Ultrasound-Guided Interventional Procedures in Pain Medicine: A Review of Anatomy, Sonoanatomy, and Procedures: Part I: Nonaxial Structures

Axillary nerve: what anesthesiologists and pain physicians should know

Innervation of the shoulder joint is complex and remains poorly understood among regional anesthesiologists and chronic pain specialists. Current literature supports the important contribution of the axillary nerve to the total innervation of the shoulder, as well as its blockade for perioperative pain and denervation for chronic shoulder pain. However, a description of the entire course of the axillary nerve, the corresponding optimal targets, and the sonoanatomy pertinent to pain intervention is lacking. This educational article discusses in detail the functional anatomy and sonographic identification of possible windows for axillary nerve intervention. We discuss the contribution, extent, and type of innervation the axillary nerve provides to the shoulder joint, which is often misunderstood. Ultimately, this article serves to stimulate thoughts and ideas for future research in an area where literature is scarce.

Use of corticosteroids for adult chronic pain interventions: sympathetic and peripheral nerve blocks, trigger point injections - guidelines from the American Society of Regional Anesthesia and Pain Medicine, the American Academy of Pain Medicine, the American Society of Interventional Pain Physicians, the International Pain and Spine Intervention Society, and the North American Spine Society

BACKGROUND

There is potential for adverse events from corticosteroid injections, including increase in blood glucose, decrease in bone mineral density and suppression of the hypothalamic-pituitary axis. Published studies note that doses lower than those commonly injected provide similar benefit.

METHODS

Development of the practice guideline was approved by the Board of Directors of American Society of Regional Anesthesia and Pain Medicine with several other societies agreeing to participate. The scope of guidelines was agreed on to include safety of the injection technique (landmark-guided, ultrasound or radiology-aided injections); effect of the addition of the corticosteroid on the efficacy of the injectate (local anesthetic or saline); and adverse events related to the injection. Based on preliminary discussions, it was decided to structure the topics into three separate guidelines as follows: (1) sympathetic, peripheral nerve blocks and trigger point injections; (2) joints; and (3) neuraxial, facet, sacroiliac joints and related topics (vaccine and anticoagulants). Experts were assigned topics to perform a comprehensive review of the literature and to draft statements and recommendations, which were refined and voted for consensus (≥75% agreement) using a modified Delphi process. The United States Preventive Services Task Force grading of evidence and strength of recommendation was followed.

RESULTS

This guideline deals with the use and safety of corticosteroid injections for sympathetic, peripheral nerve blocks and trigger point injections for adult chronic pain conditions. All the statements and recommendations were approved by all participants after four rounds of discussion. The Practice Guidelines Committees and Board of Directors of the participating societies also approved all the statements and recommendations. The safety of some procedures, including stellate blocks, lower extremity peripheral nerve blocks and some sites of trigger point injections, is improved by imaging guidance. The addition of non-particulate corticosteroid to the local anesthetic is beneficial in cluster headaches but not in other types of headaches. Corticosteroid may provide additional benefit in transverse abdominal plane blocks and ilioinguinal/iliohypogastric nerve blocks in postherniorrhaphy pain but there is no evidence for pudendal nerve blocks. There is minimal benefit for the use of corticosteroids in trigger point injections.

CONCLUSIONS

In this practice guideline, we provided recommendations on the use of corticosteroids in sympathetic blocks, peripheral nerve blocks, and trigger point injections to assist clinicians in making informed decisions.

Novel Bipolar High-Voltage Pulsed Radiofrequency Targeting the Cervical Sympathetic Chain for Treating Acute Herpetic Neuralgia

INTRODUCTION

Postherpetic neuralgia (PHN) in the oral, maxillofacial, neck, and upper limb regions is a refractory neuropathic pain and severely affects the quality of life of patients. Because of the absence of ideal treatments for this condition, relieving pain in the acute stage and preventing the occurrence of PHN are of great clinical significance. However, the optimal intervention for this acute herpetic neuralgia remains obscure.

OBJECTIVES

This study aimed to investigate whether bipolar high-voltage pulsed radiofrequency (PRF) targeting the cervical sympathetic chain could effectively treat acute herpetic neuralgia in the oral, maxillofacial, neck, and upper limb regions and reduce the incidence of PHN.

MATERIALS AND METHODS

A total of 60 patients with acute herpetic neuralgia in the oral, maxillofacial, neck, and upper limb regions were enrolled. The radiofrequency group (n = 30) received bipolar high-voltage PRF under ultrasound guidance at the level of the transverse processes of C6 and C7 to modulate the cervical sympathetic chain. In the sham group (n = 30), the electrodes were simply placed at the same position as in the radiofrequency group, but no radiofrequency energy was applied. The same treatment was repeated in each group after 72 hours. If patients were reported to have a visual analog scale (VAS) score ≥4, they would receive oral tramadol and gabapentin as rescue analgesics. The VAS score, Pittsburgh Sleep Quality Index (PSQI), 36-Item Short Form Health Survey (SF-36) score, use of tramadol and gabapentin, incidence of PHN, and adverse reactions were recorded to assess the effect and safety of therapy during three months of follow-up.

RESULTS

Decreased VAS scores, PSQI scores, and improved SF-36 scores were detected in the two groups at different time points after treatment (all p < 0.05). The VAS scores, PSQI scores, use of tramadol and gabapentin, and incidence of PHN were significantly lower, whereas the SF-36 scores were significantly higher in the radiofrequency group than in the Sham group (all p < 0.05). No serious adverseness related to the treatment was detected in either group.

CONCLUSIONS

Bipolar high-voltage PRF treatment targeting the cervical sympathetic chain could effectively relieve acute herpetic neuralgia in the oral, maxillofacial, neck, and upper limb regions and reduce PHN incidence. The efficacy and safety of this novel treatment make it worthy of recommendation for clinical application.

