Incidence Of Postoperative Neurological Symptoms Research Articles

Neuropathies Following an Ultrasound-Guided Axillary Brachial Plexus Block.

Ultrasound-guided brachial plexus block (UGBPB) has interscalene, supraclavicular, infraclavicular, and axillary approaches. The axillary block is considered to be the safest and with fewer adverse events compared to the interscalene (eg, phrenic nerve block, spinal cord or vertebral artery puncture) and supraclavicular (eg, pneumothorax). However, with regard to postoperative neurological symptoms (PONS), it is controversial whether its incidence after an axillary block was higher than that after non-axillary approaches". In this study, we investigated whether the incidence of a neuropathy after an axillary block was higher than that after non-axillary approaches. This was a single-center, retrospective cohort study. All UGBPBs were performed under general anesthesia between January 2014 and March 2020. The outcomes included the overall incidence of PONS and neuropathies for axillary and non-axillary approaches. The etiology, symptoms, and outcomes of patients were investigated. Of the 992 patients, 143 (14%) and 849 (86%) were subjected to axillary and non-axillary approaches, respectively. Among 19 cases (19.2:1000; 95% confidence interval [CI], 18.2-20.1) of PONS, four (4.0:1000; 95% CI, 3.8-4.2) were neuropathies attributed to the UGBPB, three (21.0:1000; 95% CI, 18.1-23.8) to the axillary and one (2.8:1000; 95% CI, 2.6-3.1) to non-axillary approaches. The incidence of neuropathies after an axillary block was significantly higher than that after non-axillary approaches (P = 0.005). The incidence of neuropathies after US-guided axillary block under general anesthesia was significantly higher than that after non-axillary approaches.

The Second American Society of Regional Anesthesia and Pain Medicine Evidence-Based Medicine Assessment of Ultrasound-Guided Regional Anesthesia: Executive Summary.

In 2009 and again in 2012, the American Society of Regional Anesthesia and Pain Medicine assembled an expert panel to assess the evidence basis for ultrasound guidance as a nerve localization tool for regional anesthesia. The 2012 panel reviewed evidence from the first advisory but focused primarily on new information that had emerged since 2009. A new section was added regarding the accuracy and reliability of ultrasound for determining needle-to-nerve proximity. Jadad scores are used to rank study quality. Grades of recommendations consistent with their level of evidence are provided. The panel offers recommendations based on synthesis and analysis of literature related to (1) the technical capabilities of ultrasound equipment and its operators, (2) comparison of ultrasound to other methods of nerve localization with regard to block characteristics, (3) comparison of block techniques where ultrasound is the sole nerve localization modality, and (4) major complications. Assessment of evidence strength and recommendations are made for upper- and lower-extremity, truncal, neuraxial, and pediatric blocks. Scientific evidence from the past 5 years has clarified and strengthened our understanding of ultrasound-guided regional anesthesia as a nerve localization tool. High-level evidence supports ultrasound guidance contributing to superior characteristics with selected blocks, although absolute differences with the comparator technique are often relatively small (especially for upper-extremity blocks). The clinical meaningfulness of these differences is likely of variable importance to individual practitioners. The use of ultrasound significantly reduces the risk of local anesthetic systemic toxicity as well as the incidence and intensity of hemidiaphragmatic paresis, but has no significant effect on the incidence of postoperative neurologic symptoms. WHAT'S NEW IN THIS UPDATE?: This evidence-based assessment of ultrasound-guided regional anesthesia reviews findings from our 2010 publication and focuses on new meta-analyses, randomized controlled trials, and large case series published since 2009. New to this exercise is an in-depth analysis of the accuracy and reliability of ultrasound guidance for identifying needle-to-nerve relationships. This version no longer addresses ultrasound for interventional pain medicine procedures, because the growth of that field demands separate consideration. Since our 2010 publication, new information has either supported or strengthened our original conclusions. There is no evidence that ultrasound is inferior to alternative nerve localization methods.

Ultrasound-Guided Regional Anesthesia and Patient Safety: Update of an Evidence-Based Analysis.

