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Proliferation and differentiation of chondrocytes in defined culture medium: Effects of systemic factors.
The Pathway of Injectate Spread With the Transmuscular Quadratus Lumborum Block: A Cadaver Study Mette Dam, MD,* Bernhard Moriggl, MD, PhD,† Christian K. Hansen, MD,* Romed Hoermann,† Thomas F. Bendtsen, MD, PhD,‡ and Jens Børglum, MD, PhD* BACKGROUND: The spread of injectate resulting from a transmuscular quadratus lumborum (TQL) block and a transverse oblique paramedian (TOP) TQL block has never been examined. The aim of this cadaveric study was to investigate by which pathway the injectate spreads cephalad into the thoracic paravertebral space and which nerves were dyed by the injectate cephalad and caudad to the diaphragm when performing a TQL and a TOP TQL block. We also aimed to investigate whether the thoracic and lumbar sympathetic trunks as well as the lumbar plexus were covered by the injectate. METHODS: Ultrasound-guided bilateral TQL and TOP TQL injections were administered in 8 cadavers. A total of 16 injections were performed. With the TQL injection, the curvilinear transducer was oriented in the transverse plane above the iliac crest at the posterior axillary line to identify the Shamrock sign. With the TOP TQL injection, the same transducer was placed with a TOP orientation 3 cm lateral to the L2 spinous process to identify the L2 transverse process and the adjoining quadratus lumborum muscle. For both techniques, the needle was advanced in-plane to the transducer, with the end point in the interfascial plane between the quadratus lumborum and psoas major muscles. Thirty milliliters of dye solution was injected bilaterally for each technique. The spread of the dye was evaluated by subsequent dissection. RESULTS: In all successful injections, the dye was seen to spread into the thoracic paravertebral space and the intercostal spaces to surround the somatic nerves and the thoracic sympathetic trunk. The main pathway of spread of injectate was posterior to the medial and lateral arcuate ligaments. Caudad to the diaphragm, the injected dye surrounded the subcostal, iliohypogastric, and ilioinguinal nerves in all cases, whereas the genitofemoral and lateral femoral cutaneous nerves were dyed in a varying degree. No dye was seen to surround the lumbar plexus, femoral nerve, or lumbar sympathetic trunk. The pattern of spread was similar with the TQL and TOP TQL injections. CONCLUSIONS: The spread of injectate with the TQL and TOP TQL approaches is cephalad from the lumbar point of administration between the quadratus lumborum and psoas major muscles, predominantly via a pathway posterior to the arcuate ligaments and into the thoracic paravertebral space to reach the somatic nerves and the thoracic sympathetic trunk in the intercostal and paravertebral spaces. The lumbar plexus and lumbar sympathetic trunk are not affected. (Anesth Analg 2017;XXX:00–00)
T
he ultrasound-guided (USG) transmuscular quadratus lumborum (TQL) block is a new regional anesthesia block technique that provides postoperative analgesia and dermatome anesthesia from Th4-L1.1 The TQL block has primarily been used to alleviate postoperative pain after intraperitoneal or retroperitoneal surgical procedures.1,2 Various quadratus lumborum blocks (QLBs) have been described in From the *Department of Anesthesia and Intensive Care Medicine, Zealand University Hospital, University of Copenhagen, Denmark; †Division of Clinical and Functional Anatomy, Medical University of Innsbruck, Austria; and ‡Department of Anesthesia and Intensive Care Medicine, Aarhus University Hospital, Denmark. Accepted for publication December 22, 2016.
Funding: The Department of Anesthesia and Intensive Care Medicine, Zealand University Hospital, and Division of Clinical and Functional Anatomy, Medical University of Innsbruck, provided funding for this study. The authors declare no conflicts of interest. Reprints will not be available from the authors. Address correspondence to Jens Børglum, MD, PhD, Department of Anesthesia and Intensive Care Medicine, Zealand University Hospital, University of Copenhagen, Sygehusvej 10, DK-4000 Roskilde, Denmark. Address e-mail to [email protected]. Copyright © 2017 International Anesthesia Research Society DOI: 10.1213/ANE.0000000000001922
the past decade. In 2007, Blanco initially described a “no pops” transversus abdominis plane block technique3 and later elaborated on this technique as QLB1 and QLB 2.4 Concurrently, a new TQL block approach emerged,1,2 which uses a posterior needle approach and a curvilinear transducer. The large field of vision enables a cross-sectional view of the entire lumbar region of interest. It has been speculated that the TQL approach might reduce the risk of unintentional nerve damage of the subcostal, ilioinguinal, and iliohypogastric nerves in the pararenal fat compartment between the transversus abdominis muscle and the quadratus lumborum muscle.2 The initial TQL block was described as a transverse posterior axillary approach at the L4 level (just cephalad to the iliac crest). However, in some cases, the surgical procedure entails surgical drains at the flank level (or the anatomical structures are poorly visualized at this position). Because it is not possible to align the transducer further cephalad along the posterior axillary line (because of the obstruction of the rib cage), more posteromedial and cephalad TQL approaches have recently been described (ie, the transverse oblique paramedian [TOP] TQL block and the paramedian sagittal oblique [subcostal] approach).5,6 The TOP TQL block is still performed with
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Injectate Spread With the TQL Block
injection in the plane between the quadratus lumborum and psoas major muscles, and it is also a transmuscular approach, but more medial and further cephalad. With the TQL block, the local anesthetic is deposited in the plane between the quadratus lumborum and the psoas major muscles. The quadratus lumborum muscle originates from the inner lip of the iliac crest and inserts at the apices of the transverse processes of L1-L4 and the lower border of the 12th rib. The quadratus lumborum muscle has a close relationship with the psoas major muscle. The psoas major muscle is divided into a posterior and anterior layer. The posterior layer originates from the transverse processes of L1-L5, and the anterior layer originates from the anterolateral surfaces of the vertebral bodies of T12-L5 and intervertebral discs. Both the psoas major and the quadratus lumborum muscles pass posterior to the diaphragm and attach within the thoracic cage to the thoracic spine and the 12th rib, respectively. The initial concept of the TQL block was that the injectate would spread cephalad within the plane between the quadratus lumborum and psoas major muscles posterior to the transversalis fascia, and enter the thoracic paravertebral space posterior to the medial and lateral arcuate ligaments.7,8 However, no evidence has directly documented this assumed pattern of spread with respect to the TQL blockade. The anterior surface of the quadratus lumborum muscle and the anterolateral surface of the psoas major muscle are covered by the transversalis fascia blending with the investing fasciae.9 Hence, the spread of the injectate with the TQL block is posterior to the transversalis fascia. At the level of the diaphragm, the transversalis fascia splits into 2 layers. One layer is continuous with the endothoracic fascia, and another layer becomes the inferior diaphragmatic fascia.9 The transversalis fascia also covers the subcostal (T12), iliohypogastric, ilioinguinal, genitofemoral, and the lateral femoral cutaneous nerves. Thus, the injectate administered with the TQL block might also spread to surround these nerves. However, this pattern of spread has never been tested with respect to the TQL blockade. The reduction of visceral pain after TQL block has been speculated to result from spread of local anesthetic into the thoracic paravertebral space, containing the thoracic sympathetic trunk as well as the ventral and dorsal rami of the spinal nerves.10–13 It has never been documented with cadaveric studies that the injectate with the TQL block can spread from the lumbar point of injection to the thoracic paravertebral space and the thoracic sympathetic trunk. The primary aims of our current descriptive cadaveric study were to answer the following 4 questions after injection with the TQL technique: (1) Does the injectate spread cephalad from the lumbar point of injection at the level of lumbar vertebra L4 to the thoracic paravertebral space via the pathway posterior to the arcuate ligaments? (2) Does the injectate reach and dye the ventral rami of the spinal nerves in the thoracic paravertebral space? (3) Does the injectate reach and stain the thoracic sympathetic trunk? And (4) Does the injectate follow a similar pattern of spread when performing the TOP TQL block? In addition, we aimed to answer the following research questions: Does the injectate below the diaphragm reach and color the subcostal, iliohypogastric, ilioinguinal, and lateral femoral cutaneous nerves? Does the injectate cover the
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genitofemoral nerve either before the genitofemoral nerve enters the psoas muscle or after it emerges on the anterior surface of the muscle? Does the injectate spread over the branches of the lumbar plexus within the psoas major muscle? Finally, does the injectate diffuse over the lumbar sympathetic trunk?
METHODS This cadaver study is a descriptive study, investigating the spread of dye when performing TQL and TOP TQL injections. Ten cadavers donated to the Division of Clinical and Functional Anatomy of the Medical University of Innsbruck for scientific and educational purposes were allocated to our study.14,15 All cadavers were preserved using an arterial injection of an ethanol–glycerol solution and immersion in phenolic acid in water for 1 to 3 months.16 This special embalming allows for both flexibility and excellent ultrasonographic images of cadavers in contrast to the regular preservation used for student dissection courses.17 To avoid selection bias during the days of the study, a computer-randomized sequence prospectively numbering the allotment of cadavers (1 = TQL injection and 2 = TOP TQL injection) had been prepared. Thus, with this procedure, 5 cadavers (10 sides) were a priori allocated to bilateral TQL injections, and 5 cadavers (10 sides) were a priori allocated to bilateral TOP TQL injections. Cadavers were scanned before injections, and the sonographic visualization was evaluated as good/adequate/inadequate. The ultrasound scanning was performed using the SonoSite X-porte ultrasound unit (SonoSite Inc, Bothell, WA) with a curvilinear transducer (2–5 MHz, C60). The transducer was wrapped with a sterile plastic cover (Safersonic sterile sonography cover; Safersonic Medizinprodukte Handels, Ybbs, Austria). A 21-gauge, 120-mm needle (polymedic ultrasound needle with 30 degree bevel; Temena SAS, Carrières-sur-Seine, France) was used for all USG injections.