Ultrasound-Guided vs. Fluoroscopy-Guided Interventions for Back Pain Management: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

The objective of this study was to compare the outcomes of the ultrasound- and fluoroscopy-guided techniques in the management of back pain. Using PubMed, Scopus, and the Cochrane Library, we searched randomized controlled trials (RCTs) published before May 2023, which reported relevant data on the topic. The effectiveness of the ultrasound-guided (US-guided) and fluoroscopy-guided (FL-guided) approaches for back pain management was compared in terms of postoperative pain intensity, postoperative functional outcomes, and postoperative complications. Subgroup analyses were conducted for different postoperative periods. Eight studies were included in the analysis. There was no significant difference in post-procedural pain relief at one week, two weeks, one month, two months, and three months between the US-guided and FL-guided interventions for back pain management (SMD with 95% CI is -0.01 [-0.11, 0.10]), p = 0.91, I2 = 0%). In terms of the postoperative functional outcomes assessed by the "Oswestry Disability Index" (ODI) functionality score, the model tends to favor the FL-guided injections over the US-guided injections (SMD with 95% CI: 0.13 [-0.00, 0.25], p = 0.05, I2 = 0). Finally, the US-guided and FL-guided injections did not show significantly different results in terms of postoperative complications (RR with 95% CI is 0.99 [0.49, 1.99], p = 0.97, I2 = 0). The subgroup analysis also did not demonstrate differences between the US-guided and FL-guided techniques in the following outcomes: vasovagal reaction, transient headache, and facial flushing. There was no significant difference between the US-guided and FL-guided injections for treating back pain in terms of postoperative pain intensity and complications. Still, the model tends to favor the FL-guided injections over the US-guided injections in terms of functionality.

A Review of Stellate Ganglion Block as an Adjunctive Treatment Modality

Peripheral nerve blocks are becoming increasingly used as adjunctive treatment modalities for a variety of conditions refractory to medical management. Right or left stellate ganglion blocks (SGB) are a specific type of peripheral nerve block that target the sympathetic blockade of neuronal impulses using the injection of local anesthetic and steroids into nerve bundles in the cervical area. This review article is intended to summarize the common uses of stellate ganglion blocks and explain the procedural technique, which has evolved with technological advances in ultrasonography. The similarities between these disease processes are centered around sympathetic hyperactivity. This sympathetic overdrive state is created by increased levels of nerve growth factor (NGF), which causes a cascade of sympathetic sprouting resulting in increased norepinephrine (NE) systemically. Reversal of this cascade by local anesthetic injection into the stellate ganglion thereby reduces NGF and sympathetic sprouting subsequently lowering overall norepinephrine levels. This is the unifying theory by which SGB is able to provide resolution for the varied clinical conditions described in this article.  This review article discusses the physiology of several conditions where stellate ganglion blocks are being investigated as an adjunct treatment modality, including anosmia, PTSD, long-COVID, chronic fatigue syndrome, menopausal hot flashes, and ventricular tachyarrhythmias. Overall, the current literature supporting the use of stellate ganglion blocks for several esoteric conditions is limited; however, case reports to date have shown promising evidence-based results supporting their use as an adjunctive treatment among patients with refractory symptoms to existing treatment algorithms. In conclusion, SGB should be considered among patients with refractory symptoms for medical management in the conditions discussed in this article. Further research is needed to delineate which patients will benefit from the use of SGB, the use of subsequent blocks and timelines in between injections, and unilateral versus bilateral blockade.

Easy to treat when the diagnosis is made: Three cases of clunealgia and the advantage of ultrasonography

In this article, we present three cases of clunealgia admitted with low back pain. Their pain relieved with superior cluneal nerve block. The posterior side of the iliac crest, which is the location where the superior cluneal nerve passes, was identified using a high-frequency linear transducer. The drug injected separates the erector spinae muscle and thoracolumbar fascia and accumulates between these two structures. All patients were discharged with a complete pain relief. This report highlights the fact that superior cluneal nerve entrapment should be kept in mind in patients with low back pain and that ultrasound guidance can correctly identify the infiltration and eliminate anesthetization of other surrounding structures.

Intercostal Nerve Block Using an Innovative Intraneedle Ultrasound Transducer: A Proof-of-Concept study

Intercostal nerve block is a widely used and effective approach to providing regional anesthesia in the thoracic region for pain relief. However, during ultrasound-guided intercostal nerve block, inaccurate identification of the anatomic structures or suboptimal positioning of the needle tip may result in complications and blockade failure. In this study, we designed an intraneedle ultrasound (INUS) system and validated its efficacy in identifying anatomic structures relevant to thoracic region anesthesia. The 20-MHz INUS transducer comprised a single lead magnesium niobate-lead titanate crystal, and gain was set to 20 dB. It fit into a regular 18G needle and emitted radiofrequency-mode ultrasound signals at 1 mm from the needle tip. One hundred intercostal punctures were performed in 10 piglets. Intercostal spaces were identified by surface ultrasound or palpation and located by inserting and advancing the INUS transducer needle until the appropriate anatomy was identified. Blockade success was defined by ideal saline and dye spreading and confirmed by dissection. The pleura had a distinctive ultrasound signal, and successful detection of the intercostal muscles, endothoracic fascia and double-layered parietal and visceral pleura was achieved in all 100 puncture attempts. INUS allows real-time identification of intercostal structures and facilitates successful intercostal nerve blocks.

Retrospective evaluation of pain in patients with coccydynia who underwent impar ganglion block

Background

We aimed to evaluate pain scores one year after impar ganglion block in patients with coccydynia who did not benefit from conservative treatment.

