Jean-Louis Horn

Ultrasound guidance compared with electrical neurostimulation for peripheral nerve block: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUNDnDespite the growing interest in the use of ultrasound (US) imaging to guide performance of regional anaesthetic procedures such as peripheral nerve blocks, controversy still exists as to whether US is superior to previously developed nerve localization techniques such as the use of a peripheral nerve stimulator (PNS). We sought to clarify this issue by performing a systematic review and meta-analysis of all randomized controlled trials that have compared these two methods of nerve localization.nnnMETHODSnWe searched Ovid MEDLINE, the Cochrane Central Register of Controlled Trials, and Google Scholar databases and also the reference lists of relevant publications for eligible studies. A total of 13 studies met our criteria and were included for analysis. Studies were rated for methodological quality by two reviewers. Data from these studies were abstracted and synthesized using a meta-analysis.nnnRESULTSnBlocks performed using US guidance were more likely to be successful [risk ratio (RR) for block failure 0.41, 95% confidence interval (CI) 0.26-0.66, P<0.001], took less time to perform (mean 1 min less to perform with US, 95% CI 0.4-1.7 min, P=0.003), had faster onset (29% shorter onset time, 95% CI 45-12%, P=0.001), and had longer duration (mean difference 25% longer, 95% CI 12-38%, P<0.001) than those performed with PNS guidance. US guidance also decreased the risk of vascular puncture during block performance (RR 0.16, 95% CI 0.05-0.47, P=0.001).nnnCONCLUSIONSnUS improves efficacy of peripheral nerve block compared with techniques that utilize PNS for nerve localization. Larger studies are needed to determine whether or not the use of US can decrease the number of complications such as nerve injury or systemic local anaesthetic toxicity.

Contributions of skin and muscle afferent input to movement sense in the human hand

In the stationary hand, static joint-position sense originates from multimodal somatosensory input (e.g., joint, skin, and muscle). In the moving hand, however, it is uncertain how movement sense arises from these different submodalities of proprioceptors. In contrast to static-position sense, movement sense includes multiple parameters such as motion detection, direction, joint angle, and velocity. Because movement sense is both multimodal and multiparametric, it is not known how different movement parameters are represented by different afferent submodalities. In theory, each submodality could redundantly represent all movement parameters, or, alternatively, different afferent submodalities could be tuned to distinctly different movement parameters. The study described in this paper investigated how skin input and muscle input each contributes to movement sense of the hand, in particular, to the movement parameters dynamic position and velocity. Healthy adult subjects were instructed to indicate with the left hand when they sensed the unseen fingers of the right hand being passively flexed at the metacarpophalangeal (MCP) joint through a previously learned target angle. The experimental approach was to suppress input from skin and/or muscle: skin input by anesthetizing the hand, and muscle input by unexpectedly extending the wrist to prevent MCP flexion from stretching the finger extensor muscle. Input from joint afferents was assumed not to play a significant role because the task was carried out with the MCP joints near their neutral positions. We found that, during passive finger movement near the neutral position in healthy adult humans, both skin and muscle receptors contribute to movement sense but qualitatively differently. Whereas skin input contributes to both dynamic position and velocity sense, muscle input may contribute only to velocity sense.

Case Report: Limitation of Local Anesthetic Spread During Ultrasound-Guided Interscalene Block. Description of an Anatomic Variant With Clinical Correlation

Objective: The use of ultrasound (US) for localization of neural structures allows real‐time visualization of anatomy; however, variability in the arrangement of structures has been observed. The impact of these variations on the performance and outcome of regional anesthetic techniques remains unclear. We discuss possible anatomic explanations and correlation with clinical observations. Case Report: We report limited spread of local anesthetic observed during the performance of a US‐guided interscalene block. This was associated with an anomalous vessel arising from the subclavian artery, which effectively divided the brachial plexus into 2 compartments. Spread of local anesthetic was restricted to the upper compartment around the C5 through C7 nerve roots. There was no anesthetic fluid visualized in the lower compartment. This produced a block that provided surgical anesthesia for shoulder arthroscopy as well as excellent postoperative analgesia, although the medial and distal aspects of the arm remained unaffected. Conclusions: This case illustrates the ability of US to identify anatomic variations and their relevance to the performance of regional anesthetic techniques.

