Michael Gofeld

Development and Validation of a New Technique for Ultrasound-guided Stellate Ganglion Block

Background and Objectives: Although the stellate ganglion is located anteriorly to the first rib, anesthetic block is routinely performed at the C6 level. Ultrasonography allegedly improves accuracy of needle placement and spread of injectate. The technique is relatively new, and the optimal approach has not been determined. Moreover, the location of the cervical sympathetic trunk relative to the prevertebral fascia is debatable. Methods: Three-dimensional sonography was performed on 10 healthy volunteers, and image reconstruction was completed. On the basis of analysis of pertinent anatomy, a lateral trajectory for needle placement was simulated. Accuracy was tested by injection of methylene blue in cadavers. A clinical validation study was then conducted. A block needle was inserted according to the predetermined lateral path, and 5 mL of a mixture of bupivacaine and iohexol was injected. Spread of the contrast agent was verified fluoroscopically. Results: Image reconstruction revealed that the cervical sympathetic trunk is located posterolaterally to the prevertebral fascia on the surface of the longus colli muscle. The mean anteroposterior width of the muscle at the C6 level was 11 mm. The lateral approach does not interfere with any visceral or nerve structures. Anatomic dissection in cadavers confirmed entirely subfascial spread of the dye and staining of the sympathetic trunk. The contrast agent spread was seen in all patients between the C4 and T1 levels in a typical prevertebral pattern. Conclusions: This study revealed that, at the C6 level, the cervical sympathetic trunk lies entirely subfascially. Subfascial injection via the lateral approach ensures reliable spread of a solution to the stellate ganglion.

Effect of Transversus Abdominis Plane Block With and Without Clonidine on Post–cesarean Delivery Wound Hyperalgesia and Pain

Background and Objectives The transversus abdominis plane (TAP) block is an established technique to manage post–cesarean delivery pain. Transversus abdominis plane blocks with a local anesthetic only offer no analgesic benefits compared with intrathecal morphine. Adjuvants to extend TAP block duration and possibly reduce wound hyperalgesia, known to be a risk factor for chronic pain, have not been studied. We hypothesized that a TAP block with clonidine will affect postsurgical wound hyperalgesia and improve pain outcomes. Methods Ninety women were randomly assigned to receive 1 of 3 TAP blocks after cesarean delivery: saline (placebo), bupivacaine (BupTAP), or bupivacaine + clonidine (CloTAP). The primary outcome was wound hyperalgesia index at 48 hours. Secondary outcomes included pain scores, analgesic consumption, and pain descriptors up to 12 months. Results Wound hyperalgesia index at 48 hours (median [25th–75th percentiles]) was 1.07 (0.48–3.26) in the placebo group, 1.27 (0.59–2.95) in the BupTAP group, and 0.74 (0.09–2.25) in the CloTAP group (P = 0.48). Morphine request in the postanesthesia care unit was significantly higher in the placebo group compared with the other TAP groups (P = 0.01). Postoperative pain scores and requests for breakthrough medication at 48 hours (30% in the placebo group, 24% in the BupTAP group, and 12% in the CloTAP group, P = 0.25) or chronic pain descriptors reported up to 12 months did not differ significantly among groups. Conclusions Adding clonidine to a TAP block with bupivacaine did not affect wound hyperalgesia index and it did not improve short-term or long-term pain scores in women undergoing elective cesarean delivery. Further studies are warranted to determine the benefits of antihyperalgesic adjuvants in TAP solutions for specific individuals at risk for chronic pain.

Preoperative ultrasound-guided mapping of peripheral nerves

OBJECT Surgical exposure of a peripheral nerve can be technically challenging, making the operation more extensive and time consuming, particularly in the treatment of small nerves with an anatomically variable position. This study describes the application of ultrasound to facilitate surgical access and localization of targeted peripheral nerves. METHODS A preclinical feasibility study was performed at the University of Washingtons Willed Body Program laboratory. Unembalmed cadavers were placed on the dissection table in positions mimicking those typically required for surgical access to specific nerves that can be challenging to localize. A high-frequency portable ultrasound system was used to identify the nerves. An extraneural injection of methylene blue immediately adjacent to the target nerve was performed under ultrasound guidance as the experimental nerve mapping procedure. Surgical dissections through a small skin incision parallel to skin tension lines were guided by the transducer position and angle. Success was determined by the accuracy and rapidity of surgical identification and exposure of the nerve. RESULTS Using ultrasound-guided mapping, all anticipated peripheral nerves were correctly identified via a direct approach from the skin incision. This was confirmed by performing an anatomical dissection to expose and identify the intended nerve and its relation to the injected methylene blue dye. In no case was intraneural injection of the dye observed. CONCLUSIONS Preoperative ultrasound-guided nerve mapping may be useful in facilitating surgical access to a targeted nerve and thereby minimizing tissue dissection and operating time.