Injection Procedures The ultrasound scanning and injection techniques regarding the TQL and TOP TQL approaches have both been described previously.1,2,5 Briefly, the cadavers were positioned lateral, with the side to be injected turned upward. For the TQL approach, the transducer was placed in the transverse position at the posterior axillary line just above the iliac crest and adjusted to visualize the Shamrock sign (Figure 1A) (ie, the transverse process of L4 and the 3 muscular structures consisting of the quadratus lumborum, psoas major, and erector spinae muscles).18 The needle was subsequently inserted at the posterolateral end of the transducer and advanced in-plane (Figure 1B). For the TOP TQL approach, the same curvilinear transducer was used. The transducer was placed medially and more cephalad, with a TOP orientation 3 cm lateral to the L2 spinous process to identify the L2 transverse process and the adjoining quadratus lumborum muscle (Figure 1C).5 The same 3 muscle compartments can still be distinctly visualized as with the TQL approach, and the transverse process is still the proxy marker (Figure 1D). The needle was subsequently inserted at the medial end of the transducer and advanced in-plane (Figure 1). With both techniques, the needle was advanced through the quadratus lumborum muscle until the tip of the needle penetrated
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Figure 1. TQL and TOP TQL approach. A, The TQL approach (model photo). Green dots indicate the spinous processes. Green lines indicate the rib cage and the iliac crest, respectively. B, The Shamrock sign (ie, the TP of L4 and the 3 muscular structures consisting of the QL, PM, and ES muscles). The white arrow indicates needle trajectory with the TQL approach at the L4 level, with the end point in the plane between the QL and PM muscles. C, TOP TQL approach (model photo). Green dots indicate the spinous processes. Green lines indicate the rib cage and the iliac crest, respectively. The transducer is positioned with a TOP orientation 3 cm lateral to the level of L2 spinous process. D, The white arrow indicates needle trajectory with the TOP TQL approach with the end point in the plane between the QL and PM muscles. ES indicates erector spinae; K, kidney; PM, psoas major; QL, quadratus lumborum; TOP, transverse, oblique and paramedian; TP, transverse process; TQL, transmuscular quadratus lumborum.
the investing fascia of the quadratus lumborum muscle (Figures 1 and 2). Two milliliters of saline was injected into the plane between the quadratus lumborum and psoas major muscles to confirm the correct position of the needle tip. Subsequently, 30 mL of dye solution was injected bilaterally during a standardized period of 3 minutes. Injection pressure (psi) was not measured. On the left side, the dye solution was yellow, and on the right side, it was green.
Composition of Injectate Cold-cured polymers, latex, acrylates, acrylic esters, alcohols, and different dyes are the basic individual mixed ingredients.19 Viscosity was controlled by adding alcohols and/or changing the mixing ratio. This dye solution has a slightly higher viscosity than local anesthetic and was chosen to avoid excessive (or false) spread occurring even with minimal unintended disruptions of the covering fasciae under the extensive dissection procedure (see below). All TQL and TOP TQL injections were performed by J.B., assisted by M.D. and C.K.H. They then left the dissection
room, and B.M. and R.H. (not present during the injection procedures) performed the careful dissection. Photographic documentation of the spread of dye was performed by M.D. and C.K.H. when called upon by B.M. and R.H.
Dissection Procedure In all cadavers, exactly the same dissection procedure was performed on both sides and was begun no longer than 30 minutes after injections. The first incision followed the lower border of the 10th rib starting at its cartilage–bone boundary. This cut ended 3 finger breadths away from the respective vertebral body. Lung and parietal pleura were first mobilized and then reflected ventrally. This created a window wide enough to observe both medial and lateral arcuate ligaments within the thoracic cage. The second incision started where the first incision crossed the posterior axillary line and was brought down along this line close to the iliac crest. Consequently, the peritoneal cylinder was mobilized and pushed anteromedially to expose the musculofascial compartments of the psoas major and
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Injectate Spread With the TQL Block
Figure 2. Anatomical details relevant for the TQL and TOP TQL injections. A, Axial image of the TOP TQL injection at the level of L2. The red arrow indicates the ilioinguinal and iliohypogastric nerves. The blue arrow indicates the subcostal nerve, artery, and vein deep to the 12th rib. B, Axial image of the TQL injection at the level of L4. Green arrow indicates the Genitofemoral nerve. Red arrows indicate the ilioinguinal and Iliohypogastric nerves. The white arrow indicates the lumbar plexus (L3 spinal nerve and the femoral nerve). A and B, The long white arrows indicate needle trajectory with bilateral transmuscular injections. On the right side, injected dye solution (red color) spreads in the plane between the PM and QL muscles. On the left side, truncated lines indicate the QL muscle. C–E, Sagittal image at the level of the apex of the transverse process of L4. C, QL muscle colored purple. D, PM muscle colored purple. E, Diaphragm colored purple. F, Sagittal image at the level of the apex of the 12th rib. PM (red), QL (green), and DI (blue). The QL and PM muscles adjacent to the DI create the shape of a funnel, which enables the injected local anesthetic trapped in the fascial plane between the 2 muscles to spread cephalad into the thoracic paravertebral space posterior to the diaphragmatic crus. Modified excerpt from VH Dissector with permission from Touch of Life Technologies Inc (www.toltech.net). Built on real anatomy from the National Library of Medicine Visible Human Project. DI indicates diaphragm; ES, erector spinae; PM, psoas major; QL, quadratus lumborum; TOP, transverse oblique paramedian; TQL, transmuscular quadratus lumborum; TP, transverse process.
quadratus lumborum muscles, respectively. Occasionally, the diaphragm had to be partially incised on the right side of the cadaver (depending on the individual liver size). Retroperitoneal spread of dye visible through the intact fasciae was photodocumented. Subsequently, the muscle fasciae were opened to allow for direct inspection and photodocumentation. Finally, the injected dye was meticulously followed to document whether the nervous structures of interest were stained or not.
RESULTS In 8 of 10 cadavers, the quality of the sonographic visualization was judged to be good or adequate. Two cadavers from the TOP TQL group (consisting of 5 cadavers) were excluded from the study before injections because of inadequate sonographic visualization. Massive edema and air/gas entrapment made it impossible to identify the muscular and fascial structures. Thus, 5 cadavers received bilateral USG TQL dye injections (10 sides), and 3 cadavers received bilateral USG TOP TQL dye injections (6 sides). The 8 cadavers demographically represent 3 men and 5 women with the following median (range) characteristics: age, 92 years (82–98); height, 166.5 cm (150–171); weight, 64 kg (53–82); and body mass index, 23.9 kg/m2 (21.1–28.1).
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In 1 cadaver, in which bilateral TOP TQL injections were performed, a rare anatomical variation was present on both sides (ie, no quadratus lumborum muscle was present). Instead, dissection revealed only a 1-mm thin fascial layer bilaterally. The psoas major muscle was formed by 2 equally large separate muscles. No sign of this anatomical variation was detected with dynamic ultrasound scanning before or after dye injection (ie, the sonographic visualized anatomy appeared completely normal). The results regarding the TQL injections are presented in Table 1, and the results regarding the TOP TQL injections are presented in Table 2.
TQL Injections Spread of dye cephalad to the diaphragm and into the thoracic paravertebral space was present with all 10 TQL injections (ie, 100% [confidence interval (CI)], 0.67–1.00). In 50% (CI, 0.19–0.81) of the cases, the pathway for the spread of the dye reaching the thoracic paravertebral space was posterior to both the medial and lateral arcuate ligaments (Figure 3), and in 30% (CI, 0.07–0.65) of the cases, the dye only spread posterior to the lateral arcuate ligament. Splanchnic nerve openings accounted for 20% (CI, 0.03– 0.56). The most cephalad spread of dye reached the level of
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Table 1. Spread of Dye With TQL Injections Thoracic cage Pathway
EP CS
Caudad to the diaphragm Nerves
Spread of Dye With TQL (n = 10)
Percentages (95% CI)
Lateral AL Medial AL Both AL SNDO TPVS TST Th11/Th12 VRSN Th10 VRSN Th 9 VRSN VRSN
3/10 0/10 5/10 2/10 10/10 10/10 6/10 3/10 1/10 10/10
30 (0.07–0.65) 0 (0.00–0.31) 50 (0.19–0.81) 20 (0.03–0.56) 100 (0.67–1.00) 100 (0.67–1.00) 60 (0.26–0.88) 30 (0.07–0.65) 10 (0.003–0.45) 100 (0.67–1.00)
Subcostal Iliohypogastric Ilioinguinal Genitofemoral Lateral femoral cutaneous Femoral
10/10 10/10 10/10 3/10 2/10 0/10 0/10 0/10
100 (0.67–1.00) 100 (0.67–1.00) 100 (0.67–1.00) 30 (0.07–0.65) 20 (0.03–0.56) 0 (0.00–0.31) 0 (0.00–0.31) 0 (0.00–0.31)
Lumbar plexus LST
Abbreviations: AL, arcuate ligament; CI, confidence interval; CS, cephalad spread; EP, end point; LST, lumbar sympathetic trunk; SNDO, splanchnic nerve diaphragmatic openings; TPVS, thoracic paravertebral space; TST, thoracic sympathetic trunk; VRSN, ventral rami spinal nerve.
