Serratus anterior plane block for severe neuropathic pain management in locally advanced non-small cell lung cancer: a case report

Introduction

Background

First described by Blanco in 2013 (1), the serratus anterior plane block (SAPB) is a regional anesthesia technique that provides analgesia to the anterolateral thoracic wall by targeting the lateral cutaneous branches of the thoracic intercostal nerves in the fascial plane either superficial or deep to the serratus anterior muscle, resulting in sensory blockade from the second to the ninth thoracic dermatomes in a volume- and number-of-injections-dependent manner (2). The superficial version also affects the long thoracic and thoracodorsal nerves, which innervate the serratus anterior and latissimus dorsi muscles, respectively (3).

This technique has demonstrated efficacy in managing pain across various clinical contexts, including rib fractures (4), mastectomies (5), thoracic surgery (5), and cardiac interventions (6). Its simplicity, reliance on anatomical landmarks, and consistent distribution of local anesthetic render it an attractive option for continuous regional analgesia. Case series and trials evaluating continuous SAPB catheters in patients undergoing video-assisted thoracoscopy (VATS) guidance have demonstrated effective postoperative analgesia (7,8). However, its role in managing preoperative neuropathic or cancer-related chest wall pain remains limited.

Locally advanced non-small cell lung cancer (NSCLC) involving intrathoracic structures presents with diverse clinical manifestations. Notably, when the chest wall and spine are compromised, morbidity and mortality rates increase substantially. A common feature in these patients is severe somatic and neuropathic pain, which may occur with or without neurological deficits, depending on the level of spinal and neural involvement. The therapeutic approach typically aims for complete surgical resection as part of a multimodal treatment strategy (9,10).

Rationale and knowledge gap

Perioperative pain management in this patient population is particularly complex, and the existing literature on this topic is notably limited. Most case series have primarily focused on survival outcomes and major postoperative complications, with an absence of description of perioperative acute pain control, the incidence of persistent or chronic pain, and its long-term management (10,11). Analgesic protocols commonly employed in thoracic surgery may not be feasible in these cases. Furthermore, patients who survive surgical resection might experience chronic pain and functional deficits, which represent an additional clinical challenge.

Objective

We present a case demonstrating the successful use of continuous SAPB to manage severe, opioid-refractory neuropathic pain in a patient with advanced NSCLC where neuraxial techniques were contraindicated due to anatomical distortion and ongoing anticoagulation. We present this article in accordance with the CARE reporting checklist (available at https://asj.amegroups.com/article/view/10.21037/asj-2025-1-90/rc).

Case presentation

A 67-year-old male living with his family was diagnosed with T3N0 NSCLC involving the right middle and lower lobes in August 2024. He was undergoing the third cycle of neoadjuvant chemotherapy, initiated in December 2024 (nivolumab 360 mg, carboplatin 900 mg, and paclitaxel 381 mg) in preparation for an en bloc surgical resection scheduled for March 2025. One week prior to the planned operation, he presented to the emergency department reporting persistent severe right-sided thoracic pain rated as 10 out of 10 on the Numeric Rating Scale (NRS). The pain was sharp, burning, constant, and radiated from the right axilla to the ipsilateral anterior chest wall, predominantly involving the T5–T8 dermatomes and was associated with progressive shortness of breath.

One month before admission, his functional status had rapidly declined, with progressive limitation in mobility and daily activities due to uncontrolled pain. His analgesic regimen had been escalated two weeks earlier to a total daily oral morphine equivalent (OME) of 120 mg, including up to six breakthrough doses, in addition to pregabalin 250 mg/day, acetaminophen 4,000 mg/day, and fluoxetine 30 mg/day.

On examination, the patient appeared uncomfortable with mild respiratory distress but was alert and oriented. Lung examination demonstrated wheezing over the right upper lung field, and decreased air entry at the right lung base. No lower extremity edema was present.

