A new anterior approach to the sciatic nerve block

Ultrasound-Guided Anterior Approach to a Sciatic Nerve Block: Influence of Lower Limb Positioning on the Visibility and Depth of the Sciatic Nerve

OBJECTIVES

We aimed to identify the optimal lower limb position for an ultrasound (US)-guided anterior approach to a sciatic nerve block.

METHODS

We included 45 patients who met the following criteria: American Society of Anesthesiologists physical status of 1 to 3, age between 18 and 80 years, and scheduled to undergo knee surgery that required a sciatic nerve block. The lower limbs of each patient were placed in the following 4 positions: N, neutral; ER, external rotation of the hip (angle, 45°); ER/F15, ER (angle, 45°) and flexion (angle, 15°) of the hip; and ER/F45, ER (angle, 45°) and F (angle, 45°) of the hip. An investigator acquired US scans of the sciatic nerve in each position, and the visibility score and depth of the sciatic nerve from the skin were analyzed.

RESULTS

The visibility scores were significantly higher in positions ER/F15 and ER/F45 than in positions ER and N (P < .0001). However, there was no difference between the visibility scores in positions ER/F15 and ER/F45 (P = .0959). The depth of the sciatic nerve from the skin decreased with ER and an increase in the F angle of the hip (overall P < .0001).

CONCLUSIONS

Based on the visibility score and depth from the skin, ER of the hip to 45° with a greater F angle (45° versus 15°) of the hip appears to be the optimal position for an US-guided anterior approach to a sciatic nerve block.

Lateral Supratrochanteric Approach to Sciatic and Femoral Nerve Blocks in Children: A Feasibility Study

Background

Sciatic and femoral nerve blocks (SNB and FNB) result in effective lower limb analgesia. Classical SNB and FNB require patient repositioning which can cause pain and discomfort. Alternative approaches to sciatic and femoral nerve blocks in supine patients can be useful.

Materials and Methods

Neurostimulator-guided SNB and FNB from the lateral supratrochanteric approach were performed. Local anesthetic spread in SNB and FNB after radiographic opacification was analyzed. Time and number of attempts to perform blocks, needle depth, and clinical efficacy were assessed.

Results

Mean needle passes number and procedure time for SNB were 2.5 ± 0.3 and 2.4 ± 0.2 min, respectively. Mean needle passes number and procedure time for FNB were 2.7 ± 0.27 and 2.59 ± 0.23 min, respectively. Mean skin to nerve distance was 9.1 ± 0.45 cm for SNB and 8.8 ± 0.5 cm for FNB. Radiographic opacification of SNB showed local anesthetic spread close to the sacrum and involvement of sacral plexus nerve roots. Spread of local anesthetic in FNB was typical. Intraoperative fentanyl administration was required in 2 patients (9.5%) with mean dose 1.8 ± 0.2 mcg/kg. Mean postoperative pain score was 0.34 ± 0.08 of 10.

Conclusion

The lateral supratrochanteric approach to SNB and FNB in children can be an effective lower limb analgesic technique in supine patients. The trial is registered with ISRCTN70969666.

High-resolution ultrasound of the posterior femoral cutaneous nerve: visualization and initial experience with patients

OBJECTIVE

The posterior femoral cutaneous nerve (PFCN) is a sensory nerve originating from the sacral plexus. PFCN neuropathy leads to pain within the inferior gluteal region and the posterior aspect of the thigh. As electrophysiological assessment is challenging, diagnosis of PFCN neuropathy has been, thus far, primarily based on clinical findings, which can result in misdiagnosis. Therefore, alternative confirmatory assessments such as an imaging modality that could aid in the diagnosis of PFCN neuropathy would be desirable. The purpose of this study was to determine the feasibility of visualization of the PFCN with high-resolution ultrasound (HRUS) and to test this technique in our clinical routine.

MATERIALS AND METHODS

The study consisted of two parts. In the first part, HRUS-guided perineural ink injections along the course of the PFCN were performed at the posterior aspect of the thigh in 26 lower limbs of 14 fresh non-embalmed cadavers. Subsequent dissection confirmed correct identification of the nerve. In the second part, patients with a suspected PFCN neuropathy were examined and a selective HRUS-guided nerve block was performed to verify the suspected diagnosis.

RESULTS

The PFCN was correctly identified with HRUS in 96.2% (25/26) of cadavers. Further, six patients with a suspected lesion of the PFCN were examined, and the diagnosis was proven by successful HRUS-guided block in all cases.

CONCLUSION

We confirmed the reliable visualization of the PFCN using HRUS. This offers a new technique for the assessment of the PFCN, which could also be demonstrated with the case series presented.

Use of Peripheral Nerve Blocks with Sedation for Total Knee Arthroplasty in a Patient with Contraindication for General Anesthesia

Although peripheral nerve blocks are commonly used to provide postoperative analgesia after total knee arthroplasty (TKA) and other lower extremity procedures, these blocks are rarely used for intraoperative anesthesia. Most TKAs are performed under general anesthesia (GA) or neuraxial anesthesia (NA). The knee has a complex sensory innervation that makes surgical anesthesia difficult with peripheral nerve blocks alone. Rarely are both GA and NA relatively contraindicated and alternatives are considered. We present a patient who underwent TKA performed under peripheral nerve block and sedation alone.

