Sciatic Nerve Block Research Articles

Effect of perioperative sciatic nerve block on chronic pain in patients undergoing below-knee amputation: A randomised controlled trial

Many pain syndromes such as chronic phantom limb pain (PLP) and stump pain (SP), involving nociceptive and neuropathic pain, develop after amputation. Recent literature suggests that the use of regional blocks reduces repeated stimulation of transected nerve roots and thus prevents central sensitisation. This randomised, double-blind study was conducted to evaluate the effect of pre-emptive ultrasound-guided single-shot lateral sciatic nerve block on the occurrence of chronic pain at six months after traumatic below-knee amputation. Thirty patients undergoing traumatic lower limb amputation under general anaesthesia were randomised into two groups: Group B received sciatic nerve block pre-emptively using ultrasound with 20 ml of 0.75% ropivacaine, whereas group C received 20 ml of normal saline. Follow-up of patients was done till six months post-amputation. The primary objective was to assess the occurrence of chronic pain at six months. Pain at 15 days and one month after surgery, post-operative morphine consumption and post-operative nausea and vomiting (PONV) were the secondary outcomes assessed. The occurrence of PLP at six months was comparable in the two groups, group B (46.7%) and C (66.7%). None of the patients developed SP at six months. Median intensities of phantom pain were 1.0 (range, 1-2.0) versus 1.0 (range, 1-2.0) (P = 0.36), and median intensities of SP 2 (range, 2-3.0) versus 3 (range, 2-3.0) (P = 0.39) at 1 month. Pre-emptive sciatic nerve block did not decrease the occurrence or severity of chronic pain after traumatic below-knee amputation.

Anaesthetic management of right tibia intramedullary nailing in a patient with extradural haematoma

Cases of extradural haematoma (EDH) are often encountered in the emergency department in patients with multiple traumatic injuries. If the haematoma is small, non-expanding and asymptomatic, it is often managed conservatively. However, other injuries sustained during trauma may require surgical intervention, during which anaesthetic management can become challenging. Here, we present a case where closed reduction and intramedullary nailing was done for a right tibia fracture, successfully performed in a patient with traumatic EDH under combined femoral and popliteal sciatic nerve block with supplementary dexmedetomidine infusion for sedation.

248 Ultrasound-Guided Transgluteal Sciatic Nerve Block in Emergency Department Patients With Sciatic Radiculopathy: A Multicenter Prospective Study

Acute-on-chronic pain secondary to sciatica is a common emergency department (ED) presentation and often leads to loss of work, decreased function, and emotional distress. The transgluteal sciatic nerve block (TGSNB) is used by anesthesiologists for chronic, acute, and perioperative sciatic nerve pain. The objective of this study is to assess the efficacy and safety of ED performed TGSNB for acute sciatic radiculopathy.

Comparison Between Ultrasound-guided Caudal Analgesia versus Peripheral Nerve Blocks for Lower Limb Surgeries in Pediatrics: A Randomized Controlled Prospective Study.

Background and AimUltrasound (US) guided regional analgesia is a safe and effective method in providing perioperative analgesia in pediatrics with a high success rate rapid onset and fewer side effects. The aim of this study was to compare the efficacy of US-guided caudal block versus US-guided peripheral nerve blocks (femoral and sciatic nerve blocks) in providing perioperative analgesia in pediatrics undergoing unilateral lower limb surgery.MethodsChildren aged 1–12 years scheduled for unilateral lower limb surgery during the period from January 2020 to December 2021 were randomly allocated into two groups. Group C where pediatrics received US-guided caudal block, while in group P, pediatrics received US-guided femoral and sciatic nerve blocks after the induction of general anesthesia (GA). The primary aim was to compare the postoperative pain (evaluated by the COMFORT pain score) between the two groups. Secondary aims were to compare perioperative opioids used parents’ satisfaction and occurrence of side effects.ResultsPediatrics who underwent unilateral lower limb surgeries were allocated into two groups (group C and group P). There was no significant difference between patients’ baseline characteristics and the postoperative pain score at 2, 4, 16, and 20 h.’ However there was a statistical significance at 6, 8, 12, and 24 h postoperatively, frequency of analgesia as well as the total postoperative dose of opiates (nalbuphine). Time to first analgesic (nalbuphine) requirement was significantly less in group C with a mean of (9.6±2.9 h) than in group P with a mean of (15.1±3.5 h). Parents of children in group P were more satisfied than those in group C with no recorded complications for both techniques.ConclusionUS-guided lower limb peripheral nerve block is a simple and safe method to provide adequate and more prolonged analgesia compared to US-guided caudal block for lower limb surgeries in pediatrics.