The laboratory investigations revealed anemia (hemoglobin 90 g/L) and leukocytosis (white blood cell count 13.6×10⁹/L). Platelet count was within normal limits. Serum chemistry demonstrated mild hyponatremia (sodium 132 mmol/L), with otherwise unremarkable electrolytes. Renal function was preserved, and serum glucose was 6.8 mmol/L.

Magnetic resonance imaging (MRI) revealed a right lung mass with extra-thoracic extension to the paravertebral space between T6 and T8 and involvement of T6 and T7 vertebral bodies with severe T6/7 and T7/8 foraminal stenosis and impingement of the right T6 and T7 nerves. (Figure 1A,1B). Computed tomography angiography (CTA) also demonstrated segmental and subsegmental pulmonary emboli in the left upper lobe. Based on the patient’s description of the pain, it was considered more likely to be tumor-related rather than due to the pulmonary embolism.

Figure 1 MRI. (A) Longitudinal view of the right paravertebral space demonstrates a right thoracic mass with vertebral body invasion, paravertebral extension, and severe neural foraminal compromise at T6–T8, consistent with malignant infiltration and nerve root impingement. (B) Axial MRI at T7 shows a rim-enhancing heterogeneous right paravertebral mass with hypo-enhancing components, focal signal void, and associated rib and vertebral body destruction. MRI, magnetic resonance imaging.

The patient was admitted for pain management, initiation of anticoagulation therapy for pulmonary embolism, and preoperative preparation. During admission, the pain worsened, becoming refractory to multimodal systemic analgesia including oral morphine 60 mg twice a day, subcutaneous morphine 5 mg every 2 hours for breakthrough pain, pregabalin 150 mg twice a day, acetaminophen 1,000 mg every 6 hours, and fluoxetine 40 mg daily. The OME consumption reached 165 mg, which was associated with increasing somnolence and respiratory compromise. The Acute Pain Service was consulted to manage his pain while awaiting surgery. An inferior vena cava (IVC) filter was placed prior to the scheduled surgery.

After evaluating the MRI, epidural, paravertebral, and other paraspinal either deep or superficial blocks (intertransverse or erector spinae plane) blocks were found not to be viable options due to the anatomy distortion (Figure 1A,1B). Given the anterolateral location of the pain and the contraindications to deeper blocks, a continuous SAPB was selected to target the lateral cutaneous branches of the affected intercostal nerves.

In a block room, with standard monitoring and left lateral decubitus position, after skin disinfection and sterile draping, a 5–13 MHz linear ultrasound transducer was placed along the midaxillary line at the T7 level to obtain a short-axis view of the ribs, serratus anterior muscle, and intercostal muscles (Figure 2A). Using an in-plane caudad-to-cephalad approach, after a skin wheal with 3 mL of 1% lidocaine, a 17-gauge, 8.9 cm block needle was advanced until its tip was positioned just superficial to the serratus anterior muscle (Figure 2B). Incremental injections up to a total of 10 mL of adrenalized 0.5% ropivacaine were performed to expand the fascial plane and facilitate catheter placement. Subsequently, a 19-gauge catheter was smoothly threaded 7 cm into the plane (Figure 2C), followed by the administration of 20 mL of the same local anesthetic solution plus 5 mg of preservative-free dexamethasone via the catheter. A sensory blockade of the lateral cutaneous branches of the intercostal nerves from T4 to T9 was achieved, and no procedure-related complications were observed. The pain NRS decreased from 10 to 2, with concurrent improvement in respiratory effort. A contrast-enhanced X-ray assessment of the catheter position and injectate spread, though limited by the patient’s positioning in bed, demonstrated findings compatible with the observed sensory blockade (Figure 2D).

Figure 2 Procedural images of SAPB. (A) The ultrasound image shows the serratus anterior muscle, overlying subcutaneous tissue, and intercostal muscle between the ribs in a short-axis orientation at the T7 level. (B) Needle tip placement and spread of local anesthetic between subcutaneous tissue and serratus anterior muscle. The white arrow indicates the needle tip visualized within the serratus plane. (C) The catheter inserted into the serratus anterior superficial plane. The white arrow indicates the catheter placed within the serratus plane. (D) Contrast-enhanced X-ray demonstrating the catheter position and spread of injectate. ICM, intercostal muscles; LA, local anesthetic; NT, needle tip; SAM, serratus anterior muscle; SAPB, serratus anterior plane block; SC, subcutaneous tissue.

