Spread Of Injectate Research Articles

Ultrasound-guided maxillary nerve block: an anatomical study using the suprazygomatic approach.

Although a maxillary nerve (MN) block reportedly provides satisfactory analgesia for midface surgery and chronic maxillofacial pain syndromes, a safe and reliable MN block technique has not been reported. The goal of this anatomical study was to quantify the various angles and depth of the block needle, as well as to evaluate the impact of volume on the extent of injectate spread that might influence anesthetic coverage and block-related complications. Following an ultrasound-guided suprazygomatic MN block with dye injection, a dissection was performed in the pterygopalatine fossa (PPF) of four lightly embalmed cadaveric specimens. Half of the specimens were injected with 5 mL of dye, and the other half with 1 mL of dye. The needle depth was measured from the ultrasound images and using rubber markers. Following injection, dissection was performed to map the area of dye spread. The median [interquartile range (IQR)] distance from the skin to the PPF was 37 [36-43] mm and 47 [40-50] mm by ultrasound and rubber marker methods, respectively. The median [IQR] needle orientation was 14 [11-32] degrees inferiorly and 15 [10-17] degrees posteriorly. The PPF was consistently dyed in the 5 mL group, but sporadically dyed in the 1 mL group. In the 5 mL group, spread outside of the PPF was seen. We showed that 5 mL of injectate far exceeds the capacity of the PPF, leading to drug spread outside of the PPF. Moreover, we found that 1 mL of injectate largely covered the nerve, suggesting a more efficacious and safer block procedure. This finding will need confirmation in future clinical studies.

Are single-injection erector spinae plane block and multiple-injection costotransverse block equivalent to thoracic paravertebral block?

Thoracic paravertebral block (TPVB) is considered the gold standard for hemithoracic regional anaesthesia. Erector spinae plane block (ESPB) is a new posterior thoracic wall block. Multiple-injection costotransverse block (MICB) mimics TPVB but with injection points within the thoracic intertransverse tissue complex and posterior to the superior costotransverse ligament. We aimed to compare the spread of injectate into the thoracic paravertebral space (TPVS) resulting from single-injection ESPB and MICB, respectively, with TPVB. Ten soft-embalmed cadavers were utilised. In five cadavers, the right hemithorax was randomly allocated either to ultrasound-guided single-injection ESPB or single-injection TPVB; vice versa on the other side. In another five cadavers, the right hemithorax was randomly allocated either to ultrasound-guided MICB or multiple-injection TPVB. About 20mL of dye was injected in each hemithorax with all techniques. With TPVB, the dye was consistently present in the TPVS with concomitant epidural spread in the majority of cases. The injectate spread into the TPVS with ESPB (60%) and MICB (100%). MICB consistently stained the ventral rami (T1-7), communicating rami and thoracic sympathetic trunk without epidural spread. Dissection after MICB revealed dye spread into the TPVS via the costotransverse foramina and along the dorsal branches of the posterior intercostal veins. Consistent spread of dye into the TPVS colouring the ventral rami, the communicating rami, and the sympathetic trunk was observed with MICB; in this respect equivalent to TPVB. ESPB exhibited only partial success and was not equivalent to TPVB. No epidural spread was found with neither MICB nor ESPB.

Cross-sectional CT Assessment of the Extent of Injectate Spread at CT Fluoroscopy-guided Cervical Epidural Interlaminar Steroid Injections.