Methods

The medical records of 29 patients with coccydynia were reviewed. Patients who were referred to the algology clinic and underwent impar ganglion blocks were retrospectively evaluated. Demographic data, time to the onset of pain, causes of pain, X-ray findings, administered invasive procedures, and visual analog scale (pain) scores were recorded.

Results

A total of 29 patients were included in the study, 10 males (34%) and 19 females (66%). The average age and body mass index were 53.45 ± 9.6 and 29.55 ± 4.21 respectively. In 21 patients, the onset of pain was associated with trauma. Nineteen patients (65.5%) had anterior coccygeal angulation. The average visual analog scale score before undergoing an impar ganglion block was 7.4 ± 1. After the procedure, the scores at < 3 months, 3–6 months and 6 months-1 year follow-up intervals were significantly lower (p < 0.05). Furthermore, visual analog scale scores at the 3–6 months and 6 months-1 year periods were significantly lower in patients who received diagnostic blocks plus pulse radiofrequency thermocoagulation than in patients who underwent a diagnostic block only.

Conclusions

The impar ganglion block provides effective analgesia without complications in patients with coccydynia. Pulse radiofrequency thermocoagulation combined with a diagnostic block prolongs the analgesic effect of the procedure.

Ultrasound practice for chronic pain procedures: A comprehensive review

Chronic pain management techniques have evolved in recent years. With regard to this, ultrasound (US) technology has become a standard for most acute pain procedures and essential for postsurgical pain relief and enhanced recovery after surgery protocols. This manuscript summarizes clinical studies evaluating US use for chronic pain management and compares efficacy with standard techniques including fluoroscopy (FL). US possesses several unique benefits when compared with FL, including elimination of radiation exposure while providing similar clinical outcomes. In summary, US use for chronic pain procedures is emerging as a viable, safe, and effective modality. Additional studies are needed to best appreciate US and its role in chronic pain management.

Tissue classification in intercostal and paravertebral ultrasound using spectral analysis of radiofrequency backscatter

Paravertebral and intercostal nerve blocks have experienced a resurgence in popularity. Ultrasound has become the gold standard for visualization of the needle during injection of the analgesic, but the intercostal artery and vein can be difficult to visualize. We investigated the use of spectral analysis of raw radiofrequency (RF) ultrasound signals for identification of the intercostal vessels and six other tissue types in the intercostal and paravertebral spaces. Features derived from the one-dimensional spectrum, two-dimensional spectrum, and cepstrum were used to train four different machine learning algorithms. In addition, the use of the average normalized spectrum as the feature set was compared with the derived feature set. Compared to a support vector machine (SVM) (74.2%), an artificial neural network (ANN) (68.2%), and multinomial analysis (64.1%), a random forest (84.9%) resulted in the most accurate classification. The accuracy using a random forest trained with the first 15 principal components of the average normalized spectrum was 87.0%. These results demonstrate that using a machine learning algorithm with spectral analysis of raw RF ultrasound signals has the potential to provide tissue characterization in intercostal and paravertebral ultrasound.

Evaluation of Ultrasound-guided Genitofemoral Nerve Block Combined with Ilioinguinal/iliohypogastric Nerve Block during Inguinal Hernia Repair in the Elderly

To evaluate the anesthetic effect of ultrasound-guided (USG) ilioinguinal/iliohypogastric nerve (II/IHN) block combined with genital branch of genitofemoral nerve (GFN) block in the elderly undergoing inguinal hernia repair, 54 old patients (aged 60-96years, ASA I-III) with indirect hernia were enrolled and scheduled for unilateral tension-free herniorrhaphy. Patients were grouped randomly to receive either USG II/IHN plus GFN block (Group G) or USG II/IHN block alone (Group I). The intraoperative visual analogue scale (VAS) scores were recorded at skin incision, at spermatic cord/round ligament traction and at sac ligation. The resting and dynamic VAS scores were recorded postoperatively. The requirements of extra sedatives and analgesics for intra- and postoperative analgesia were assessed. Occurrence of complications of the block, postoperative nausea and vomiting and femoral nerve palsy was also reported. Both groups showed similar sensory block. When stretching spermatic cord/round ligament, the patients in group G had significantly lower VAS scores than in group I. And group G used much fewer adjuvant sedatives and analgesics to achieve adequate anaesthesia. In addition, group G was presented with better intraoperative anaesthesia and lower postoperative dynamic VAS scores at all time points tested. No significant difference was found in the postoperative requirement of rescue medication. Both groups showed no complications related to the block and group G reported no femoral nerve palsy. The addition of GFN block to II/IHN block improves the quality of perioperative anesthesia and analgesia in the elderly and reduces the consumption of extra sedatives and analgesics during the surgery.

Ultrasound-guided Pulsed Radiofrequency in the Management of Thoracic Postherpetic Neuralgia: A Randomized, Double-blinded, Controlled Trial

OBJECTIVES

This study was designed to evaluate the efficacy and safety of ultrasound-guided pulsed radiofrequency (PRF) for the intercostal nerves (ICNs) in the management of thoracic postherpetic neuralgia.

METHODS

After 2 weeks of treatment by pregabalin 150 mg/12 hours, patients were randomly allocated into 2 groups. The PRF group, after ultrasound-guided localization of the ICN of the affected thoracic dermatome, sensory stimulation of the ICN was tested. Thereafter, the patient received 2 cycles PRF at 42°C temperature, for 120 seconds. The sham group, after stimulation, the same time was spent to mimic PRF. The same procedures were repeated to the upper and lower adjacent ICNs. Pain intensity using Visual Analogue Scale (VAS), and total analgesics consumption were assessed at the baseline, every 2 weeks for 6 months then after 9 and 12 months. The duration of effective pain relief was recorded. Quality of life was evaluated using self-evaluation questionnaires (SF-36) at baseline then after 1, 3, 6, and 12 months.