Ultrasound-guided popliteal block through a common paraneural sheath versus conventional injection: a prospective, randomized, double-blind study

BACKGROUND AND OBJECTIVES

The macroscopic anatomy of a common paraneural sheath that surrounds the sciatic nerve in the popliteal fossa has been studied recently in a human cadaveric study. It has been suggested that an injection through this sheath could be an ideal location for local anesthetic administration for popliteal block. The aim of the present study was to evaluate the hypothesis that popliteal sciatic nerve blockade through a common paraneural sheath results in shorter onset time when compared with conventional postbifurcation injection external to the paraneural tissue. To illustrate the microscopic anatomy of the paraneural tissues, we performed histological examinations of a human leg specimen.

METHODS

Following institutional review board approval and written informed consent, 89 patients undergoing an ultrasound-guided popliteal block for foot or ankle surgery were included in the study. They were prospectively randomized to receive a single injection of local anesthetic at the site of bifurcation through a common paraneural sheath (group 1) or 2 separate circumferential injections of the tibial and common peroneal nerves distally to sciatic nerve bifurcation (group 2).

RESULTS

Patients in group 1 had a 30% shorter onset time of both sensory and motor block. This was associated with a more extensive proximal and distal longitudinal spread of local anesthetic in this group. Nerve diameter and cross-sectional area remained unchanged in both groups after injection, which is consistent with extraneural injection. A greater proportion of patients in group 1 required a single needle pass for block performance.

DISCUSSION

An ultrasound-guided popliteal sciatic nerve block through a common paraneural sheath at the site of sciatic nerve bifurcation is a simple, safe, and highly effective block technique. It results in consistently short onset time, while respecting the integrity of the epineurium and intraneural structures.

Magnetic resonance neurography-guided nerve blocks for the diagnosis and treatment of chronic pelvic pain syndrome

Magnetic resonance (MR) neurography - guided nerve blocks and injections describe a techniques for selective percutaneous drug delivery, in which limited MR neurography and interventional MR imaging are used jointly to map and target specific pelvic nerves or muscles, navigate needles to the target, visualize the injected drug and detect spread to confounding structures. The procedures described, specifically include nerve blocks of the obturator nerve, lateral femoral cutaneous nerve, pudendal nerve, posterior femoral cutaneous nerve, sciatic nerve, ganglion impar, sacral spinal nerve, and injection into the piriformis muscle.

High-resolution magnetic resonance-guided posterior femoral cutaneous nerve blocks

OBJECTIVE

To assess the feasibility, technical success, and effectiveness of high-resolution magnetic resonance (MR)-guided posterior femoral cutaneous nerve (PFCN) blocks.

MATERIALS AND METHODS

A retrospective analysis of 12 posterior femoral cutaneous nerve blocks in 8 patients [6 (75%) female, 2 (25%) male; mean age, 47 years; range, 42-84 years] with chronic perineal pain suggesting PFCN neuropathy was performed. Procedures were performed with a clinical wide-bore 1.5-T MR imaging system. High-resolution MR imaging was utilized for visualization and targeting of the PFCN. Commercially available, MR-compatible 20-G needles were used for drug delivery. Variables assessed were technical success (defined as injectant surrounding the targeted PFCN on post-intervention MR images) effectiveness, (defined as post-interventional regional anesthesia of the target area innervation downstream from the posterior femoral cutaneous nerve block), rate of complications, and length of procedure time.

RESULTS

MR-guided PFCN injections were technically successful in 12/12 cases (100%) with uniform perineural distribution of the injectant. All blocks were effective and resulted in post-interventional regional anesthesia of the expected areas (12/12, 100%). No complications occurred during the procedure or during follow-up. The average total procedure time was 45 min (30-70) min.

CONCLUSIONS

Our initial results demonstrate that this technique of selective MR-guided PFCN blocks is feasible and suggest high technical success and effectiveness. Larger studies are needed to confirm our initial results.

Comparison of ultrasound-guided anterior versus transgluteal sciatic nerve blockade for knee surgery

BACKGROUND

Ultrasound-guided sciatic nerve block, in combination with femoral nerve and lateral femoral cutaneous nerve blocks, is frequently used to induce anesthesia for lower limb surgery. The anterior approach to the sciatic nerve is performed in the supine position and repositioning of the patient between injections is avoidable. We compared the relative utility and efficiency of anterior versus transgluteal sciatic nerve blocks in conjunction with femoral nerve and lateral femoral cutaneous nerve blockade.

MATERIALS AND METHODS

Twenty-four patients were enrolled in this prospective double-blind randomized study and were randomly divided into two equal groups: Anterior (Group A) and transgluteal (Group T). We evaluated the following parameters: ultrasound view quality, procedural duration, onset time to block, quality of anesthesia during surgery and postoperative analgesia, required administration of supplemental sedation or narcotics during surgery, amount of pethidine administered within 24 hours post surgery, and overall patient satisfaction.

RESULTS

There were no significant differences between patient groups with regard to the demographic data, onset time to block, quality of ultrasound view, use of narcotics to augment the anesthesia during surgery, and patient satisfaction. Although procedural completion time for the sciatic injection alone was shorter in Group T, the total completion time of all blocks together was significantly less in Group A.