Ambulatory continuous posterior lumbar plexus blocks following hip arthroscopy: a review of 213 cases

STUDY OBJECTIVEnTo evaluate complications associated with ambulatory continuous lumbar plexus blocks.nnnDESIGNnRetrospective review of all patients who received a continuous lumbar plexus block for analgesia following arthroscopic hip surgery from January 2004 to July 2009.nnnSETTINGnAcademic medical center.nnnMEASUREMENTSnData from 213 patients who were discharged home with a continuous lumbar plexus block following hip arthroscopy were studied. Side effects and complications, including impaired ambulation, systemic local anesthetic toxicity, abnormal local anesthetic spread, and neurologic injury, were recorded.nnnMAIN RESULTSnOf the 281 patients who received a continuous lumbar plexus block following hip arthroscopy, 213 were discharged home with the continuous lumbar plexus block. Significant complications occurred in 3.8% of patients (8/213). Twenty of 213 patients (9.4%) reported prolonged sensory or motor deficits after the continuous lumbar plexus block was removed. Most of these deficits were minor and resolved spontaneously, but 4 patients (1.9%) experienced persistent neurologic symptoms. One patient had a fall, one patient was readmitted for possible bilateral spread from the continuous lumbar plexus block, and two patients experienced symptoms of local anesthetic systemic toxicity (LAST).nnnCONCLUSIONSnWhile complications associated with hip arthroscopy with ambulatory continuous lumbar plexus blocks do occur, significant complications are uncommon. Most complications are managed easily on an outpatient basis. However, nearly 1% of patients presented with symptoms concerning for LAST and were treated without any hemodynamic compromise.

Effects of Intrathecal Midazolam on Postoperative Analgesia When Added to a Bupivacaine-Clonidine Mixture

Background: Previous clinical and experimental studies have shown that a midazolam-clonidine mixture has a synergistic antinociceptive effect. This study evaluated the postoperative analgesic effect of adding midazolam to an intrathecal bupivacaine-clonidine mixture. Methods: One hundred ten patients scheduled to undergo elective lower-extremity surgery were enrolled in this double-blind, randomized trial. Spinal anesthesia was administered by using 1 of 2 mixtures. Group B-C received 12.5 mg isobaric 0.5% bupivacaine, 30 μg clonidine, and 0.4 mL 0.9% saline. Group B-C-M received the B-C mixture plus 2 mg of midazolam in a 0.4-mL solution. Motor and sensory block levels were assessed before, during, and after the procedure until regression of the block to S2. Sedation levels were determined before anesthesia, during surgery, and at the end of the procedure. Postoperative analgesia was assessed every 15 minutes by using a visual analog scale. Duration of sensory and motor blocks was determined based on a modified Bromage scale, and time of the first pain relief request was noted. Results: Duration of sensory block, time of first postoperative analgesic request, and amount of postoperative morphine administered were comparable between groups. However, the motor blockade lasted significantly longer in the B-C-M group compared with the B-C group (287 ± 73 minutes vs 257 ± 72 minutes, respectively; P < .05). Conclusion: Addition of midazolam to an intrathecal B-C mixture does not potentiate postoperative analgesia but prolongs the motor blockade.

Progression of forearm intravenous regional anesthesia with ropivacaine.

The progression of sensory blockade in the hand following a forearm Bier block with ropivacaine is currently unknown. The hands of 10 healthy adult human subjects were anesthetized with ropivacaine, and their sensitivities to cold and touch were tested until the completion of anesthesia. On average, insensitivity to cold occurred uniformly throughout the hand within 9 mins; however, touch sensation was not complete until approximately 20 mins after injection. The spread of anesthesia occurred in a semisystematic way, spreading proximally and distally from the site of injection (mid-dorsum of the hand), and, at a slower rate, from the dorsum of the hand to the palm.

Poster 138: Residual Limb Neuroma Formation in Transfemoral Amputees

parameters, and results were compared with outcomes measured with these 6 instruments. Main Outcome Measures: SF-36, SMFA, AOFAS, FADI, FADI-Sports, CAIT. Results: Overall 5 of the 6 instruments failed to show changes that could be correlated with patients’ outcomes. Only the Cumberland Ankle Instability Tool (CAIT) demonstrated enough sensitivity to the changes and correlated well with clinical outcomes. Based on study’s success criteria (proper function, no pain, no adverse events, and patient satisfaction), 78% of the ankles treated with a single session of noninvasive mcRF had successful outcomes while 83% evidenced significant improvement based on CAIT. No adverse events were present in this study. Conclusions: Many ankle scoring/rating systems have been described to evaluate ankle performance. However, the study of FAI is generally hampered by the lack of diseasespecific questionnaires, which oftentimes introduce ceiling or flooring effects. The CAIT, as a validated tool designed to specifically measure FAI, was capable of detecting changes in patients’ condition and response to the intervention with noninvasive mcRF. In fact no ceiling or flooring effects were seen in this prospective cohort. In this study the CAIT was found to be reliable, valid and sensitive to changes of clinical importance and is short and practical to use.