Ultrasound-Guided Sacral Erector Spinae Plane Block: A Feasible Option for Pain Management During Magnetic Resonance Imaging: A Case Report.

Inability to remain motionless owing to pain during magnetic resonance imaging (MRI) may increase the need for sedation and analgesia. Here, we present a case where ultrasound-guided sacral erector spinae plane block (ESPB) was used successfully for pain management during an MRI in a patient suffering from severe sacral pain. Sacral ESPB was performed with a total of 30 mL of 0.25% bupivacaine at the level of the intermediate sacral crest. The patient achieved sensory block in the L5-S4 dermatomes without motor block, resulting in complete pain relief. This case report highlights the feasibility of ultrasound-guided sacral ESPB as a potential pain management technique.

A novel comparison of erector spinae plane block and paravertebral block in laparoscopic cholecystectomy.

OBJECTIVE: Erector spinae plane block is an updated method than paravertebral block, possessing a lower risk of complications. This study aimed to compare erector spinae plane and paravertebral blocks to safely reach the most efficacious analgesia procedure in laparoscopic cholecystectomy cases. METHODS: The study included 90 cases, aged 18-70 years, classified as American Society of Anesthesiologists I-II, who underwent an laparoscopic cholecystectomy procedure. They were randomly separated into three groups, namely, Control, erector spinae plane, and paravertebral block. No block procedure was applied to Control, and a patient-controlled analgesia device was prepared containing tramadol at a 10 mg bolus dose and a 10-min locked period. The pain scores were recorded with a visual analog scale for 24 h postoperatively. RESULTS: The visual analog scale values at 1, 5, 10, 20, and 60 min at rest and 60 min coughing were found to be significantly higher in Control than in paravertebral block. A significant difference was revealed between Control vs. paravertebral block and paravertebral block vs. erector spinae plane in terms of total tramadol consumption (p=0.006). Total tramadol consumption in the first postoperative 24 h was significantly reduced in the paravertebral block compared with the Control and erector spinae plane groups. CONCLUSION: Sonography-guided-paravertebral block provides sufficient postoperative analgesia in laparoscopic cholecystectomy surgery. Erector spinae plane seems to attenuate total tramadol consumption.

Comparisons in analgesic effects between ultrasound-guided erector spinae plane block and surgical intercostal nerve block after video-assisted thoracoscopic surgery: A randomized controlled trial.

STUDY OBJECTIVE: This study aimed to compare the analgesic effects of anesthesiologist-administrated erector spinae plane block (ESPB) and surgeon-administrated intercostal nerve block (ICNB) following video-assisted thoracoscopic surgery (VATS). DESIGN: Randomized, controlled, double-blinded study. SETTING: Operating room, postoperative recovery room and ward in two centers. PATIENTS: One hundred patients, ASA I-III and scheduled for elective VATS. INTERVENTIONS: The anesthesiologist-administrated ESPB under ultrasound guidance or surgeon-administrated ICNB under video-assisted thoracoscopy was randomly provided during VATS. Regular oral non-opioid analgesic combined with intravenous rescue morphine were prescribed for multimodal analgesia after surgery. MEASUREMENTS: The primary outcomes were the pain score and morphine consumption during 48 h after surgery. Postoperative pain intensity were assessed using the 10-cm visual analogue scale at 1 h, 24 h, and 48 h after surgery. Morphine consumption at these time points was compared between the two study groups. Furthermore, oral weak opioid rescue analgesic was also provided at 24 h after surgery. Postoperative quality of recovery at 24 h was also assessed using the QoR-15 questionnaire, along with duration of chest tube drainage and hospital stay were compared as secondary outcomes. MAIN RESULTS: Patients in the two study groups had comparable baseline characteristics, and surgical types were also similar. Postoperative VAS changes at 1 h, 24 h, and 48 h after surgery were also comparable between the two study groups. Both groups had low median scores (<4.0) at all time points (all p > 0.05). Patients in the ESPB group required statistically non-significant higher 48-h morphine consumption [3 (0-6) vs. 0 (0-6) mg in the ESPB group and ICNB group respectively; p = 0.135] and lower numbers of oral rescue analgesic (0.4 ± 1.2 vs. 1.0 ± 1.8 in the ESPB group and ICNB group respectively; p = 0.059). Additionally, patients in the two study groups had similar QoR15 scores and lengths of hospital stay. CONCLUSIONS: Both anesthesiologist-administered ultrasound-guided ESPB and surgeon-administered VATS ICNB were effective analgesic techniques for patients undergoing VATS for tumor resection.