CONCLUSION

Ultrasound-guided anterior blockade of the sciatic nerve has advantages over the transgluteal approach - it provides efficient anesthesia and results in excellent patient satisfaction.

Ultrasound-guided medial mid-thigh approach to sciatic nerve block with a patient in a supine position

We report the use of a ‘medial mid-thigh approach (medial approach),’ a new approach for performing ultrasound-guided sciatic nerve blockade (SNB) with patients in a supine position. Fifty-four patients undergoing knee surgery under general anesthesia and a combined femoral nerve block (FNB) and SNB were included in the study. After FNB, an ultrasound-guided medial approach was used to perform the SNB. The patient was placed in a supine position, and the hip and knee joints were flexed with the leg rotating externally. A linear ultrasound transducer was positioned perpendicular to the skin at the level of the upper mid-thigh. The sciatic nerve was identified in all patients using ultrasound imaging, and the distance to the nerve was 3.0–5.5 cm. A combined ultrasound- and nerve stimulator-guided SNB was then performed, and 0.375% ropivacaine was administered. The block was successful in all patients, and the mean duration of the sensory and motor blockade was 11.9 and 8.2 h, respectively. In this study, the medial approach was highly successful and easy to perform. As performing a simultaneous FNB and SNB with patients in a supine position has several potential advantages, future studies should compare this approach with other more proximal approaches for performing SNB.

[Postoperative analgesia in knee arthroplasty using an anterior sciatic nerve block and a femoral nerve block]

OBJECTIVE

To evaluate the efficacy of a nerve block as an alternative technique for analgesia after knee arthroplasty and to indicate the usefulness and advantages of the anterior approach to the sciatic nerve block.

MATERIAL AND METHODS

Between April 2004 and March 2006, we studied a series of consecutive patients undergoing knee arthroplasty in which a subarachnoid block was used as the anesthetic technique and postoperative analgesia was provided by means of a combined peripheral femoral nerve block and an anterior sciatic nerve block. We evaluated the mean length of time free from pain, quality of analgesia, and length of stay in hospital.

RESULTS

Seventy-eight patients were included in the study. The mean (SD) length of time free from pain for the group was 42.1 (3.9) hours. Patients reported mild pain after 34.8 (4.1) hours and moderate to severe pain after 42.4 (3.5) hours. By the third day, 62.8% of patients were able to bend the knee to 90 degrees. There were no complications resulting from the technique and the level of patient satisfaction was high.

CONCLUSIONS

A combined femoral-sciatic nerve block is effective in knee arthroplasty. It controls postoperative pain and allows for early rehabilitation. The anterior approach to the sciatic nerve is relatively simple to perform without removing the pressure bandaging from the thigh after surgery. This approach also makes it unnecessary to move the patient.

Specific nerve blocks: an update

Recently there has been a considerable increase in interest in regional anesthesia and neural blockade. Many traditional nerve block techniques have been significantly modified to better fit the realm of both inpatient and outpatient surgery. The introduction of long acting local anesthetics with better safety profile as well as better equipment for continuous neuronal blockade has further increased the utility of peripheral nerve blocks. A significant effort has also been invested in studying and improving the safety of various techniques. These developments, coupled with an increased emphasis on teaching of regional blocks by organized anesthesia societies are likely to result in a wider use of these techniques in years to come.

A Comparison of Epidural Analgesia With Combined Continuous Femoral-Sciatic Nerve Blocks After Total Knee Replacement

Epidural analgesia remains the "gold standard" of pain relief after total knee replacement. However, peripheral nerve block is gaining popularity because the incidence of side effects may be reduced. Our study tests this postulate. Sixty patients were prospectively randomized to receive either epidural infusion or combined continuous femoral and sciatic nerve blocks. Ropivacaine 2 mg/mL plus sufentanil 1 mug/mL was given either epidurally or through the femoral nerve catheter, and ropivacaine 0.5 mg/mL was given through the sciatic nerve catheter using elastomeric infusers (delivering 5 mL/h for 55 h). The primary outcome measure was the total incidence of side effects (urinary retention and moderate to severe degrees of dizziness, pruritus, sedation, and nausea/vomiting on the first postoperative day). Intensity of motor blockade, pain at rest and on mobilization, and rehabilitation indices were also registered for 72 h. One or more side effects were present in 87% of patients in the epidural group whereas only 35% of patients in the femoral and sciatic block groups were affected on the first postoperative day (P = 0.0002). Motor blockade was more intense in the operated limb on the day of surgery and the first postoperative day in the peripheral nerve block group (P = 0.001), whereas the non-operated limb was more blocked in the epidural group on the day of surgery (P = 0.0003). Pain on mobilization was well controlled in both groups and there were no differences in the length of hospital stay. Rehabilitation indices were similar. The results demonstrate a reduced incidence of side effects in the femoral/sciatic nerve block group than in the epidural group on the first postoperative day.

A New Approach: Regional Nerve Blockade for Angioplasty of the Lower Limb

PURPOSE

An audit study investigated the pilot use of regional nerve block analgesia (as an alternative to sedative/opiate, general or central neuraxial anesthesia) performed by radiologists with the assistance of imaging techniques during complex prolonged angiography.