Ultrasound-guided injection of lumbar zygapophyseal joints: an anatomic study with fluoroscopy validation.

Background Diagnostic and therapeutic injections of the zygapophyseal joint (z-joint) are routinely performed under radiologic guidance (eg, fluoroscopy, computed tomography). Technically, these procedures could also be completed using ultrasound guidance, but existing evidence insufficiently supports this alternative imaging method, and it cannot therefore be recommended as a standard practice. There has also been no published proof-of-concept study using a routine fluoroscopy control for ultrasound-guided z-joint injections. Methods A cadaver study was performed to validate ultrasound as an imaging modality for z-joint injections. Fifty z-joint injections were performed on 5 nonembalmed specimens. In-plane ultrasound approach was implemented. Zygapophyseal joints were accessed through a needle placement under the joint capsule into the posterior synovial recess. Iohexol was thereby injected, and fluoroscopy was subsequently performed. Results In 44 (88%) of 50 performed injections, the intra-articular spread of the contrast agent was clearly observed on the fluoroscopy image. In 6 (12%) of 50 cases, the contrast flow appeared in the soft tissues. In 4 of the 6 failed injections, the z-joint gap was not evident on an ultrasound image. No intravascular, nerve root, or epidural injections were observed. Conclusions Ultrasound may be a viable alternative to fluoroscopy or computed tomography as a guidance method for lumbar z-joint injections.

Pulsed Radiofrequency of Suprascapular Nerve for Chronic Shoulder Pain: A Randomized Double‐Blind Active Placebo‐Controlled Study

Background:  The suprascapular nerve block is frequently implemented to treat chronic shoulder pain. Although effective the nerve blockade provides only a short‐term relief, and more compelling apaproaches have been investigated. Pulsed radiofrequency (pRF) has been anecdotally reported as safe and reliable method. However, formal efficacy study has not been published. Ostensibly evidence‐based validation of a new method is necessary for both scholastic and practical purposes.

Ultrasound-guided Lumbar Transforaminal Injections: Feasibility and Validation Study

Study Design. Preclinical feasibility study. Objective. Evaluation and validation of ultrasound-guided lumbar transforaminal injections. Summary of Background Data. Lumbar transforaminal injections are routinely implemented in the interventional management of spinal radicular pain. Typically, these injections are administered under fluoroscopy or computed tomography. Although radiological guidance provides anatomical precision and accuracy, it is associated with radiation exposure and cannot be performed during outpatient visits or at bedside. Ultrasound-guided techniques have been previously described; however, the methodological generalizability remained unknown and validation against routine fluoroscopy has never been conducted on multiple spinal levels. Methods. We addressed the procedural accuracy of ultrasound-guided lumbar transforaminal injections and proposed anatomically sound approach. Fluoroscopic validation was performed. Results. Of the 50 planned injections, 46 procedures were performed. L5/S1 foraminal access was impossible in 4 cases (8%). Fluoroscopy confirmed the correct foraminal placement in all 46 injections (100%). The contrast-spread pattern was intraforaminal in 42 cases (91.3%) and extraforaminal (nerve root) in 4 cases (8.7%). When intraforaminal pattern was detected on anteroposterior image, lateral fluoroscopy demonstrated ventral epidural flow in all occasions. In 3 cases, intravascular injection was detected (6.5%). Conclusion. Ultrasound-guided lumbar transforaminal injections are accurate and feasible in the preclinical setting.

Ultrasound‐Guided Intrathecal Pump Access and Prevention of the Pocket Fill

OBJECTIVE Intrathecal pump drug refill may result in significant adverse outcome and complications. Thus far, 351 reports from around the world have been received by Medtronic Inc. related to occurrence of pocket fill, including eight lethal events. Ultrasound-assisted pump port access has been previously described, but did not result in wide acceptance in routine practice due to cumbersome and unreliable setup. This study outlines the methodology of real-time ultrasound-guided pump refill. DESIGN Preclinical feasibility study. SETTING   University of Washington Body Willed Program laboratory. INTERVENTIONS Using unembalmed cadaver model clinical scenarios of either inverted or deeply implanted pump were replicated. Sonographic images of those conditions were studied and an ultrasound-guided technique for accessing the pump injection port was developed. The ability to correctly identify pump versus pocket fill using ultrasonography was evaluated. OUTCOME MEASUREMENTS Positive and negative predictive value of correct needle placement, assessment of learning curve for inexperienced user, description of ultrasonography of inverted pump. RESULTS Both positive and negative predictive values reached 100%. Mastering the technique easy and uneventful. Inverted pump has a distinctive sonographic appearance. CONCLUSIONS Ultrasound-guided intrathecal pump access is a feasible and simple technique that may improve maintenance, routine device care, and prevent serious complications related to erroneous subcutaneous injections of concentrated medications. Clinical validation will be necessary in the future.

