Thoracoabdominal nerves block through the perichondrial approach: a narrative review

Abstract

The thoracoabdominal nerves block using the perichondrial approach (TAPA) was first described by Tulgar et al. as a trunk nerve block technique designed to provide analgesia for abdominal surgery. Subsequently, the modified TAPA (M-TAPA) was proposed, in which a local anesthetic was injected only at the lower aspect of the costal cartilage. More recently, a re-modified TAPA was developed to achieve a more consistent blockade of the lateral cutaneous nerve branches. Despite increasing clinical adoption of the TAPA and its modifications, many important details remain insufficiently understood. In this review, we provide a comprehensive update on the available cadaveric and clinical studies of the TAPA and its modifications. The PubMed, Embase, and Web of Science databases were searched, and 276 studies of interest were identified. After excluding irrelevant articles, 75 studies were finally included in the review. The literature indicated that, among these techniques, the M-TAPA has been extensively studied. The anterior sensory coverage achieved by the M-TAPA was marginally better and more stable than its lateral coverage. The TAPA and its modifications are applicable to surgery in the abdominal and inguinal regions. Single-shot and continuous infusions have been described. To date, no complications associated with these blocks have been reported. Thus, the various TAPA blocks are promising techniques. Randomized controlled trials of high methodological quality are required to elucidate the roles of these techniques further.

Introduction

The thoracoabdominal nerves block using the perichondrial approach (TAPA) has been promoted as a valuable analgesic technique in abdominal surgery. The TAPA provides an extensive sensory block of the abdominal region by blockading signaling through both the anterior and lateral cutaneous branches of the thoracoabdominal nerves [1]. In the original TAPA, local anesthetic (LA) is administered to both the lower and upper surfaces of the chondrium at the costochondral corner. Shortly after its first description by Tulgar et al. [2] in 2019, this group described a modified TAPA (M-TAPA), in which the LA is delivered only to the lower surface of the chondrium. The TAPA and M-TAPA have been successfully used in a range of clinical scenarios, such as laparoscopic cholecystectomy (LC), laparoscopic hernia repair surgery, laparoscopic sleeve gastrectomy (LSG), gynecological surgery, liver transplantation, post-bariatric mammoplasty, and abdominoplasty [3–9].

More recently, Ohgoshi et al. [10] proposed the remodified TAPA (RM-TAPA) technique, which targets the newly identified anatomical space between the endothoracic fascia, diaphragm, and costodiaphragmatic recess (SEDIC) [10]. This approach has been reported to enhance the consistency of lateral cutaneous branch blockade. The RM-TAPA has been described as a postoperative analgesic option for laparoscopic distal gastrectomy and open abdominal aortic aneurysm repair [11].

Despite its growing popularity, many fundamental aspects of the TAPA and its modifications remain poorly understood. For instance, the dermatomal coverage of sensory blocks achieved using these techniques remains controversial. The precise mechanisms underlying these techniques have not yet been fully elucidated. The optimal concentration and volume of LA used in these blocks have yet to be determined.

This review summarizes the currently available evidence regarding the TAPA block and its modifications, and highlights the unresolved issues that can guide both clinical practice and future research on these blocks. Specifically, we discuss the anatomy, history, techniques, potential mechanisms of action, dermatomal coverage of these sensory blocks, and the complications of the TAPA and its modifications. We also summarize the existing evidence supporting their clinical use in common surgical procedures. Finally, we identify areas that require further investigation.

Methods

We searched the PubMed, Embase, and Web of Science databases from May 1, 2019 to September 22, 2025, using the following key terms: “thoracoabdominal nerves block through the perichondrial approach,” “thoracoabdominal nerves block,” “modified perichondrial thoracoabdominal nerves block,” “TAPA block,” “M-TAPA block.” The inclusion criteria were articles related to the TAPA, M-TAPA, and RM-TAPA blocks, including reviews, correspondences, case reports, case series, cadaver studies, observational studies, meta-analyses, and randomized controlled trials (RCTs) in adult and pediatric patients. Articles not published in English were excluded from the analysis.

The initial search yielded 276 publications, of which 148 articles were excluded as duplicates. Additionally, one article was identified from a different source and was included in the review. Of the 129 remaining articles, 50 were excluded as being unrelated to TAPA block after reading the abstracts. A full-text assessment was then performed for the remaining 79 articles. Four of these were excluded because only abstracts were available. Finally, 75 articles were included in the review: 23 case reports, 22 RCT reports, 10 observational studies, 8 correspondence papers, 9 anatomical and volunteer studies, and 3 review articles (Fig. 1).

Fig. 1.

Study flow diagram.

History

Several regional anesthesia techniques have been used to provide abdominal surgical analgesia, including the rectus sheath, transversus abdominis plane (TAP), serratus intercostal plane, erector spinae plane, and quadratus lumborum blocks. However, the TAP and rectus sheath blocks provide inadequate sensory coverage of the lateral abdominal wall, while the serratus intercostal plane block is insufficient for covering the middle abdomen [1,12]. Use of the erector spinae plane and quadratus lumborum blocks is generally not feasible when the patient is positioned supine.

In most abdominal surgeries, blockade of both the lateral and anterior cutaneous branches of the thoracoabdominal nerves is required to achieve complete analgesia. Therefore, Tulgar et al. [1] introduced the TAPA technique, an interfascial plane block designed to provide analgesia for both lateral and anterior abdomen. In their approach, the LA can spread cranially to T4–T5 and caudally to T11–T12 from the anterior axillary line to the midline [1,13,14]. For some procedures, certain dermatomes need to be blocked, depending on the site of the surgical incision. Consequently, Tulgar et al. [2] subsequently proposed the M-TAPA technique, which is based on a single injection.

However, later volunteer and cadaveric studies demonstrated that the M-TAPA primarily affects the anterior cutaneous branches of the thoracoabdominal nerves [15,16]. Blockade of the lateral cutaneous thoracoabdominal nerves branches by the M-TAPA is inconsistent and may even be absent [17–19]. To address this limitation, Ohgoshi et al. [10] described the RM-TAPA technique. As the lateral cutaneous branches of the T1–T11 thoracoabdominal nerves bifurcate within the thoracic cavity, they modified the injection site from the abdominal plane to the thoracic plane. They showed that LA administration into the SEDIC resulted in stable blockade of the lateral cutaneous branches, in addition to the anterior branches, of the thoracoabdominal nerves, particularly in the right abdominal region.

Anatomy

The anterolateral abdominal wall involves four muscles: the rectus abdominis, external oblique, internal oblique, and transversus abdominis muscles. The external oblique muscle originates from the external aspect of the 5th to 12th ribs, the internal oblique muscle inserts into the lower aspects of the costal cartilage of the lower four ribs, and the transversus abdominis muscle inserts into the inner aspect of the 7th to 12th costal cartilages [1]. The TAP compartment is an anatomical plane located between the internal oblique and transversus abdominis muscles and contains the T7–L1 thoracolumbar nerves [20].