METHODS

Radiologists were trained by anesthetic consultants to administer and use lower limb peripheral nerve block for difficult prolonged angioplasty procedures for patients with severe lower limb rest pain who were unable to lie in the supine position. In a pilot study 25 patients with limb-threatening ischemia received sciatic and femoral nerve blockade for angioplasty. The technique was developed and perfected in 12 patients and in a subsequent 13 patients the details of the angiography procedures, peripheral anesthesia, supplementary analgesia, complications, and pain assessment scores were recorded. Pain scores were also recorded in 11 patients prior to epidural/spinal anesthesia for critical ischemic leg angioplasty.

RESULTS

All patients with peripheral nerve blockade experienced a reduction in their ischemic rest pain to a level that permitted angioplasty techniques to be performed without spinal, epidural or general analgesia. In patients undergoing complex angioplasty intervention, the mean pain score by visual analogue scale was 3.7, out of a maximum score of 10.

CONCLUSIONS

The successful use of peripheral nerve blocks was safe and effective as an alternative to sedative/opiate, epidural or general anesthesia in patients undergoing complex angiography and has optimized the use of radiological and anesthetic department resources. This has permitted the frequent radiological treatment of patients with limb-threatening ischemia and reduced delays caused by the difficulty in enlisting the help of anesthetists, often at short notice, from the busy operating lists.

Continuous peripheral nerve blockade in lower extremity surgery

Peripheral nerve blocks afford numerous benefits for lower extremity surgery. There is growing interest in continuous peripheral nerve blocks, mainly for treatment of postoperative pain, a field that represents a challenge to the anaesthesiologist. This paper seeks to review the efficacy of continuous lower limb blocks for postoperative pain relief. Not only do continuous peripheral nerve blocks afford specificity of analgesic area but current research has shown that they enhance postoperative analgesia and patient satisfaction. New techniques and devices are increasingly appearing, and catheters are constantly being developed and improved; an example being the stimulating catheter, which represents one of the newest advances in this area. The above techniques show that continuous postoperative analgesia with catheters in the lower extremities is not only possible, but indeed provides sustained effective postoperative analgesia, reduces use of opioids, and improves rehabilitation and patient well-being with minimal side-effects. These techniques could prove an alternative to postoperative pain treatment following ambulatory surgery.

Anterior sciatic nerve block--new landmarks and clinical experience

BACKGROUND

Anterior sciatic nerve blocks can be complicated by several problems. Pain can be caused by bony contacts and, in obese patients, identification of the landmarks is frequently difficult.

METHODS

In a first step, 100 normal anterior-posterior pelvic X-rays were analyzed. The landmarks of the classical anterior approach were drawn on these X-rays and assessed for their sufficiency. Then, in a prospective case study, 200 consecutive patients undergoing total knee replacement were investigated. These patients received femoral and sciatic nerve catheters for postoperative pain management. Using modified anatomical landmarks, sciatic nerve catheters were inserted 5 cm distal from the insertion site of the femoral nerve block perpendicularly in the midline of the lower extremity. This midline connected the insertion site of the femoral nerve catheter to the midpoint between the medial and lateral epicondyle. Correct catheter positioning was verified by magnetic resonance imaging (MRI) in six patients.

RESULTS

Evaluation of pelvic X-rays showed that puncture following the classical landmarks pointed in 51% at the lesser trochanter, in 5% medial to the lesser trochanter and in 42% directly at the femur. In the latter patients, location of the sciatic nerve would have been difficult or even impossible. Using our modified anterior approach, the sciatic nerve could be blocked in 196 patients (98%). In nine patients (4.5%) blockade of the posterior femoral cutaneous nerve failed. Vascular puncture happened in 10 (5%) and bony contact in 35 patients (17.5%). Median puncturing depth was 9.5 (7.5-14) cm. Correct sciatic nerve catheter positioning was verified in all patients who underwent MRI.

CONCLUSION

Our landmarks for locating the sciatic nerve help to avoid bony contacts and thereby reduce pain during puncture. Our method reliably enabled catheter placement.

The level of the sciatic nerve division and its relations to the piriform muscle

Background. The sciatic nerve, as the terminal branch of the sacral plexus, leaves the pelvis through the greater sciatic foramen beneath the piriform muscle. Afterwards, it separates into the tibial and the common peroneal nerve, most frequently at the level of the upper angle of the popliteal fossa. Higher level of the sciatic nerve division is a relatively frequent phenomenom and it may be the cause of an incomplete block of the sciatic nerve during the popliteal block anesthesia. There is a possibility of different anatomic relations between the sciatic nerve or its terminal branches and the piriform muscle (piriformis syndrome). The aim of this research was to investigate the level of the sciatic nerve division and its relations to the piriform muscle. It was performed on 100 human fetuses (200 lower extremities) which were in various gestational periods and of various sex, using microdissection method. Characteristic cases were photographed. Results. Sciatic nerve separated into the tibial and common peroneal nerve in popliteal fossa in 72.5% of the cases (bilaterally in the 66% of the cases). In the remainder of the cases the sciatic nerve division was high (27.5% of the cases) in the posteror femoral or in the gluteal region. Sciatic nerve left the pelvis through the infrapiriform foramen in 192 lower extremities (96% of the cases), while in 8 lower extremities (4% of the cases) the variable relations between sciatic nerve and piriform muscle were detected. The common peroneal nerve penetrated the piriform muscle and left the pelvis in 5 lower extremities (2.5% of the cases) and the tibial nerve in those cases left the pelvis through the infrapiriform foramen. In 3 lower extremities (1.5% of the cases) common peroneal nerve left the pelvis through suprapiriform, and the tibial nerve through the infrapiriform foramen. The high terminal division of sciatic nerve (detected in 1/3 of the cases), must be kept in mind during the performing of popliteal block anesthesia. Conclusion. Although very rare, anatomical abnormalities of common peroneal nerve in regard to piriform muscle are still possible.