Effectiveness of erector spinae plane block in reducing opioid consumption after colorectal surgery: A comprehensive meta-analysis.

Despite the life-saving nature of colorectal surgeries, patients often experience intra and post-operative problems, especially pain and discomfort. This meta-analysis aimed to evaluate the effectiveness of erector spinae plane block (ESP block) in postoperative pain management for patients undergoing colorectal surgeries. A comprehensive systematic literature search was conducted in PubMed and Cochrane Library databases from inception until December 2023. Eight studies were deemed appropriate for inclusion. The pooled analysis demonstrated a significant decrease with the ESP block compared to the control group in postoperative opioid consumption [MD â€‹= â€‹-15.96 â€‹mg; 95 â€‹% CI (-28.74 to -3.18); p â€‹= â€‹0.014, I2 â€‹= â€‹87 â€‹%], intraoperative opioid consumption [MD â€‹= â€‹-35.51 â€‹mg; 95 â€‹% CI (-62.63 to -8.40); p â€‹= â€‹0.010, I2 â€‹= â€‹87 â€‹%], pain scores [MD â€‹= â€‹-0.94; 95 â€‹% CI (-1.27 to -0.60); p â€‹< â€‹0.000001, I2 â€‹= â€‹86 â€‹%], with a significantly shorter duration of hospital stay [MD â€‹= â€‹-1.25 days; 95 â€‹% CI (-2.02 to -0.48); p â€‹= â€‹0.002, I2 â€‹= â€‹23 â€‹%]. This meta-analysis support the use of erector spinae plane block (ESP) for postoperative pain management in colorectal surgeries. ESP shows significant reductions in opioid consumption, pain scores and hospital stay.

Analgesic Efficacy of Erector Spinae Plane Block in Pediatric Abdominal Surgery: Guidance with Conventional Method and NOL: Case Series.

Background: Erector spinae plane (ESP) block is a regional anesthesia technique that blocks both somatic and visceral nerve fibers. Despite its high analgesic potential, its mechanism of action is not yet fully understood. The ultrasound-guided ESP block, which can be easily performed, makes important contributions to the control of intraoperative pain in pediatric patients undergoing abdominal surgery. The follow-up of pain in the intraoperative period is usually done by evaluating the changes in hemodynamic parameters. Due to physiological differences in pediatric patients, it is more difficult to do this with only hemodynamic changes than in adult patients. Aim: The NOL® (Nociception Level) monitor calculates the nociception/pain score by evaluating many parameters through a proprietary algorithm. Our primary aim was to demonstrate the effectiveness of ESP block with an advanced pain monitor in this patient group; our secondary aim was to investigate the necessity of pain monitors in the pediatric patient group. Methods: In this case series, we applied intraoperative NOL® monitoring in addition to standard monitoring (ECG, SpO2, heart rate, EtCO2) in pediatric patients (16 cases) who were scheduled for abdominal surgery and underwent ESP block. Results: Considering the hemodynamic data, NOL values, postoperative pain scores, side effects, and complications, it was concluded that ESP block can be used safely in this patient group. Although the hemodynamic data and the NOL® index were compatible with each other after a nociceptive stimulus, the NOL index was less affected by other variables and gave the clinician clearer information about pain.

Convolutional neural networks for the automatic segmentation of lumbar paraspinal muscles in people with low back pain.