Background Previous studies analyzed contrast agent spread during cervical interlaminar epidural steroid injections (CILESIs) by using planar fluoroscopy and reported wide variance of the rate of spread to the ventral epidural space (VES). Cross-sectional CT allows for direct viewing of contrast agent in the VES, providing improved spread assessment and thereby informing needle placement decisions when targeting pain generators. Purpose To determine the extent of injectate spread at CT fluoroscopy-guided CILESI, with particular attention to the VES and bilateral neuroforamina, by using cross-sectional CT. Materials and Methods This study reviewed 83 consecutive CT fluoroscopy-guided CILESIs at which a postprocedural cervical spine CT was performed (June 2016 to December 2017). All procedures used the same injectate (2 mL corticosteroid, 3 mL contrast agent). Postprocedural CT scans were reviewed for the presence of contrast within the VES, dorsal epidural space, ipsilateral neuroforamen, and contralateral neuroforamen in every cervical interlaminar level. Descriptive data are presented as frequencies or means. McNemar tests or hierarchical logistic models were used to assess associations between covariates and contrast agent spread to particular locations. Results The study cohort included 73 individual patients (59% women; 43 of 73) (mean patient age, 57.6 years ± 11.5 [standard deviation]). Mean number of levels of cranial spread were 0.6 level for VES, 1.9 levels for contralateral neuroforamen, 2.1 levels for ipsilateral neuroforamen, and 3 levels for dorsal epidural space. No VES spread in any level was found with 35% (29 of 83) of injections. VES spread was more likely to occur in the level of needle placement (43%; 36 of 83) than in other interlaminar levels (19.5%; 97 of 498; P < .001). Spread was more likely to occur in the neuroforamen ipsilateral to the needle approach compared with contralateral (P < .001). Conclusion Cervical interlaminar epidural steroid injections have injectate spreads with a mean of less than one level cranially in the ventral epidural space (VES) and approximately two levels in the neuroforamen. VES spread occurs more frequently at the level of needle placement and within the ipsilateral neuroforamen. © RSNA, 2019.

Evaluation of the iPACK block injectate spread: a cadaveric study

Background and objectivesUltrasound-guided infiltration of the interspace between the popliteal artery and capsule of the knee (iPACK) block, a new regional analgesic technique, is believed to relieve posterior knee pain,...

The ultrasound-guided proximal intercostal block: anatomical study and clinical correlation to analgesia for breast surgery

BackgroundThe ultrasound-guided proximal intercostal block (PICB) is performed at the proximal intercostal space (ICS) between the internal intercostal membrane (IIM) and the endothoracic fascia/parietal pleura (EFPP) complex. Injectate spread may follow several routes and allow for multilevel trunk analgesia. The goal of this study was to examine the anatomical spread of large-volume PICB injections and its relevance to breast surgery analgesia.MethodsFifteen two-level PICBs were performed in ten soft-embalmed cadavers. Radiographic contrast mixed with methylene blue was injected at the 2nd(15 ml) and 4th(25 ml) ICS, respectively. Fluoroscopy and dissection were performed to examine the injectate spread. Additionally, the medical records of 12 patients who had PICB for breast surgery were reviewed for documented dermatomal levels of clinical hypoesthesia. The records of twelve matched patients who had the same operations without PICB were reviewed to compare analgesia and opioid consumption.ResultsMedian contrast/dye spread was 4 (2–8) and 3 (2–5) vertebral segments by fluoroscopy and dissection respectively. Dissection revealed injectate spread to the adjacent paravertebral space, T3 (60%) and T5 (27%), and cranio-caudal spread along the endothoracic fascia (80%). Clinically, the median documented area of hypoesthesia was 5 (4–7) dermatomes with 100 and 92% of the injections covering adjacent T3 and T5 dermatomes, respectively. The patients with PICB had significantly lower perioperative opioid consumption and trend towards lower pain scores.ConclusionsIn this anatomical study, PICB at the 2nd and 4th ICS produced lateral spread along the corresponding intercostal space, medial spread to the adjacent paravertebral/epidural space and cranio-caudal spread along the endothoracic fascial plane. Clinically, combined PICBs at the same levels resulted in consistent segmental chest wall analgesia and reduction in perioperative opioid consumption after breast surgery. The incomplete overlap between paravertebral spread in the anatomical study and area of hypoesthesia in our clinical findings, suggests that additional non-paravertebral routes of injectate distribution, such as the endothoracic fascial plane, may play important clinical role in the multi-level coverage provided by this block technique.

Extrafasicular and Intraperineural, but No Endoneural, Spread after Deliberate Intraneural Injections in a Cadaveric Study.