The thoracic spinal nerves divide into ventral and dorsal rami immediately after exiting their respective intervertebral foramina. The ventral rami of the nerves exiting T1–T11 form the intercostal nerves, whereas the anterior ramus of the T12 nerve is referred to as the subcostal nerve. The intercostal nerves enter the intercostal space between the posterior internal intercostal membrane and the endothoracic fascia, and their course is inferior to the associated rib between the innermost and the internal intercostal muscles [21]. At the anterior chest wall, close to the sternum, the first six intercostal nerves terminate by piercing the internal intercostal muscle and the external intercostal membrane, to form the anterior cutaneous branches (Fig. 2A). When the last five intercostal nerves (T7–T11) approach the anterior ends of the ribs, they pass under the chondrium, between the origin of the transversus abdominis muscle and the cartilage, and then enter the TAP [20]. Given that they innervate both the thoracic and abdominal walls, these nerves are also referred to as the thoracoabdominal nerves [22]. In the abdominal region, the thoracoabdominal nerves course through the TAP and enter the rectus sheath to run deep to the posterior surface of the rectus abdominis muscle. They then continue anteriorly through openings inside the lineae semilunaris, ultimately emerging as the anterior cutaneous branches (Fig. 2B).

Fig. 2.

Schematic illustration of intercostal nerves in the thoracic and abdominal regions. (A) The anatomical course of the thoracic intercostal nerves (T1–T6). (B) The pathways of the thoracoabdominal nerves, which continue beyond the costal margin, entering the transversus abdominis plane.

Each intercostal nerve produces two primary branches: the lateral and anterior cutaneous branches (Fig. 2A). The lateral cutaneous branches depart from their respective anterior rami near the rib angle or around the midaxillary line [23]. After traversing the external intercostal muscle, they penetrate either the serratus anterior or the external oblique muscles, and divide into the anterior and posterior branches. Thus, most lateral cutaneous branches of the thoracoabdominal nerves arise before the main nerves penetrate the lateral TAP compartment, and only those of T11 and T12 may have a short course within or through the TAP [24]. The anterior division of the lateral cutaneous branches mainly supplies the skin of the anterolateral chest and abdomen. The posterior branches run backwards and supply the skin over the scapula and the latissimus dorsi. The anterior cutaneous branches are terminal divisions of the intercostal nerves. They further bifurcate into the medial and lateral branches, which provide sensory innervation to the skin of the anterior thoracic and abdominal walls, extending approximately from the midline to the midclavicular lines [24].

Potential mechanisms

At present, the specific mechanism of action of the TAPA and its modifications remain to be elucidated. However, some predictions regarding the potential mechanisms can be made based on the results of cadaveric studies.

Superficial injection TAPA

Superficial injection TAPA, where the LA is administered above the 9th to 10th costal cartilages, was designed to block the lateral cutaneous branches of the thoracoabdominal nerves [1]. A cadaveric study has demonstrated that the dye spread over the upper surface of the costal margin following administration of the TAPA, with staining of the deep surface of the external oblique muscle suggesting spread along the plane between the external oblique and intercostal muscles, thereby blocking the lateral cutaneous branches [25]. As this plane continues cranially, deep into the serratus anterior muscle, cranial spread toward the upper lateral cutaneous branches is theoretically possible [26].

However, the hypothesis has been challenged: Ohgoshi et al. [15] reported no effect of superficial injections in healthy volunteers [15]. A subsequent cadaveric study showed that the injectate failed to reach the penetration sites of the lateral cutaneous branches [27]. That study explained that the narrow space near the penetration points of the lateral cutaneous branches limited the spread of the injectate and that progressively more dorsal penetration sites toward T12 further increased the distance from the superficial injection site. Differences in tissue properties associated with cadaver preservation methods (fresh or embalmed cadavers), as well as puncture variations between studies, may have contributed to this discrepancy. Imaging studies on living subjects are therefore warranted.

The external oblique intercostal block (EOIB) also relies on spread of the injectate within the external oblique intercostal plane, affecting both the anterior and lateral cutaneous branches of the thoracoabdominal nerves [26,28]. The EOIB has a more medial and cranial injection site around the midclavicular line, facilitating the medial spread of the injectate. The external oblique muscle fascia interact with the fascia of other muscles to form the anterior rectus sheath. The LA follows this pathway to reach the rectus sheath (which is the entry point of the anterior cutaneous branches of the thoracoabdominal nerves), blocking these nerves [29]. In contrast, superficial TAPA is administered using lateral and caudal injection sites, making the LA less likely to reach the anterior cutaneous branches.

M-TAPA

Anterior cutaneous branch blockade

(1) TAP

A cadaveric study has demonstrated the spread of the injectate over the TAP after M-TAPA administration [16]. The M-TAPA can block areas higher than T8 in many cases, without requiring injection medial to the linea semilunaris, suggesting the potential involvement of other mechanisms [4,5,30].

(2) “Tunnel” structure

Tanaka et al. [18] found that the injectate spread via a “tunnel” structure (the space between the costal cartilage and the origin of the transversus abdominis muscle) after administration of the M-TAPA with 25 or 30 mL of dye. Thus, it may be a potential strategy for blocking the dermatomes above T8 without inhibiting the linea semilunaris. However, dye distribution was observed only at T8–T11 in their study. In a study using 40 mL of LA for M-TAPA, Ciftci et al. [25] reported that the injectate spread to the inferior surface of the upper rectus abdominis muscle. Spread deep into the rectus abdominis muscle may occur through the “tunnel” structure, and appears to be volume-dependent.

(3) Endothoracic fascia plane

The mechanisms mentioned above do not adequately explain the reason for the blockade of the upper intercostal nerves by the M-TAPA. A previous study suggested that the endothoracic fascial plane may be a pathway by which multiple intercostal nerves can be blocked [31]. Nevertheless, the available evidence has not demonstrated that the dye spreads to the intercostal space in the inner aspect of the thoracic cage upon M-TAPA administration [16]. Instead, cranial spread was observed between the diaphragm and the parietal peritoneum [32]. Ohgoshi et al. [10] found that the M-TAPA plane was completely separated from the plane between the intercostal muscles and diaphragm in the thoracic cavity. Thus, future studies are needed to investigate whether, and through which pathway, the injectate spreads into the endothoracic fascial plane.