The size, shape, and composition of paraspinal muscles have been widely reported in disorders of the cervical and lumbar spine. Measures of size, shape, and composition have required time-consuming and rater-dependent manual segmentation techniques. Convolutional neural networks (CNNs) provide alternate timesaving, state-of-the-art performance measures, which could realise clinical translation. Here we trained a CNN for the automatic segmentation of lumbar paraspinal muscles and determined the impact of CNN architecture and training choices on segmentation performance. T2-weighted MRI axial images from 76 participants (46 female; age (SD): 45.6 (12.8) years) with low back pain were used to train CNN models to segment the multifidus, erector spinae, and psoas major muscles (left and right segmented separately). Using cross-validation, we compared 2D and 3D CNNs with and without data augmentation. Segmentation accuracy was compared between the models using the Sørensen-Dice index as the primary outcome measure. The effect of increasing network depth on segmentation accuracy was also investigated. Each model showed high segmentation accuracy (Sørensen-Dice index ≥ 0.885) and excellent reliability (ICC2,1 ≥ 0.941). Overall, across all muscles, 2D models performed better than 3D models (p = 0.012), and training without data augmentation outperformed training with data augmentation (p < 0.001). The 2D model trained without data augmentation demonstrated the highest average segmentation accuracy. Increasing network depth did not improve accuracy (p = 0.771). All trained CNN models demonstrated high accuracy and excellent reliability for segmenting lumbar paraspinal muscles. CNNs can be used to efficiently and accurately extract measures of paraspinal muscle health from MRI.

Erector spinae plane block vs. peri-articular injection for pain control after arthroscopic shoulder surgery: a randomised controlled trial.

Interscalene brachial plexus block is the standard regional analgesic technique for shoulder surgery. Given its adverse effects, alternative techniques have been explored. Reports suggest that the erector spinae plane block may potentially provide effective analgesia following shoulder surgery. However, its analgesic efficacy for shoulder surgery compared with placebo or local anaesthetic infiltration has never been established. We conducted a randomised controlled trial to compare the analgesic efficacy of pre-operative T2 erector spinae plane block with peri-articular infiltration at the end of surgery. Sixty-two patients undergoing arthroscopic shoulder repair were randomly assigned to receive active erector spinae plane block with saline peri-articular injection (n = 31) or active peri-articular injection with saline erector spinae plane block (n = 31) in a blinded double-dummy design. Primary outcome was resting pain score in recovery. Secondary outcomes included pain scores with movement; opioid use; patient satisfaction; adverse effects in hospital; and outcomes at 24 h and 1 month. There was no difference in pain scores in recovery, with a median difference (95%CI) of 0.6 (-1.9-3.1), p = 0.65. Median postoperative oral morphine equivalent utilisation was significantly higher in the erector spinae plane group (21 mg vs. 12 mg; p = 0.028). Itching was observed in 10% of patients who received erector spinae plane block and there was no difference in the incidence of significant nausea and vomiting. Patient satisfaction scores, and pain scores and opioid use at 24 h were similar. At 1 month, six (peri-articular injection) and eight (erector spinae plane block) patients reported persistent pain. Erector spinae plane block was not superior to peri-articular injection for arthroscopic shoulder surgery.

Role of erector spinae plane block in controlling functional abdominal pain: Case reports.

RATIONALE: Functional abdominal pain is an intractable medical condition that often reduces quality of life. Celiac plexus block is a representative intervention for managing intractable abdominal pain. However, celiac plexus block can be technically difficult to perform and carries the risk of potential complications. During erector spinae plane block (ESPB), the injectate can enter the paravertebral space and reach the sympathetic chain. If local anesthetics spread to the sympathetic chain that supplies fibers to the splanchnic nerve, abdominal pain theoretically could be reduced. PATIENT CONCERNS: Three patients suffered from abdominal pain of unknown cause, and no medical abnormalities were found in various examinations. DIAGNOSIS: As a result of collaboration with related medical departments, the abdominal symptoms of the patients were suspected to be functional abdominal pain. INTERVENTIONS: We successfully controlled symptoms by performing ESPB at the lower thoracic level in 3 patients with functional abdominal pain. OUTCOMES: After the procedure, the patients' abdominal pain improved significantly over several months. LESSONS: We suggest that lower thoracic ESPB could be an option for management of functional abdominal pain.