RESULTS

PRF group expressed a significant decrease on the VAS throughout the study period. VAS<30 was reported in the PRF group until the 22nd week. Pregabalin and acetaminophen consumption was significantly lower in the PRF group. The 8 domains of the SF-36 revealed a significant improvement in the PRF group when compared with the sham group throughout the study period except for the physical role which displayed nonsignificant improvement.

CONCLUSIONS

Ultrasound-guided PRF for ICNs in combination with pharmacotherapy seems to be a safe and effective treatment modality for postherpetic neuralgia.

Effect of Stellate Ganglion Block on the Regional Hemodynamics of the Upper Extremity: A Randomized Controlled Trial

BACKGROUND

The success of stellate ganglion block (SGB) is traditionally determined on the basis of findings such as Horner's syndrome, temperature rise in the face, hyperemia of the tympanic membrane, and nasal congestion. However, decreases in vascular resistance and increases in blood flow in the arm may be more meaningful findings. To date, the effect of SGB on the regional hemodynamics of the arm has not been evaluated using pulsed-wave Doppler ultrasound.

METHODS

A total of 52 patients who were to undergo orthopedic surgery of the forearm were randomly assigned to either the mepivacaine group (SGB with 5 mL of 0.5% mepivacaine) or the saline group (SGB with 5 mL of normal saline). Before surgery, a single anesthesiologist performed a SGB under ultrasound guidance. The temperature of the upper extremity and the resistance index and blood flow in the brachial artery were measured before SGB, 15 and 30 minutes after SGB, and 1 hour after surgery. The severity of pain, requirement for rescue analgesics, and side effects of the local anesthetic agent were all documented.

RESULTS

After SGB, the resistance index decreased significantly and the blood flow increased significantly in the brachial artery of members of the mepivacaine group (15 minutes: P = .004 and P < .001, respectively; 30 minutes: P < .001 and P < .001, respectively). However, these values normalized after surgery. The severity of pain, need for rescue analgesics, and incidence of adverse effects were not significantly different between the 2 groups.

CONCLUSIONS

Although SGB did not decrease the pain associated with forearm surgery, ultrasound-guided SGB did increase blood flow and decrease vascular resistance in the arm. Therefore, pulsed-wave Doppler may be used to monitor the success of SGB.

A prospective study to evaluate the efficacy of ultrasound-guided ganglion impar block in patients with chronic perineal pain

BACKGROUND

The blockade of the ganglion impar has been described to relieve the intractable perineal pain of sympathetic origin in patients with coccydynia. Chronic perineal pain (CPP) has been effectively managed by ganglion impar block. The feasibility, safety, and efficacy of ultrasound (US)-guided ganglion impar block by transsacrococcygeal approach was analyzed in the present study.

METHODS

A total of 15 patients with CPP were administered US-guided ganglion impar block using out of plane approach. Patients were followed for VAS and quality of life using Karnofsky performance status (KS), Linear Analog Scale Assessment (LASA), and constipation score up to 2 months at different time intervals. Time required to perform the procedure, number of attempts, and any complications were also noted.

RESULTS

The mean time required to perform the procedure was 7.67 ± 1.23 min. There were no adverse events. All the patients had significant pain relief during 2 month follow-up (P < 0.05 compared to baseline VAS). The KS and LASA score improved post block which was statistically significant. The dose of nonsteroidal anti-inflammatory drugs (NSAIDS) decreased from preblock state with statistically significant difference, while the difference in dose of tramadol and morphine was statistically insignificant.

CONCLUSION

US-guided ganglion impar block is technically feasible and safe technique. USG can be used to locate sacrococcygeal junction (SCJ) and facilitate the performance of ganglion impar block. The efficacy and safety of the US-guided ganglion impar blockades needs a proper evaluation in the randomized controlled trials.

Ultrasound- versus fluoroscopy-guided injections in the lower back for the management of pain: a systematic review

PURPOSE

Ultrasound-guided spinal injections are less common than fluoroscopy-guided injections. Although unable to penetrate bones, ultrasound guidance has a number of advantages including convenience and reduced exposure to ionizing radiation. However, it is not known how ultrasound-guided injections compare to fluoroscopy-guided injections in the management of lower back pain. Our objective is to systematically review the literature comparing ultrasound-guided injections to fluoroscopy-guided injections for the management of lower back pain.

METHODS

Medline, Cochrane CENTRAL Register of Controlled Trials, Embase, and NHSEED were searched from 2007 to September 26, 2017. Inclusion criteria included (1) randomized controlled trial design, (2) compared ultrasound-guided and fluoroscopy-guided injections for lower back pain, (3) dose and volume of medications injected were identical between trial arms, and (4) reported original data.

RESULTS

One hundred one unique records were identified, and 21 studies were considered for full-text inclusion. Nine studies formed the final data set. Studies comparing ultrasound- and fluoroscopy-guided injections for lower back pain management reported no difference in pain relief, procedure time, number of needle passes, changes in disability indices, complications or adverse events, post-procedure opioid consumption, or patient satisfaction.

CONCLUSION

Fluoroscopic guidance of injections for the management of lower back pain is similar in efficacy to ultrasound guidance. The exact role of ultrasound guidance needs to be further studied, especially for nerve root injections, where safety is the major concern.

KEY POINTS

• There were no differences in pain relief, procedure time, number of needle passes, changes in disability indices, complications or adverse events, post-procedure opioid consumption, or patient satisfaction between ultrasound- and fluoroscopy-guided injections for the management of lower back pain. • Given the lack of evidence to demonstrate superior efficacy and the added harms with fluoroscopic guidance, ultrasound guidance may be the preferred method of guidance for injections to manage lower back pain in appropriate patients. Further study is required to understand the exact role of ultrasound in image-guided injections.