Magnetic resonance imaging study of the sciatic nerve variation in the pediatric gluteal region: Implications for the posterior approach of the sciatic nerve blockade.

In pediatric patients, the sciatic nerve is one of the most commonly blocked peripheral nerves during orthopedic procedures of the lower limb. Ultrasound guidance is the current standard for a successful localization of the sciatic nerve in the gluteal region. Relevant anatomical landmarks are also used to determine the nerve location when ultrasound is not available or inadequate. However, reports have demonstrated paucity of information regarding the sciatic nerve location and variation in the hip throughout pediatric development. This imaging study aimed to document and analyze the relative morphometric relationship of the sciatic nerve in the pediatric gluteal region throughout development. The location of the sciatic nerve in relation to bony landmarks was measured in 84 pediatric magnetic resonance imaging of patients aged 0.7-15.8 years. The sciatic nerve was identified medial to the most lateral point of greater trochanter at the level of ischial spine and the tip of coccyx. The strong positive correlation between sciatic nerve to landmark distances and age and stature demonstrated linear variation between sciatic nerve location with age and growth of children. To predict the nerve location in the gluteal region, regression equations using patient age were created, having implications for the posterior approach of the sciatic nerve blockade in children. Clinically significant differences were found between sexes, specifically in the older age group. Despite the small sample size of younger age group, this study is the first to document the morphometric changes of the sciatic nerve in the gluteal region across pediatric development and may be useful for providing confirmatory guidelines for nerve location when ultrasound is not accessible or cannot be utilized for practice.

The Influence of Diabetic Peripheral Neuropathy on the Duration of Sciatic Nerve Block with 1.3% Liposomal Bupivacaine and 0.25% Bupivacaine Hydrochloride in a Mouse Model.

Little is known regarding the pharmacological properties of extended-release local anesthetics in the setting of diabetic peripheral neuropathy. We investigated and compared the duration of sciatic nerve block following administration of clinically relevant concentrations of liposomal bupivacaine (LB) and bupivacaine hydrochloride (BH) in diabetic mice with peripheral neuropathy. In this prospective, randomized, and double-blind study, twenty-four female C57BL/6J-OlaHsd mice were assigned to a streptozotocin-induced type 1 diabetes group and a control group without diabetes. The presence of peripheral neuropathy was established by assessing the duration of thermal latency of the plantar and tail-flick tests, following which both groups were subdivided into two subgroups in which 35 mg/kg of 1.31% LB and 7 mg/kg of 0.25% BH were respectively administered for sciatic nerve block. The average sensory block duration with BH was 106 min and 117.1 min in the control and diabetic groups, respectively. With LB, the average sensory block duration was 118 min in the control mice, while in mice with diabetic peripheral neuropathy, the average block duration was significantly longer and above the 270 min limit set in our study. Accordingly, sensory block duration was longer with LB compared to BH, and diabetic peripheral neuropathy significantly increased sciatic nerve block duration with LB.

A Bioinformatics Study of Ropivacaine plus Dexamethasone Prolonging the Duration of Nerve Block.

The study focuses on the potential function of dexamethasone on ropivacaine in sciatic nerve blocks. Nine Sprague–Dawley (SD) rats were randomly divided into three groups: normal group (NG), control group (CG), and experimental group (EG), with three rats in each group. The CG was injected with diluted ropivacaine (0.5% concentration); the EG was injected with a diluted ropivacaine+dexamethasone mixture, and the NG was injected with an equal amount of saline. The sciatic nerve in the thigh was collected for sequencing two days after injection in each group. Differential analysis was performed for NG-vs-CG, NG-vs-EG, and CG-vs-EG based on the sequencing dataset. The modular genes associated with ropivacaine and ropivacaine+ dexamethasone were screened by weighted coexpression network analysis (WGCNA), differentially expressed modules among them were enriched for analysis, and protein-protein interaction (PPI) networks were constructed to observe high and low expression among key genes in immune cells. Twenty-two and three differential genes associated with ropivacaine (green-yellow module) and ropivacaine+dexamethasone (palevioletred3 module) were acquired, respectively, which played important roles in biological processes such as erythrocyte homeostasis, erythroid differentiation, and hemoglobin metabolic processes. PPI revealed that AHSP, ALAS2, EPB42, HBB, and SLC4A1 were interacting and the expression of these five genes was upregulated in the CG compared with the NG, while the expression of them was downregulated in the EG compared with the CG. The immunological analysis also showed significant differences in the expression of various immune cells in the 3 groups. AHSP, ALAS2, EPB42, HBB, and SLC4A1 are genes associated with hemoglobin, and dexamethasone combined with ropivacaine may prolong anesthesia by affecting local vasoconstriction to some extent.