Nalbuphine and dexmedetomidine as adjuvants to ropivacaine in ultrasound-guided erector spinae plane block for video-assisted thoracoscopic lobectomy surgery: A randomized, double-blind, placebo-controlled trial.

BACKGROUND: Adjuvants to local anesthetics, such as nalbuphine and dexmedetomidine, can be used to improve the quality and duration of peripheral nerve block effects. Dexmedetomidine has been successfully used as an adjuvant of erector spinae plane block (ESPB) with ropivacaine in video-assisted thoracoscopic lobectomy surgeries (VATLS). This study aimed to compare the effects of nalbuphine and dexmedetomidine used as adjuvants to ropivacaine for ESPB in VATLS. METHODS: A total of 102 patients undergoing VATLS with ESPB were enrolled and randomized into 3 groups, each of which received a different adjuvant to ropivacaine. The visual analogue scale score, onset and duration of sensory block, use of patient-controlled analgesia (PCA), rate of rescue analgesia, duration of postoperative hospitalization, incidence of postoperative nausea and vomiting, and chronic pain were measured and observed. RESULTS: The visual analogue scale score, total PCA use, rate of rescue analgesia, and postoperative chronic pain in the ropivacaine with dexmedetomidine (RD), and ropivacaine with nalbuphine (RN) groups were lower than those in the ropivacaine (RC) group (P < .05). The duration of sensory block was longer and the first use of PCA occurred later in the RD and RN groups than they did in the RC group (P < .05). CONCLUSIONS: As an adjuvant to ropivacaine in ESPB, nalbuphine and dexmedetomidine are comparable in terms of the associated analgesia, sensory block duration, need for rescue analgesia, and incidence of chronic pain in patients after VATLS.

Safety of Erector Spinae Plane Blocks in Patients With Chest Wall Trauma on Venous Thromboembolism Prophylaxis.

BACKGROUND: Current guidelines for severe rib fractures recommend neuraxial blockade in addition to multimodal pain therapies. While the guidelines for venous thromboembolism prevention recommend chemoprophylaxis, these medications must be held for neuraxial blockade placement. Erector spinae plane block (ESPB) is a newly described block for thoracic pain control. Advantages include its quick learning curve and potential for less bleeding complications. We describe the use of ESPB for rib fractures in patients on chemoprophylaxis. We hypothesize that ESPB can be performed in this patient population without holding chemoprophylaxis. MATERIALS AND METHODS: This was a retrospective observational cohort study of a level 1 trauma center from 9/2016 to 12/2018. All patients with trauma with rib fractures undergoing neuraxial blockade or ESPB were included. Demographics, chemoprophylaxis and anticoagulation regimens, outcomes, and complications were collected. RESULTS: Nine hundred sixty-four patients with rib fracture(s) were admitted. Of these, 73 had a pain management consult. Thirteen had epidural catheters and 25 had ESPBs placed. There was no difference in demographics, injury patterns, bleeding complications, or venous thromboembolism rates among the groups. Patients with ESPB were less likely to have a dose of chemoprophylaxis held because of placement of a catheter (25% versus 100%, P < 0.00001). Three patients with ESPB were on oral anticoagulation on admission, and two were able to continue their regimen during placement. CONCLUSIONS: ESPB can be safely placed in patients on chemoprophylaxis. It should be considered over traditional blocks in patients with blunt chest wall trauma because of its technical ease and ability to be performed with chemoprophylaxis.

Erector spinae plane block in chronic pain management: a scoping review.