Lateral cutaneous branch blockade

Tulgar et al. [1] hypothesized that the M-TAPA could block the lateral cutaneous branches. One study demonstrated that, after administration of the M-TAPA with 40 mL of dye, the injectate spread along the plane between the external oblique and intercostal muscles, suggesting a possible mechanism for lateral cutaneous branch blockade [25]. However, the volume used in that study was considerably higher than the typical volumes: when the M-TAPA was performed using commonly applied clinical volumes (25 or 30 mL), no injectate spread along the external oblique muscle plane [16,18]. Therefore, achieving effective coverage of the lateral cutaneous branches may require larger LA volumes.

Taken together, the mechanisms by which the M-TAPA blocks the anterior and lateral cutaneous branches of the thoracic intercostal nerves require further investigation.

RM-TAPA

To date, no cadaveric studies have explored the spread of the injected LA in the RM-TAPA. The target of the RM-TAPA is the space within the thoracic cavity, adjacent to the M-TAPA plane, and extends between the 6th and 11th intercostal spaces in the sagittal direction, delimited by the endothoracic fascia, diaphragm, and parietal pleura [10]. Although the SEDIC itself may not directly participate in vital activities, LA spread to the SEDIC could potentially facilitate blockade of the lateral and anterior cutaneous branches before they penetrate the intercostal muscle. Asymmetric positioning of the diaphragm, due to the liver and heart, may alter the diaphragmatic attachment to the ribs, thereby influencing LA spread.

Critical appraisal

The current understanding of the mechanisms underlying the effects of the TAPA and its modifications is derived from a limited number of cadaveric studies, most of which involved embalmed cadavers. The biomechanical properties of cadaveric tissues, particularly those of embalmed cadavers, are markedly different from those of living tissues. Reduced tissue compliance may restrict plane opening and alter injectate spread, rendering cadaveric injections only a rough approximation of the in vivo behavior of the LA. This may partly explain the observed discrepancies between extant cadaveric findings and clinical results. Imaging studies on radiocontrast dye injections in living subjects provide the most compelling evidence of the physical spread of the injectate. Further research using contrast agents and imaging in living bodies, including those of both volunteers and patients, is warranted.

Techniques

TAPA

To administer the TAPA with the patient in the supine position, a linear transducer is placed on the costal margin at the level of the 9th to 10th costal cartilages at the costochondral angle, in the sagittal plane, and is angled deeply to view the lower aspect of the chondrium centrally [1]. The external oblique, internal oblique, and transverse abdominis muscles are also identified. The needle is then inserted in the caudal to cranial direction using an in-plane technique. After confirming its location using hydrodissection, LA is administered in two directions: between the upper surface of the chondrium and the external oblique and between the lower surface of the chondrium and the transversus abdominus muscle, both in the interfascial plane (Fig. 3A) [33].

Fig. 3.

Ultrasound probe position and sonographic image of the (A) TAPA and (B) M-TAPA. In the TAPA, local anesthetic is administered to the cranial side (between the external oblique muscle and the upper aspect of the chondrium) and the caudal side (between the lower aspect of the chondrium and the transversus abdominis muscle) of the costal cartilage. In the M-TAPA, local anesthetic is administered between the upper fascia of the transversus abdominis muscle and the lower fascia of the costochondral tissue at the level of the 9th or 10th ribs. EOM: external oblique muscle, IOM: internal oblique muscle, TAM: transversus abdominis muscle, Cc: costal cartilage.

M-TAPA

For ultrasonography-guided M-TAPA, a linear transducer is placed at the costochondral angle in the sagittal plane and is angled deeply to view the lower aspect of the chondrium centrally. The LA is only injected between the upper fascia of the transversus abdominis muscle and the lower fascia of the costochondral tissue at the level of the 9th or 10th ribs (Fig. 3B) [2]. Because M-TAPA involves only a single injection site, it is well suited to catheter placement to facilitate a continuous blockade. After the loading dose of LA is injected, an indwelling catheter is placed at the same place [34].

Typically, the TAPA and M-TAPA are performed by using in-plane techniques. However, in patients with obesity or those with a protruding thorax (emaciation or pectus carinatum), the angle of needle insertion is limited when the in-plane technique is used, making the procedure more challenging. In these cases, an out-of-plane technique or a “hybrid” technique can be used to facilitate block performance. In the hybrid technique, needle insertion is initiated out-of-plane and is subsequently advanced in a manner similar to that used in the in-plane approach [14,18].

As anesthesiologists must apply force on the abdominal wall during the procedure, which may cause discomfort to the patient, performing these blocks after induction of general anesthesia is advised [3].

RM-TAPA

For RM-TAPA, the patients are placed in the supine position. A linear ultrasound probe is positioned parallel to the 9th/10th costal space on the costal arch to visualize key anatomical structures: the external oblique muscle, intercostal muscles, diaphragm, and transversus abdominis muscle. A distinct histological boundary between the transversus abdominis muscle and the diaphragm should be clearly visible. The needle is inserted using an in-plane approach, in the caudal to cranial direction. The LA is injected into the plane between the intercostal muscles and diaphragm, above the junction of the diaphragm and the transverse abdominis muscle. Saline is essential for accurate needle tip placement. More recently, Nakazawa et al. [11] reported the successful use of continuous RM-TAPA. After bolus injection, the catheter is advanced approximately 5 cm beyond the needle tip.

Technical considerations

Using the standard puncture method is critical for reproducibility across studies; this includes the injection level, needle tip position, hydrodissection, injectate speed, and optimal pattern of LA diffusion. The slightly caudal needle tip position of the M-TAPA may restrict the spread of the injectate within the TAP [16]. In contrast, if the needle is advanced too far cranially, the needle tip may enter the space deep into the diaphragm, resulting in the spread of the injectate between the diaphragm and parietal peritoneum [32]. LA diffusion into the cephalic aspect of the 10th costal cartilage under ultrasonography appears necessary to obtain a wide analgesic range [35]. However, this spread pattern did not preclude the possibility of diffusion of the injectate deep into the diaphragm [32]. In these cases, the limited sensory coverage may be related to non-standardized techniques instead of to methodological limitations. The role of hydrodissection in the TAPA and its modifications should be emphasized, given its importance in opening the correct plane, facilitating LA spread, and ensuring procedure reproducibility.

Differences between studies can be interpreted appropriately by using a reproducible and standardized puncture protocol. Strict uniformity in the puncture method may be lacking among studies to date [36]. Further investigations are warranted to establish procedural standardization.

Dermatomal coverage of sensory block

TAPA

Current evidence on the dermatomal coverage of the TAPA is limited to three case reports and one observational trial (Table 1) [1,13,14,37]. Blockade of the lateral cutaneous branches appeared to be consistent. These studies indicated that 30–40 mL can spread cranially to T4–T5 and caudally to T11–T12. For the anterior cutaneous branches, caudal spread was generally confined to the T11–T12 dermatomes, whereas cranial spread showed variability, typically ranging from T5 to T8 (Fig. 4A).