Multimodal analgesic technique in a peacock (Pavo cristatus) anaesthetised for orthopaedic surgery

AbstractA 6‐month‐old, male peacock (Pavo cristatus) underwent right‐sided corrective tibiotarsal osteotomy under general anaesthesia. Butorphanol (1 mg/kg) and midazolam (1 mg/kg) were administered in the pectoral muscle as pre‐anaesthetic medications. Anaesthesia was induced with intravenous alfaxalone (2.5 mg/kg) and maintained with isoflurane in oxygen. Intermittent positive‐pressure ventilation was applied. A nerve stimulator‐guided femoral nerve block and a nerve stimulator‐ and ultrasound‐guided sciatic nerve block were performed before surgery with lidocaine. An intravenous bolus of ketamine (1 mg/kg), followed by infusion (20 µg/kg/min) was administered intraoperatively. No nociception was recorded during surgery. This case report describes a successful multimodal analgesic technique in a peacock anaesthetised for orthopaedic surgery.

Review on Nerve Blocks Utilized for Perioperative Total Knee Arthroplasty Analgesia.

Total Knee Arthroplasty (TKA) is an increasingly common procedure performed for advanced osteoarthritis. Optimal perioperative pain management strategies are critical for early mobilization and shorter hospital stays in TKA. Peripheral nerve blocks commonly used in TKA perioperative analgesia including individual and combined femoral, obturator, sciatic, lumbar plexus, and adductor canal nerve blocks. Overall, the safety profile varies depending on which block is utilized, but the current evidence suggests when optimally chosen and delivered, peripheral nerve blocks may provide a safe, effective option for perioperative analgesia. Determining optimal analgesic regimens for total knee arthroplasty is critical to improve postoperative pain, patient satisfaction, decreasing opioid usage, recovery times and functional outcomes, and as such, peripheral nerve blocks may represent a viable option to supplement analgesic requirements in the perioperative period.

Block duration is substantially longer with a liposomal suspension of bupivacaine than with 0.5% bupivacaine HCl potentiated with dexmedetomidine following an ultrasound-guided sciatic nerve block in Beagles

To compare the duration of bupivacaine liposome suspension in the dog with that of bupivacaine and dexmedetomidine following a perineural injection. 8 healthy Beagles. The left sciatic nerve of each dog was randomly assigned to an ultrasound-guided perineural injection with either bupivacaine liposome suspension (BLS) or with 0.5% bupivacaine with dexmedetomidine (1 µg/mL) (BUP-DEX). The contralateral nerve was assigned to the alternate agent. The sensory, motor, and proprioceptive functions were evaluated before the injection (baseline) and at 4, 10, 24, 48, 72, and 96 hours. The block in 1 limb in the BLS treatment appeared to have failed (data set excluded). The motor scores of 2 individuals could not be evaluated leaving 5 limbs to evaluate in the BLS treatment and 6 in the BUP-DEX. A total of 6 out of 7 limbs in the BLS achieved a complete sensory block. In 3 out of 5 treatments with BLS, motor block was only partial and in 2 not apparent at all. Proprioceptive block was partial in 5 out of 7 dogs in the BLS treatment. All functions were still completely obliterated at 10 hours in 6 cases in treatment BUP-DEX. All functions were restored in all cases by 96 and 24 hours after administration of BLS and BUP-DEX, respectively. The blockade characteristics of bupivacaine liposome suspension were effective and long lasting. Motor and proprioceptive deficits may be inconsistent over time.

Postoperative Pain Control by Local Infiltration Analgesia and Peripheral Nerve Block in Primary Prosthetic Total Knee Arthroplasty.