Table 2. Spread of Dye With TOP TQL Injections Thoracic cage Pathway
EP CS
Caudad to the diaphragm Nerves
Spread of Dye With TOP TQL (n = 4)
Percentages (95% CI)
Lateral AL Medial AL Both AL SNDO TPVS TST Th11/Th12 VRSN Th10 VRSN Th 9 VRSN VRSN
0/4 1/4 3/4 0/4 4/4 4/4 2/4 2/4 0/4 4/4
0 (0.00–0.60) 25 (0.006–0.81) 75 (0.19–0.99) 0 (0.00–0.60) 100 (0.39–1.00) 100 (0.39–1.00) 50 (0.07–0.93) 50 (0.07–0.93) 0 (0.00–0.60) 100 (0.39–1.00)
Subcostal Iliohypogastric Ilioinguinal Genitofemoral Lateral femoral cutaneous Femoral
4/4 4/4 4/4 1/4 3/4 0/4 0/4 0/4
100 (0.39–1.00) 100 (0.39–1.00) 100 (0.39–1.00) 25 (0.006–0.81) 75 (0.19–0.99) 0 (0.00–0.60) 0 (0.00–0.60) 0 (0.00–0.60)
Lumbar plexus LST
Abbreviations: AL, arcuate ligament; CI, confidence interval; CS, cephalad spread; EP, end point; LST, lumbar sympathetic trunk; SNDO, splanchnic nerve diaphragmatic openings; TPVS, thoracic paravertebral space; TST, thoracic sympathetic trunk; VRSN, Ventral rami spinal nerve.
the T9 vertebral body. In all cadaver sides, the ventral rami of the spinal nerves were dyed as proximal as the cranial distribution of dye spread. In all cases, the thoracic sympathetic trunk was dyed (Figure 4, A–C). Caudad to the diaphragm, the subcostal, iliohypogastric (Figure 5, A and B), and ilioinguinal nerves were dyed in 100% (CI, 0.67–1.00) of the cases, whereas the genitofemoral and lateral femoral cutaneous nerves were dyed to a varying degree (Table 1). The lumbar plexus was never dyed within the psoas major muscle (Figure 5C); nor were the femoral nerve or lumbar sympathetic trunk. In addition, no dye was detected intraperitoneally, and there was no dye observed spreading into the transversus abdominis plane.
Finally, the spread of dye was never caudad to the attachment of the transversalis fascia to the iliac crest.
TOP TQL Injections Spread of dye cephalad to the diaphragm and into the thoracic paravertebral space was present in 100% (CI, 0.39–1.00) of the TOP TQL injections. For the 4 TOP TQL injections, the pathway of dye reaching the thoracic paravertebral space was posterior to both the medial and lateral arcuate ligaments in 75% (CI, 0.19–0.99) of the cases, and in 25% (CI, 0.006–0.81) of the cases, the dye spread only posterior to the medial arcuate ligament (Table 2). The most cephalad spread of dye reached the level of the lumbar vertebra
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Injectate Spread With the TQL Block
Figure 3. Pathway. A, Visualization of spread of dye posterior to the transversalis fascia from the lumbar position and into the thoracic paravertebral space. The 2 tweezers are placed posterior to both arcuate ligaments. The dye spreads posterior to the medial and lateral arcuate ligaments (blue circle). The Magenta dotted line indicates diaphragm. B, Red arrow: Green dye is visualized posterior to endothoracic fascia within the thoracic cage. The magenta dotted line indicates the diaphragm; PM, psoas major.
T10. As with the TQL approach, the ventral rami of the spinal nerves were dyed as proximal as the cranial distribution of dye spread. The thoracic sympathetic trunk was dyed in 100% (CI, 0.39–1.00) of the cases. Caudad to the diaphragm, the subcostal, iliohypogastric, and ilioinguinal nerves were dyed in 100% (CI, 0.39–1.00) of the cases, whereas the genitofemoral and lateral femoral cutaneous nerves were dyed to a varying degree (Table 2). The lumbar plexus was never dyed within the psoas major muscle; nor was the femoral nerve or the lumbar sympathetic trunk. In addition, no dye was detected intraperitoneally, and there was no dye observed spreading into the transversus abdominis plane. We observed no discernable difference in the pattern of injectate spread with the 2 transmuscular approaches apart from the 2 unsuccessful injections in the cadaver with an anatomical variation.
DISCUSSION This cadaver dissection study investigates the spread of dye solution with the USG TQL and TOP TQL techniques. Previous studies have used both magnetic resonance imaging and computed tomography scanning techniques to
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evaluate the spread of injectate with different variants of the QLB.1,4,18,20 The main finding was that the pathway for the spread of dye to the thoracic paravertebral space was predominantly posterior to the medial and lateral arcuate ligaments. In the majority of the cadavers, the pathway of spread of dye was posterior to one or both arcuate ligaments, but the diaphragmatic openings for the splanchnic nerves also proved to be able to serve as the pathway. The ventral rami of the segmental nerves (ie, intercostal nerves) were always dyed. The dissection did not include the dorsal rami. In addition, there was a consistent spread of dye reaching the thoracic sympathetic trunk in all cadavers with “normal” anatomy. Finally, dye was detected neither intraperitoneally nor in the transversus abdominis plane with any of the injection procedures. Our data also demonstrate for both TQL techniques that the injectate will spread to the subcostal, iliohypogastric, and ilioinguinal nerves consistently, and it will reach and surround the lateral femoral cutaneous nerve and the genitofemoral nerve to a varying degree. These anatomical findings might be useful knowledge when planning perioperative pain relief for surgical procedures such as
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Figure 4. Dye surrounding the thoracic sympathetic trunk. A, Within the thoracic cage, the lung is gently reflected away, and the thoracic paravertebral space is dissected. The dye (yellow) can be clearly visualized as the pleura is removed. B, Dye (yellow) can be visualized within the thoracic paravertebral space (blue arrows). C, Dye surrounding the thoracic sympathetic trunk and the segmental nerves (blue arrows). The white dotted line indicates the opening of the thoracic cage.
undescended testicles, hydrocele, inguinal hernia repair, and bone graft harvest from the iliac crest and hip repair. Finally, we never observed the dye solution staining the lumbar sympathetic trunk. In addition, neither the lumbar plexus nor the femoral nerve was stained with any of the 16 injections. The absence of spread of injectate to the lumbar
plexus is clinically relevant for patient ability to ambulate after intraperitoneal and retroperitoneal surgery. These new findings regarding TQL injections in this study entirely contradict the very recent published results by Carline et al.21 In a very relevant study, Carline et al21 investigated 5 cadavers (10 sides) (ie, 4 TQL injections and 3
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Injectate Spread With the TQL Block
Figure 5. The spread of dye in the abdominal cavity. A, Green dye is visualized surrounding the subcostal nerve (blue dotted circle) cephalad to the diaphragm (magenta dotted line). B, Green dye is visualized surrounding the iliohypogastic nerve (blue dotted circle). C, Green dye is visualized to spread posterior to the transversalis fascia on the PM muscle. The PM muscle is carefully dissected. No dye surrounds the lumbar plexus (white arrows). PM indicates psoas major.