Since the original 2010 publication of this analysis, evidence has continued to support the concept that ultrasound (US) guidance does not meaningfully affect the incidence of peripheral nerve injury (PNI) associated with regional anesthesia. Similar confirmatory evidence attests to US guidance reducing the incidence and intensity of hemidiaphragmatic paresis (HDP) but not eliminating it. Literature published since late 2009 reports the effective role of US guidance in reducing the incidence of local anesthetic systemic toxicity and allows calculation of a lower predicted frequency of pneumothorax associated with US-guided supraclavicular blocks.

Complications associated with 27 031 ultrasound-guided axillary brachial plexus blocks: a web-based survey of 36 French centres.

Ultrasound guidance improves the efficacy of peripheral nerve blocks, reducing performance time and local anaesthetic doses. It should also reduce the risk of systemic toxicity of local anaesthetic and nerve injuries. The primary objective of this prospective study was to estimate the incidence of immediate complications related to ultrasound-guided axillary brachial plexus blocks in a multicentre observational cohort. Prospective multicentre observational study. Thirty-six French centres participated in the study between 2009 and 2012. A total of 27 031 axillary brachial plexus blocks were recorded. The study objective, the incidence of immediate complications related to ultrasound-guided axillary brachial plexus blocks (intravascular injection of local anaesthetic and neurological deficit at hospital discharge), was based on data collected by anaesthesiologists through a web-based case report form. Incidence of immediate complications related to ultrasound-guided axillary brachial plexus blocks. Of 27 031 blocks performed, the incidence of systemic toxicity of local anaesthetic was very low at 1.5 per 10 000, and the overall incidence of postoperative neurological symptoms was 0.37 per 10 000. We have reported a large series of ultrasound-guided axillary brachial plexus blocks in a multicentre study. Our results confirm the low incidence of local anaesthetic systemic toxicity and postoperative neurological complications as previously described.

Using the Freehand Pedicle Screw Placement Technique in Adolescent Idiopathic Scoliosis Surgery

Retrospective case series. This study evaluated the incidence of postoperative neurological symptoms after a freehand pedicle screw insertion technique in idiopathic posterior scoliosis surgery. It is generally accepted that pedicle screws can be inserted by a freehand technique in the thoracic and lumbar spine in patients with adolescent idiopathic scoliosis (AIS) with a very low frequency of major complications. The prevalence of clinically significant screw misplacement, with or without the need for revision surgery is less well defined. Between January 1, 2000, and October 2, 2012, five hundred fifty-nine patients with AIS had thoracolumbar posterior instrumented spine surgery at the Children's Hospital of Pittsburgh. Each patient's chart and radiographs were reviewed and only those with AIS were included. Patients with neuromuscular and syndromic diagnoses were excluded as well as those with congenital or traumatic etiologies, incomplete charts, less than 3 months of follow-up and those without pedicle screws. The records were studied for complaints of radicular pain, neurological deficit, or severe headache that could be indicative of potential screw misplacement. Four hundred eighty-one patients with 5923 pedicle screws met the inclusion criteria. Nine patients (1.9%) developed symptoms and underwent computed tomographic scanning. Six patients were found to have pedicle screw malposition (8 screws) and 3 of these patients underwent revision surgery. Of the 3 revision patients, 2 presented with radicular symptoms (leg pain) and 1 with an orthostatic headache due to cerebrospinal fluid leakage. At the final follow-up, all revision patients had complete symptom resolution. In total, there were 8 symptomatic, misplaced pedicle screws (0.14%) in 6 patients (1.25%). During a 12-year period in a dedicated pediatric orthopedic hospital using the freehand placement technique, the incidence of symptomatic misplaced pedicle screws was exceedingly low. 4.

Interscalene brachial plexus blocks under general anesthesia in children: is this safe practice?: A report from the Pediatric Regional Anesthesia Network (PRAN).