There is confusion regarding the spread of intraneurally injected local anesthetic agents during regional anesthesia. The aim of this research was to deliberately inject a marker that does not leave the neural compartment into which it is injected, and then to study the longitudinal and circumferential spread and possible pathways of intraneural spread. After institutional review board approval, we intraneurally injected 20 and 5 ml of heparinized blood solution under ultrasound guidance into 12 sciatic nerves in the popliteal fossa and 10 median nerves, respectively, of eight fresh, unembalmed cadavers using standard 22-gauge "D" needles, mimicking the blocks in clinical conditions. Ultrasound evidence of nerve swelling confirmed intraneural injection. Samples of the nerves were then examined under light and scanning electron microscopy. Extrafascicular spread was observed in all the adipocyte-containing neural compartments of the 664 cross-section samples we examined, but intrafascicular spread was seen in only 6 cross-sections of two nerves. None of the epineurium, perineurium, or neural components were disrupted in any of the samples. Spread between the layers of the perineurium was a route of spread that included the perineurium surrounding the fascicles and the perineurium that formed incomplete septa in the fascicles. Similar to the endoneurium proper, subepineural compartments that did not contain any fat cells did not reveal any spread of heparinized blood solution cells. No "perineural" spaces were observed within the endoneurium. We also did not observe any true intrafascicular spread. After deliberate intraneural injection, longitudinal and circumferential extrafascicular spread occurred in all instances in the neural compartments that contained adipocytes, but not in the relatively solid endoneurium of the fascicles.

Comparing two posterior quadratus lumborum block approaches with low thoracic erector spinae plane block: an anatomic study

Background and objectivesBoth posterior quadratus lumborum (QL) and erector spinae plane (ESP) blocks have been described as new truncal interfascial plane blocks. Distribution of injectate is influenced by fascial anatomy;...

Comparing Ultrasound‐Guided and Unguided Lumbar Injection of Psoas Major Muscle for Clinical Management of Hip Flexor Spasticity

ObjectiveHip flexor spasticity, resulting from brain injury or neurological disorders, can result in decreases in range of motion, leading to joint immobility. Spasticity can be managed with Botulinum Toxin A (BT‐A) injections, which decreases muscle tone, thereby increasing range of motion. Psoas major (PM) plays a significant role in hip flexor spasticity and is targeted inferior to the inguinal ligament. However, at this location, only the illiacus muscle is injected as PM is tendinous. To target the muscle belly of PM, a lumbar approach must be used. This approach has been described in the literature, yet has been rarely used for BT‐A injection due to the perceived risk to vascular structures (abdominal aorta and inferior vena cava (IVC)), lumbar plexus, and/or kidney. The lumbar approach has been performed with and without image guidance, yet potential injury to adjacent structures has not been assessed. The purpose of this cadaveric study was to compare ultrasound (US) guided and non‐guided PM lumbar injection to assess the injectate spread, location and proximity to adjacent structures.Methods8 lightly embalmed specimens were injected bilaterally with 2ml of toluidine blue; on one side using US guidance, and on the other no guidance (unguided). The abdominal contents were removed to expose the structures of the posterior abdominal wall. Extramuscular dye spread was noted. The following were digitized (Microscribe® MLX Digitizer) and reconstructed into 3D models (Autodesk® Maya®): quadratus lumborum, iliacus, PM, great vessels, and vertebral column. The volume of PM was serially dissected at the fiber bundle level to allow digitization of the dye spread. The extent, location of dye spread was documented relative to the great vessels. Descriptive statistics were used to characterize and compare the US‐guided and unguided approaches.ResultsThe dye was found in PM in all US‐guided specimens. No intramuscular dye spread was found in 4/8 specimens using the unguided approach. The US‐guided specimens had a mean area of dye spread of 24.4 ± 2.8 cm2 whereas the unguided specimens had a mean area of 54.2 ± 28.0 cm2. The dye (guided approach) was located consistently between the superior margin of vertebral body of L3 and inferior margin of vertebral body of L4, whereas the unguided approach had its dye localized between vertebral bodies of L4 and L5. The mean distance of dye spread from: 1) the aorta was 3.19 ± 1.24cm (US‐guided approach) and 1.40 ± 0.0002cm (unguided approach), 2) the IVC was 1.81 ± 0.38cm (US‐guided approach) and 2.79 ± 0.11cm (unguided approach). There was no dye spread to the kidney using either US‐guided or unguided approaches, however the lumbar plexus was stained in 2/8 specimens using the unguided approach.ConclusionsThe US‐guided lumbar approach was found to target PM more consistently, with greater distance from the aorta than the unguided approach. This cadaveric study demonstrates that the US‐guided approach may have distinct advantages over the unguided approach, however this needs to be further investigated in the clinic.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Influence of fuel injection strategies on efficiency and particulate emissions of gasoline and ethanol blends in a turbocharged multi-cylinder direct injection engine