Nerve Stimulator-Assisted Evoked Motor Response Predicts the Latency and Success of a Single-Injection Sciatic Block

Variable onset latency of single-injection sciatic nerve block (SNB) may result from drug deposition insufficiently close to all components of the nerve. We hypothesized that this variability is caused by the needle tip position relative to neural components, which is objectified by the type of evoked motor response (EMR) elicited before local anesthetic injection. One-hundred ASA I-II patients undergoing reconstructive ankle surgery received infragluteal-parabiceps SNB using 0.4 mL/kg (maximum 35 mL) of levobupivacaine 0.625%. The end-point for injection was the first elicited EMR: inversion (I), plantar flexion (PF), dorsiflexion (DF), or eversion (E) at 0.2-0.4 mA. The frequencies of the EMRs were: I 40%, PF 43%, E 14%, and DF 3%. SNB was considered complete if both tibial and common peroneal nerves were blocked and failed if either analgesia to pinprick was not observed at 30 min or anesthesia at 60 min. Patients with an EMR of I demonstrated shorter mean times (+/-95% confidence interval [CI]) to complete the block with 8.5 (95% CI, 6.2-10.8) min compared to 27.0 (95% CI, 20.6-33.4) min after PF (P < 0.001) and 30.4 (95% CI, 24.9-35.8) min after E (P < 0.001). No rescue blocks were required in group I compared with 24% (P = 0.001) and 71% (P < 0.001) of patients in groups PF and E, respectively. We conclude that EMR type during nerve stimulator-assisted single-injection SNB predicts latency and success of complete SNB because the observed EMR is related to the positioning of the needle tip relative to the tibial and common peroneal nerves.

Anterior Approach to the Sciatic Nerve Block: Adaptation to the Patient??s Height

To improve the incidence of block of the posterior femoral cutaneous nerve (PFCN) when using an anterior approach as described recently, we hypothesized that the distance between the inguinal line and the puncture site depends on the patient's height. A preliminary radiological study performed in 13 patients established a formula describing the relationships between the patient's height and the puncture site "S." A line was drawn between the anterior iliac spine and the superior angle of the pubic tubercle (inguinal line) and another line from the midpoint of the inguinal line to the puncture site "S." "S" was calculated from the midpoint of the inguinal line as "S" = (height in cm--100)/10. A prospective study was conducted in 53 patients. Results are presented as median (range, 0.25-0.75). Two minutes were required to locate the sciatic nerve at a depth of 12 cm (10.5-13.0 cm). Complete sciatic and PFCN blocks were observed in 92% of the patients. We conclude that consideration should be given to the patient's height when the sciatic nerve is blocked using an anterior approach. This technique seems to improve the success of block of the PFCN, essential to tolerate a thigh tourniquet.

IMPLICATIONS

This prospective but noncomparative work was performed to evaluate a new anterior technique of sciatic block, an adaptation of the anatomic landmarks described by Chelly and Delaunay, to patient height.

The anterior combined approach via a single skin injection site allows lower limb anesthesia in supine patients

PURPOSE

Lower limb anesthesia (LLA) requires the combination of, at least, three-in-one and sciatic nerve (SCN) blocks. Anterior approaches are easier to perform with minimal discomfort in supine patients, specially for traumatology. Feasibility of a single needle entry combined approach is reported.

CLINICAL FEATURES

The combined landmark was applied in 119 ASA I and II patients (32-68 yr) scheduled for surgery below the knee. Needle (nerve stimulation applied through a single 150-mm long b-bevelled insulated needle) was inserted at the midpoint between the two classical approaches. Thirty and 15 mL of 0.5% ropivacaine were injected close to the femoral and the SCN, respectively. During the following 45 min, the extent of sensory block and knee and ankle motor block were assessed. Landmarks were determined within 1.7 min (0.7-2.2 min). The entire procedure was performed within 4.2 min (2.9-7.1 min) from the determination of the landmark to the SCN infiltration. The three-in-one technique was successful in 89.9% while SCN was successful in 94.9%. Femoral and tibial nerves were always blocked. Blockade of the posterior cutaneous femoral nerve was observed in 78% of patients. The extent and the quality of the sensory block always allowed surgery. Additional iv sedation was needed in 32.6% of patients. Motor block (adapted Bromage's scale > 2) was observed in the femoral (98.3%), the obturator (84.8%), the tibial (97.4%) and the common peroneal (85.7%) nerve distributions. No important adverse effects were recorded.

CONCLUSION

The anterior combined approach via a single needle entry represents a technically easy and reliable technique to perform LLA in the supine patient.