Background and ObjectivePostoperative (post-op) pain control has an important impact on post-op rehabilitation. The logistics of its maintenance challenge the effect of peripheral nerve block on post-op pain control, with the risk for post-op complications. We hypothesized that perioperative use of local infiltration analgesia (LIA) is comparable to post-op pain control by peripheral nerve block.Materials and MethodsWe evaluated three groups of patients treated with primary total knee arthroplasty (TKA) due to symptomatic end-stage osteoarthritis with post-op pain control by LIA (LIA group, n=52), femoral plus sciatic nerve block (FSNB) (FSNB group, n=54), and without local or regional analgesia as controls (Control group, n=53). The primary outcome variable was the post-op pain level intensity as measured by the visual analog scale (VAS). Secondary outcome variables were knee function measured by the Knee Society Score (KSS) and the quadriceps muscle strength recovery profile.ResultsUp to 4 hours post-op, pain intensity was significantly lower in FSNB patients (P<0.05). This effect of the peripheral nerve block on the pain level disappeared 6 hours post-op. The LIA and FSNB patients showed a significant decrease in pain intensity on days 2 and 3 post-op (P<0.05) with no mutual differences (P>0.05). This effect disappeared on day 4 post-op (P>0.05). The KSS score showed similar significant improvement of functional abilities (P<0.001) in all three groups. There was no difference in KSS scores among the groups 6 months after surgery (P>0.05). Quadriceps muscle recovery profile was similar in the LIA and Control groups, but significantly poorer in the FSNB group (P<0.001).ConclusionThe value of very short-term and improved pain relief of post-op FSNB over LIA of the surgical wound should be carefully weighed against its cost, logistics, and potential complication threat.

An Evaluation of Peripheral Sciatic Nerve Block in Patients Undergoing Hallux Valgus Surgery

An Evaluation of Peripheral Sciatic Nerve Block in Patients Undergoing Hallux Valgus Surgery

Intelligent Three-Dimensional Reconstruction Algorithm-Based Ultrasound-Guided Nerve Block in Intraoperative Anesthesia and Postoperative Analgesia of Orthopedic Surgery

This research was aimed at analyzing the role of ultrasound-guided nerve block based on intelligent three-dimensional (3D) reconstruction algorithm in intraoperative anesthesia and postoperative analgesia of orthopedic surgery. 68 elderly patients were undergoing orthopedic surgery on the lower extremities, and they were randomly rolled into two groups with 34 patients in each group. The patients in control group received sciatic nerve block anesthesia (SNBA), and the patients in the experimental group received ultrasound-guided SNBA (UG-SNBA) under 3D reconstruction algorithm to analyze and compare the anesthesia effect and the postoperative analgesia effect. The results showed that compared with other algorithms, the evaluation index of ultrasound images processed by the 3D reconstruction algorithm was better. In terms of anesthesia effect, there was no significant difference in systolic blood pressure, diastolic blood pressure, and heart rate between the two groups before surgery (P > 0.05). Intraoperative and postoperative indicators of the experimental group were significantly better than those of the control group; the drug dosage (61 mg) was less than that of the control group (78 mg). In addition, the onset time of anesthesia, the time of pain blockade, and the postoperative awake time (5 minutes, 8 minutes, and 8 minutes, respectively) were shorter than those in the control group (13 minutes, 15 minutes, and 15 minutes, respectively). The visual analogue scale (VAS) scores of the experimental group were better than those of the control group on the day after surgery, one day after surgery, two days after surgery, and three days after surgery, with significant differences (P < 0.05). In summary, 3D reconstruction algorithm-based ultrasound image effect was clearer, the effect of UG-SNBA was more stable, and the postoperative analgesic effect was better. This work provided a higher reference for the selection of safe and effective anesthesia options in orthopedic surgery.

Comparison of the effectiveness of ultrasound-guided and ultrasound-guided subgluteal nerve blocks with peripheral nerve electrical stimulation: A randomized controlled feasibility trial

AIM: The efficacy of sciatic nerve blockade with subchondral access under ultrasound guidance (USG) versus ultrasound guidance in combination with EPN (USEPN) is unknown. Data on studies of these techniques for blockade of other peripheral nerves are inconsistent. This study evaluated the feasibility of a randomized trial to compare the efficacy of sciatic nerve blockade with USG-guided sciatic access with the current practice of USEPN.&#x0D; MATERIALS AND METHODS: Forty patients were randomized into two groups in which USG or USEPN guidance was used to perform sciatic nerve blockade with sciatic access. The primary endpoint was the quality of the sensory block. The secondary endpoint was the quality of the motor block.&#x0D; RESULTS: Two groups of 20 patients each were analyzed. All patients developed successful motor and sensory blocks of the sciatic nerve when using USG and USEPN. All cases were followed. Three patients were excluded before randomization because of the unsatisfactory ultrasound imaging of the sciatic nerve.&#x0D; CONCLUSION: The results show that a prospective study of alternative techniques of sciatic nerve block by subchondral access is possible. In our pilot study, sciatic nerve block performed under USG guidance without EPN was effective in all cases.