A practice advisory on regional anesthesia in children in 2008, published in this journal, supported the placement of regional blocks in children under general anesthesia (GA). Interscalene brachial plexus (IS) blocks were specifically excluded, based on case reports (level 3 evidence) of injury, which occurred predominantly in heavily sedated or anesthetized adult patients. Apart from case reports, there is a paucity of data that explore the safety of IS blocks placed in patients under GA, and the level of evidence available on which to base recommendations is limited. Querying the database of the Pediatric Regional Anesthesia Network (PRAN), we report on the incidence of postoperative neurological symptoms, local anesthetic systemic toxicity, and other reported adverse events in children receiving IS blocks under GA or sedated. A total of 518 interscalene blocks were performed, 390 under GA and 123 with the patient sedated or awake (5 cases had missing status); 472 of these were single injection, and 46 involved the placement of infusion catheters. Eighty-eight percent of blocks were placed with ultrasound guidance, 7.7% with no location device, and 2.5% with a nerve stimulator. No local anesthetic systemic toxicity, postoperative neurological symptoms, cardiovascular complications, or dural puncture was reported in this cohort. There were 1 vascular puncture and 1 postoperative infection. These negative results are compatible with 0 to 7.7/1000 events for each of these complications for IS blocks placed under GA. There was no paralysis, motor block, or sensory deficit beyond the expected block duration time. Analyzing interscalene blocks in children placed under GA, we identified no serious adverse events. The upper limit of the confidence interval for these events is similar to that in awake or sedated adults receiving IS blocks. Based on these prospectively collected data, placement of IS blocks under GA in children is no less safe than placement in awake adults, calling into question the American Society of Regional Anesthesia and Pain Medicine advisory proscribing GA during IS block in pediatric patients.

Complicaciones neurológicas asociadas a bloqueos interescalénico y supraclavicular guiados con ecografía en cirugía electiva de hombro y extremidad superior. Estudio observacional prospectivo en un hospital universitario

ObjectivesThe incidence of postoperative neurological symptoms after performing interscalene block varies between 4 and 16%. The majority of cases are resolved spontaneously within a year, but some patients have their symptoms permanently. Our objective was to assess the incidence of postoperative neurological symptoms after performing the ultrasound-assisted interscalene and supraclavicular anaesthetic blocks. Material and methodsA prospective and observational study was conducted on consecutive patients who had undergone upper extremity surgery with an interscalene or supraclavicular block as an isolated technique, or as a complement to general anaesthesia. Seven days after the intervention, a telephone interview was conducted that focused on the detection of neurological symptoms in the operated limb. Further serial interviews were conducted on patients with symptoms (after the first, the third and the sixth month, and one year after surgery) until resolution of symptoms. Neurological evaluation was offered to those patients with persistent symptoms after one year. ResultsA total of 121 patients were included, on whom 96 interscalene blocks and 22 supraclavicular blocks were performed. Postoperative neurological symptoms were detected in 9.9% (95% CI, 5-15%) of patients during the first week. No significant differences were observed between interscalene (9%) and supraclavicular block (14%). After 3 months the symptoms persisted in 9 patients (7.4%), with symptoms remaining in 4 patients (3.3%) after 1.5 years. Electromyogram was performed on 3 patients who tested positive for nerve damage. ConclusionsA high incidence of postoperative neurological symptoms was observed, and a worrying percentage of permanence of them. There were no significant differences in incidence according to the type of block, or any features of the patient or the anaesthesia technique that were associated with the incidence of these symptoms, except a marginal relationship with age. These complications must be clearly explained to the patients before performing these blocks.

Nerve Stimulator-guided Supplemental Popliteal Sciatic Nerve Block after a Failed Sciatic Block Does Not Increase the Incidence of Transient Postoperative Neurologic Sequelae