Table 1.

Summary of Sensory Block Obtained with the TAPA, M-TAPA, and RM-TAPA

Author Year [Reference]	Technique	Study design	Sample size	Type of surgery	Local anesthetic	Blocked sensory dermatomes	Efficacy of TAPA or M-TAPA
Tulgar 2019 [1]	TAPA	Case report	3	Laparoscopic cholecystectomy; laparoscopic incisional hernia repair	40 mL of 0.25% bupivacaine	Anterior axillary line: T5–T12	NRS scores were 0–1/10 in the recovery room and < 3/10 at about 12-h postoperatively.
						Midline: T7–T12/T5–T12
Balaban 2019 [13]	TAPA	Case report	1	Pericholecystic drainage catheter placement	20 mL of 0.5% bupivacaine and 10 mL of 2% lidocaine	T6–T11	No need for additional analgesics during surgery. TAPA block can lead to adequate surgical anesthesia for a minor abdominal surgery.
Chen 2020 [14]	TAPA (out-of-plane)	Case report	2	Laparoscopic cholecystectomy; subtotal gastrectomy	Patient 1: 40 mL of 0.33% ropivacaine;	Patient 1: anterior axillary line: T4–T12	NRS score of the patient was 0/10 in the recovery room and no additional analgesics were administered.
					Patient 2: 30 mL of 0.25% ropivacaine per side	midline: T8–T12
						Patient 2: anterior axillary line/midline: T5–T12
Argun 2024 [37]	TAPA	Observational study	45 for TAPA	Major abdominal surgery	40 mL of 0.2% bupivacaine-	Anterior cutaneous branch: up to T5	TAPA decreased opioid consumption, recovery times, and NRS scores.
Tulgar 2019 [2]	M-TAPA	Case report	1	Laparotomy	25 mL of 0.25% bupivacaine per side	Anterior axillary line/midline: T7–T11	NRS score was < 3/10 during the first 24-h postoperatively and no additional analgesia was required.
Altıparmak 2019 [4]	M-TAPA	Case report	1	Laparoscopic ventral hernia repair	20 mL of 0.25% bupivacaine per side	Anterior axillary line/midline: T5–T10	NRS scores during coughing were 2–3/10 at 15 h and 30 min postoperatively. The patient described a moderate discomfort at the T11–T12 dermatomal levels.
Aikawa 2019 [5]	M-TAPA	Case report	1	Laparoscopic sleeve gastrectomy	30 mL of 0.25% ropivacaine per side	Posterior axillary line/midline: T3–T12	The patient had no pain at discharge from the operation theater.
Aikawa 2022 [17]	M-TAPA	Prospective observational study	30	Laparoscopic gynecological surgery	25 mL of 0.25% ropivacaine	Anterior area: T4–L1, high blocking rate for T7–T11	The highest sensory level was T7 (T5–T8) in the anterior and T9 (T7–T10) in the lateral area. Sensory loss was not observed in the lateral area in five patients.
						lateral area: T4–L1, high blocking rate for only T9–T10 (about 70%)
Tanaka 2022 [18]	M-TAPA	Prospectiveobservational study	10	Open hysterectomy	30 mL of 0.25% ropivacaine per side (25 mL if bodyweight < 50 kg)	Midline: T6–T12, high blocking rate for T6–T11	NRS scores at rest were 5 (2–6.5), 0.5 (0–2), and 1 (0–2) at 2-, 24-, and 48-h postoperatively, respectively.
						midaxillary line: T6–T12 or no effect
Çiftçi 2022 [40]	M-TAPA	Case series	5	Laparoscopic cholecystectomy; laparoscopic hernia repair	15 mL of 0.25% bupivacaine per side (n = 3)	Anterior area: T6–T12; T6–T11; T8–T12; T6–12; T7–T11	NRS was low during the first 24-h postoperative period and no additional analgesia was needed for any of the patients.
					20 mL of 0.25% bupivacaine per side (n = 2)	lateral area: T7–T10; T8–T11; T9–T11; T7–T11; T7–T10
Bilge 2023 [19]	M-TAPA	RCT	38 for M-TAPA	Laparoscopic cholecystectomy	25 mL of 0.25% bupivacaine per side	Midclavicular line: T4–L1, high blocking rate for T7–T10	M-TAPA reduced opioid consumption at 24-h postoperatively and decreased NRS movement scores at 12-h postoperatively.
						midaxillary line: T3–T12, high blocking rate for T6–T8 (about 80%)
Genc 2024 [38]	M-TAPA	Prospectiveobservational study	12	Laparoscopic cholecystectomy	25 mL of 0.25% bupivacaine per side	Anterior area: T5–T12	The percentage of blocked dermatomes was 100% for T7–T10 in the M-TAPA group, with lower success rates in dermatomes T5 and T12.
Ökmen 2025 [39]	M-TAPA	Prospective observational study	30 for M-TAPA	Laparoscopic cholecystectomy	0.3 mL/kg of 0.25% bupivacaine per side	Parasternal line/midaxillary line: T6–T12, high blocking rate for T7–T10	M-TAPA reduced opioid consumption and decreased NRS scores during 24-h postoperatively.
Şehirlioğlu 2025 [56]	M-TAPA	RCT	53 for M-TAPA	Laparoscopic cholecystectomy	20 mL of 0.25% bupivacaine	Midclavicular line: T6–T12, high blocking rate for T7–T10	M-TAPA provides similar analgesia as that provided by the quadratus lumborum block.
Wan 2025 [49]	M-TAPA	RCT	31 for M-TAPA	Laparoscopic renal cyst decompression	30 mL of 0.25% ropivacaine	Anterior axillary line: T6–T12	M-TAPA reduced pain scores, opioid consumption and the need for antiemetic drugs.
Ohgoshi 2024 [10]	RM-TAPA (10th intercostal space)	Volunteer descriptive study	10	NA	20 mL of 0.2% ropivacaine	Right side: anterior area: T6–T12, high blocking rate for T9–T10;	Left side: anterior area: T6–T12, high blocking rate for T9–T11;
						lateral area: T8–T12, high blocking rate for T9–T12	lateral area: T9–T12, blocking rate for T9–T12 was about 50%.
Ohgoshi 2026 [42]	RM-TAPA (9th intercostal space)	Volunteer descriptive study	10	NA	20 mL of 0.2% ropivacaine	Right side: anterior area: T4–T11, high blocking rate for T6–T10;	Left side: anterior area: T4–T11, high blocking rate for T6–T10;
						lateral area: T4–T12, high blocking rate for T8–T9 (70%)	lateral area: T7–T12, blocking rate all below 50%.
Nakazawa 2025 [11]	Continuous RM-TAPA	Case report	2	laparoscopic gastrectomy; abdominal aortic aneurysm repair	Loading dose: 20 or 30 mL of 0.25% levobupivacaine per side continuous infusion: 0.125% levobupivacaine at 4 mL/h	Case 1: anterior axillary line/midline: T7–T11	NRS scores are ≤3 at rest and during movement. No additional bolus of PCA pump was needed.
						Case 2: right side:
						anterior area: T7–T11; lateral area: T9–T11
						left side: anterior area: T7–T11;
						lateral area: partial sensory loss at T9–T10

TAPA: thoracoabdominal nerves block through the perichondrial approach, M-TAPA: modified thoracoabdominal nerves block through the perichondrial approach, RM-TAPA: re-modified thoracoabdominal nerves block through the perichondrial approach, NRS: Numeric Rating Scale, RCT: randomized controlled trial, NA: not applicable, PCA: patient-controlled analgesia.