Effect of Ultrasound-Guided Intercostal Nerve Block Versus Fluoroscopy-Guided Epidural Nerve Block in Patients With Thoracic Herpes Zoster: A Comparative Study

OBJECTIVES

To compare the efficacy of a conventional fluoroscopy-guided epidural nerve block and an ultrasound (US)-guided intercostal nerve block in patients with thoracic herpes zoster (HZ).

METHODS

This work was a comparative study of 38 patients with thoracic HZ pain and a chest wall herpetic eruption, aged 18 years or older, with pain intensity of 5 or greater on a numeric rating scale (NRS) for less than a 1-month duration. Patients were consecutively enrolled and assigned to 2 groups in which the intervention was either the US-guided intercostal nerve block or the fluoroscopy-guided epidural nerve block approach with the addition of a 5-mL mix of 2.5 mg of dexamethasone plus 0.5% lidocaine. The primary outcome measure was the NRS score reduction for the pain. Secondary outcomes included the duration of treatment, number of repeated injections until the final visit, and proportion of patients with pain relief after the first and final visits.

RESULTS

All patients within both intervention groups showed significant pain relief on the NRS at the final follow-up point (P < .05). There was no significant difference in the mean value of NRS improvement based on the intervention type. There was also no statistically significant difference in the duration of treatment and the frequency of injection for pain relief.

CONCLUSIONS

These findings showed that both the US-guided intercostal nerve block and the fluoroscopy-guided epidural nerve block were effective in patients with thoracic HZ. Compared data showed no significant differences in the pain reduction, duration of treatment, and frequency of injection. The US-guided intercostal nerve block, which is more accessible than the fluoroscopy-guided epidural nerve block, might be an alternative option for thoracic HZ.

Echo-guided invasive pain therapy: indications and limitations

PURPOSE OF REVIEW

The purposes of this review are to summarize the advantages and limitations of ultrasound-guided pain interventions, and to illustrate those interventions with peripheral, axial and musculoskeletal pain procedures.

RECENT FINDINGS

With the capability of locating the interfascial plane, ultrasonography has led to the emergence of a series of plane blocks for the thoracoabdominal region in the recent decade.Ultrasonography for musculoskeletal procedures has been of growing interest because of the major advantage of direct visualization and scanning of various soft tissues and real-time spread in the injectate, thereby enhancing precision and efficacy, reducing risk of trauma and avoidance of radiation. For spine and intra-articular structures, ultrasonography is complicated by the bony shadow artefact and often deep location of the structure, making acquisition of ultrasound image challenging. Despite these difficulties, there is growing interest in applying ultrasonography for cervical spine and sacroiliac joint procedures.

SUMMARY

Pain intervention under ultrasound guidance is particularly valuable in peripheral and musculoskeletal procedures. There is growing interest of its application in cervical spine and sacroiliac joint. More outcome studies are required in the future to make ultrasound-guided pain intervention as the established procedure.

Spectral Analysis of Ultrasound Radiofrequency Backscatter for the Detection of Intercostal Blood Vessels

Spectral analysis of ultrasound radiofrequency backscatter has the potential to identify intercostal blood vessels during ultrasound-guided placement of paravertebral nerve blocks and intercostal nerve blocks. Autoregressive models were used for spectral estimation, and bandwidth, autoregressive order and region-of-interest size were evaluated. Eight spectral parameters were calculated and used to create random forests. An autoregressive order of 10, bandwidth of 6 dB and region-of-interest size of 1.0 mm resulted in the minimum out-of-bag error. An additional random forest, using these chosen values, was created from 70% of the data and evaluated independently from the remaining 30% of data. The random forest achieved a predictive accuracy of 92% and Youden's index of 0.85. These results suggest that spectral analysis of ultrasound radiofrequency backscatter has the potential to identify intercostal blood vessels. (jokling@siue.edu) © 2018 World Federation for Ultrasound in Medicine and Biology.

Retention of finger blood flow against postural change as an indicator of successful sympathetic block in the upper limb

Background

Sympathetic block in the upper limb has diagnostic, therapeutic and prognostic utility for disorders in the upper extremity that are associated with sympathetic disturbances. Increased skin temperature and decreased sweating are used to identify the adequacy of sympathetic block in the upper limb after stellate ganglion block (SGB). Baroreflexes elicited by postural change induce a reduction in peripheral blood flow by causing sympathetic vasoconstriction. We hypothesized that sympathetic block in the upper limb reduces the decrease in finger blood flow caused by baroreflexes stimulated by postural change from the supine to long sitting position. This study evaluated if sympathetic block of the upper limb affects the change in finger blood flow resulting from postural change. If change in finger blood flow would be kept against postural changes, it has a potential to be a new indicator of sympathetic blockade in the upper limb.

Methods

Subjects were adult patients who had a check-up at the Department of Pain Management in our university hospital over 2 years and 9 months from May 2012. We executed a total of 91 SGBs in nine patients (N=9), which included those requiring treatment for pain associated with herpes zoster in seven of the patients, tinnitus in one patient and upper limb pain in one patient. We checked for the following four signs after performing SGB: Horner’s sign, brachial nerve blockade, finger blood flow measured by a laser blood flow meter and skin temperature of the thumb measured by thermography, before and after SGB in the supine position and immediately after adopting the long sitting position.