Supplemental peripheral nerve blocks are not commonly performed in adults because of concerns of cumulative exposure of the nerve to the local anesthetic as well as increased ischemia from epinephrine. The purpose of this study was to compare the incidence of postoperative neurologic symptoms after a failed subgluteal sciatic nerve block and a supplemental popliteal sciatic nerve block. Five hundred twelve adult patients undergoing ambulatory surgery were prospectively studied (1 yr). Sciatic nerve blocks were performed using levobupivacaine 0.625% with epinephrine 1:200,000 (0.5 ml/kg). Patients who failed to achieve sensory and motor anesthesia at 30-60 min were given a popliteal sciatic nerve block (lidocaine 2% 10 ml + levobupivacaine 0.5% 10 ml). Subjects were contacted at 24 h to 48 h, 2 weeks, and 1 month. Symptomatic patients were contacted biweekly and reevaluated during follow-up surgeon visits until symptom resolution. Four hundred thirty-nine subjects were analyzed. Fifty-six received a popliteal sciatic nerve block. Four subjects (0.9%) had self-reported neurologic symptoms in the distribution of the sciatic nerve. Investigator-initiated follow-up revealed 33 subjects (8.7%) who received a single subgluteal sciatic block and 4 subjects (7.1%) after a supplemental sciatic nerve block with neurologic symptoms (P = 0.80). The median duration of symptoms was 4 weeks (95% CI 3-5) in the subgluteal and 4 weeks (95% CI 3-5) weeks in the popliteal group (P = 0.98). All symptoms resolved by 14 weeks postprocedure. Blocking the sciatic nerve at a more distal site after a failed subgluteal sciatic nerve block does not appear to influence the incidence or duration of neurologic sequelae.

Important Predictors of DWI Lesions and Neurological Sequelae Following Carotid Intervention

Embolic detection on diffusion weighted imaging (DWI) by magnetic resonance imaging (MRI) is a promising outcome measure for carotid interventions. We previously reported that patients undergoing carotid artery stenting (CAS) have a 50% greater chance of developing new microemboli on DWI compared to carotid endarterectomy (CEA). We sought to re-evaluate these outcomes in a larger patient set after technical modifications to our CAS program. We also examined the risk factors for DWI lesions and correlated neurologic symptoms with DWI-derived MLV. From July 2004 to December 2010, a total of 228 patients (143 CEA, 85 CAS) who underwent carotid interventions also received preoperative and postoperative DWI evaluations at a single academic institution. A novel neuroimaging analysis technique was used to derive MLV on DWI. Hospital records for all patients were reviewed for comorbidities, lesion characteristics, postoperative outcomes, and incidence of periprocedural microemboli. Forty patients (47%) with CAS compared to 15 patients (10%) with CEA had postoperative DWI lesions (P < .01), and a higher incidence of contralateral microembolization (P = .01). Multivariant analysis demonstrated that the strongest predictors of DWI lesions after CAS or CEA were body mass index (BMI) > 30 (P < .01; confidence interval [CI], 1.4-8), preoperative stroke (P < .01; CI, 2.9-15.3), chronic obstructive pulmonary disease (COPD; P = .03; CI, 1.1-6.2), and coronary artery disease (CAD; P = .05; CI, 1-6.2; Table). Subset analysis of MLV demonstrated a significant correlation with the incidence of postoperative neurological symptoms (P = .04; R2 0.248). MLV was not different between CAS and CEA (P = .13).TableMultivariant analysis of perioperative factorsFactorP valueCIAge >70.705.2-2.6Gender.090.02-1.3Smoking.680.4-1.9Hypertension.530.1-3.4Hyperlipidemia.890.2-5.3Obesity (BMI >30)< .011.4-8CAD.051-6.2COPD.031.1-6.2PVD.160.2-1.3Preoperative stroke< .012.9-15.3Carotid lesion calcificationBMI, Body mass index; CAD, coronary artery disease; CI, confidence interval; COPD, chronic obstructive pulmonary disease; PVD, peripheral vascular disease. Open table in a new tab BMI, Body mass index; CAD, coronary artery disease; CI, confidence interval; COPD, chronic obstructive pulmonary disease; PVD, peripheral vascular disease. The incidence of microembolic events after CAS is higher compared to CEA, but the MLV is similar for the two groups. DWI-derived MLV highly correlates with postprocedural neurological sequelas. Further investigational use of periprocedural DWI is needed to determine the utility and cost-effectiveness of identifying patients at risk of neurological sequelas after carotid intervention.