Fig. 4.

Comparative schematic illustration of the dermatomal distribution of the (A) TAPA, (B) M-TAPA, and (C) RM-TAPA performed at the 10th, and (D) 9th intercostal spaces. This figure presents a direct visual comparison across the techniques. Dark blue areas indicate dermatomes with a reported blockade success rate exceeding 80%, whereas light blue areas indicate dermatomes in which blockade has been reported, but with lower success rates. R: right, L: left.

M-TAPA

Anterior cutaneous branch blockade

The maximal reported dermatomal coverage extends from T3–T4 to T12–L1 [5,17]. Blockade is most reliable at T7–T10, with success rates consistently exceeding 90% across studies [15,19,38–40]. In contrast, cranial spread to T5 was unreliable (Fig. 4B). The success rate at T12 is low, and L1 is rarely affected when using 20–30 mL of LA [17,19,38,39]. These findings suggest that the M-TAPA has limited utility for surgery in the thoracic and inguinal regions.

The reported block efficacy at T11 varies markedly across studies. Two studies observed limited coverage of T11 (60%–70%) with 25 mL of LA by 2-h postoperatively [17,19]. In contrast, another study reported a higher success rate (90%) at the same timepoint, which was possibly related to the use of a larger LA volume (30 mL) [18]. Absence of pneumoperitoneum may have further facilitated caudal injectate spread by avoiding an increase in the intra-abdominal pressure. Okmen et al. [39] reported a high success rate (80%) at 30 min after block administration when using only 20 mL of LA, which may be explained by the lack of pneumoperitoneum. Additionally, the different assessment timepoints may have contributed to the discrepancy between the studies.

At T6, dermatomal coverage generally ranges from 50% to 80% when using 20–30 mL of LA [17–19]. However, Genc et al. [38] reported a higher success rate (90%) when they used 25 mL of LA. In their study, the M-TAPA was performed after surgery and sensory assessment was conducted at 45 min after block placement. The potential residual effects of intraoperative analgesics should therefore be considered.

Lateral cutaneous branch blockade

The reported efficacy of the M-TAPA in blocking lateral cutaneous nerve branches varies substantially across studies. Aikawa et al. [17] reported blockade of T9–T10 in 70–80% of patients when using 25 mL of 0.25% ropivacaine, with low success rates in other dermatomes. Increasing the volume to 30 mL extended the coverage to T8–T11, with a success rate of 80%–85% [18]. In contrast, Bilge et al. [41] observed a more cranially distributed pattern, with consistent blockade (approximately 80%) at T6–T8, whereas success rates dropped below 30% at T10 and more caudal dermatomes. Notably, several studies have reported the complete absence of lateral cutaneous branch blockade after M-TAPA administration [15,17]. Overall, the current evidence suggests that the efficacy of the M-TAPA for blockade of the lateral cutaneous branches is inconsistent, variable, and sometimes even absent.

RM-TAPA

Only two volunteer studies have investigated the sensory block provided by RM-TAPA. At the 10th intercostal space, the administration of 20 mL of LA into the SEDIC results in anterior cutaneous branch coverage from T6 to T12 (Fig. 4C). The success rate at T9–T11 was 80%–100%, whereas the efficacy at other levels was considerably lower. For the lateral cutaneous branches, spread was observed from T8 to T12, but with a marked right–left difference: success rates reached up to 90% on the right side for T10–T12, whereas those on the left side rarely exceeded 60% [10]. Administering the LA at the 9th intercostal space resulted in sensory loss spanning T4–T11, with particularly satisfactory effects from T6 to T10 (Fig. 4D). However, the lateral cutaneous branches remained unaffected. On the right side, the injectate extended from T4 to T11 but achieved only a moderate success rate (60%–80%) between T8 and T10. On the left side, both the dermatomal coverage and success rates were limited [42]. Consequently, the RM-TAPA has not fully addressed the issue of inconsistent lateral cutaneous branch blockade by M-TAPA. Additionally, the optimal puncture level for RM-TAPA requires further investigation.

Critical appraisal

Although previous studies have investigated the dermatomal coverage provided by the TAPA and its modifications, the overall quality of these studies remains limited. First, the available literature is sparse and consists of case reports, volunteer studies, and small-sample observational studies, resulting in low levels of evidence, particularly for the TAPA and RM-TAPA. Second, substantial methodological heterogeneity exists across studies, including in terms of the surgical type, patient characteristics, LA type and dose, block administration timing, and sensory assessment. These variations considerably undermine the comparability of reported dermatomal distributions. Moreover, subtle technical variations, including needle tip position, hydrodissection, and injection pressure, may markedly affect injectate distribution and result in heterogeneous blockade patterns. Future studies should focus on large-sample studies using standardized techniques to delineate the distribution of dermatomal coverage of the TAPA and its modifications.

Pharmacokinetics

Performing the M-TAPA with 25 mL of 0.25% levobupivacaine mixed with 1:200 000 epinephrine on each side results in the highest individual peak plasma concentration of 1.03 μg/mL at 60 min, which is lower than the toxic level of 2.6 μg/mL [43]. The mean peak plasma LA concentration and time to peak are 0.73 (0.60–0.85) μg/mL and 85.5 (59.2–111.8) min, respectively. Without epinephrine, the mean peak plasma LA concentration achieved is 1.17 μg/mL and the time to peak concentration reduces to 15 min in the majority cases, with some cases showing a peak at 60 min [44].

The M-TAPA block provides sustained analgesia for up to 24 h. Administration of 30 ml of LA achieves nearly complete blockade of the anterior cutaneous branches at T6–T8 and approximately 80% blockade at T9–T10 by 24-h postoperatively. For the lateral cutaneous branches, success rates of 80%–90% have been observed at T6–T9 [18]. Aikawa et al. [5] showed that 36 h after M-TAPA administration, an almost complete sensory blockade of the T4–T12 dermatomes persisted, with a progressive sensory return, and that this effect ceased after 56 h [5]. These findings demonstrate the long-lasting analgesic effects of the M-TAPA.