injections with the QLB1 and QLB2 technique each). Carline et al21 reported that all TQL injections consistently spread to L1 and L3 nerve roots and also within psoas and quadratus lumborum muscles. No thoracic spread was recorded. From the excellent schematic drawing provided by Carline et al21 regarding the transmuscular block, it appears that the needle tip is placed in the correct plane between the quadratus lumborum and psoas major muscles. There are some differences regarding the injection technique that might explain the discrepancy in results between Carline et al21 and our current study. First, Carline et al21 used a linear 3 to 9 MHz transducer compared with our curvilinear transducer (2–5 MHz). In theory, a low-frequency curvilinear transducer will probably be considered more suitable to visualize anatomical structures in deep blocks like the TQL block, the Shamrock lumbar plexus block, or other lumbar paravertebral blocks. Second, Carline et al21 used an 18-gauge Tuohy needle compared with our 21-gauge nontraumatic needle. Third, Carline et al21 report in “a summary of block characteristics” for all 4 transmuscular injections that the quadratus lumborum and psoas major muscles were consistently “pierced.” With our TQL and TOP TQL techniques, we avoided piercing the psoas major muscle because this could easily facilitate spread within the psoas major muscle to reach the lumbar plexus. Fourth, Carline et al21 performed their dissection procedure 72 hours after having injected their dye solution, whereas we performed our dissection procedure 30 minutes after the injections. Finally, the TQL block is intended to provide analgesia for intraperitoneal and retroperitoneal surgeries, not to anesthetize the lumbar
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plexus. From the anatomical image depicted in Figure 2B (at the L4 level), it is easy to understand that if you advance the needle further from the plane between the psoas major and quadratus lumborum muscles, to actually pierce the psoas major muscle, the injectate could easily spread to reach the L3 spinal nerve and the femoral nerve. For the clinician, it is worth remembering that anatomical variations can explain an “unsuccessful” block, as clearly shown in our study with 1 cadaver, and we believe that the study by Carline et al21 also highlights the potential to accidentally block the spinal nerve roots of the lumbar plexus if the needle tip pierces the psoas major muscle. In addition, our results showed that the caudad spread of dye stopped at the iliac crest. This can be speculated to imply that the TQL block techniques will not produce urinary bladder paralysis, hypotension, or motor impairment of the lower limbs, as might result from other regional anesthetic techniques.22 Whether the TQL block has the ability to substitute epidural catheters for postoperative analgesia after major abdominal and retroperitoneal surgeries remains to be elucidated in future clinical studies. Because part of the analgesic effect of the TQL block in patients presumably can be attributed to spread of local anesthetic into the thoracic paravertebral space, the clinician might well choose a direct thoracic paravertebral block as an obvious first choice of analgesic technique. However, thoracic paravertebral block is associated with a risk of pneumothorax (even with ultrasound guidance).23 In addition, with direct paravertebral block, anticoagulation therapy probably presents a larger risk of procedure-related
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bleeding or hematoma in the thoracic paravertebral space compared with the TQL blocks. However, that is still speculative. Epidural spread up to 70% of the cases has been reported for thoracic paravertebral block.11,24 In several studies, it has been reported that the opening injection pressure is proportional to the risk of epidural spread through the epidural sleeve with thoracic paravertebral block. In our study, we did not extend the dissection to include the epidural space, and further studies are needed to examine whether there is epidural spread when performing TQL and TOP TQL injections. The velocity of cephalad spread of local anesthetic from the lumbar position of injection with the TQL block into the thoracic paravertebral space is probably not related to the injection pressure, but rather to elastic recoil of the quadratus lumborum and psoas major muscles, and the pressure gradients associated with the respiratory function. This can be speculated to reduce the risk of spread of local anesthetic into the epidural space with the TQL block technique. However, future studies are needed to elucidate this question. There are several limitations to this cadaver study. First, postmortem changes regarding temperature and lack of muscle tone might alter the spread of the injectate compared with the living. Second, in alive patients, the intra-abdominal and intrathoracic pressures vary with diaphragmatic movement during respiration.24,25 It is possible that these pressure variations will enhance cephalad spread of the injected local anesthetic. Third, the viscosity of our injected dye solution in the current study was higher compared with normal ropivacaine or saline solutions. As mentioned previously, we chose our specific dye to avoid overly excessive artefactual spread in the cadavers that might have happened because of the substantial dissection procedure, but we acknowledge that the viscosity of the dye solution may have caused us to underestimate the extent of spread of the injectate. Fourth, we had intended to study a total of 10 cadavers. As mentioned, 2 cadavers proved unsuitable for inclusion in the study. Because we utilized soft-embalmed cadavers, we were unable to substitute the excluded 2 cadavers with 2 new specimens; this resulted in 10 TQL and 6 TOP TQL injections. However, in 1 cadaver, in which bilateral TOP TQL injections were performed, a rare anatomical variation was present on both sides (ie, no quadratus lumborum muscle was present). The psoas major muscle was formed by 2 equally large separate muscles, and the dye solution was injected between the 2 muscle bulks of the psoas muscle, resulting in no further spread. Finally, with the current sample size, it will be difficult to adjust for the within-cadaver correlations based on repeated injections. In conclusion, our data show that the dye solution spreads from the lumbar point of injection into the thoracic paravertebral space predominantly posterior to the arcuate ligaments with both TQL injection techniques. In this cadaveric study, the injectate reaches and dyes the thoracic sympathetic trunk and the ventral rami of the lower thoracic (T9-T12) spinal nerves. Further, the subcostal, iliohypogastric, and ilioinguinal terminal nerves are also stained consistently. Sometimes, the genitofemoral nerve and the lateral femoral cutaneous nerve are also covered. Importantly, the dye solution never reached the lumbar plexus within the psoas major muscle or
the lumbar sympathetic trunk. Our findings from this cadaver study will need confirmation from future randomized controlled clinical trials for selected surgical procedures. E DISCLOSURES Name: Mette Dam, MD. Contribution: This author designed the study, authored the manuscript, conducted the photodocumentation, and created the figures. Name: Bernhard Moriggl, MD, PhD. Contribution: This author designed the study and performed all dissections. Name: Christian K. Hansen, MD. Contribution: This author conducted the photodocumentation and created the figures. Name: Romed Hoermann. Contribution: This author performed all dissections. Name: Thomas F. Bendtsen, MD, PhD. Contribution: This author created the figures. Name: Jens Børglum, MD, PhD. Contribution: This author designed the study, authored the manuscript, created the figures, and performed all injections with the help of Mette Dam and Christian Kruse Hansen. This manuscript was handled by: Honorio T. Benzon, MD. REFERENCES 1. Børglum J, Moriggl B, Jensen K, et al. Ultrasound-guided transmuscular quadratus lumborum blockade. Br J Anaesth. 2013. Letter to the editor. Available at: http://bja.oxfordjournals. org/forum/topic/brjana_el%3b9919. Accessed June 15, 2015. 2. Hansen CK, Dam M, Bendtsen TF, Børglum J. Ultrasound-guided quadratus lumborum blocks: definition of the clinical relevant endpoint of injection and the safest approach. A A Case Rep. 2016;6:39. 3. Blanco R. Tap block under ultrasound guidance: the description of a “no pops” technique. Reg Anesth Pain Med. 2007;32:130. 4. Blanco R, McDonnell J. Optimal point of injection: The quadratus lumborum type I and II block. Letter to the Editor. Available at: http://www.respond2articles.com/ANA/forums/ post/1550.aspx . Accessed June 15, 2015 5. Dam M, Hansen CK, Børglum J, Chan V, Bendtsen TF. A transverse oblique approach to the transmuscular Quadratus Lumborum block. Anaesthesia. 2016;71:603–604. 6. Elsharkawy H. Quadratus lumborum block with paramedian sagittal oblique (subcostal) approach. Anaesthesia. 2016;71:241–242. 7. Saito T, Den S, Tanuma K, Tanuma Y, Carney E, Carlsson C. Anatomical bases for paravertebral anesthetic block: fluid communication between the thoracic and lumbar paravertebral regions. Surg Radiol Anat. 1999;21:359–363. 8. Karmakar MK, Gin T, Ho AM. Ipsilateral thoraco-lumbar anaesthesia and paravertebral spread after low thoracic paravertebral injection. Br J Anaesth. 2001;87:312–316. 9. Gallaudet BB. A description of the planes of fascia of the human body, with special reference of the fascia of the abdomen, pelvis and perineum. Am J Surg. 1932;17:458–459. 10. Karmakar MK. Ultrasound-guided thoracic paravertebral block. Tech Reg Anesth Pain Manag. 209;13:142–149. 11. Cowie B, McGlade D, Ivanusic J, Barrington MJ. Ultrasoundguided thoracic paravertebral blockade: a cadaveric study. Anesth Analg. 2010;110:1735–1739. 12. Cheema SP, Ilsley D, Richardson J, Sabanathan S. A ther mographic study of paravertebral analgesia. Anaesthesia. 1995;50:118–121. 13. Klein SM, Nielsen KC, Ahmed N, Buckenmaier CC, Steele SM. In situ images of the thoracic paravertebral space. Reg Anesth Pain Med. 2004;29:596–599. 14. McHanwell S, Brenner E, Chirculescu ARM, et al. The legal and ethical framework governing body donation in Europe—a review of current practice and recommendations for good practice. Eur J Anat. 2008;12:1–24. 15. Riederer BM, Bolt S, Brenner E, et al. The legal and ethical framework governing Body Donation in Europe—1st update on current practice. Eur J Anat. 2012;16:1–21.
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16. Kessler J, Moriggl B, Grau T. Ultrasound-guided regional anesthesia: learning with an optimized cadaver model. Surg Radiol Anat. 2014;36:383–392. 17. Platzer W, Putz R, Poisel S. [New system for the preservation and storage of anatomical matter]. Acta Anat. (Basel) 1978;102:60–67.67. 18. Sauter AR, Ullensvang K, Niemi G, et al. The Shamrock lumbar plexus block: A dose-finding study. Eur J Anaesthesiol. 2015;32:764–770. 19. Hörmann R, Moriggl B, Brenner E. Development of a new vascular and tissue casting solution. Paper presented at: Anatomische Gesellschaft 111th Annual Meeting; September 21–24, 2016; Göttingen, Germany. http://anatomische-gesellschaft.de/data/uploads/content/abstract-archiv/2016-poster. pdf. Accessed November 28, 2016. 20. Carney J, Finnerty O, Rauf J, Bergin D, Laffey JG, Mc Donnell JG. Studies on the spread of local anaesthetic solution in transversus abdominis plane blocks. Anaesthesia. 2011;66:1023–1030.