The effects of a broad range of fuel injection strategies on thermal efficiency and engine-out emissions (CO, total hydrocarbons, NOx and particulate number) were studied for gasoline and ethanol fuel blends. A state-of-the-art production multi-cylinder turbocharged gasoline direct injection engine equipped with piezoelectric injectors was used to study fuels and fueling strategies not previously considered in the literature. A large parametric space was considered including up to four fuel injection events with variable injection timing and variable fuel mass in each injection event. Fuel blends of E30 (30% by volume ethanol) and E85 (85% by volume ethanol) were compared with baseline E0 (reference grade gasoline). The engine was operated over a range of loads with intake manifold absolute pressure from 800 to 1200 mbar. A combined application of ethanol blends with a multiple injection strategy yielded considerable improvement in engine-out particulate and gaseous emissions while maintaining or slightly improving engine brake thermal efficiency. The weighted injection spread parameter defined in this study, combined with the weighted center of injection timing defined in the previous literature, was found well suited to characterize multiple injection strategies, including the effects of the number of injections, fuel mass in each injection and the dwell time between injections.

A Prospective Comparison of CT-Epidurogram Between Th1-Transforaminal Epidural Injection and Th1/2-Parasagittal Interlaminar Epidural Injection for Cervical Upper Limb Pain

Background: Cervical epidural injections for treating neck and upper limb pain are performed by 2 methods: transforaminal and interlaminar. Many serious complications caused by inadvertent intravascular injection have been reported with the use of cervical transforaminal epidural steroid injection through the anterior-lateral approach. Despite international practical guidelines that have been proposed, cervical transforaminal epidural injection is still less recommended than cervical interlaminar epidural injection. Objectives: The objective of this study is to introduce Th1-transforaminal epidural injection (Th1- TFEI) through the posterior-lateral approach, compare the injectate spread in Th1-TFEI with that of Th1/2-parasaggital interlaminar epidural injection (Th1/2-pILEI), and clarify the clinical characteristics of Th1-TFEI. Study Design: This research involved a prospective study of 30 patients receiving both Th1-TFEI and Th1/2-pILEI. Methods: Thirty patients with unilateral upper limb pain were enrolled for this prospective study. Th1-TFEI and Th1/2-pILEI were administered on each case in random order under fluoroscopy, and computed tomographic (CT) epidurograms were compared. Changes in circulatory dynamics, presence of Horner’s syndrome, changes in the Numerical Rating Scale (NRS-11), and adverse events were investigated. Results: Patients included 15 men and 15 women and included 24 cases of cervical spine disease and 6 cases with other upper limb pain. The Th1-TFEI group had significantly higher rates of “Th1 root filling” (100%), “ventral spread” (70.0%), and “lateral limitation” (26.7%) compared to the Th1/2-pILEI group. In the Th1-TFEI group, cephalad spread averaged 2.97 vertebral bodies, reaching approximately up to C6. The Th1/2-pILEI group had an average of 4.76 vertebral bodies, approximately up to C4. The 2 groups showed significant differences in cephalad spread. Horner’s syndrome appeared in the Th1-TFEI group at a rate of 56.7%, significantly higher than that in the Th1/2-pILEI group at 17.2%. The presence of Horner’s syndrome showed significant correlations with “ventral spread” and “spread up to C6.” There were no significant differences in NRS-11 improvement and changes in circulatory dynamics between the groups. There were no major complications. Limitations: The components of injectate were standardized; however, the needle gauge numbers were varied. In addition, interpretation of the CT-epidurogram was not blinded. The sample size was small; therefore, multivariate analysis was not possible. Conclusions: CT-epidurogram comparison revealed that Th1/2-pILEI was not localized on the injection side, and there was better dorsal spread – although ventral spread was small. Contrarily, Th1-TFEI was localized on the injection side, and better ventral spread was shown while cephalad spread was limited. We expected the addition of a sympathetic block effect suggested by the Horner’s syndrome as well as the merits of the ventral spread. However, short-term clinical effects were equal to those of Th1/2 pILEI. In future research, we need to standardize the diseases to include and to increase the number of cases to enable evaluation of clinical effectiveness.Key words: Epidural, cervical, transforaminal, interlaminar, fluoroscopy, CT-epidurogram, dorsal, ventral, cephalad, Horner’s syndrome