Chronic pain is reaching epidemic levels. Chronic pain represents a significant burden for patients, healthcare systems, and society, given its impact on quality of life, increased disability, and risk of hospitalization and mortality. Unmet needs of chronic pain management are also significant as only a small percentage of patients respond to medical (drug) therapy. Erector spinae plane block (ESPB) was rapidly adapted in clinical practice and numerous cases have been published assessing its effectiveness, but no systematic review of evidence on ESPB in chronic pain management is available. The purpose of this scoping review is to perform a comprehensive overview of existing evidence on ESPB in chronic pain management. We analyzed cases and case series reporting 43 patients. ESPB was performed in patients with severe pain and in all cases resulted in some degree of pain relief. However, because there was heterogeneity in mechanisms and underlying causes of chronic pain, preprocedural analgesic therapy, and pain assessment in reporting the cases, with the information currently available (case reports) we cannot make a definitive conclusion regarding efficacy and safety of ESPB in chronic pain management. Lack of homogeneity was present in medication use before the procedure, indicating a significant variation in how patients with chronic pain are managed. Variation in clinical practice can indicate the need to improve the quality of care to alleviate the chronic pain burden. Randomized controlled clinical trials are warranted to establish efficacy and safety of ESPB in chronic pain management.

Anatomo-sonographic identification of the longissimus capitis and splenius cervicis muscles: principles for possible application to ultrasound-guided botulinum toxin injections in cervical dystonia.

OBJECTIVE: The main objective of this study was to define and verify anatomo-sonographic landmarks for ultrasound-guided injection of botulinum toxin into the longissimus capitis (LC) and splenius cervicis (SC) muscles. METHODS AND RESULTS: After a preliminary work of anatomical description of the LC and SC muscles, we identified these muscles on two cadavers and then on a healthy volunteer using ultrasound and magnetic resonance imaging (MRI) to establish a radio-anatomical correlation. We defined an anatomo-sonographic landmark for the injection of each of these muscles. The correct positioning of vascular glue into the LC muscle and a metal clip into the SC muscle of a fresh cadaver as verified by dissection confirmed the utility of the selected landmarks. DISCUSSION: For the LC muscle, the intramuscular tendon of the cranial part of the muscle appears to be a reliable anatomical landmark. The ultrasound-guided injection can be performed within the cranial portion of the muscle, between the intra-muscular tendon and insertion into the mastoid process at dens of the axis level. For the SC muscle, the surface topographic landmarks of the spinous processes of the C4-C5 vertebrae and the muscle body of the levator scapulae muscle seem to be reliable landmarks. From these, the ultrasound-guided injection can be carried out laterally by transfixing the body of the levator scapulae. CONCLUSION: The study defined two cervical anatomo-sonographic landmarks for injecting the LC and SC muscles.

Bilateral Erector Spinae Plane Block for Postoperative Analgesia in Laparoscopic Cholecystectomy: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

BACKGROUND: Erector spinae plane (ESP) block is a novel regional anesthetic technique. Its application for postoperative analgesia has been increasing since 2016; however, its effectiveness remains uncertain and varies according to the type of surgery. This meta-analysis aimed to assess the analgesic efficacy of ESP block in patients undergoing laparoscopic cholecystectomy. METHODS: Literature searches of electronic databases and manual searches up to June 1, 2020 were performed. Review Manager Version 5.3 was used for pooled estimates. We included only randomized controlled trials (RCTs) in this meta-analysis. The random-effects meta-analysis model was used, and metaregression was applied when appropriate. RESULTS: A total of five RCTs consisting of 250 patients were included (124 in the ESP block group vs. 126 in the control group). Bilateral ESP block showed a significant reduction in postoperative intravenous opioid consumption reported up to 24 hours after surgery (mean difference [MD] = -4.46, 95% confidence interval [CI] [-5.50 to -3.42], P < 0.001) and in the time to first rescue analgesic (MD = 73.27 minutes, 95% CI [50.39 to 96.15], P < 0.001). According to the results of four studies, the postoperative pain score was lower in the ESP group compared with the control group at both rest and movement. There were no differences between the two groups as concerns nausea (odds ratio [OR] = 0.45, 95% CI [0.13 to 1.52], P = 0.20) and vomiting (OR = 0.37, 95% CI [0.10 to 1.35], P = 0.13). No block-related complications were noted. CONCLUSION: This meta-analysis showed that bilateral ultrasound-guided ESP block could be considered as an effective option to reduce opioid consumption and the time to first rescue analgesic and seems to be also a safe technique in adults undergoing laparoscopic cholecystectomy.