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21. Carline L, McLeod GA, Lamb C. A cadaver study comparing spread of dye and nerve involvement after three different quadratus lumborum blocks. Br J Anaesth. 2016;117:387–394. 22. Rawal N. Current issues in postoperative pain management. Eur J Anaesthesiol. 2016;33:160–171. 23. Abrahams M, Derby R, Horn JL. Update on ultrasound for truncal blocks: a review of the evidence. Reg Anesth Pain Med. 2016;41:275–288. 24. Kawamata M, Omote K, Namiki A, Miyabe M. Measurement of intercostal and pleural pressures by epidural catheter. Anaesthesia. 1994;49:208–210. 25. Visser WA, Gielen MJ, Giele JL, Scheffer GJ. A comparison of epidural pressures and incidence of true subatmospheric epidural pressure between the mid-thoracic and low-thoracic epidural space. Anesth Analg. 2006;103:1318–1321. 26. Purcell-Jones G, Pither CE, Justins DM. Paravertebral somatic nerve block: a clinical, radiographic, and computed tomographic study in chronic pain patients. Anesth Analg. 1989;68:32–39.
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T
he ultrasound-guided (USG) transmuscular quadratus lumborum (TQL) block is a new regional anesthesia block technique that provides postoperative analgesia and dermatome anesthesia from Th4-L1.1 The TQL block has primarily been used to alleviate postoperative pain after intraperitoneal or retroperitoneal surgical procedures.1,2 Various quadratus lumborum blocks (QLBs) have been described in From the *Department of Anesthesia and Intensive Care Medicine, Zealand University Hospital, University of Copenhagen, Denmark; †Division of Clinical and Functional Anatomy, Medical University of Innsbruck, Austria; and ‡Department of Anesthesia and Intensive Care Medicine, Aarhus University Hospital, Denmark. Accepted for publication December 22, 2016.
Funding: The Department of Anesthesia and Intensive Care Medicine, Zealand University Hospital, and Division of Clinical and Functional Anatomy, Medical University of Innsbruck, provided funding for this study. The authors declare no conflicts of interest. Reprints will not be available from the authors. Address correspondence to Jens Børglum, MD, PhD, Department of Anesthesia and Intensive Care Medicine, Zealand University Hospital, University of Copenhagen, Sygehusvej 10, DK-4000 Roskilde, Denmark. Address e-mail to [email protected]. Copyright © 2017 International Anesthesia Research Society DOI: 10.1213/ANE.0000000000001922
the past decade. In 2007, Blanco initially described a “no pops” transversus abdominis plane block technique3 and later elaborated on this technique as QLB1 and QLB 2.4 Concurrently, a new TQL block approach emerged,1,2 which uses a posterior needle approach and a curvilinear transducer. The large field of vision enables a cross-sectional view of the entire lumbar region of interest. It has been speculated that the TQL approach might reduce the risk of unintentional nerve damage of the subcostal, ilioinguinal, and iliohypogastric nerves in the pararenal fat compartment between the transversus abdominis muscle and the quadratus lumborum muscle.2 The initial TQL block was described as a transverse posterior axillary approach at the L4 level (just cephalad to the iliac crest). However, in some cases, the surgical procedure entails surgical drains at the flank level (or the anatomical structures are poorly visualized at this position). Because it is not possible to align the transducer further cephalad along the posterior axillary line (because of the obstruction of the rib cage), more posteromedial and cephalad TQL approaches have recently been described (ie, the transverse oblique paramedian [TOP] TQL block and the paramedian sagittal oblique [subcostal] approach).5,6 The TOP TQL block is still performed with
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Injectate Spread With the TQL Block
injection in the plane between the quadratus lumborum and psoas major muscles, and it is also a transmuscular approach, but more medial and further cephalad. With the TQL block, the local anesthetic is deposited in the plane between the quadratus lumborum and the psoas major muscles. The quadratus lumborum muscle originates from the inner lip of the iliac crest and inserts at the apices of the transverse processes of L1-L4 and the lower border of the 12th rib. The quadratus lumborum muscle has a close relationship with the psoas major muscle. The psoas major muscle is divided into a posterior and anterior layer. The posterior layer originates from the transverse processes of L1-L5, and the anterior layer originates from the anterolateral surfaces of the vertebral bodies of T12-L5 and intervertebral discs. Both the psoas major and the quadratus lumborum muscles pass posterior to the diaphragm and attach within the thoracic cage to the thoracic spine and the 12th rib, respectively. The initial concept of the TQL block was that the injectate would spread cephalad within the plane between the quadratus lumborum and psoas major muscles posterior to the transversalis fascia, and enter the thoracic paravertebral space posterior to the medial and lateral arcuate ligaments.7,8 However, no evidence has directly documented this assumed pattern of spread with respect to the TQL blockade. The anterior surface of the quadratus lumborum muscle and the anterolateral surface of the psoas major muscle are covered by the transversalis fascia blending with the investing fasciae.9 Hence, the spread of the injectate with the TQL block is posterior to the transversalis fascia. At the level of the diaphragm, the transversalis fascia splits into 2 layers. One layer is continuous with the endothoracic fascia, and another layer becomes the inferior diaphragmatic fascia.9 The transversalis fascia also covers the subcostal (T12), iliohypogastric, ilioinguinal, genitofemoral, and the lateral femoral cutaneous nerves. Thus, the injectate administered with the TQL block might also spread to surround these nerves. However, this pattern of spread has never been tested with respect to the TQL blockade. The reduction of visceral pain after TQL block has been speculated to result from spread of local anesthetic into the thoracic paravertebral space, containing the thoracic sympathetic trunk as well as the ventral and dorsal rami of the spinal nerves.10–13 It has never been documented with cadaveric studies that the injectate with the TQL block can spread from the lumbar point of injection to the thoracic paravertebral space and the thoracic sympathetic trunk. The primary aims of our current descriptive cadaveric study were to answer the following 4 questions after injection with the TQL technique: (1) Does the injectate spread cephalad from the lumbar point of injection at the level of lumbar vertebra L4 to the thoracic paravertebral space via the pathway posterior to the arcuate ligaments? (2) Does the injectate reach and dye the ventral rami of the spinal nerves in the thoracic paravertebral space? (3) Does the injectate reach and stain the thoracic sympathetic trunk? And (4) Does the injectate follow a similar pattern of spread when performing the TOP TQL block? In addition, we aimed to answer the following research questions: Does the injectate below the diaphragm reach and color the subcostal, iliohypogastric, ilioinguinal, and lateral femoral cutaneous nerves? Does the injectate cover the
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genitofemoral nerve either before the genitofemoral nerve enters the psoas muscle or after it emerges on the anterior surface of the muscle? Does the injectate spread over the branches of the lumbar plexus within the psoas major muscle? Finally, does the injectate diffuse over the lumbar sympathetic trunk?
METHODS This cadaver study is a descriptive study, investigating the spread of dye when performing TQL and TOP TQL injections. Ten cadavers donated to the Division of Clinical and Functional Anatomy of the Medical University of Innsbruck for scientific and educational purposes were allocated to our study.14,15 All cadavers were preserved using an arterial injection of an ethanol–glycerol solution and immersion in phenolic acid in water for 1 to 3 months.16 This special embalming allows for both flexibility and excellent ultrasonographic images of cadavers in contrast to the regular preservation used for student dissection courses.17 To avoid selection bias during the days of the study, a computer-randomized sequence prospectively numbering the allotment of cadavers (1 = TQL injection and 2 = TOP TQL injection) had been prepared. Thus, with this procedure, 5 cadavers (10 sides) were a priori allocated to bilateral TQL injections, and 5 cadavers (10 sides) were a priori allocated to bilateral TOP TQL injections. Cadavers were scanned before injections, and the sonographic visualization was evaluated as good/adequate/inadequate. The ultrasound scanning was performed using the SonoSite X-porte ultrasound unit (SonoSite Inc, Bothell, WA) with a curvilinear transducer (2–5 MHz, C60). The transducer was wrapped with a sterile plastic cover (Safersonic sterile sonography cover; Safersonic Medizinprodukte Handels, Ybbs, Austria). A 21-gauge, 120-mm needle (polymedic ultrasound needle with 30 degree bevel; Temena SAS, Carrières-sur-Seine, France) was used for all USG injections.