MuRF1 and MuRF2 are key players in skeletal muscle regeneration involving myogenic deficit and deregulation of the chromatin‐remodeling complex

AbstractBackgroundSkeletal muscle regeneration is a powerful and highly synchronized process and it is well described that intracellular pathways related to anabolic responses are readily activated. On the other hand, the role of catabolic pathways in the skeletal muscle regenerative response is much less understood. In the present study, we hypothesized that MuRF1, a key gene involved in skeletal muscle mass loss, and its close counterpart MuRF2 play a role in skeletal muscle regeneration.Methods and resultsWild type, single MuRF1 knock out, single MuRF2 knock out and double MuRF1&amp;2 dKO mice had their tibialis anterior muscle injured by a single round of 4 sequential injections of cardiotoxin (CTX‐10ūM, 5ūl each injection) spread along the length of the muscle. The animals were killed after 1, 3, 10 and 28 days after injury and the muscles were used to address general histology, satellite cells, myogenic markers and apoptosis. In addition, we silenced MuRF1 and MuRF2 in a primary myogenic cell culture to evaluate myogenesis and BAF57, a SWI/SNF chromatin‐remodeling complex component. Finally, we employed Chromatin Immuno Precipitation assays to investigate whether MuRF1 associates with the myogenic promoters MyoD and myogenin. After cardiotoxin (CTX) injection, MuRF1 and MuRF2 expression was strongly increased and spread out inside the remaining fibers and also along satellite cells. In line with a critical role during regeneration, MuRF1&amp;2 dKO deficient injured muscles were unable to properly regenerate. In addition, dKO injured muscle failed to express activators of the myogenic program, Myf‐5, FHL2 and MARP2, while myogenin levels were normally increased. Accordingly, siRNA reduced levels of MuRF1 and MuRF2 caused a severe myogenic deficit in primary myogenic cells, without any proliferation deficiency. Finally, in MuRF1&amp;2 siRNA knockdown studies and Chromatin Immuno Precipitation analysis of primary myogenic cultures we have shown an impaired nuclear clearance of BAF57 and a shortage in chromatin remodeling as a likely mechanism underlying the deficient myogenic differentiation.ConclusionIn summary, our results indicate a key cooperative role of the E3 ligases MuRF1 and MuRF2 in skeletal muscle regenerative response and myogenesis by inducing chromatin opening at myogenic promoters after BAF57 removal during muscle regeneration.