The effect of injection speed on the spinal block characteristics of hyperbaric bupivacaine 0.5% in the elderly

The purpose of this prospective, randomized, double-blind study was to compare anesthetic characteristics after two speeds of intrathecal injection of hyperbaric bupivacaine in elderly patients. Fifty-six patients, aged ≥65years, undergoing transurethral surgery under spinal anesthesia were allocated randomly to two groups according to rate of intrathecal injection of 2ml hyperbaric bupivacaine 0.5%: group Fast (maximum possible rate; mean 0.38ml/s) n=26; group Slow (over 40s; 0.05ml/s), n=25. Spinal blocks were administered in the lateral position. Data collection at different times included sensory level, motor block, hemodynamic changes, and occurrence of neurological symptoms. There was no significant difference between the groups regarding maximum sensory anesthetic level achieved (group Fast: T7 (T4-T10), median (range); group Slow T8 (T6-T10), P=0.184); times (min) to reach (a) T10 sensory level (group Fast 5.3±4.2 (mean±SD), group Slow 8.0±6.5, P=0.093); (b) maximum sensory level (group Fast 11.6±4.7; group Slow 13.6±6.1, P=0.199); and (c) 2-segment regression of anesthesia (group Fast 92.2±29.6; group Slow 104.7±36.1, P=0.182). Degree and duration of motor block were similar (P=0.947 and P=0.895, respectively). Hemodynamic changes, ephedrine and atropine requirement, incidence of postoperative neurological symptoms after 24h and 1week were similar (all P>0.05). An eightfold difference in speed of intrathecal injection of 0.5% hyperbaric bupivacaine did not affect the clinical characteristics of spinal anesthesia in elderly patients undergoing transurethral surgery.

A Prospective Clinical Registry of Ultrasound-Guided Regional Anesthesia for Ambulatory Shoulder Surgery

There is a lack of clinical registries to document efficacy and safety of ultrasound-guided regional anesthesia. Interscalene blocks are effective for shoulder arthroscopy, and ultrasound guidance may reduce risk. Furthermore, ultrasound-guided supraclavicular block is a novel approach for shoulder anesthesia that may have less risk for neurological symptoms than interscalene block. One thousand one hundred sixty-nine patients undergoing ultrasound-guided regional anesthesia for ambulatory shoulder arthroscopy were enrolled in our prospective registry. Standardized perioperative data were collected including a preoperative neurological screening tool. Either interscalene or supraclavicular block was performed at the discretion of the clinical team. Standardized follow-up was performed in the postanesthesia care unit and at 1 week. Postoperative neurological symptoms (PONS) were assessed at the 1-week follow-up with the same screening tool by a blinded neurologist. Ultrasound-guided interscalene (n = 515) and supraclavicular (n = 654) blocks had excellent anesthetic success (99.8%; 95% confidence interval [CI], 99.4%-99.9%) with 0% (95% CI, 0%-0.3%) incidence of vascular puncture or intravascular injection. The incidence of hoarseness in the postanesthesia care unit was significantly less with supraclavicular (22% with 95% CI, 19%-26%) than interscalene block (31% with 95% CI, 27%-35%). The incidence of dyspnea was similar (7% for supraclavicular vs 10% with interscalene). No patient had a clinically apparent pneumothorax. The incidence of PONS was very low (0.4% with 95% CI, 0.1%-1%), and there was a 0% (95% CI, 0%-0.3%) incidence of permanent nerve injury. Ultrasound-guided interscalene and supraclavicular blocks are effective and safe for shoulder arthroscopy. Temporary and permanent PONS is uncommon.