Results

We executed a total of 91 SGBs in nine patients. Two SGBs were excluded from the analysis due to the absence of Horner’s sign. We divided 89 procedures into two groups according to elevation in skin temperature of the thumb: by over 1°C (sympathetic block group, n=62) and by <1°C (nonsympathetic block group, n=27). Finger blood flow decreased significantly just after a change in posture from the supine to long sitting position after SGB in both groups. In the sympathetic block group, the ratio of finger blood flow in the long sitting position/supine position with a change in posture significantly increased after SGB compared with before SGB (before SGB: range 0.09–0.94, median 0.53; after SGB: range 0.33–1.2, median 0.89, p<0.0001).

Conclusion

Our study shows that with sympathetic block in the upper limb, the ratio of finger blood flow significantly increases despite baroreflexes stimulated by postural change from the supine to long sitting position. Retention of finger blood flow against postural changes may be an indicator of sympathetic block in the upper limb after SGB or brachial plexus block.

Deep and superficial circumflex iliac arteries and their relationship to the ultrasound-guided femoral nerve block procedure: A cadaver study

The in-plane lateral to medial approach is a standard technique for ultrasound-guided femoral nerve block (USG-FNB). The first bifurcation of the femoral artery, which consists of the deep artery of the thigh (DAT) or occasionally the lateral circumflex femoral artery (LCFA), is regarded as the distal border for this procedure. We sometimes detect arteries along the estimated needle trajectory for USG-FNB. The superficial (SCIA) and deep (DCIA) circumflex iliac arteries run laterally parallel to the inguinal ligament from the femoral or external iliac artery. The relationship between the SCIA and DCIA and other anatomical structures related to USG-FNB around the femoral triangle region was studied by gross anatomical examination of 100 formalin-fixed adult cadavers. At least one SCIA and one DCIA were identified around each femoral triangle; 81.8% of SCIA and 58% of DCIA originated from the femoral artery. All DCIA coursed between the fascia lata and fascia iliaca and 80% of SCIA penetrated the fascia lata. In 94% of femoral triangles, at least one arterial branch heading towards the lateral part of the thigh originated from the femoral artery from the level of the inguinal ligament to the first bifurcation of the femoral artery. The presence of SCIA and DCIA should be considered during USG-FNB using the in-plane lateral to medial approach to avoid inadvertently injuring them, as they are occasionally located along the presumed needle trajectory superficial to the fascia iliaca. Clin. Anat. 30:413-420, 2017. © 2017 Wiley Periodicals, Inc.

Ultrasound-guided pulsed radiofrequency treatment of the cervical sympathetic chain for complex regional pain syndrome: A retrospective observational study

The stellate ganglion is a common target to manage neuropathic pain in the upper extremities. However, the effect duration of a single stellate ganglion block is often temporary. To overcome the short-term effects of a single sympathetic block, pulsed radiofrequency (PRF) can be applied. The aim of the present study was to investigate the efficacy of PRF on the cervical sympathetic chain under ultrasound guidance for complex regional pain syndrome (CRPS).Twelve CRPS patients who underwent PRF on the cervical sympathetic chain were enrolled in this retrospective analysis. Under ultrasound guidance, PRF was performed for 420 seconds at 42°C on the C6- and C7-level sympathetic chain.The pain intensity decreased significantly at 1 week after the procedure. Overall, 91.7% of patients experienced at least moderate improvement. A positive correlation was observed between the extent of pain reduction at 1 week after PRF and the degree of overall benefit (r = 0.605, P = 0.037). This reduction in symptoms was maintained for a mean of 31.41 ± 26.07 days after PRF. There were no complications associated with this procedure.PRF on the cervical sympathetic chain, which can be performed easily and safely under ultrasound guidance, should be considered an option for managing CRPS of the upper extremities.

Pain relief following thoracic surgical procedures: A literature review of the uncommon techniques

Thoracic surgical procedures can be either thoracotomy or thoracoscopy. In thoracotomy, the incision could be either muscle-cutting or muscle-sparing incision. The posterolateral thoracotomy incision is used for most general thoracic surgical procedures. This incision, which involves division of the latissimus dorsi and serratus anterior muscles, affords excellent exposure of the thoracic cavity. However, it is associated with significant morbidity, including impaired pulmonary function, postoperative chest pain, and restricted arm and shoulder movement. Various muscle-sparing incisions have been proposed to decrease the morbidity. Postthoracotomy pain originates from pleural and muscular damage, costovertebral joint disruption, and intercostal nerve damage during surgery. Inadequate pain relief after surgery affects the quality of patient's recovery and exposes the patients to postoperative morbidities. There is a tendency nowadays among thoracic surgeons and anesthesiologists toward the area of enhanced recovery after thoracic surgery which requires careful titration of the anesthetic drugs in awake patients undergoing thoracoscopic procedures. There is a common feeling among thoracic anesthesiologists that potthoracoscopy procedures produce less pain intensity versus thoracotomy which is partially true. However, effective management of acute pain following either thoracotomy/thoracoscopy is needed and may prevent these complications and reduce the likelihood of developing chronic pain. In this report, we are going to review the newly introduced postthoracotomy/thoracoscopy pain relief modalities with special reference to the new tendency of awake thoracic surgical procedures and its impact on enhanced recovery after surgery.

Ultrasound indications for chronic pain management: an update on the most recent evidence

PURPOSE OF REVIEW

The ability of ultrasound to provide detailed anatomic visualization while avoiding radiation exposure continues to make it an appealing tool for many practitioners of chronic pain management. This review will present the most recent evidence regarding the use of ultrasound-guidance for the performance of interventional procedures in the treatment of chronic pain.

RECENT FINDINGS

For a variety of different procedures, studies continue to compare ultrasound-guided techniques to commonly used fluoroscopic or landmark-based techniques. Small, randomized controlled trials are beginning to demonstrate that ultrasound-guided approaches to interventional pain procedures can be as well tolerated and effective as the traditionally used techniques, while providing some potential advantages in terms of decreased radiation exposure, avoidance of vascular structures, and in some cases, improved efficiency and decreased rates of adverse effects.