Infragluteal-parabiceps sciatic nerve block: an evaluation of a novel approach using a single-injection technique

Clinical use of the sciatic nerve block (SNB) has been limited by technical difficulties in performing the block using standard approaches, substantial patient discomfort during the procedure, or the need for two injections to block the tibial and peroneal nerves. In this report, we describe a single-injection method for SNB using an infragluteal-parabiceps approach, where the nerve is located along the lateral border of the biceps femoris muscle. SNB was performed in the prone or lateral decubitus position. The needle was positioned (average depth, 56 +/- 15 mm) to the point where plantar flexion (53%) or inversion (45%) of the ipsilateral foot was obtained at < or =0.4 mA. Levobupivacaine 0.625% with epinephrine (1:200:000) was administered at a dose of 0.4 mL/kg. The procedure was completed in 6 +/- 3 min. Discomfort during block placement was treated with fentanyl 50-100 microg in 24% of patients. Complete sensory loss and motor paralysis occurred in 92% of subjects at a median time of 10 (range, 5-25) min after injection. Compared with plantar flexion, foot inversion was associated with a more frequent incidence (86% versus 100%), and shorter latency for both sensory loss and motor paralysis of the peroneal, tibial, and sural nerves. There were no immediate or delayed complications. We conclude that the infragluteal-parabiceps approach to SNB is reliable, efficient, safe, and well tolerated by patients.

IMPLICATIONS

Sciatic nerve block using the infragluteal-parabiceps approach produces sensory loss and motor paralysis after a single 0.4 mL/kg injection of levobupivacaine 0.625% with epinephrine (1:200,000) in >90% of patients. The approach is reliable, uses consistent soft-tissue landmarks, is not typically painful, and does not produce significant complications.

The anatomic relationship of the sciatic nerve to the lesser trochanter: implications for anterior sciatic nerve block

Classic descriptions of the anterior sciatic nerve block suggest needle placement at the level of the lesser trochanter of the femur. Recently, investigators have reported that the sciatic nerve is not accessible at this level. To define more accurately the anatomic relationship of the sciatic nerve to the lesser trochanter, we analyzed magnetic resonance scans performed on 20 patients in the supine position. After IRB approval, magnetic resonance scans of the hip and proximal femur were reviewed in 20 supine patients in the neutral position. Images from five axial levels were studied, specifically, at the level of the lesser trochanter and at 1-cm intervals inferior to the lesser trochanter for 4 cm. In each axial image, the medial or lateral distance was measured from the sciatic nerve to a sagittal plane at the medial border of the femur. If the sciatic nerve was lateral to this sagittal plane (inaccessible), the distance was assigned a negative value, and if the sciatic nerve was medial to the sagittal plane (accessible), the distance was assigned a positive value. The distance between the coronal plane at the anterior border of the femur and the coronal plane through the sciatic nerve was also recorded for each level. At the level of the lesser trochanter, the sciatic nerve was lateral to the femoral border (inaccessible) in 13 of 20 patients with a mean distance of -4.0 +/- 7.7 mm. At 4 cm below the lesser trochanter, the sciatic nerve was medial to the femoral border (accessible) in 19 of 20 patients with a mean distance 7.8 +/- 5.8 mm. The distance from the anterior border of the femur to the sciatic nerve was 42.9 +/- 5.8 mm at the level of the lesser trochanter and 45.7 +/- 9.5 mm at 4 cm below the lesser trochanter. The classic description of the anterior approach to the sciatic nerve suggests that the needle be walked off medially at the level of the lesser trochanter. Our data are consistent with recent reports suggesting that in the majority of subjects, the position of the sciatic nerve relative to lesser trochanter made it inaccessible from an anterior approach at this level. In contrast, at 4 cm below the lesser trochanter, the sciatic nerve was medial to the femur in 19 of 20 subjects. We conclude that needle insertion medial to the proximal femur, 4 cm below the lesser trochanter, is a more direct anatomical approach to the anterior sciatic nerve block.

IMPLICATIONS

Magnetic resonance images suggest that in the majority of supine subjects, the sciatic nerve is lateral to the lesser trochanter of the femur and therefore not accessible using the classic anterior approach. By contrast, 4 cm below the lesser trochanter, the sciatic nerve is consistently medial to the femoral shaft and therefore may be more accessible using an anterior approach.

New landmarks for the anterior approach to the sciatic nerve block: imaging and clinical study

In this study, we assessed the reliability of the inguinal crease and femoral artery as anatomic landmarks for the anterior approach to the sciatic nerve and determined the optimal position of the leg during this approach. An imaging study was conducted before the clinical study. The sciatic nerve was located twice in 20 patients undergoing ankle or foot surgery, once with the leg in the neutral position and once with the leg in the externally rotated position. The patient was lying supine. A 22-gauge, 150-mm insulated b-beveled needle connected to a nerve stimulator was inserted 2.5 cm distal to the inguinal crease and 2.5 cm medial to the femoral artery and was directed posteriorly and laterally with a 10 degrees -15 degrees angle relative to the vertical plane. The sciatic nerve was located in all patients at a depth of 10.6 +/- 1.8 cm when the leg was in the neutral position and 10.4 +/- 1.5 cm when the leg was in the externally rotated position (not significant). In the neutral position and in the externally rotated position, the time needed to identify anatomic landmarks was 28 +/- 15 s and 26 +/- 14 s, respectively (not significant), and the time needed to locate the sciatic nerve was 79 +/- 53 s and 46 +/- 25 s (P < 0.006), respectively. We conclude that the inguinal crease and femoral artery are reliable and effective anatomic landmarks for the anterior approach to the sciatic nerve and that the optimal position of the leg is the externally rotated position.