A Prospective, Randomized, Controlled Trial Comparing Ultrasound Versus Nerve Stimulator Guidance for Interscalene Block for Ambulatory Shoulder Surgery for Postoperative Neurological Symptoms

Visualization with ultrasound during regional anesthesia may reduce the risk of intraneural injection and subsequent neurological symptoms but has not been formally assessed. Thus, we performed this randomized clinical trial comparing ultrasound versus nerve stimulator-guided interscalene blocks for shoulder arthroscopy to determine whether ultrasound could reduce the incidence of postoperative neurological symptoms. Two hundred thirty patients were randomized to a standardized interscalene block with either ultrasound or nerve stimulator with a 5 cm, 22 g Stimuplex insulated needle with 1.5% mepivacaine with 1:300,000 epinephrine and NaCO3 (1 meq/10 mL). A standardized neurological assessment tool (questionnaire and physical examination) designed by a neurologist was administered before surgery (both components), at approximately 1 wk after surgery (questionnaire), and at approximately 4-6 weeks after surgery (both components). Diagnosis of postoperative neurological symptoms was determined by a neurologist blinded to block technique. Two hundred nineteen patients were evaluated. Use of ultrasound decreased the number of needle passes for block performance (1 vs 3, median, P < 0.001), enhanced motor block at the 5-min assessment (P = 0.04) but did not decrease block performance time (5 min for both). No patient required conversion to general anesthesia for failed block, and patient satisfaction was similar in both groups (96% nerve stimulator and 92% ultrasound). The incidence of postoperative neurological symptoms was similar at 1 wk follow-up with 11% (95% CI of 5%-17%) for nerve stimulator and 8% (95% CI of 3%-13%) for ultrasound and was similar at late follow-up with 7% (95% CI of 3%-12%) for nerve stimulator and 6% (95% CI of 2%-11%) for ultrasound. The severity of postoperative neurological symptoms was similar between groups with a median patient rating of moderate. Symptoms were primarily sensory and consisted of pain, tingling, or paresthesias. Ultrasound reduced the number of needle passes needed to perform interscalene block and enhanced motor block at the 5 min assessment; however, we did not observe significant differences in block failures, patient satisfaction or incidence, and severity of postoperative neurological symptoms.

Comparing the Steam Engine With a Horse-Drawn Carriage?

In Response: In the study cited by Heller et al., we demonstrated similar rates of postoperative neurologic symptoms (PONS) after nerve stimulator or paresthesia techniques of nerve localization (1). Heller et al.'s negative views of paresthesia techniques are shared by many members of the anesthesia community. However, as clinicians and scientists, we should not be dealing with opinions, but rather on facts supported by rigorous scientific studies. First, Heller et al. state that the incidence of PONS in our patients is “strikingly high,” and they use a recent prospective case series (2), their “own experience,” and “European leaders' opinion” as support for this statement. “Opinions” and “experience” aside, the study referenced by Heller et al. that indicated a 3% incidence of PONS, followed patients who underwent many different operative procedures and who received either upper or lower extremity continuous peripheral nerve blockade for 2–7 days. We studied a single anesthetic and a single surgical procedure. Furthermore, in many patients, PONS presented and resolved within the timeframe of the continuous infusion referenced. Comparing these two studies is simply not appropriate. There are many more appropriate comparison studies that describe an incidence of PONS in the range we report (3–6). Second, although we agree with Heller et al. that ultrasound is a potentially useful method to assist in nerve localization for peripheral nerve block, there are few randomized, controlled trials evaluating the safety and efficacy of ultrasound in preventing PONS. Until the results of more such studies are available, we should keep an open mind. As Heller et al. correctly state, the relationship between needle tip and nerve are unclear (at best) with both paresthesia and nerve stimulator studies (7–9). In addition, a recent report by Bigeleisen (10) clearly shows that ultrasound techniques may not be reliable to avoid nerve contact. Furthermore, we do not understand the relevance of Heller et al.'s reference to the closed claims analysis (11). None of our patients suffered lasting injury, and there is no evidence that ultrasound-guided nerve blocks are safer than nerve blocks performed with other techniques. Third, Heller et al.'s comment that the volume of local anesthetic used is “outdated and potentially toxic” is another example of a commonly held, yet scientifically unsupported opinion. A comprehensive review on this topic attempts to differentiate between opinion and fact (12). Finally, it is true that it is difficult to statistically prove that two procedures yield equivalent results. We found a 9.3% incidence of PONS with the paresthesia technique (90% CI: 4.7%–13.9%) and a 10.1% incidence with the nerve stimulator technique (90% CI: 5.3%–14.7%). It is likely that if any difference did exist, it would be too small to be clinically significant. Anesthesiologists should be guided by facts supported by randomized, controlled trials, and not swayed by personal experiences and opinions. If we focus on facts, it is quite possible that other myths in anesthesia will be dispelled. We are certain that at some point during the 20th century, popular opinion was that steam engines would be the primary source of transportation energy for decades to come. Popular opinion is not always correct. Gregory A. Liguori, MD Jacques T. YaDeau, MD, PhD Victor M. Zayas, MD Richard Kahn, MD Leonardo Paroli, MD, PhD Valeria Buschiazzo, BS Department of Anesthesiology Hospital for Special Surgery Weill Medical College of Cornell University New York, New York [email protected]