Impact of varying degrees of peripheral nerve blockade on experimental pressure and ischemic pain: adductor canal and sciatic nerve blocks in a human model of compartment syndrome pain

IntroductionEarly diagnosis of acute extremity compartment syndrome is crucial to timely surgical management. Pain is commonly used as an early diagnostic sign for acute extremity compartment syndrome, making regional anesthesia...

Sciatic nerve block downregulates the BDNF pathway to alleviate the neonatal incision-induced exaggeration of incisional pain via decreasing microglial activation

Sciatic nerve block is under investigation as a possible therapeutic strategy for neonatal injury-induced exaggeration of pain responses to reinjury. Spinal microglial priming, brain-derived neurotrophic factor (BDNF) and Src homology-2 domain-containing protein tyrosine phosphatase-2 (SHP2) participate in exaggerated incisional pain induced by neonatal incision. However, effects of sciatic nerve block on exacerbated incisional pain and underlying mechanisms remain unclear. Here, we demonstrated that sciatic nerve block alleviates pain hypersensitivity and microglial activation in rats subjected to neonatal incision and adult incision (nIN-IN). Chemogenetic activation or inhibition of spinal microglia attenuates or mimics effects of sciatic nerve block on pain hypersensitivity, respectively. Moreover, α-amino-3-hydroxy- 5-methy- 4-isoxazole propionate (AMPA) receptor subunit GluA1 contributes to the exaggeration of incisional pain. The inhibition of BDNF or SHP2 blocks upregulations of downstream molecules in nIN-IN rats. Knockdown of SHP2 attenuates the increase of GluA1 induced by injection of BDNF in adult rats with only neonatal incision. The inhibition of microglia or ablation of microglial BDNF attenuates upregulations of SHP2 and GluA1. Additionally, sciatic nerve block downregulates the expression of these three molecules. Upregulation of BDNF, SHP2 or AMPA receptor attenuates sciatic nerve block-induced reductions of downstream molecules and pain hypersensitivity. Microglial activation abrogates reductions of these three molecules induced by sciatic nerve block. These results suggest that decreased activation of spinal microglia contributes to beneficial effects of sciatic nerve block on the neonatal incision-induced exaggeration of incisional pain via downregulating BDNF/SHP2/GluA1-containing AMPA receptor signaling. Thus, sciatic nerve block may be a promising therapy.

Reevaluation of the topographical anatomy of the mid-thigh: A magnetic resonance and ultrasound imaging study.

Adductor canal (AC) and sciatic nerve (SN) blockades are commonly used during total knee arthroplasties for postoperative pain control. Medical professionals have begun to utilize single injection combined regional anesthesia methods due to increased patient comfort. In this study, we examined the topographical anatomy of the mid-thigh, which is recommended as the appropriate intervention level for combined AC and SN blockades, in order to provide a safe approach for clinicians. We examined 184 thigh magnetic resonance images (MRI) from 98 patients. We measured the diameter of the mid-thigh, anterior thigh muscle thickness, subcutaneous adipose tissue thickness, and SN depth on the MRIs. We obtained ultrasound (US) images of the vastoadductor membranes (VAM) of 26 volunteers, and measured the vertical distances between the greater trochanter and the adductor tubercle (A) and the greater trochanter and the upper edge of the VAM (B). We then proportioned B to A in order to determine in which part of the thigh the AC was located. The AC was in the distal third of the thigh, and the SN's depth was located in the third quarter of the thigh's diameter. Only the adductor magnus, and no neurovascular structure, was at risk of injury between the AC and the SN. The upper edge of the VAM was 6.5 cm below the mid-thigh, therefore it is not appropriate to suggest performing an AC blockade at mid-thigh. We think that it is safe to perform a combined AC and SN blockade in a single injection in selected patients.