Diagnostic usefulness of denervation edema in the multifidus muscles using 3-Tesla magnetic resonance imaging in cervical radiculopathy.

BACKGROUND: Diagnosing cervical radiculopathy (CR) can be difficult because of symptomatic overlap with peripheral neuropathies. In this retrospective observational study, we aimed to determine whether short-tau inversion recovery (STIR) magnetic resonance imaging (MRI) sequences are useful for detecting signs of denervation in the multifidus muscles in patients with CR. METHODS: We analyzed the data of 18 patients with CR who developed arm weakness within 1 year. We also included 10 patients with sensorimotor symptoms involving the upper extremities who did not have intervertebral foraminal stenosis on MRI as controls. For each patient with CR, the signal intensity (SI) of the affected multifidus muscles was measured and compared to that on the contralateral side (signal intensity ratio: SIR). RESULTS: Control patients without CR did not exhibit STIR signal abnormalities in the multifidus muscles. Most of the 18 patients with CR were male (83.3%), and the mean age was 59.4 years. Thirteen of 18 CR patients (72.2%) were determined to have STIR signal abnormalities by a radiologist. The mean SIR in the 13 patients with increased SI was significantly higher than that in the five patients without signal abnormalities (1.23 vs 0.97, P = .004), supporting the radiologist's diagnosis. The distribution of signal abnormalities closely followed those identified via clinical and electrophysiological tests, especially severe weakness (P = .044). CONCLUSIONS: Denervation edema of the multifidus muscles can be detected in CR and correlates with clinical/electrophysiological tests and weakness severity, which may aid in CR diagnostics.

Bilateral Ultrasound-Guided Erector Spinae Plane Block Versus Transversus Abdominis Plane Block on Postoperative Analgesia after Total Abdominal Hysterectomy.

BACKGROUND: Transversus abdominis plane (TAP) blocks provide postoperative pain relief after various abdominal surgeries. Recently, erector spinae plane (ESP) block has obtained vast attention due to its simplicity and usage in truncal procedures. OBJECTIVES: This study aims to compare the ultrasound-guided bilateral ESP block versus bilateral TAP block on postoperative analgesia after open total abdominal hysterectomy. STUDY DESIGN: A prospective, double-blinded, randomized, controlled, clinical trial. SETTING: Zagazig University Hospitals. METHODS: After ending of surgical procedure and before reversing of the muscle relaxant, 48 women were randomly allocated into 2 equal groups: erector spinae (ES) group received bilateral ultrasound-guided ESP block with 20 mL of bupivacaine 0.375% plus 5 ug/mL adrenaline (1:200000) in each side at the level of T9, and transversus abdominis (TA) group received bilateral ultrasound-guided TAP block with the same volume of bupivacaine plus adrenaline. RESULTS: Visual Analog Scale scores at 30 minutes, 2, 4, 6, 8, 12, 16, 20, and 24 hours were statistically significantly lower in the ES group compared with the TA group. The time for requirement of first morphine was highly statistically significantly prolonged in the ES group (14.81 ± 3.52 hours) compared with the TA group (10.58 ± 2.35 hours). The total amount of morphine consumption in 24 hours postoperatively was statistically significantly decreased in the ES group; P = 0.01. Incidence of postoperative nausea and vomiting was higher but statistically insignificant in the TA group than the ES group. There were statistically significant numbers of unsatisfied patients (4) in the TA group compared with the ES group (no patient). LIMITATIONS: Sensorial evaluation of patients was not performed because both blocks had been done under general anesthesia but did not affect outcome. Therefore we recommend further studies comparing between both blocks. CONCLUSIONS: Bilateral ultrasound-guided ESP block provides more potent and longer postoperative analgesia with less morphine consumption than TAP block after open total abdominal hysterectomy. KEY WORDS: Abdominal hysterectomy, transversus abdominis plane block, erector spinae plane block, postoperative analgesia.