SUMMARY

Despite continued interest in ultrasound-guided techniques for chronic pain management procedures, the evidence is still limited mainly to small, randomized trials and case series. For some procedures, such as stellate ganglion block and peripheral joint injections, recent evidence appears to be tilting in favor of ultrasound-guidance as the preferred technique, though fluoroscopy continues to be a much more reliable method for detection of intravascular uptake of injectate.

Ultrasound-guided truncal blocks: A new frontier in regional anaesthesia

The practice of regional anaesthesia is rapidly changing with the introduction of ultrasound into the working domain of the anaesthesiologist. New techniques are being pioneered. Among the recent techniques, notable are the truncal blocks, for example, the transversus abdominis plane block, rectus sheath block, hernia block and quadratus lumborum block in the abdomen and the pectoral nerves (Pecs) block 1 and 2, serratus anterior plane block and intercostal nerve block. This narrative review covers the brief anatomical discourse along with technical description of the ultrasound-guided truncal blocks.

Ultrasound-guided interventional procedures for chronic pain management

Ultrasonography has multiple advantages over traditional radiologic imaging modalities when used for interventional procedures. It allows improved visualization of the anatomy while avoiding ionizing radiation and risks associated with contrast use. It has proved superiority at accuracy of delivery and procedural effectiveness over blind procedures when used in association with interventional pain procedures. Although limited in its ability to see through bony structures, ultrasound has utility in visualizing soft tissues and vascular structures in anatomic regions of interest resulting in increased use for posterior neuraxial, periaxial, peripheral nerve and joint-related structures. Current evidence for use in these settings is presented here. In some cases, optimal utility may be improved by combining ultrasonography with other imaging modalities.

A randomized comparison of the efficacy of 2 techniques for piriformis muscle injection: ultrasound-guided versus nerve stimulator with fluoroscopic guidance

BACKGROUND

Piriformis muscle injections are most often performed using fluoroscopic guidance; however, ultrasound (US) guidance has recently been described extensively in the literature. No direct comparisons between the 2 techniques have been performed. Our objective was to compare the efficacy and efficiency of fluoroscopic- and US-guided techniques.

METHODS

A randomized, comparative trial was carried out to compare the 2 techniques. Twenty-eight patients with a diagnosis of piriformis syndrome, based on history and physical examination, who had failed conservative treatment were enrolled in the study. Patients were randomized to receive the injection either via US or fluoroscopy. Injections consisted of 10 mL of 1% lidocaine with 80 mg of triamcinalone. The primary outcome measure was numeric pain score, and secondary outcome measures included functional status as measured by the Multidimensional Pain Inventory, patient satisfaction as measured by the Patient Global Impression of Change scale, and procedure timing characteristics. Outcome data were measured preprocedure, immediately postprocedure, and 1 to 2 weeks and 3 months postprocedure.

RESULTS

We found no statistically significant differences in numeric pain scores, patient satisfaction, procedure timing characteristics, or most functional outcomes when comparing the 2 techniques. Statistically significant differences between the 2 techniques were found with respect to the outcome measures of household chores and outdoor work.

CONCLUSIONS

Ultrasound-guided piriformis injections provide similar outcomes to fluoroscopically guided injections without differences in imaging, needling, or overall procedural times.

The American Society of Regional Anesthesia and Pain Medicine, the European Society of Regional Anaesthesia and Pain Therapy, and the Asian Australasian Federation of Pain Societies Joint Committee recommendations for education and training in ultrasound-guided interventional pain procedures

The use of ultrasound in pain medicine for interventional axial, nonaxial, and musculoskeletal pain procedures is rapidly evolving and growing. Because of the lack of specialty-specific guidelines for ultrasonography in pain medicine, an international collaborative effort consisting of members of the Special Interest Group on Ultrasonography in Pain Medicine from the American Society of Regional Anesthesia and Pain Medicine, the European Society of Regional Anaesthesia and Pain Therapy, and the Asian Australasian Federation of Pain Societies developed the following recommendations for education and training in ultrasound-guided interventional pain procedures. The purpose of these recommendations is to define the required skills for performing ultrasound-guided pain procedures, the processes for appropriate education, and training and quality improvement. Training algorithms are outlined for practice- and fellowship-based pathways. The previously published American Society of Regional Anesthesia and Pain Medicine and European Society of Regional Anaesthesia and Pain Therapy education and teaching recommendations for ultrasound-guided regional anesthesia served as a foundation for the pain medicine recommendations. Although the decision to grant ultrasound privileges occurs at the institutional level, the committee recommends that the training guidelines outlined in this document serve as the foundation for educational training and the advancement of the practice of ultrasonography in pain medicine.

Ultrasound-guided pain interventions - a review of techniques for peripheral nerves

Ultrasound has emerged to become a commonly used modality in the performance of chronic pain interventions. It allows direct visualization of tissue structure while allowing real time guidance of needle placement and medication administration. Ultrasound is a relatively affordable imaging tool and does not subject the practitioner or patient to radiation exposure. This review focuses on the anatomy and sonoanatomy of peripheral non-axial structures commonly involved in chronic pain conditions including the stellate ganglion, suprascapular, ilioinguinal, iliohypogastric, genitofemoral and lateral femoral cutaneous nerves. Additionally, the review discusses ultrasound guided intervention techniques applicable to these structures.