Injection Procedures The ultrasound scanning and injection techniques regarding the TQL and TOP TQL approaches have both been described previously.1,2,5 Briefly, the cadavers were positioned lateral, with the side to be injected turned upward. For the TQL approach, the transducer was placed in the transverse position at the posterior axillary line just above the iliac crest and adjusted to visualize the Shamrock sign (Figure 1A) (ie, the transverse process of L4 and the 3 muscular structures consisting of the quadratus lumborum, psoas major, and erector spinae muscles).18 The needle was subsequently inserted at the posterolateral end of the transducer and advanced in-plane (Figure 1B). For the TOP TQL approach, the same curvilinear transducer was used. The transducer was placed medially and more cephalad, with a TOP orientation 3 cm lateral to the L2 spinous process to identify the L2 transverse process and the adjoining quadratus lumborum muscle (Figure 1C).5 The same 3 muscle compartments can still be distinctly visualized as with the TQL approach, and the transverse process is still the proxy marker (Figure 1D). The needle was subsequently inserted at the medial end of the transducer and advanced in-plane (Figure 1). With both techniques, the needle was advanced through the quadratus lumborum muscle until the tip of the needle penetrated
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Figure 1. TQL and TOP TQL approach. A, The TQL approach (model photo). Green dots indicate the spinous processes. Green lines indicate the rib cage and the iliac crest, respectively. B, The Shamrock sign (ie, the TP of L4 and the 3 muscular structures consisting of the QL, PM, and ES muscles). The white arrow indicates needle trajectory with the TQL approach at the L4 level, with the end point in the plane between the QL and PM muscles. C, TOP TQL approach (model photo). Green dots indicate the spinous processes. Green lines indicate the rib cage and the iliac crest, respectively. The transducer is positioned with a TOP orientation 3 cm lateral to the level of L2 spinous process. D, The white arrow indicates needle trajectory with the TOP TQL approach with the end point in the plane between the QL and PM muscles. ES indicates erector spinae; K, kidney; PM, psoas major; QL, quadratus lumborum; TOP, transverse, oblique and paramedian; TP, transverse process; TQL, transmuscular quadratus lumborum.
the investing fascia of the quadratus lumborum muscle (Figures 1 and 2). Two milliliters of saline was injected into the plane between the quadratus lumborum and psoas major muscles to confirm the correct position of the needle tip. Subsequently, 30 mL of dye solution was injected bilaterally during a standardized period of 3 minutes. Injection pressure (psi) was not measured. On the left side, the dye solution was yellow, and on the right side, it was green.
Composition of Injectate Cold-cured polymers, latex, acrylates, acrylic esters, alcohols, and different dyes are the basic individual mixed ingredients.19 Viscosity was controlled by adding alcohols and/or changing the mixing ratio. This dye solution has a slightly higher viscosity than local anesthetic and was chosen to avoid excessive (or false) spread occurring even with minimal unintended disruptions of the covering fasciae under the extensive dissection procedure (see below). All TQL and TOP TQL injections were performed by J.B., assisted by M.D. and C.K.H. They then left the dissection
room, and B.M. and R.H. (not present during the injection procedures) performed the careful dissection. Photographic documentation of the spread of dye was performed by M.D. and C.K.H. when called upon by B.M. and R.H.
Dissection Procedure In all cadavers, exactly the same dissection procedure was performed on both sides and was begun no longer than 30 minutes after injections. The first incision followed the lower border of the 10th rib starting at its cartilage–bone boundary. This cut ended 3 finger breadths away from the respective vertebral body. Lung and parietal pleura were first mobilized and then reflected ventrally. This created a window wide enough to observe both medial and lateral arcuate ligaments within the thoracic cage. The second incision started where the first incision crossed the posterior axillary line and was brought down along this line close to the iliac crest. Consequently, the peritoneal cylinder was mobilized and pushed anteromedially to expose the musculofascial compartments of the psoas major and
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Injectate Spread With the TQL Block
Figure 2. Anatomical details relevant for the TQL and TOP TQL injections. A, Axial image of the TOP TQL injection at the level of L2. The red arrow indicates the ilioinguinal and iliohypogastric nerves. The blue arrow indicates the subcostal nerve, artery, and vein deep to the 12th rib. B, Axial image of the TQL injection at the level of L4. Green arrow indicates the Genitofemoral nerve. Red arrows indicate the ilioinguinal and Iliohypogastric nerves. The white arrow indicates the lumbar plexus (L3 spinal nerve and the femoral nerve). A and B, The long white arrows indicate needle trajectory with bilateral transmuscular injections. On the right side, injected dye solution (red color) spreads in the plane between the PM and QL muscles. On the left side, truncated lines indicate the QL muscle. C–E, Sagittal image at the level of the apex of the transverse process of L4. C, QL muscle colored purple. D, PM muscle colored purple. E, Diaphragm colored purple. F, Sagittal image at the level of the apex of the 12th rib. PM (red), QL (green), and DI (blue). The QL and PM muscles adjacent to the DI create the shape of a funnel, which enables the injected local anesthetic trapped in the fascial plane between the 2 muscles to spread cephalad into the thoracic paravertebral space posterior to the diaphragmatic crus. Modified excerpt from VH Dissector with permission from Touch of Life Technologies Inc (www.toltech.net). Built on real anatomy from the National Library of Medicine Visible Human Project. DI indicates diaphragm; ES, erector spinae; PM, psoas major; QL, quadratus lumborum; TOP, transverse oblique paramedian; TQL, transmuscular quadratus lumborum; TP, transverse process.
quadratus lumborum muscles, respectively. Occasionally, the diaphragm had to be partially incised on the right side of the cadaver (depending on the individual liver size). Retroperitoneal spread of dye visible through the intact fasciae was photodocumented. Subsequently, the muscle fasciae were opened to allow for direct inspection and photodocumentation. Finally, the injected dye was meticulously followed to document whether the nervous structures of interest were stained or not.
RESULTS In 8 of 10 cadavers, the quality of the sonographic visualization was judged to be good or adequate. Two cadavers from the TOP TQL group (consisting of 5 cadavers) were excluded from the study before injections because of inadequate sonographic visualization. Massive edema and air/gas entrapment made it impossible to identify the muscular and fascial structures. Thus, 5 cadavers received bilateral USG TQL dye injections (10 sides), and 3 cadavers received bilateral USG TOP TQL dye injections (6 sides). The 8 cadavers demographically represent 3 men and 5 women with the following median (range) characteristics: age, 92 years (82–98); height, 166.5 cm (150–171); weight, 64 kg (53–82); and body mass index, 23.9 kg/m2 (21.1–28.1).
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In 1 cadaver, in which bilateral TOP TQL injections were performed, a rare anatomical variation was present on both sides (ie, no quadratus lumborum muscle was present). Instead, dissection revealed only a 1-mm thin fascial layer bilaterally. The psoas major muscle was formed by 2 equally large separate muscles. No sign of this anatomical variation was detected with dynamic ultrasound scanning before or after dye injection (ie, the sonographic visualized anatomy appeared completely normal). The results regarding the TQL injections are presented in Table 1, and the results regarding the TOP TQL injections are presented in Table 2.
TQL Injections Spread of dye cephalad to the diaphragm and into the thoracic paravertebral space was present with all 10 TQL injections (ie, 100% [confidence interval (CI)], 0.67–1.00). In 50% (CI, 0.19–0.81) of the cases, the pathway for the spread of the dye reaching the thoracic paravertebral space was posterior to both the medial and lateral arcuate ligaments (Figure 3), and in 30% (CI, 0.07–0.65) of the cases, the dye only spread posterior to the lateral arcuate ligament. Splanchnic nerve openings accounted for 20% (CI, 0.03– 0.56). The most cephalad spread of dye reached the level of
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Table 1. Spread of Dye With TQL Injections Thoracic cage Pathway
EP CS
Caudad to the diaphragm Nerves
Spread of Dye With TQL (n = 10)
Percentages (95% CI)
Lateral AL Medial AL Both AL SNDO TPVS TST Th11/Th12 VRSN Th10 VRSN Th 9 VRSN VRSN
3/10 0/10 5/10 2/10 10/10 10/10 6/10 3/10 1/10 10/10
30 (0.07–0.65) 0 (0.00–0.31) 50 (0.19–0.81) 20 (0.03–0.56) 100 (0.67–1.00) 100 (0.67–1.00) 60 (0.26–0.88) 30 (0.07–0.65) 10 (0.003–0.45) 100 (0.67–1.00)
Subcostal Iliohypogastric Ilioinguinal Genitofemoral Lateral femoral cutaneous Femoral
10/10 10/10 10/10 3/10 2/10 0/10 0/10 0/10
100 (0.67–1.00) 100 (0.67–1.00) 100 (0.67–1.00) 30 (0.07–0.65) 20 (0.03–0.56) 0 (0.00–0.31) 0 (0.00–0.31) 0 (0.00–0.31)
Lumbar plexus LST
Abbreviations: AL, arcuate ligament; CI, confidence interval; CS, cephalad spread; EP, end point; LST, lumbar sympathetic trunk; SNDO, splanchnic nerve diaphragmatic openings; TPVS, thoracic paravertebral space; TST, thoracic sympathetic trunk; VRSN, ventral rami spinal nerve.