Clinical indications

As the available RCTs have predominantly focused on the M-TAPA, we will focus mainly on this approach. The M-TAPA has been used for a multitude of procedures, such as LC, LSG, laparoscopic inguinal hernia repair, gynecological surgery, laparoscopic renal cyst decompression, and treatment of postherpetic neuralgia (Table 2) [45–50].

Table 2.

Summary of Clinical Randomized Controlled Trials Involving the TAPA and M-TAPA

Author Year [Reference]	Type of surgery	Technique	Sample size	Comparison methods	Local anesthetic	Efficacy of TAPA or M-TAPA	Block-related complications
Ertürk 2022 [76]	Laparoscopic cholecystectomy	TAPA	28 for both TAPA and M-TAPA	M-TAPA	TAPA: 35 mL of 0.25% bupivacaine	Mean pain scores, total tramadol use, and use of additional analgesics were comparable between the groups. At 1 and 12 h, pain scores were lower in the TAPA group.	None
					M-TAPA: 20 mL of 0.25% bupivacaine
Bilge 2022 [41]	Laparoscopic cholecystectomy	M-TAPA	34 for M-TAPA	No block	25 mL of 0.25% bupivacaine per side	Decreased pain scores and reduced tramadol consumption within the first 24-h postoperatively; higher QoR-40 scores at 24-h postoperatively.	None
Güngör 2023 [53]	Laparoscopic cholecystectomy	M-TAPA	30 for M-TAPA	Local infiltration	20 mL of 0.25% bupivacaine per side	Decreased static pain scores at 4-h postoperatively and dynamic scores at 16-h postoperatively; lower incidence of nausea, lower need for rescue analgesia and higher patient satisfaction scores.	None
Cho 2023 [55]	Laparoscopic cholecystectomy	M-TAPA	28 for M-TAPA	Subcostal TAPB	15 mL of 0.375% ropivacaine per side	No significant difference was observed in the analgesic effect between the two techniques.	None
Bilge 2023 [19]	Laparoscopic cholecystectomy	M-TAPA	38 for M-TAPA	Subcostal TAPB	25 mL of 0.25% bupivacaine per side	Reduced opioid consumption at 24-h postoperatively, decreased NRS movement scores at 12-h postoperatively and more blocked dermatomes.	None
Alver 2023 [58]	Laparoscopic inguinal hernia repair surgery	M-TAPA	30 for M-TAPA	Local infiltration	20 mL of 0.25% bupivacaine per side	Decreased pain scores within the first 8-h postoperatively and reduced tramadol consumption at 24 h; higher QoR-40 scores at 24 h; lower nausea frequency.	None
Erten 2023 [54]	Laparoscopic cholecystectomy	M-TAPA	31 for M-TAPA	Local infiltration	20 mL of 0.25% bupivacaine per side	Decreased pain scores and reduced opioid consumption in first 24-h postoperatively; lower nausea frequency; higher 24th h QoR-15 score.	None
Avci 2024 [45]	Laparoscopic cholecystectomy	M-TAPA	21 for M-TAPA	No block	25 mL of 0.25% bupivacaine per side	Decreased pain scores and reduced opioid consumption in 24-h postoperatively; lower nausea frequency.	None
Erten 2024 [73]	laparoscopic appendectomy	M-TAPA	30 for M-TAPA (pediatric patients)	Local infiltration	0.25 mL/kg of 0.25% bupivacaine	Decreased pain scores and the need for rescue analgesic.	None
Turunc 2024 [59]	Laparoscopic sleeve gastrectomy	M-TAPA	28 for M-TAPA	EOIB	30 mL of 0.25% bupivacaine per side	EOIB and M-TAPA block showed similar efficacy in terms of opioid consumption, pain scores and quality of recovery within 24-h postoperatively.	None
Bilgili 2024 [63]	Open major abdominal surgery	M-TAPA	23 for M-TAPA	Local infiltration	20 mL of 0.25% bupivacaine per side	Reduced opioid consumption, decreased pain scores, and improved patient satisfaction.	None
Suzuka 2024 [44]	Laparoscopic hysterectomy	M-TAPA	18 for M-TAPA	Oblique subcostal TAPB	25 mL of 0.25% levobupivacaine per side	OSTAPB and M-TAPA block provided similar effects in terms of QoR-15 scores at 24-h and 48-h postoperatively.	None
Ciftci 2025 [29]	Laparoscopic cholecystectomy	M-TAPA	30 for M-TAPA	EOIB	20 mL of 0.25% bupivacaine per side	Decreased pain scores in the first 2-h postoperatively and reduced opioid consumption for M-TAPA. The QoR-15 scores at 24-h postoperatively were comparable between groups.	None
Erten 2025 [61]	Total laparoscopic hysterectomy	M-TAPA	32 for M-TAPA	Local infiltration	20 mL of 0.25% bupivacaine per side	M-TAPA and local infiltration provide similar analgesic effects.
Baytar 2025 [46]	Laparoscopic sleeve gastrectomy	M-TAPA	30 for M-TAPA	No block	20 mL of 0.25% bupivacaine per side	Reduced postoperative respiratory dysfunction at 1-h postoperatively, pain scores within the 12-h postoperatively, opioid consumption and higher QoR-15 scores at 24 h.	None
Wan 2025 [49]	laparoscopic renal cyst decompression	M-TAPA	31 for M-TAPA	No block	30 mL of 0.25% ropivacaine	Decreased pain scores, reduced opioid consumption and a lower need for antiemetic drugs within 48-h postoperatively in the M-TAPA group.	None
Şehirlioğlu 2025 [56]	Laparoscopic cholecystectomy	M-TAPA	53 for M-TAPA	Anterior quadratus lumborum block	20 mL of 0.25% bupivacaine per side	No significant differences were observed between the two groups in terms of opioid consumption and NRS scores.	None
Jayan 2025 [72]	Upper abdominal surgery	M-TAPA	20 for M-TAPA (pediatric patients)	No block	0.5 mL/kg of 0.2% ropivacaine	Reduced pain scores, intraoperative and median fentanyl consumption.	None
Gungor 2025 [64]	Open living donor hepatectomy	M-TAPA	25 for M-TAPA	No block	30 mL of 0.25% bupivacaine per side	The M-TAPA group showed significantly lower total opioid consumption and reduced pain scores.	None
Matsuura 2025 [50]	Laparoscopic cholecystectomy	M-TAPA	14 for M-TAPA	EOIB and subcostal TAPB	25 mL of 0.3% ropivacaine per side	No significant differences were observed between the M-TAPA and TAPB in terms of the analgesic effect and quality of recovery.	None
Yamaç 2025 [57]	Laparoscopic cholecystectomy	TAPA	30 for TAPA	Lateral TAPB	30 mL of 0.25% bupivacaine	Opioid consumption at 12-h postoperatively was significantly lower in the TAPA group.	None
Teke 2025 [60]	Laparoscopic sleeve gastrectomy	M-TAPA	30 for M-TAPA	Subcostal TAPB	20 mL of 0.25% bupivacaine per side	Opioid consumption at 6-h postoperatively was significantly lower in the M-TAPA group.	None

TAPA: thoracoabdominal nerves block through the perichondrial approach, M-TAPA: modified thoracoabdominal nerves block through the perichondrial approach, QoR: quality of recovery, TAPB: transversus abdominis plane block, NRS: Numeric Rating Scale, EOIB: external oblique intercostal plane block.