The continuous SAPB was maintained for seven days until the day of surgery using 0.2% ropivacaine at a 5 mL/hour rate with 15 mL bolus available every 4 hours. The OME consumption ranged from 7.5 to 20 mg, with two to three breakthrough doses per day and no overnight breakthrough pain. The respiratory distress improved, with respiratory rates ranging from 12 to 15 breaths per minute. These findings demonstrated consistent analgesia, preserved respiratory effort, and improved sleep quality.

On the day of surgery, the SAPB catheter was removed after induction of anesthesia. There were no intraoperative complications related to anesthesia management. To complement postoperative analgesia, an epidural catheter was inserted at the L3–L4 level, and epidural morphine 3 mg was administered prior to the start of surgery. The patient underwent extensive en bloc resection and spinal fusion. Postoperatively, epidural morphine 3 mg was administered every 12-hour following the initial intraoperative dose. Nevertheless, the postoperative course was marked by the development of respiratory failure in the context of sepsis, culminating in patient death on postoperative Day 8.

Ethical considerations

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient and his family for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

Key findings

Epidural and paravertebral blocks are considered the standard techniques for regional analgesia in thoracic procedures expecting severe postoperative pain (12). However, both are classified as deep blocks, and their use in patients receiving anticoagulation therapy is governed by guidelines (13) that restrict their applicability.

In recent years, more superficial paraspinal blocks have emerged, offering a relatively favorable balance between effectiveness and safety for thoracic wall analgesia. Among these, the erector spinae plane block (14), achieved by injecting local anesthetic into the myofascial plane between the erector spinae muscle group and the transverse processes of the spine, has gained significant popularity. This block targets both the anterior and posterior rami of the spinal nerves, providing sensory blockade of the anterolateral and posterior chest wall.

The SAPB has gained considerable popularity in regional anesthesia, particularly for breast and thoracic surgical procedures (4-6). Its effectiveness and safety have been consistently demonstrated, with the technique offering a high degree of reproducibility. SAPB is relatively simple to perform and provides reliable diffusion of the injectate, making it a practical option in various clinical settings (4-6). Unlike injections into posterior paraspinal fascial planes, SAPB specifically targets somatic pain originating from the anterolateral chest wall and does not produce visceral analgesia. Although described as cutaneous branches of the intercostal nerves, the block of these nerves has, somehow, proven to improve pain control in scenarios involving deep thoracic incisions and rib trauma.

In this case, the patient presented with ipsilateral right chest wall pain with neuropathic features. MRI of the spine revealed a right lung mass with extra-thoracic extension involving the T6–T8 vertebral bodies and invasion of the paravertebral space. As a result, deep regional techniques including epidural, paravertebral, and superficial paraspinal blocks such as the erector spinae plane block were considered contraindicated due to the proximity of the tumor and ongoing anticoagulation therapy. In addition, the efficacy and safety of these techniques depend on the anatomical integrity of the injection site to ensure accurate needle placement and reliable spread of the local anesthetic. The SAPB was therefore considered the most suitable option for this patient, as it can be performed on the lateral chest wall, distant from the tumor site, provides coverage of the lateral cutaneous branches supplying the lateral chest wall. The SAPB demonstrated clinical utility in a complex scenario involving a patient receiving anticoagulation therapy and presenting with significant anatomical distortion. Its implementation was associated with reduced opioid consumption, improved ventilatory parameters, decreased somnolence, and enhanced mobilization. These findings underscore the relevance of SAPB in patients for whom traditional deep blocks may be contraindicated or technically challenging.