Table 2. Spread of Dye With TOP TQL Injections Thoracic cage Pathway
EP CS
Caudad to the diaphragm Nerves
Spread of Dye With TOP TQL (n = 4)
Percentages (95% CI)
Lateral AL Medial AL Both AL SNDO TPVS TST Th11/Th12 VRSN Th10 VRSN Th 9 VRSN VRSN
0/4 1/4 3/4 0/4 4/4 4/4 2/4 2/4 0/4 4/4
0 (0.00–0.60) 25 (0.006–0.81) 75 (0.19–0.99) 0 (0.00–0.60) 100 (0.39–1.00) 100 (0.39–1.00) 50 (0.07–0.93) 50 (0.07–0.93) 0 (0.00–0.60) 100 (0.39–1.00)
Subcostal Iliohypogastric Ilioinguinal Genitofemoral Lateral femoral cutaneous Femoral
4/4 4/4 4/4 1/4 3/4 0/4 0/4 0/4
100 (0.39–1.00) 100 (0.39–1.00) 100 (0.39–1.00) 25 (0.006–0.81) 75 (0.19–0.99) 0 (0.00–0.60) 0 (0.00–0.60) 0 (0.00–0.60)
Lumbar plexus LST
Abbreviations: AL, arcuate ligament; CI, confidence interval; CS, cephalad spread; EP, end point; LST, lumbar sympathetic trunk; SNDO, splanchnic nerve diaphragmatic openings; TPVS, thoracic paravertebral space; TST, thoracic sympathetic trunk; VRSN, Ventral rami spinal nerve.
the T9 vertebral body. In all cadaver sides, the ventral rami of the spinal nerves were dyed as proximal as the cranial distribution of dye spread. In all cases, the thoracic sympathetic trunk was dyed (Figure 4, A–C). Caudad to the diaphragm, the subcostal, iliohypogastric (Figure 5, A and B), and ilioinguinal nerves were dyed in 100% (CI, 0.67–1.00) of the cases, whereas the genitofemoral and lateral femoral cutaneous nerves were dyed to a varying degree (Table 1). The lumbar plexus was never dyed within the psoas major muscle (Figure 5C); nor were the femoral nerve or lumbar sympathetic trunk. In addition, no dye was detected intraperitoneally, and there was no dye observed spreading into the transversus abdominis plane.
Finally, the spread of dye was never caudad to the attachment of the transversalis fascia to the iliac crest.
TOP TQL Injections Spread of dye cephalad to the diaphragm and into the thoracic paravertebral space was present in 100% (CI, 0.39–1.00) of the TOP TQL injections. For the 4 TOP TQL injections, the pathway of dye reaching the thoracic paravertebral space was posterior to both the medial and lateral arcuate ligaments in 75% (CI, 0.19–0.99) of the cases, and in 25% (CI, 0.006–0.81) of the cases, the dye spread only posterior to the medial arcuate ligament (Table 2). The most cephalad spread of dye reached the level of the lumbar vertebra
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Injectate Spread With the TQL Block
Figure 3. Pathway. A, Visualization of spread of dye posterior to the transversalis fascia from the lumbar position and into the thoracic paravertebral space. The 2 tweezers are placed posterior to both arcuate ligaments. The dye spreads posterior to the medial and lateral arcuate ligaments (blue circle). The Magenta dotted line indicates diaphragm. B, Red arrow: Green dye is visualized posterior to endothoracic fascia within the thoracic cage. The magenta dotted line indicates the diaphragm; PM, psoas major.
T10. As with the TQL approach, the ventral rami of the spinal nerves were dyed as proximal as the cranial distribution of dye spread. The thoracic sympathetic trunk was dyed in 100% (CI, 0.39–1.00) of the cases. Caudad to the diaphragm, the subcostal, iliohypogastric, and ilioinguinal nerves were dyed in 100% (CI, 0.39–1.00) of the cases, whereas the genitofemoral and lateral femoral cutaneous nerves were dyed to a varying degree (Table 2). The lumbar plexus was never dyed within the psoas major muscle; nor was the femoral nerve or the lumbar sympathetic trunk. In addition, no dye was detected intraperitoneally, and there was no dye observed spreading into the transversus abdominis plane. We observed no discernable difference in the pattern of injectate spread with the 2 transmuscular approaches apart from the 2 unsuccessful injections in the cadaver with an anatomical variation.
DISCUSSION This cadaver dissection study investigates the spread of dye solution with the USG TQL and TOP TQL techniques. Previous studies have used both magnetic resonance imaging and computed tomography scanning techniques to
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evaluate the spread of injectate with different variants of the QLB.1,4,18,20 The main finding was that the pathway for the spread of dye to the thoracic paravertebral space was predominantly posterior to the medial and lateral arcuate ligaments. In the majority of the cadavers, the pathway of spread of dye was posterior to one or both arcuate ligaments, but the diaphragmatic openings for the splanchnic nerves also proved to be able to serve as the pathway. The ventral rami of the segmental nerves (ie, intercostal nerves) were always dyed. The dissection did not include the dorsal rami. In addition, there was a consistent spread of dye reaching the thoracic sympathetic trunk in all cadavers with “normal” anatomy. Finally, dye was detected neither intraperitoneally nor in the transversus abdominis plane with any of the injection procedures. Our data also demonstrate for both TQL techniques that the injectate will spread to the subcostal, iliohypogastric, and ilioinguinal nerves consistently, and it will reach and surround the lateral femoral cutaneous nerve and the genitofemoral nerve to a varying degree. These anatomical findings might be useful knowledge when planning perioperative pain relief for surgical procedures such as
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Figure 4. Dye surrounding the thoracic sympathetic trunk. A, Within the thoracic cage, the lung is gently reflected away, and the thoracic paravertebral space is dissected. The dye (yellow) can be clearly visualized as the pleura is removed. B, Dye (yellow) can be visualized within the thoracic paravertebral space (blue arrows). C, Dye surrounding the thoracic sympathetic trunk and the segmental nerves (blue arrows). The white dotted line indicates the opening of the thoracic cage.
undescended testicles, hydrocele, inguinal hernia repair, and bone graft harvest from the iliac crest and hip repair. Finally, we never observed the dye solution staining the lumbar sympathetic trunk. In addition, neither the lumbar plexus nor the femoral nerve was stained with any of the 16 injections. The absence of spread of injectate to the lumbar
plexus is clinically relevant for patient ability to ambulate after intraperitoneal and retroperitoneal surgery. These new findings regarding TQL injections in this study entirely contradict the very recent published results by Carline et al.21 In a very relevant study, Carline et al21 investigated 5 cadavers (10 sides) (ie, 4 TQL injections and 3
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Injectate Spread With the TQL Block
Figure 5. The spread of dye in the abdominal cavity. A, Green dye is visualized surrounding the subcostal nerve (blue dotted circle) cephalad to the diaphragm (magenta dotted line). B, Green dye is visualized surrounding the iliohypogastic nerve (blue dotted circle). C, Green dye is visualized to spread posterior to the transversalis fascia on the PM muscle. The PM muscle is carefully dissected. No dye surrounds the lumbar plexus (white arrows). PM indicates psoas major.