LC

LC is the most widely studied surgery for the TAPA and M-TAPA. Park et al. [51] conducted the first meta-analysis investigating the efficacy of the M-TAPA in abdominal surgery, and included five RCTs, four of which focused on LC. The authors reported that the M-TAPA provided no benefit in terms of postoperative analgesia. However, this result should be interpreted with caution, as the inclusion of various control procedures (e.g., local infiltration, TAP block, and TAPA) constitutes a methodological limitation. Subsequently, Cassai et al. [52] restricted the scope of the control group to no block or a placebo. They concluded that the M-TAPA resulted in reduced 24-h opioid consumption, decreased pain scores at 12- and 24-h postoperatively, and lower incidences of nausea or vomiting.

Two studies to date have suggested that the M-TAPA outperforms local infiltration in LC [53,54]. They showed that use of the M-TAPA decreased pain scores, reduced the need for rescue analgesia, lowered the incidence of nausea, and enhanced Quality of Recovery-15 (QoR-15) scores.

Comparisons between the M-TAPA and other regional techniques in LC settings are available. Two trials have compared the M-TAPA and subcostal TAP blocks, reporting inconsistent results regarding postoperative opioid consumption [19,55]. Bilge et al. demonstrated a significant reduction in opioid use after administration of the M-TAPA, whereas Cho et al. observed no such difference. This discrepancy may be explained by the differences in trocar placement. In the study by Cho et al. [55], the lateral port was located near the lateral border of the rectus abdominis muscle and the area could be covered by a subcostal TAP block. Consequently, the advantage of the M-TAPA in blocking the lateral abdominal wall would not be evident. No differences were detected in terms of pain score, complications, or quality of recovery. One previous study compared the efficacies of the M-TAPA and EOIB in LC [29]. Although the M-TAPA reduced the need for rescue analgesia, the QoR-15 scores did not differ significantly. A comparison between the M-TAPA and an anterior quadratus lumborum block also showed comparable postoperative opioid consumption and pain scores [56].

Few RCTs have investigated the TAPA. Yamac et al. [57] found that, compared with the lateral TAP block, the TAPA reduced opioid consumption at 12-h postoperatively. However, the choice of the lateral TAP block as a control group may be suboptimal, as LC is an upper abdominal procedure. Future studies comparing TAPA blocks with subcostal TAP blocks are warranted.

Overall, the TAPA and M-TAPA may be valuable analgesic techniques for LC. Their superiority over other regional anesthesia techniques remains uncertain, given the limited and conflicting evidence available.

Laparoscopic inguinal hernia repair

Only one randomized trial has investigated the benefits of the M-TAPA in laparoscopic inguinal hernia repair. Alver et al. [58] concluded that, compared with local infiltration, the M-TAPA improves the quality of recovery, decreases pain scores in the first 8-h postoperatively, and reduces the need for rescue analgesia.

In inguinal hernia repair surgery, the dermatomal coverage should extend over T12‒L1. However, whether the M-TAPA reliably provides analgesia to these dermatomes remains controversial. Available dermatomal distribution studies have reported low blockade success rates at T12–L1 [17,38]. We suggest that future studies investigating the efficacy of the M-TAPA in laparoscopic inguinal hernia repair should also evaluate dermatomal coverage.

LSG

Three studies have evaluated the efficacy of M-TAPA in LSG to date. One study demonstrated that, compared to no block, the M-TAPA was associated with an improved quality of recovery, better pulmonary function, lower pain scores, and reduced opioid consumption [46]. Turunc et al. [59] compared the effects of the M-TAPA and EOIB and reported that both had similar efficacies in terms of postoperative analgesia and quality of recovery. Compared with the oblique subcostal TAP block, the M-TAPA resulted in less tramadol consumption by 6-h postoperatively, whereas opioid consumption and Numerical Rating Scale (NRS) pain scores were similar at other timepoints [60].

Laparoscopic gynecological surgery

The use of the M-TAPA in laparoscopic gynecological surgery has been limited to date. Two trials have shown that the M-TAPA provides an efficacy similar to local infiltration in terms of opioid consumption, pain intensity, and quality of recovery [47,61]. However, one study was not conducted in the context of a standardized multimodal analgesic regimen [47]. Visceral pain following total laparoscopic hysterectomy is thought to be more pronounced than incisional pain [62]. Therefore, sufficient visceral pain control is required in future studies to evaluate the efficacy of the M-TAPA in clinical settings.

One pilot trial reported that the M-TAPA may not be superior to the subcostal TAP block for total laparoscopic hysterectomy in terms of quality of recovery, although the M-TAPA group displayed decreased moderate pain [44]. Further studies are required to investigate the potential benefits of the M-TAPA in open gynecological surgery.

Laparoscopic renal cyst decompression

Wan et al. [49] investigated the efficacy of the M-TAPA when using 30 ml of 0.25% ropivacaine for laparoscopic renal cyst decompression and showed that this block resulted in significantly lower NRS scores, fewer rescue analgesic requirements, and faster postoperative recovery than did placebo injection. The incisions in their clinical setting were located on the lateral abdominal wall, necessitating the blockade of the lateral cutaneous branches. The wide dermatomal coverage from the midclavicular line to the posterior axillary line observed in their study may be associated with its relatively high LA volume. Further studies using different LA volumes are warranted to confirm the effect of the M-TAPA in this procedure.

Open major abdominal surgery

Two randomized trials have investigated the effects of the M-TAPA for open major abdominal surgeries, including the Whipple procedure, gastrectomy, and hemicolectomy [63,64]. They reported that, compared with local infiltration or no block, the M-TAPA resulted in lower postoperative pain scores and opioid consumption, as well as improved patient satisfaction. Accordingly, the M-TAPA can be considered to form part of multimodal analgesia in major open abdominal surgery. The effect of the M-TAPA on the quality of recovery scores should be further evaluated.