Comparing the injectate spread and nerve involvement between different injectate volumes for ultrasound-guided greater occipital nerve block at the C2 level: a cadaveric evaluation

PurposeThe spread patterns between different injectate volumes have not yet been investigated in ultrasound-guided greater occipital nerve (GON) block at the C2 level. This cadaveric study was undertaken to compare the spread pattern and nerve involvements of different volumes of dye using this technique.Materials and methodsAfter randomization, ultrasound-guided GON blocks with 1 or 5 mL dye solution were performed at the C2 level on the right or left side of five fresh cadavers. The suboccipital regions were dissected, and nerve involvement was investigated.ResultsTen injections were successfully completed. In all cases of 5 mL dye, we observed the deeply stained posterior neck muscles, including the suboccipital triangle space. The suboccipital and third occipital nerves, in addition to GONs, were consistently stained when 5-mL dye was used in all injections (100%). Although all GONs were successfully stained in the 1-mL dye cases, three of five injections (60%) concomitantly stained the third occipital nerves.ConclusionThe clinical efficacy of this technique using the 5-mL injectate seems unlikely to arise from the blockade of GON alone. Instead, its efficacy likely arises from the blockade of most nerves originating from the dorsal ramus of the upper cervical spinal nerve at the suboccipital area. Even using 1 mL of injectate may not guarantee blockade of the GON alone.

Interspace between Popliteal Artery and posterior Capsule of the Knee (IPACK) Injectate Spread: A Cadaver Study

Local anesthetic injection into the interspace between the popliteal artery and the posterior capsule of the knee (IPACK) has the potential to provide motor-sparing analgesia to the posterior knee after total knee arthroplasty. The primary objective of this cadaveric study was to evaluate injectate spread to relevant anatomic structures with IPACK injection. After receipt of Institutional Review Board Biospecimen Subcommittee approval, IPACK injection was performed on fresh-frozen cadavers. The popliteal fossa in each specimen was dissected and examined for injectate spread. Ten fresh-frozen cadaver knees were included in the study. Injectate was observed to spread in the popliteal fossa at a mean ± SD of 6.1 ± 0.7 cm in the medial-lateral dimension and 10.1 ± 3.2 cm in the proximal-distal dimension. No injectate was noted to be in contact with the proximal segment of the sciatic nerve, but 3 specimens showed injectate spread to the tibial nerve. In 3 specimens, the injectate showed possible contact with the common peroneal nerve. The middle genicular artery was consistently surrounded by injectate. This cadaver study of IPACK injection demonstrated spread throughout the popliteal fossa without proximal sciatic involvement. However, the potential for injectate to spread to the tibial or common peroneal nerve was demonstrated. Consistent surrounding of the middle genicular artery with injectate suggests a potential mechanism of analgesia for the IPACK block, due to the predictable relationship between articular sensory nerves and this artery. Further study is needed to determine the ideal site of IPACK injection.

Visualization of injectate spread of intercostal nerve block: a cadaveric study

IntroductionIntercostal nerve block and neurolysis are widely used procedures, but their injectate spread has not been well understood. Previous studies have reported unexpected outcomes (paravertebral or epidural anesthesia) and spinal cord injury after intercostal nerve block and neurolysis. To investigate a possible mechanism for these complications, we aimed to visualize the flow of liquid injected near the intercostal nerve, using cadavers.MethodsWe performed a simulated intercostal nerve block study using two Thiel-embalmed cadavers. Dye was injected into the interfascial plane between the internal and innermost intercostal muscles under ultrasound guidance (blue, 10 ml) or under direct vision (green, 5 ml).ResultsDye leakage began with injection of only 0.5–2 ml and occurred between the innermost intercostal muscle fibers. The dye injected around the intercostal nerve penetrated into the extrapleural space and reached the paravertebral space.ConclusionsInjectate placed around the intercostal nerve easily penetrate the extrapleural space and reach the paravertebral space. Intercostal nerve block or neurolysis has a risk of impairing at least the sympathetic chain and conceivably affecting the central nervous system.

Comparing the injectate spread and nerve involvement between different injectate volumes for ultrasound-guided greater occipital nerve block at the C2 level: a cadaveric evaluation.