Comparison with similar research

The SAPB is effective for managing somatic chest wall pain and has been shown in several comparative studies to reduce opioid consumption and postoperative pain scores (8,15). However, these trials primarily evaluated acute postoperative pain following surgery. In addition, the efficacy of SAPB is limited for deep visceral pain or sympathetic pathways arising from intrathoracic structures such as the pleura and internal organs (8). In this patient, the SAPB catheter was placed preoperatively to control chest wall pain while awaiting surgery, with breakthrough opioids were prescribed to address potential visceral pain if needed. Notably, the block provided excellent analgesia, and the patient required minimal breakthrough opioid doses while the catheter was in place.

Strengths and limitations

The role of SAPB in neuropathic and cancer-related chest wall pain remains uncertain as evidence in neuropathic and cancer pain are mainly derived from case reports and small case series (16-20). Continuous SAPB catheters are generally impractical in these patients because of the risk of displacement or dislodgement, and prolonged catheter placement is associated with an increased risk of infection, unless definitive interventions such as neurolysis are performed (20). Further studies are required to better define the effectiveness of SAPB in cancer pain management.

Explanations of findings

Regarding its complications, pneumothorax has been reported after deep SAPB in breast surgery (21). As with other regional anesthesia techniques, SAPB carries risks including infection, hematoma, nerve injury, and local anesthetic systemic toxicity (LAST). Identification of the thoracodorsal artery may reduce the risk of vascular puncture. In superficial SAPB, the injection plane lies between the latissimus dorsi and serratus anterior muscles (or more anteriorly between the subcutaneous tissue and the serratus anterior muscle), making pleural puncture unlikely when needle depth is controlled and continuously visualized under ultrasound. Infection risk can be minimized by following current American Society of Regional Anesthesia and Pain Medicine (ASRA) recommendations for both single-shot and continuous blocks.

Postoperative analgesia in this case was particularly challenging. A lumbar epidural catheter was placed to provide postoperative pain control with intermittent epidural morphine. However, despite initial postoperative stabilization, the patient developed late respiratory complications, leading to progressive hypoxic respiratory failure. This outcome highlights the substantial respiratory risk associated with extensive combined thoracic, chest wall, and spinal oncologic surgery, particularly in patients with recent exposure to chemotherapy (10). Although the use of SAPB likely contributed to improve preoperative respiratory mechanics and opioid sparing, such strategies cannot fully mitigate the risk of severe postoperative pulmonary complications following such high-risk surgery. Regretfully, the negative postoperative outcome prevented us from obtaining more reliable information on the efficacy of intermittent epidural morphine.

Implications and actions needed

This case study demonstrated that continuous SAPB provided effective analgesia for neuropathic, cancer-related chest wall pain, as evidenced by reduced opioid requirements and improved respiratory mechanics. Moreover, the relative simplicity of the technique and its favorable safety profile compared with neuraxial, paravertebral, or erector spinae plane blocks make SAPB a practical option for patients with complex spinal anatomy or contraindications to deeper regional techniques.

However, some limitations should be acknowledged. As a single-case report, the observed analgesic efficacy of SAPB cannot be generalized. Further studies are required to confirm its effectiveness in managing cancer-related chest wall pain. In addition, the patient’s death limited the ability to collect further postoperative data, preventing a comprehensive assessment of longer-term outcomes.

Conclusions

In conclusion, continuous SAPB can provide effective, opioid-sparing analgesia in patients with severe neuropathic chest wall pain from advanced NSCLC, particularly when neuraxial or deep paraspinal blocks are contraindicated. It also represents a valuable component of the anesthesiologist’s armamentarium for managing various sources of lateral chest wall pain, offering a favorable balance of simplicity, safety, and efficacy.

Acknowledgments

We thank the patient and family for granting permission to publish this report.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://asj.amegroups.com/article/view/10.21037/asj-2025-1-90/rc

Peer Review File: Available at https://asj.amegroups.com/article/view/10.21037/asj-2025-1-90/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://asj.amegroups.com/article/view/10.21037/asj-2025-1-90/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient and his family for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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