Evaluation of Sensory Mapping of Erector Spinae Plane Block.

BACKGROUND: Erector spinae plane (ESP) block is an effective regional analgesic technique for thoracic and abdominal pain. The volume of local anesthetic (LA) needed to produce sensory block in the spinal segment is unknown. OBJECTIVES: The aim of the present study was to examine the extent of dermatomal spread following ultrasound-guided administration of ESP block, with a fixed-volume dose of a LA at the midthoracic area for analgesia in acute thoracic pain patients. Secondary objectives were postprocedure analgesia and patient satisfaction. STUDY DESIGN: This research used a prospective unicentric exploratory cohort design. SETTING: The study was conducted at an academic university hospital. METHODS: A total of 18 patients with acute severe chest pain including rib fractures, thoracic postoperative rescue analgesia, zoster herpetic neuritis, and myofascial pain syndrome received ESP block under ultrasound guidance at the T5-T7 levels. Twenty mL of 0.5% plain bupivacaine was injected. Evaluation of the sensory block was carried out 60 minutes following the completion of the ESP block via a change in sensation to pinprick and cold methods. The Visual Analog Scale (VAS) for pain was recorded one hour after the procedure. Patient satisfaction was reported using a 4-point Likert scale. This study was registered with the clinicaltrials.gov database (identifier: NCT03831581). RESULTS: Sixteen patients had a successful ESP block; 2 patients were excluded for a failed block. The mean dermatomal spread was 9 (range, 8-11). VAS scores improved by at least 50% from baseline (P < .05), one hour after the ESP block. The degree of satisfaction reported by all patients on the Likert scale was 4 points. No major complications were observed. LIMITATIONS: This study was limited by its sample size. CONCLUSIONS: An ultrasound-guided ESP block with a single injection at the midthoracic level with 20 mL of 0.5% plain bupivacaine provides a mean dermatomal spread of 9 dermatomes (range, 8-11) with a high rate of analgesic efficacy and low incidence of adverse effects. KEY WORDS: Acute pain, dermatomal spread, erector spine plane nerve block, thoracic pain, thoracic postoperative analgesia.

The Novel Costotransverse Foramen Block Technique: Distribution Characteristics of Injectate Compared with Erector Spinae Plane Block.

BACKGROUND: The costotransverse foramen (CTF) is a space continuous with the paravertebral space. We hypothesized that injections passing through the CTF will result in a successful injectate spread to the paravertebral space. OBJECTIVES: We investigated patterns of dye spread to assess characteristics of neural blockade following ultrasound-guided CTF and erector spinae plane (ESP) injection in an anatomic and clinical study. STUDY DESIGN: Prospective cadaveric study, and case studies. SETTING: University hospital. METHODS: Six soft cadavers were studied. The boundaries of the CTF and the needle pathway of CTF injection were identified in the first cadaver. The CTF and ESP injections were performed on either the left or right sides of the T4 vertebral level in cadavers 2 to 6. Fifteen milliliters of 0.2% methylene blue was injected in each block, and the spread of dye was assessed by anatomic dissection. We also report 2 case studies of CTF and ESP blocks. RESULTS: Cadaver studies of CTF injection demonstrate that with injection to the inferior aspect of the base of the transverse process, the dye mainly passes anteriorly through the CTF into the paravertebral space, with minimal track-back to the deep back muscles. Consistent sensory blockade was achieved in 2 case studies. With the ESP injection, the spread of dye was observed cephalocaudad to the fascia of the erector spinae muscle, with no dye spreading within the paravertebral space in all cadavers. LIMITATIONS: Prospective case series. CONCLUSIONS: CTF block was consistently associated with a mainly anterior spread of injectate into the paravertebral space that involved the thoracic spinal nerves, and minimal posterior spread of injectate to the deep back muscles. KEY WORDS: Thoracic vertebrae, rib cage, paraspinal muscle, nerve block, joints.