The spread patterns between different injectate volumes have not yet been investigated in ultrasound-guided greater occipital nerve (GON) block at the C2 level. This cadaveric study was undertaken to compare the spread pattern and nerve involvements of different volumes of dye using this technique. After randomization, ultrasound-guided GON blocks with 1 or 5 mL dye solution were performed at the C2 level on the right or left side of five fresh cadavers. The suboccipital regions were dissected, and nerve involvement was investigated. Ten injections were successfully completed. In all cases of 5 mL dye, we observed the deeply stained posterior neck muscles, including the suboccipital triangle space. The suboccipital and third occipital nerves, in addition to GONs, were consistently stained when 5-mL dye was used in all injections (100%). Although all GONs were successfully stained in the 1-mL dye cases, three of five injections (60%) concomitantly stained the third occipital nerves. The clinical efficacy of this technique using the 5-mL injectate seems unlikely to arise from the blockade of GON alone. Instead, its efficacy likely arises from the blockade of most nerves originating from the dorsal ramus of the upper cervical spinal nerve at the suboccipital area. Even using 1 mL of injectate may not guarantee blockade of the GON alone.

The tendinous septum of the semispinalis capitis muscle spatially separates the dorsal ramus between C3 and C4.

Local anesthetic injection into the medial head of the semispinalis capitis muscle can anesthetize the greater occipital nerve (GON) and third occipital nerve (TON) simultaneously (greater and third occipital nerve block: GTO block). Alternatively, inter-semispinal plane (ISP) block can anesthetize the dorsal rami of the cervical spinal nerves from C4 to T4. The GON, TON, and the dorsal rami of the inferior level cannot be blocked with a single injection. To elucidate this phenomenon from an anatomical standpoint, we performed an ISP block either alone or with a GTO block using water-based acrylic dye in three thiel-embalmed cadavers. Both dyes were clearly separated by the tendinous septum running obliquely inside the semispinalis capitis muscle (SCA). The tendinous septum of the SCA may have a relatively strong connection with the dorsal edge of the semispinalis cervicis muscle, and this structure may stem the injectate spread. Therefore, the GON and TON, running through the medial head of the SCA, and the dorsal rami of the inferior level are spatially separated by the tendinous septum, and cannot be blocked with a single injection.

Rhomboid Intercostal and Subserratus Plane Block: A Cadaveric and Clinical Evaluation.

Fascial plane blocks are rapidly emerging to provide safe, feasible alternatives to epidural analgesia for thoracic and abdominal pain. We define a new option for chest wall and upper abdominal analgesia, termed the rhomboid intercostal and subserratus plane (RISS) block. The RISS tissue plane extends deep to the erector spinae muscle medially and deep to the serratus anterior muscle laterally. We describe a 2-part proof-of-concept study to validate the RISS block, including a cadaveric study to evaluate injectate spread and a retrospective case series to assess dermatomal coverage and analgesic efficacy. For the cadaveric portion of the study, bilateral ultrasound-guided RISS blocks were performed on 6 fresh cadavers with 30 mL of 0.5% methylcellulose with india ink. For the retrospective case series, we present 15 patients who underwent RISS block or RISS catheter insertion for heterogeneous indications including abdominal surgery, rib fractures, chest tube-associated pain, or postoperative incisional chest wall pain. In the cadaveric specimens, we identified staining of the lateral branches of the intercostal nerves from T3 to T9 reaching the posterior primary rami deep to the erector spinae muscle medially. In the clinical case series, dermatomal coverage was observed in the anterior hemithorax with visual analog pain scores less than 5 in patients who underwent both single-shot and continuous catheter infusions. Our preliminary cadaveric and clinical data suggest that RISS block anesthetizes the lateral cutaneous branches of the thoracic intercostal nerves and can be used in multiple clinical settings for chest wall and upper abdominal analgesia.

