasound guidance – We suggest the use of ultrasound guidance for the fascial plane blocks of the chest (Grade 2C), to increase the success rate and reduce complications. We also use ultrasound guidance for intercostal nerve blocks, though an anatomic landmark based technique is possible. (See 'Fascial plane blocks of the chest wall' above and 'Intercostal nerve block technique' above.)