New Horizons in Neuromodulation

Electrical stimulation of the nervous system is a method used for several centuries which just in the past decades received wide recognition as an effective and safe modality in the management of neuropathic pain and other maladies. Explosion of new technologies and discovery of new neuromodulation targets are two parallel and interconnected processes. Using a paraphrase from the famous novel of Samuel Sham, The House of God, one can say that there is no nervous tissue in the human body that cannot be reached with a stimulating lead directed by a good strong arm. Neuromodulation devices are being used for the stimulation of the entire nervous system, from the cutaneous terminals to brain centers. Autonomic regulation is also subject to stimulation via implanted devices. Future research and development is tightly related to the process of discovery, experimental courage, and philosophical exploration of neurobehavioral mechanisms.

Comparison of anatomic landmarks and ultrasound guidance for intercostal nerve injections in cadavers.

Background and Objectives Intercostal nerve (ICN) injections are routinely performed under anatomic landmark or fluoroscopic guidance for acute and chronic pain indications. Ultrasound (US) is being used increasingly to perform ICN injections, but there is lack of evidence to support categorically the benefits of US over conventional techniques. We compared guidance with US versus anatomic landmarks for accuracy and safety of ICN injections in cadavers in a 2-phase study that included evaluation of deposition of injected dye by dissection and spread of contrast on fluoroscopy. Methods A cadaver experiment was performed to validate US as an imaging modality for ICN blocks. In the first phase of the study, 12 ICN injections with 2 different volumes of dye were performed in 1 cadaver using anatomic landmarks on one side and US-guidance on the other (6 injections on each side). The cadaver was then dissected to evaluate spread of the dye. The second phase of the study consisted of 74 ICN injections (37 US-guided and 37 using anatomic landmarks) of contrast dye in 6 non-embalmed cadavers followed by fluoroscopy to evaluate spread of the contrast dye. Results In the first phase of the study, the intercostal space was identified with US at all levels. Injection of 2 mL of dye was sufficient to ensure compete staining of the ICN for 5 of 6 US-guided injections but anatomic landmark guidance resulted in correct injection at only 2 of 6 intercostal spaces. No intravascular injection was found on dissection with either of the guidance techniques. In the second phase of the study, US-guidance was associated with a higher rate of intercostal spread of 1 mL of contrast dye on fluoroscopy compared with anatomic landmarks guidance (97% vs 70%; P = 0.017). Conclusions Ultrasound confers higher accuracy and allows use of lower volumes of injectate compared with anatomic landmarks as a guidance method for ICN injections in cadavers. Ultrasound may be a viable alternative to anatomic landmarks as a guidance method for ICN injections.

Bilateral pain relief after unilateral thoracic percutaneous sympathectomy.

PurposeTo present a case of unexpected bilateral pain relief following unilateral thoracic percutaneous sympathectomy.Clinical findingsWe present a case report where severe ischemic pain due to paraneoplastic Raynauďs syndrome with distal gangrene was successfully treated by means of percutaneous thoracic sympathectomy. A unilateral T2, T3 radiofrequency sympathectomy combined with small volume phenol injection resulted in unexpected bilateral pain relief.ConclusionOur observations from this case report suggest possible crossover of sympathetic innervation at the cervical nd thoracic levels. Percutanenous thoracic radiofrequency ympathectomy is a feasible option for the treatment of refractory ischemic upper limb pain.RésuméObjectifPrésenter un cas de contrôle bilatéral inattendu de la douleur à la suite ďune sympathectomie thoracique percutanée.Constatations cliniquesNous présentons un cas où une douleur ischémique sévère causée par un syndrome paranéoplasique de Raynaud, accompagnée de gangrène distale, a été traitée avec succès par une sympathectomie thoracique percutanée. La sympathectomie unilatérale à radiofréquence en T2, T3 combinée à une injection de phénol de faible volume a produit un contrôle bilatéral inattendu de la douleur.ConclusionNos observations suggèrent une innervation sympathique croisée possible aux niveaux cervical et thoracique. La sympathectomie thoracique percutanée peut traiter la douleur ischémique réfractaire aux membres supérieurs.Objectif Presenter un cas de controle bilateral inattendu de la douleur a la suite ďune sympathectomie thoracique percutanee.