The spread of Injectate after ultrasound-guided lateral elbow injection \u2013 a cadaveric study

BackgroundInjections into the tendinous portion of the common extensor origin are a common intervention in the treatment of Lateral Elbow Tendinopathy (LET). Clinical trials report a heterogeneous selection of injectate volumes and delivery techniques, with systematic reviews finding no clear consensus. The aim of this study was to assess the intratendinous distribution and surrounding tissue contamination of ultrasound-guided injections into the Common Extensor Tendon (CET) of the elbow.MethodsTwenty cadaveric elbows were injected by a Consultant Radiologist under Ultrasound guidance. Elbows were randomised to equal groups of 1 or 3 mls of methylene blue injection, delivered using single shot or fenestrated techniques. Following injection, each cadaver underwent a dry arthroscopy and dissection of superficial tissues. The CET was excised, set and divided into 1 mm sections using microtome. Each slice was photographed and analysed to assess spread and pixel density of injectate in four colour graduations. The cross-sectional area of distribution was calculated and compared between groups.ResultsIn all 20 cadaveric samples, contamination of the joint was noted on arthroscopy and dissection. Injectate spread through over 97% of the cross-sectional area. No differences were found in intratendinous spread of injectate between differing volumes or techniques.ConclusionThis study found that commonly used injection volumes and techniques distribute widely throughout cadaveric CETs. There was no improvement when the volume was increased from 1 to 3 mls or between single shot of fenestrated injection techniques. It should be noted that joint contamination using these techniques and volumes may be inevitable.

Fascial layers influence the spread of injectate during ultrasound-guided infraclavicular brachial plexus block: a cadaver study

Fascial layers of the neurovascular sheath containing the brachial plexus influence distribution of local anaesthetic, hence increasing the risk of block failure when performing infraclavicular brachial plexus block (ICB). Ultrasound-guided infraclavicular brachial plexus block was performed on cadavers using a single injection technique with dye (20-30 ml). After injection, we carried out consecutive dissection of the neurovascular bundle to study dye injectate spread and identify the presence of fascial layers. Ultrasound video images (scout scan and injection) and recordings of dissections were evaluated by independent experts (regional anaesthetists and anatomists). Well defined fascial layers were identified at dissection in seven out of 12 infraclavicular spaces studied. These fascial layers impeded the spread of dye injectate substantially in six cases and partially in one case. No fascial layers were identified at dissection in five cases, in each of which the spread of injectate was complete throughout the neurovascular bundle. The sensitivity and specificity of ultrasonography and haptic sensation for detection of fascial layers were poor. When fascial layers are present in the neurovascular sheath, they impede the spread of injectate during infraclavicular brachial plexus block. Ultrasound detection of these fascial layers is unreliable in cadavers. These findings support the use of greater volumes of injectate or a multiple injection technique when performing this block.

Cadaveric Evaluation of Different Approaches for Quadratus Lumborum Blocks.

Background A quadratus lumborum (QL) block is an abdominal truncal block technique that primarily provides analgesia and anaesthesia to the abdominal wall. This cadaveric study was undertaken to compare the dye spread between different needle approaches for ultrasound-guided QL blocks in soft-embalmed cadavers. Methods After randomization, an experienced anesthesiologist performed two lateral, three posterior, and five alternative QL blocks on the left or right sides of five cadavers. The target injection point for the alternative approach was the lumbar interfascial triangle, same as that of conventional posterior QL block, with a different needle trajectory. For each block, 20 ml of dye solution was injected. The lumbar region and abdominal flank were dissected. Results Ten blocks were successfully performed. Regardless of the approach used, the middle thoracolumbar fascia was deeply stained in all blocks, but the anterior layer was less stained. The alternative approach was more associated with spread of injectate to the transversus abdominis and transversalis fascia plane. Despite accurate needle placement, all lateral QL blocks were associated with a certain amount of intramuscular or subcutaneous infiltration. Two posterior QL blocks showed a deeply stained posterior thoracolumbar fascia, and one of them was associated with obvious subcutaneous staining. The subcostal, iliohypogastric, and ilioinguinal nerves were mostly involved, but the thoracic paravertebral space and lumbar plexus were not affected in all blocks. Conclusions The alternative approach for QL blocks was able to achieve a comparable extent when compared to the conventional approach.