Ultrasound imaging of embedded shrapnel facilitates diagnosis and management of myofascial pain syndrome

Trigger points can result from a variety of inciting events including muscle overuse, trauma, mechanical overload, and psychological stress. When the myofascial trigger points occur in cervical musculature, they have been known to cause headaches. Ultrasound imaging is being increasingly used for the diagnosis and interventional management of various painful conditions. A veteran was referred to the pain clinic for management of his severe headache following a gunshot wound to the neck with shrapnel embedded in the neck muscles a few years prior to presentation. He had no other comorbid conditions. Physical examination revealed a taut band in the neck. An ultrasound imaging of the neck over the taut band revealed the deformed shrapnel located within the levator scapulae muscle along with an associated trigger point in the same muscle. Ultrasound guided trigger point injection, followed by physical therapy resolved his symptoms. This is a unique report of embedded shrapnel and coexisting myofascial pain syndrome revealed by ultrasound imaging. The association between shrapnel and myofascial pain syndrome requires further investigation.

Evaluation of sonoanatomy relevant to performing stellate ganglion blocks using anterior and lateral simulated approaches: an observational study

PURPOSE

Stellate (cervicothoracic) ganglion block (SGB) can be associated with serious complications, such as esophageal and vascular injury. The objective of this study was to evaluate the potential for vascular and esophageal injury in healthy subjects by examining the sonoanatomy of the neck relevant to the SGB at the sixth (C6) and seventh (C7) cervical vertebral levels and determining the incidence of blood vessels and esophagi in the simulated path of needle insertion in the conventional and two different ultrasound-guided approaches used to perform a SGB.

METHODS

Ultrasound scanning of the neck at the C6 and C7 cervical vertebral levels was performed in 100 adult subjects, and the following measurements were obtained: the degree of deviation of the esophagus relative to the larynx/trachea; the likelihood of encountering a vessel in the simulated path of needle insertion in the two different approaches to SGB; the incidence of the vertebral artery being situated outside the foramen transversarium at the C6 level; and the distance of the simulated path of needle insertion in the anterior and lateral approaches to SGB at the C6 level.

RESULTS

The position of the esophagus was found to be variable but lateral to the airway in 50% and 74% of the subjects at C6 and C7, respectively. The esophagus covered more than half of the distance between the airway and the carotid artery in 14% and 44% of the subjects at the C6 and C7 levels, respectively. With the anterior approach, a major vessel was observed in up to 29% and 43% of patients at the C6 and C7 levels, respectively. The vertebral artery was outside the foramen transversarium in 7% of subjects at the C6 level.

CONCLUSION

Major blood vessels and the esophagus are in close proximity to needle pathways during the anterior approach to SGB performed with either anatomic landmarking or fluoroscopic guidance. An ultrasound-guided lateral approach at the C6 level may possibly confer a greater margin of safety for performing SGB.

Ultrasound-guided combined intermediate and deep cervical plexus nerve block for regional anaesthesia in oral and maxillofacial surgery

OBJECTIVES

We examined the application of an ultrasound-guided combined intermediate and deep cervical plexus nerve block for regional anaesthesia in patients undergoing oral and maxillofacial surgery.

METHODS

A total of 19 patients receiving ultrasound-guided combined intermediate and deep cervical plexus anaesthesia followed by neck surgery were examined prospectively. The sternocleidomastoid and the levator of the scapula muscles as well as the cervical transverse processes were used as easily depicted ultrasound landmarks for the injection of local anaesthetics. Under ultrasound guidance, a needle was advanced in the fascial band between the sternocleidomastoid and the levator of the scapula muscles and 15 ml of ropivacaine 0.75% was injected. Afterwards, the needle was advanced between the levator of the scapula and the hyperechoic contour of the cervical transverse processes and a further 15 ml of ropivacaine 0.75% was injected. The sensory block of the cervical nerve plexus, the analgesic efficacy of the block within 24 h after injection and potential block-related complications were assessed.

RESULTS

All patients showed a complete cervical plexus nerve block. No patient required analgesics within the first 24 h after anaesthesia. Two cases of blood aspiration were recorded. No further cervical plexus block-related complications were observed.

CONCLUSIONS

Ultrasound-guided combined intermediate and deep cervical plexus block is a feasible, effective and safe method for oral and maxillofacial surgical procedures.

Ultrasound-guided peripheral nerve blockade of the upper extremity

PURPOSE OF REVIEW

Is ultrasound guidance changing the practice of upper extremity regional anesthesia? This review will aim to describe the findings published in the literature during the previous 18 months.

RECENT FINDINGS

In some approaches to brachial plexus blockade, local anesthetic volumes may be reduced without deterioration of analgesic effect. However, even 10 ml of local injected into the interscalene space may result in diaphragmatic paresis. High-resolution ultrasonography has revealed anatomical variations of C5, C6 and C7 nerve roots in almost half of the patients examined, without negative block effectiveness. The addition of dexamethasone may prolong analgesia after single-shot interscalene and supraclavicular blocks. Insertion of brachial plexus perineural catheters using ultrasound guidance can be successful and provides better postoperative analgesia than single-shot blocks for up to 24 h postoperatively. Infraclavicular catheters provide superior analgesia when compared with supraclavicular catheters. Multiple-site injections of local offer no advantage over a single-site injection during an infraclavicular block. Ultrasound guidance compared with neurostimulation may reduce patient discomfort during axillary blocks compared with neurostimulation. Intra-epineural injections are common during an interscalene blockade, but the incidence of neurological injury remains low. There is an ongoing debate on the effectiveness and safety of ultrasound-guided intra-epineurial injections.

SUMMARY

Current literature suggests a reduction of the volume of local anesthetics used for ultrasound-guided upper extremity blockades. Dexamethasone may prolong duration of brachial plexus blocks and more frequent use of perineural catheters is encouraged. Controversy over intra-epineurial injections exists and requires additional large-scale studies.