Nerve Localization Techniques for Interscalene Brachial Plexus Blockade: A Prospective, Randomized Comparison of Mechanical Paresthesia Versus Electrical Stimulation

Postoperative neurologic symptoms (PONS) are relatively common after upper extremity orthopedic surgery performed under peripheral neural blockade. In this study, we prospectively compared the incidence of PONS after shoulder surgery under interscalene (IS) block using the electrical stimulation (ES) or mechanical paresthesia (MP) techniques of nerve localization. For patients randomized to the MP group, a 1-in, 23-g long-beveled needle was placed into the IS groove to elicit a paresthesia to the shoulder, arm, elbow, wrist, or hand. For patients randomized to the ES group, a 5-cm, 22-g short-beveled insulated needle was placed into the IS groove to elicit a motor response including flexion or extension of the elbow, wrist, or fingers or deltoid muscle stimulation at a current between 0.2 and 0.5 mA. Each IS block was performed with 50-60 mL of 1.5% mepivacaine containing 1:300,000 epinephrine and 0.1meq/L sodium bicarbonate. Two-hundred-eighteen patients were randomized between the two groups. One patient was lost to follow-up. Twenty-five patients (23%) in the ES group experienced paresthesia during needle insertion. The incidence of PONS using the ES technique was 10.1% (11/109), whereas the incidence with the MP technique was 9.3% (10/108) (not significant). The PONS lasted a median duration of 2 mo, and symptoms in all patients resolved within 12 mo. The success rate, onset time, and patient satisfaction were also comparable between groups. We conclude that the choice of nerve localization technique can be made based on the patient's and anesthesiologist's comfort and preferences and not on concern for the development of PONS.

Neurologic Sequelae of Open-Heart Surgery in Children

As pediatric cardiac surgical techniques have improved in recent years, mortality rates have dropped and attention has turned to residual morbidity, especially neurologic sequelae. Although the majority of children undergoing open-heart surgery for correction of congenital heart defects apparently emerge with no adverse consequences, a small percentage suffer permanent neurologic injury (seizures, motor disorders). Another small and not well-defined population may be left with disorders of higher cortical function, such as mental retardation or learning disabilities. A survey of six major pediatric cardiac surgery units in North America was undertaken in 1988-1989 to ascertain current approaches to the detection and management of neurologic sequelae of pediatric open-heart surgery. All units reported seeing a small but definite incidence of postoperative neurologic symptoms, including alterations of consciousness, seizures, and localized abnormalities such as hemiparesis or delayed choreoathetoid syndromes. Postoperative neuroimaging procedures have shown a disturbing incidence of hypoxic-ischemic encephalopathy, unsuspected cerebral atrophy, and subdural hematomas. Pathogenesis may include factors related to preoperative brain anomalies and/or hypoxic insults, altered cerebral blood flow and metabolism during hypothermic cardiopulmonary bypass with or without total circulatory arrest, embolization, and low cardiac output states postoperatively. Further studies are needed to examine the mechanisms of injury and to develop techniques to minimize the occurrence of these sequelae, as they may be associated with life-long neurologic disability and reduced quality of life.