injections with the QLB1 and QLB2 technique each). Carline et al21 reported that all TQL injections consistently spread to L1 and L3 nerve roots and also within psoas and quadratus lumborum muscles. No thoracic spread was recorded. From the excellent schematic drawing provided by Carline et al21 regarding the transmuscular block, it appears that the needle tip is placed in the correct plane between the quadratus lumborum and psoas major muscles. There are some differences regarding the injection technique that might explain the discrepancy in results between Carline et al21 and our current study. First, Carline et al21 used a linear 3 to 9 MHz transducer compared with our curvilinear transducer (2–5 MHz). In theory, a low-frequency curvilinear transducer will probably be considered more suitable to visualize anatomical structures in deep blocks like the TQL block, the Shamrock lumbar plexus block, or other lumbar paravertebral blocks. Second, Carline et al21 used an 18-gauge Tuohy needle compared with our 21-gauge nontraumatic needle. Third, Carline et al21 report in “a summary of block characteristics” for all 4 transmuscular injections that the quadratus lumborum and psoas major muscles were consistently “pierced.” With our TQL and TOP TQL techniques, we avoided piercing the psoas major muscle because this could easily facilitate spread within the psoas major muscle to reach the lumbar plexus. Fourth, Carline et al21 performed their dissection procedure 72 hours after having injected their dye solution, whereas we performed our dissection procedure 30 minutes after the injections. Finally, the TQL block is intended to provide analgesia for intraperitoneal and retroperitoneal surgeries, not to anesthetize the lumbar
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plexus. From the anatomical image depicted in Figure 2B (at the L4 level), it is easy to understand that if you advance the needle further from the plane between the psoas major and quadratus lumborum muscles, to actually pierce the psoas major muscle, the injectate could easily spread to reach the L3 spinal nerve and the femoral nerve. For the clinician, it is worth remembering that anatomical variations can explain an “unsuccessful” block, as clearly shown in our study with 1 cadaver, and we believe that the study by Carline et al21 also highlights the potential to accidentally block the spinal nerve roots of the lumbar plexus if the needle tip pierces the psoas major muscle. In addition, our results showed that the caudad spread of dye stopped at the iliac crest. This can be speculated to imply that the TQL block techniques will not produce urinary bladder paralysis, hypotension, or motor impairment of the lower limbs, as might result from other regional anesthetic techniques.22 Whether the TQL block has the ability to substitute epidural catheters for postoperative analgesia after major abdominal and retroperitoneal surgeries remains to be elucidated in future clinical studies. Because part of the analgesic effect of the TQL block in patients presumably can be attributed to spread of local anesthetic into the thoracic paravertebral space, the clinician might well choose a direct thoracic paravertebral block as an obvious first choice of analgesic technique. However, thoracic paravertebral block is associated with a risk of pneumothorax (even with ultrasound guidance).23 In addition, with direct paravertebral block, anticoagulation therapy probably presents a larger risk of procedure-related
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bleeding or hematoma in the thoracic paravertebral space compared with the TQL blocks. However, that is still speculative. Epidural spread up to 70% of the cases has been reported for thoracic paravertebral block.11,24 In several studies, it has been reported that the opening injection pressure is proportional to the risk of epidural spread through the epidural sleeve with thoracic paravertebral block. In our study, we did not extend the dissection to include the epidural space, and further studies are needed to examine whether there is epidural spread when performing TQL and TOP TQL injections. The velocity of cephalad spread of local anesthetic from the lumbar position of injection with the TQL block into the thoracic paravertebral space is probably not related to the injection pressure, but rather to elastic recoil of the quadratus lumborum and psoas major muscles, and the pressure gradients associated with the respiratory function. This can be speculated to reduce the risk of spread of local anesthetic into the epidural space with the TQL block technique. However, future studies are needed to elucidate this question. There are several limitations to this cadaver study. First, postmortem changes regarding temperature and lack of muscle tone might alter the spread of the injectate compared with the living. Second, in alive patients, the intra-abdominal and intrathoracic pressures vary with diaphragmatic movement during respiration.24,25 It is possible that these pressure variations will enhance cephalad spread of the injected local anesthetic. Third, the viscosity of our injected dye solution in the current study was higher compared with normal ropivacaine or saline solutions. As mentioned previously, we chose our specific dye to avoid overly excessive artefactual spread in the cadavers that might have happened because of the substantial dissection procedure, but we acknowledge that the viscosity of the dye solution may have caused us to underestimate the extent of spread of the injectate. Fourth, we had intended to study a total of 10 cadavers. As mentioned, 2 cadavers proved unsuitable for inclusion in the study. Because we utilized soft-embalmed cadavers, we were unable to substitute the excluded 2 cadavers with 2 new specimens; this resulted in 10 TQL and 6 TOP TQL injections. However, in 1 cadaver, in which bilateral TOP TQL injections were performed, a rare anatomical variation was present on both sides (ie, no quadratus lumborum muscle was present). The psoas major muscle was formed by 2 equally large separate muscles, and the dye solution was injected between the 2 muscle bulks of the psoas muscle, resulting in no further spread. Finally, with the current sample size, it will be difficult to adjust for the within-cadaver correlations based on repeated injections. In conclusion, our data show that the dye solution spreads from the lumbar point of injection into the thoracic paravertebral space predominantly posterior to the arcuate ligaments with both TQL injection techniques. In this cadaveric study, the injectate reaches and dyes the thoracic sympathetic trunk and the ventral rami of the lower thoracic (T9-T12) spinal nerves. Further, the subcostal, iliohypogastric, and ilioinguinal terminal nerves are also stained consistently. Sometimes, the genitofemoral nerve and the lateral femoral cutaneous nerve are also covered. Importantly, the dye solution never reached the lumbar plexus within the psoas major muscle or
the lumbar sympathetic trunk. Our findings from this cadaver study will need confirmation from future randomized controlled clinical trials for selected surgical procedures. E DISCLOSURES Name: Mette Dam, MD. Contribution: This author designed the study, authored the manuscript, conducted the photodocumentation, and created the figures. Name: Bernhard Moriggl, MD, PhD. Contribution: This author designed the study and performed all dissections. Name: Christian K. Hansen, MD. Contribution: This author conducted the photodocumentation and created the figures. Name: Romed Hoermann. Contribution: This author performed all dissections. Name: Thomas F. Bendtsen, MD, PhD. Contribution: This author created the figures. Name: Jens Børglum, MD, PhD. Contribution: This author designed the study, authored the manuscript, created the figures, and performed all injections with the help of Mette Dam and Christian Kruse Hansen. This manuscript was handled by: Honorio T. Benzon, MD. REFERENCES 1. Børglum J, Moriggl B, Jensen K, et al. Ultrasound-guided transmuscular quadratus lumborum blockade. Br J Anaesth. 2013. Letter to the editor. Available at: http://bja.oxfordjournals. org/forum/topic/brjana_el%3b9919. Accessed June 15, 2015. 2. Hansen CK, Dam M, Bendtsen TF, Børglum J. Ultrasound-guided quadratus lumborum blocks: definition of the clinical relevant endpoint of injection and the safest approach. A A Case Rep. 2016;6:39. 3. Blanco R. Tap block under ultrasound guidance: the description of a “no pops” technique. Reg Anesth Pain Med. 2007;32:130. 4. Blanco R, McDonnell J. Optimal point of injection: The quadratus lumborum type I and II block. Letter to the Editor. Available at: http://www.respond2articles.com/ANA/forums/ post/1550.aspx . Accessed June 15, 2015 5. Dam M, Hansen CK, Børglum J, Chan V, Bendtsen TF. A transverse oblique approach to the transmuscular Quadratus Lumborum block. Anaesthesia. 2016;71:603–604. 6. Elsharkawy H. Quadratus lumborum block with paramedian sagittal oblique (subcostal) approach. Anaesthesia. 2016;71:241–242. 7. Saito T, Den S, Tanuma K, Tanuma Y, Carney E, Carlsson C. Anatomical bases for paravertebral anesthetic block: fluid communication between the thoracic and lumbar paravertebral regions. Surg Radiol Anat. 1999;21:359–363. 8. Karmakar MK, Gin T, Ho AM. Ipsilateral thoraco-lumbar anaesthesia and paravertebral spread after low thoracic paravertebral injection. Br J Anaesth. 2001;87:312–316. 9. Gallaudet BB. A description of the planes of fascia of the human body, with special reference of the fascia of the abdomen, pelvis and perineum. Am J Surg. 1932;17:458–459. 10. Karmakar MK. Ultrasound-guided thoracic paravertebral block. Tech Reg Anesth Pain Manag. 209;13:142–149. 11. Cowie B, McGlade D, Ivanusic J, Barrington MJ. Ultrasoundguided thoracic paravertebral blockade: a cadaveric study. Anesth Analg. 2010;110:1735–1739. 12. Cheema SP, Ilsley D, Richardson J, Sabanathan S. A ther mographic study of paravertebral analgesia. Anaesthesia. 1995;50:118–121. 13. Klein SM, Nielsen KC, Ahmed N, Buckenmaier CC, Steele SM. In situ images of the thoracic paravertebral space. Reg Anesth Pain Med. 2004;29:596–599. 14. McHanwell S, Brenner E, Chirculescu ARM, et al. The legal and ethical framework governing body donation in Europe—a review of current practice and recommendations for good practice. Eur J Anat. 2008;12:1–24. 15. Riederer BM, Bolt S, Brenner E, et al. The legal and ethical framework governing Body Donation in Europe—1st update on current practice. Eur J Anat. 2012;16:1–21.
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16. Kessler J, Moriggl B, Grau T. Ultrasound-guided regional anesthesia: learning with an optimized cadaver model. Surg Radiol Anat. 2014;36:383–392. 17. Platzer W, Putz R, Poisel S. [New system for the preservation and storage of anatomical matter]. Acta Anat. (Basel) 1978;102:60–67.67. 18. Sauter AR, Ullensvang K, Niemi G, et al. The Shamrock lumbar plexus block: A dose-finding study. Eur J Anaesthesiol. 2015;32:764–770. 19. Hörmann R, Moriggl B, Brenner E. Development of a new vascular and tissue casting solution. Paper presented at: Anatomische Gesellschaft 111th Annual Meeting; September 21–24, 2016; Göttingen, Germany. http://anatomische-gesellschaft.de/data/uploads/content/abstract-archiv/2016-poster. pdf. Accessed November 28, 2016. 20. Carney J, Finnerty O, Rauf J, Bergin D, Laffey JG, Mc Donnell JG. Studies on the spread of local anaesthetic solution in transversus abdominis plane blocks. Anaesthesia. 2011;66:1023–1030.
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21. Carline L, McLeod GA, Lamb C. A cadaver study comparing spread of dye and nerve involvement after three different quadratus lumborum blocks. Br J Anaesth. 2016;117:387–394. 22. Rawal N. Current issues in postoperative pain management. Eur J Anaesthesiol. 2016;33:160–171. 23. Abrahams M, Derby R, Horn JL. Update on ultrasound for truncal blocks: a review of the evidence. Reg Anesth Pain Med. 2016;41:275–288. 24. Kawamata M, Omote K, Namiki A, Miyabe M. Measurement of intercostal and pleural pressures by epidural catheter. Anaesthesia. 1994;49:208–210. 25. Visser WA, Gielen MJ, Giele JL, Scheffer GJ. A comparison of epidural pressures and incidence of true subatmospheric epidural pressure between the mid-thoracic and low-thoracic epidural space. Anesth Analg. 2006;103:1318–1321. 26. Purcell-Jones G, Pither CE, Justins DM. Paravertebral somatic nerve block: a clinical, radiographic, and computed tomographic study in chronic pain patients. Anesth Analg. 1989;68:32–39.
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