Serratus posterior superior intercostal plane block provides effective analgesia for patients undergoing dorsal mass excision: The first report of use in anesthesia practice

Abstract

The ultrasound-guided serratus posterior superior intercostal plane (SPSIP) block is a newly introduced regional anesthesia technique that has shown promising results in adult patients undergoing uniportal video-assisted thoracoscopic lung resections and other thoracic procedures. However, its use in dorsal mass excisions has not yet been reported. In the reported case, a 66-year-old female patient received an SPSIP block for the surgical removal of a 7 cm lesion located in the upper scapular region. The surgery and postoperative period proceeded without complications, and the patient remained pain-free until discharge. This case underscores the SPSIP block’s safety and effectiveness in providing postoperative analgesia for dorsal mass excision.

Introduction

The ultrasound-guided serratus posterior superior intercostal plane (SPSIP) block is a regional anesthesia technique, first described by Tulgar in 2023, that provides near-complete sensory blockade of the upper ipsilateral hemithorax.[1]

Over the past two years, this block has been effectively used for postoperative pain management in patients undergoing uniportal video-assisted thoracoscopic lung resections and other thoracic procedures.[2,3,4,5] However, its application in patients with thoracic wall lesions has not been previously reported.

This case reports the first documented use of the SPSIP block for postoperative pain relief in a patient undergoing dorsal mass excision, highlighting its safety and effectiveness.

Case Report

A 66-year-old woman with no underlying medical conditions presented with six months of left shoulder pain, hand paresthesia, and restricted movement. Physical examination revealed a firm, hard-elastic lesion in the upper scapular region. A Computed Tomography (CT) scan identified a 7 cm poorly defined mass near the second costal arch, adherent to the deep fascia of the serratus posterior superior muscle (SPSM) and extending toward the supraspinous fossa and acromion [Figure 1]. Radiological findings suggested a differential diagnosis of myosarcoma, myxoid lesion, or a benign connective tumor (e.g., elastofibroma dorsi), prompting surgical excision.

Figure 1.

CT scan showing the 7 cm solid mass with low contrast enhancement, located beneath the trapezius, rhomboid, and serratus posterior superior muscles. The lesion extends to the superior supraspinous fossa (Figure 1a, dotted circle), with a small portion beneath the scapular body (Figure 1b, dotted circle)

Following the induction of general anesthesia, the patient was positioned prone, with the left shoulder at the edge of the operating table [Figure 2]. Initially, the left arm was allowed to dangle before being flexed, adducted, slightly internally rotated, and placed on a specialized support.

Figure 2.

The patient is positioned on the operating table. The angle and medial border of the scapula are highlighted with a marker stroke. Asterisks indicate the spinous processes of the first three thoracic vertebrae, while the arrow marks the site of the surgical incision

Ultrasound imaging of the left upper posterior trunk was performed using a high-frequency (13–6 MHz) linear probe (Sonosite HFL38x; Fujifilm Sonosite, Inc., Bothell, Washington, United States). The mass appeared as a solid, lenticular lesion measuring approximately 7–8 × 4 cm at the T2–T3 level, located beneath the SPSM, and tightly adherent to the costal plane and intercostal muscles. Color Doppler evaluation revealed no intralesional vascularization.

Under sterile conditions, an ultrasound-guided SPSIP block was performed. The linear transducer probe was placed at the T2–T3 level to visualize the second and third ribs, the lesion, and the surrounding muscles (SPSM, rhomboid, and trapezius). The probe was then rotated to obtain an oblique view, including the upper medial border of the scapula. Using the in-plane technique, an 80 mm needle was inserted medial to the scapula and advanced toward the space between the second and third ribs to reach the fascial plane. After contacting the second rib, 1–2 mL of saline was injected to confirm correct placement, followed by the injection of 30 mL of 0.5% ropivacaine between the SPSM and the intercostal muscles [Figure 3].

Figure 3.

Sonoanatomy and spread of LA during SPSIP block. The arrows indicate the needle. *: trapezius mescle; **: rhomboid muscle; ***: serratus posterior superior muscle; white dotted circle: lesion; yellow-dotted circle: LA spread

Intraoperatively, 10 mcg of sufentanil was administered before incision, and 1 g of paracetamol was given 30 min before awakening. No hemodynamic instability requiring additional opioids occurred. At the end of surgery, the patient was extubated and monitored for 2 hours in the recovery room.

The cold test, performed 15 min after the admission to the recovery room, revealed dermatomal coverage from C3 to T8. Pain was assessed using the Numeric Rating Scale (NRS) at awakening and at 60 and 120 min after extubation, with a score of 0 (no pain) recorded for both static (at rest) and dynamic (during coughing) pain. At 6 and 12 hours postoperatively, static and dynamic pain scores were 0–0 and 0–2, respectively. No rescue analgesics were needed, and the patient was discharged the next day without pain. Histological analysis confirmed the lesion as an elastofibroma dorsi (ED) in an atypical superior scapular location.

Discussion

Tumors in the posterior trunk present significant surgical and anesthetic challenges. Many grow beneath the scapula, making excision difficult and painful, often precluding removal under local anesthesia.[6] Additionally, patients frequently experience moderate to severe postoperative pain radiating below the scapula into the shoulder, which can be difficult to manage with local anesthesia alone and may respond poorly to NSAIDs and opioids.[7]

To optimize pain control, various locoregional techniques have been proposed. In 2018, Tulgar introduced the rhomboid intercostal block (RIB) for ED excision extending into the subscapular space.[8] The erector spinae plane block (ESPB) has also been used for bilateral ED excisions.[9] However, all previously reported cases involved EDs in their typical infrascapular location.

In this case, the dorsal mass was located in the upper dorsal region, making the SPSIP block the optimal choice for several reasons. First, it provided excellent postoperative analgesia to the most cephalic dermatomes, which would have been nearly impossible to achieve with fascial blocks such as the RIB and the serratus anterior plane block (SAPB), as these techniques do not provide dermatomal coverage over the third thoracic dermatome and fail to anesthetize theaxillary and cervical areas.[1] Moreover, it effectively eliminated shoulder pain and reduced the need for additional analgesics, even though the procedure required scapular elevation.

Second, the SPSIP block facilitated surgical excision by creating a cleavage plane between the tumor and surrounding structures—at least in the medial portion of the mass—an effect that would have been difficult to achieve with fascial blocks performed at a paravertebral level, such as the cervical ESPB.

Finally, it allowed for preoperative confirmation of the lesion’s benign nature, aiding in its distinction from malignancies. The superior subscapular region is a potential site for ED development.[10] However, when the tumor appears in this location, it is typically accompanied by a synchronous lesion at the scapular angle or lower scapular region.[10] Isolated tumors in the suprascapular region are exceptionally rare. In such cases, diagnosis may be challenging, and a benign lesion could be misinterpreted as metastasis, fibroma, hemangioma, desmoid tumor, or even sarcoma, as initially suspected by our radiologists.[10] The ease with which the tumor detached from the deep fascia of the SPSM during the ultrasound-guided procedure allowed us to rule out malignancy before surgery and histological analysis.

In conclusion, the ultrasound-guided SPSIP block appears to provide effective, safe, and long-lasting perioperative and postoperative analgesia for patients undergoing surgical excision of lesions in the upper scapular region. Its ease of execution and ability to extend analgesia to lower cervical dermatomes suggest it may be a valuable alternative to other thoracic fascial blocks, such as RIB, SAPB, and ESPB. Further research is needed to evaluate its role in multimodal analgesia for dorsal mass excision.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.