IMPLICATIONS

This new anterior approach to the sciatic nerve using the inguinal crease and femoral artery as landmarks is an easy and reliable technique.

A double-blinded, randomized comparison of either 0.5% levobupivacaine or 0.5% ropivacaine for sciatic nerve block

To compare intraoperative and postoperative clinical properties of levobupivacaine and ropivacaine for sciatic nerve block, 50 ASA physical status I and II patients undergoing hallux valgus repair received a femoral nerve block with 15 mL of 2% mepivacaine. They were then randomly allocated in a double-blinded fashion to receive a sciatic nerve block with either 0.5% levobupivacaine (n = 25) or 0.5% ropivacaine (n = 25). An independent blinded observer evaluated the onset time of surgical anesthesia as well as the quality of the surgical block and postoperative analgesia. The median (range) onset time of surgical block at the sciatic nerve distribution was 30 min (5-60 min) with levobupivacaine and 15 min (5-60 min) with ropivacaine (P = 0.63). Four patients (two patients in each group) received a supplementary ankle block by the surgeon just before the beginning of surgery. All four patients also received IV fentanyl supplementation, but in three of them, propofol infusion was required to complete surgery (two in the Levobupivacaine group [8%] and one in the Ropivacaine group [4%]; P = 0.99). In six patients of the Levobupivacaine group (24%) and five patients of the Ropivacaine group (20%), IV fentanyl supplementation was required to complete surgery (P = 0.99). No differences in the time to recovery of sensory and motor function were observed between the two groups, whereas median (range) duration of postoperative analgesia was 16 h (8-24 h) with levobupivacaine and 16 h (8-24 h) with ropivacaine (P = 0.83). We conclude that 0.5% levobupivacaine and 0.5% ropivacaine provide comparable surgical anesthesia and postoperative analgesia.

IMPLICATIONS

No studies have compared the clinical properties of levobupivacaine with those of ropivacaine when providing sciatic nerve block for hallux valgus repair. Results from this prospective, randomized, double-blinded study demonstrate that 20 mL of either 0.5% levobupivacaine or 0.5% ropivacaine provide comparable surgical block with prolonged postoperative analgesia.

Postoperative analgesia with continuous sciatic nerve block after foot surgery: a prospective, randomized comparison between the popliteal and subgluteal approaches

To compare the posterior popliteal and subgluteal continuous sciatic nerve block for anesthesia and acute postoperative pain management after foot surgery, 60 ASA physical status I and II patients undergoing elective orthopedic foot surgery were randomly assigned to either a Subgluteal group (n = 30) or Popliteal group (n = 30). Before surgery and after performing a femoral nerve block with 15 mL of 2% mepivacaine, we performed the sciatic nerve block with 20 mL of 0.75% ropivacaine using either a subgluteal or posterior popliteal approach, and the placement of a catheter came afterward. In the recovery room, the catheter was connected to a patient-controlled analgesia pump to infuse 0.2% ropivacaine (basal infusion rate of 5 mL/h, incremental bolus of 10 mL, and a lockout time of 60 min). There were no technical problems in catheter placement. Intraoperative efficacy of nerve block was similar in the two groups. Postoperative catheter displacement and occlusion were recorded in four patients in the Popliteal group and two patients in the Subgluteal group (P = 0.67). Both approaches provided similar postoperative analgesia. We conclude that the subgluteal approach is as effective and safe as the previously described posterior popliteal approach for continuous sciatic block and can be considered a useful alternative to anesthesia and acute postoperative analgesia after foot procedures.

IMPLICATIONS

Comparing two different approaches for continuous sciatic nerve block after orthopedic foot surgery, this prospective, randomized study demonstrated that the subgluteal approach is as effective and safe as the previously described posterior popliteal approach, and can be considered a useful alternative to anesthesia and acute postoperative analgesia after foot procedures.

Clinical properties of levobupivacaine or racemic bupivacaine for sciatic nerve block

STUDY OBJECTIVE

To compare the intraoperative and postoperative clinical properties of the sciatic nerve block performed with either 0.5% bupivacaine or 0.5% levobupivacaine for orthopedic foot procedures.

DESIGN

Randomized, double-blind study.

SETTING

Inpatient unit of a university-affiliated hospital.

PATIENTS

30 ASA physical status I and II patients undergoing elective hallux valgus repair under regional anesthesia.

INTERVENTIONS

After administering intravenous (IV) midazolam premedication (0.05 mg/kg), a femoral nerve block was performed with 15 mL of mepivacaine 2%. Patients were then randomly allocated to receive, in a double-blind fashion, a sciatic nerve block with 20 mL of either 0.5% bupivacaine (n = 15) or 0.5% levobupivacaine (n = 15).