M-TAPA for pediatric patients

Several case reports have described the successful use of the TAPA and M-TAPA in pediatric procedures, including LC, splenectomy, nephrectomy, kidney transplantation, pyloromyotomy, and hydatid cyst removal [65–71]. One randomized trial reported that compared with no block, the M-TAPA resulted in lower intraoperative and postoperative opioid consumption and decreased pain scores in pediatric patients undergoing upper abdominal surgery [72]. Evidence also suggests a potential role for the M-TAPA in providing analgesia after pediatric lower abdominal surgery. Erten et al. [73] found that the M-TAPA demonstrated superior efficacy in postoperative analgesia as compared with local infiltration for laparoscopic appendectomy. Notably, a case report described successful use of the M-TAPA for thoracotomy in five pediatric patients, indicating that the technique may be used to block the upper intercostal nerves [74].

Regarding pharmacological considerations, bupivacaine and ropivacaine are the most commonly used LA, typically administered at concentrations of 0.125%, 0.2%, or 0.25%, with a volume of 0.25–0.5 mL/kg. However, the optimal dose for pediatric patients has not yet been determined.

Critical appraisal

Given the contradictory findings, scarcity of evidence, and methodological shortcomings of some RCTs, drawing definitive clinical recommendations is difficult. A multimodal analgesia regimen is crucial when evaluating the efficacy of a regional anesthesia technique; however, its absence may have confounded the observed effects. Moreover, clinical significance, rather than statistical differences, should be emphasized, as statistically significant findings do not necessarily translate into meaningful clinical benefits. Finally, in terms of primary outcomes, the use of morphine consumption or pain scores has been criticized [75]. Future research should focus on patient-centered outcomes, such as QoR-15 scores, to assess their impact on postoperative recovery.

Complications

The TAPA and its modifications are interfascial plane blocks, with a low risk of serious complications when applied under ultrasound guidance. To date, no complications associated with these blocks have been reported. Puncture site infections, abdominal wall hematomas, vascular injuries, and visceral abdominal injuries are rare complications. As the RM-TAPA block is located close to the lungs, lung injury is a potential risk, particularly when the injection site is above the 8th intercostal space. Thus, visualizing the entire length of the needle during block administration is crucial.

An important consideration when performing fascial plane blocks is the risk of systemic LA toxicity. Both Aikawa et al. [43] and Suzuka et al. [44] have demonstrated that the peak plasma LA concentration following M-TAPA administration using 25 mL of 0.25% levobupivacaine per side, with or without epinephrine, are below the toxic level (2.6 μg/mL). However, the RM-TAPA involves administering LA into the anatomical compartment between the endothoracic fascia and diaphragm. This region is highly vascularized with proximity to the intercostal vessels, which could potentially lead to the rapid systemic absorption of LA. Moreover, bilateral TAPA requires a large LA volume. Therefore, the LA dose should be monitored carefully.

Comparative summary

Based on the available anatomical and clinical studies, as discussed above, the TAPA, M-TAPA, and RM-TAPA demonstrate differences in technique, dermatomal coverage, and injectate volume (Supplementary Table 1).

The TAPA and M-TAPA are relatively superficial blocks that are generally considered safe and easy to perform. Compared to TAPA, M-TAPA requires a significantly shorter procedural time and is therefore more widely used in current clinical practice [76]. In contrast, RM-TAPA targets the plane within the thoracic cavity and carries the potential risk of pleural or lung injury, which may limit its applicability.

Current evidence suggests that TAPA has the potential to block both the anterior and lateral cutaneous branches; however, this remains to be confirmed in cadaveric and large-sample clinical studies. M-TAPA offers a more consistent anterior branch coverage, particularly from T7 to T10, making it suitable for analgesia during middle and upper abdominal surgeries [38]. The blockade pattern for lateral cutaneous branches is variable and unstable, and a higher volume of LA may increase the success rate [18,49]. RM-TAPA performed at the 9th intercostal space reliably anesthetizes the anterior cutaneous branches, whereas injection at the 10th intercostal space provides consistent blockade of both the anterior and lateral branches between T10 and T12 on the right side, suggesting its potential utility in lower abdominal procedures [10,42].

According to published studies (Table 2 and Supplementary Table 2), TAPA is usually performed with 30–40 mL of LA, M-TAPA with 20–30 mL, and RM-TAPA with approximately 20 mL, most commonly at a concentration of 0.25%. However, the optimal volume for these techniques has not yet been determined.

However, comparative evidence evaluating these three techniques in identical clinical scenarios is scarce. Only one study found that TAPA and M-TAPA provided comparable analgesia for LC [76]. Current evidence does not allow definitive conclusions regarding the superiority of a single technique.

Future directions

Presently, high-quality evidence regarding the TAPA and its modifications remains limited, and substantial knowledge gaps indicate the need for further investigation.

First, further studies are warranted to help establish procedural standardization, including needle tip position, hydrodissection, injection level, and the optimal pattern of LA diffusion under ultrasound.

Secondly, the dermatomal coverage of these techniques requires further investigation, particularly with respect to the lateral cutaneous branches. In addition, the effects of the LA dose on dermatomal distribution, as well as dermatomal spread over a 24-h follow-up period, warrant systematic evaluation.

Third, imaging studies in living subjects are required to clarify the mechanisms of the TAPA and its modifications. Given that the injectate spread of the RM-TAPA may be influenced by many factors, such as pneumoperitoneum, patient position, and respiratory parameters, studies on patients are more appropriate for investigating its underlying mechanism and dermatomal distribution.

Fourth, large-scale RCTs have been limited to date. The TAPA and M-TAPA should be compared in clinical settings; the effect of the M-TAPA on procedures in the lower abdomen and inguinal region should be elucidated. The TAPA and M-TAPA should be investigated in other procedures in comparison with no block, local infiltration, or existing regional anesthesia techniques; and the optimal concentration and volume should be confirmed. More importantly, patient-centered outcomes, such as QoR-15 scores, should be a particular focus, to offer a more holistic assessment of block efficacy.

Conclusion

The TAPA and its modifications are emerging regional anesthesia techniques that target both the anterior and lateral cutaneous branches of the thoracoabdominal nerves. Since their initial description, all these techniques have shown promise in providing effective postoperative analgesia across a range of abdominal procedures. However, current evidence is largely limited to case reports and a small number of randomized trials, underscoring the need for well-designed RCTs to investigate their safety, efficacy, and optimal indications. As our understanding of their anatomical basis and clinical performance evolves, the TAPA and its modifications may become valuable components of multimodal analgesia strategies in perioperative care.

Supplementary Materials

Supplementary Table 1.

Comparison of TAPA and the modified techniques.

Supplementary Table 2.

Summary of case reports and series of TAPA, M-TAPA and RM-TAPA.