MEASUREMENTS AND MAIN RESULTS

An observer who was blinded to the study drug recorded the onset time, quality, and duration of the sciatic nerve block. Postoperative analgesia consisted of 100 mg IV ketoprofen every 8 hours, with the first administration given at the patient's request. Mean (+/-SEM) onset time of the sciatic nerve block was 35 +/- 5 minutes for bupivacaine and 31 +/- 6 minutes for levobupivacaine (p = not significant [NS]). The duration of motor and sensory blocks with bupivacaine was 761 +/- 112 minutes and 790 +/- 110 minutes, respectively, and 716 +/- 80 minutes and 814 +/- 73 minutes, respectively, with levobupivacaine (p = NS). The first pain medication was requested after 844 +/- 96 minutes with bupivacaine and 872 +/- 75 minutes after levobupivacaine (p = NS). No differences in the quality of nerve block and patient satisfaction were reported between the two groups.

CONCLUSIONS

A dose of 20 mL of 0.5% levobupivacaine induces sciatic nerve block of similar onset, duration, and intensity as the block produced by the same volume and concentration of the racemic solution of bupivacaine.

Regional anaesthesia for orthopaedic surgery

Recently, there has been considerable interest in regional anaesthetic techniques, particularly in peripheral nerve blockade, for orthopaedic limb surgery. Many traditional nerve-block techniques have been significantly modified to improve their role in both in-patient and out-patient surgery. The introduction of long-acting local anaesthetic with a better safety profile as well as better equipment for continuous nerve blockade has further increased the use of such techniques in the provision of postoperative analgesia. The recent developments described in this review are likely to result in wider use of these techniques in years to come.

A new posterior approach to the sciatic nerve block: a prospective, randomized comparison with the classic posterior approach

To evaluate the efficacy and acceptance of a new posterior subgluteus approach to the sciatic nerve, as compared with the classic posterior approach, 128 patients undergoing foot orthopedic procedures were randomly allocated to receive either the classic posterior sciatic nerve block (Group Labat, n = 64) or a modified subgluteus posterior approach (Group subgluteus, n = 64). All blocks were performed with the use of a nerve stimulator (stimulation frequency, 2 Hz; intensity, 1-0.5 mA). In Group subgluteus, a line was drawn from the greater trochanter to the ischial tuberosity; then, from the midpoint of this line, a second line was drawn perpendicularly and extended caudally for 4 cm. The end of this line represented the needle entry. In both groups, a proper sciatic stimulation was elicited at 0.5 mA; then 20 mL of 0.75% ropivacaine was injected. The time from needle insertion to successful sciatic nerve stimulation was 60 s (range, 10-180 s) with the Labat's approach and 32 s (range, 5-120 s) with the new subgluteus approach (P = 0.0005). The depth of appropriate sciatic stimulation was 45 +/- 13 mm (mean +/- SD) after 2 (range, 1-7) needle redirections in Group subgluteus and 67 +/- 12 mm after 4 (range, 1-10) needle redirections in Group Labat (P = 0.0001 and P = 0.00001, respectively). The failure rate was similar in both groups. Severe discomfort during the procedure was less frequent and acceptance better in Group subgluteus (5 patients [8%] and 60 patients [94%], respectively) than in Group Labat (20 patients [31%] and 49 patients [77%], respectively) (P = 0.0005 and P = 0.005, respectively). We conclude that this new subgluteus posterior approach to the sciatic nerve is an easy and reliable technique and can be considered an effective alternative to the more traditional Labat's approach.

IMPLICATIONS

Evaluating the efficacy and acceptance of a new approach to the sciatic nerve block, this prospective, randomized study demonstrated that the new subgluteus posterior approach is an easy and reliable technique and can be considered an useful alternative to the more traditional Labat's approach in patients undergoing foot surgery, facilitating the performance of the sciatic nerve blocks.

A comparison of 0.5% ropivacaine and 1% mepivacaine for sciatic nerve block in the popliteal fossa

BACKGROUND

The purpose of this study was to compare anesthetic efficacy and postoperative analgesia of 0.5% ropivacaine and 1% mepivacaine for sciatic nerve block in the popliteal fossa (popliteal block).

METHODS

A prospective, double-blind study was carried out in 58 adult patients scheduled for outpatient foot or ankle surgery. They were randomized to receive popliteal block with 40 ml of either 0.5% ropivacaine (group R) or 1% mepivacaine (group M). An atraumatic, Teflon-coated needle connected to a neurostimulator was used to make a single puncture using a posterior approach. The times to onset of sensory and motor block, and the need for intraoperative sedation were recorded. Before discharge, patients were asked to document the time to first analgesic use, time to return of full sensation in the foot, and their evaluation of the technique.

RESULTS

Onset time (mean+/-standard deviation, 95% confidence interval) of both sensory block (6.5+/-5.1 min, 4.47-8.49, in group R and 6.2+/-3.7 min, 4.83-7.69, in group M) and motor block (6.6+/-4.4 min, 4.81-8.23, in group R and 7.9+/-4.1 min, 6.29-9.53, in group M) was similar in both groups. Postoperative analgesia lasted longer in group R (15.2+/-5.1 h, 13.25-17.21) than in group M (5.7+/-1.8 h, 5.01-6.41; P<0.001). Duration of sensory block was longer in group R (20.7+/-6.2 h, 18.51-23.01) than in group M (6.5+/-1.7 h, 5.86-7.16; P<0.001). Acceptance of the anesthetic procedure was similar in both groups.

CONCLUSION

In this study we demonstrated that both 0.5% ropivacaine and 1% mepivacaine for popliteal block produced rapid, effective and safe anesthesia but postoperative analgesia was more long-lasting with ropivacaine.