The reversing effect of ondansetron on bupivacaine-induced sciatic nerve block.

This experimental study was designed to test the hypothesis that ondansetron, a selective 5-HT3 receptor antagonist, would decrease the duration of motor, sensory, and proprioception blockade in a dose-dependent fashion in a bupivacaine-induced sciatic nerve blockade. Forty-nine male Wistar Albino rats who underwent unilateral sciatic nerve block were divided into seven groups with an equal number in each group. Group B: only perineural block (PB), Group BO200: PB and perineural 200 μg ondansetron, Group BO400: PB and perineural 400 μg ondansetron, Group BO800: PB and perineural 800 μg ondansetron, Group BO800IP: PB and intraperitoneal 800 μg ondansetron, Group O800: only perineural 800 μg ondansetron, Group S: sham-operated. The rats' motor, sensory, and proprioception functions were evaluated by a blinded investigator every 10 min until they returned to normal function. The recovery times of the motor, sensory, and proprioception functions were recorded and compared. All sciatic nerves were removed and examined by electron microscopy for neurotoxic signs. In which sciatic nerve block was formed with bupivacaine, the duration of the motor, sensory, and proprioception functions blockade was decreased, and the duration to return to normal functions was significantly shortened at Group BO800 (p < 0.05). According to electron microscopy results, perineural 200 μg, 400 μg, and 800 μg ondansetron were not neurotoxic. This is the first study showing that perineural ondansetron administration (800 μg dose) reverses the effect of the local anesthetics and shortens the duration of the motor, sensory, and proprioception functions blockade.

The Effect of Electroacupuncture Preconditioning on Regional Cerebral Oxygen Saturation Levels in Elderly Patients with Diabetes.

ObjectiveThis study aimed to evaluate the effect of electroacupuncture preconditioning on regional cerebral oxygen saturation (rSO2) levels in elderly patients with diabetes.MethodsForty patients undergoing elective diabetic foot surgery were enrolled in this study. All patients were aged 65 years and above and weighed 45–75 kg. All were characterized as class II or III according to the American Society of Anesthesiologists’ physical status classification system. Patients were divided randomly into an electroacupuncture group (group E) and a control group (group C); both groups comprised 20 patients. In group E, the DU20 (Baihui), DU24 (Shenting), and EX-HN1 (Sishencong) acupoints were selected for electroacupuncture 30 min prior to administering anesthesia, while in group C, patients underwent routine anesthesia without electroacupuncture. The patients in both groups were anesthetized using a sciatic nerve block. The number of cases with increased or decreased regional oxygen saturation (rSO2) compared with the baseline as well as rSO2 variability in the two groups were recorded and compared.ResultsThere was no significant difference in the preoperative rSO2 values between the two groups (54.4 ± 4.8 (L), 53.9 ± 5.2 (R) [group C] vs 54.1 ± 5.2 (L), 54.5 ± 4.6 (R)[group E]). Compared with group C, the rSO2 in group E increased (50.3 ± 3.9 [group C] vs 58.4 ± 3.2[group E]), and this difference was statistically significant (P < 0.001).ConclusionElectroacupuncture stimulation can increase rSO2 levels in patients with diabetes.Clinical Registration NumberChiCTR2100048783 (http://www.chictr.org.cn).

Estimation of the minimum effective volume of 0.5% bupivacaine for ultrasound-guided popliteal sciatic nerve block in diabetic patients with neuropathy.

Background and Aims:The safety of conventional regional nerve block techniques in patients with established neuropathies, such as diabetic peripheral neuropathy (DPN), is still unclear. We designed this prospective dose finding study to identify the minimum effective local anaesthetic volume of 0.5% bupivacaine for ultrasound-guided subparaneural popliteal sciatic nerve block in 90% of DPN patients undergoing below-knee surgery (MELAV90).Methods:Fifty-three patients with diabetic peripheral neuropathy and scheduled for below knee surgical procedure received popliteal sciatic nerve block under ultrasound guidance. The initial local anaesthetic volume used was 10 ml of 0.5% bupivacaine. The subsequent local anaesthetic volume allocation was based on biased-coin-design. Accordingly, the local anaesthetic volume given to each subject was based on the block outcome of the previous patient. The study included patients prospectively until 45 successful blocks were obtained. The primary measurement was the minimum effective local anaesthetic volume resulting in a successful subparaneural popliteal sciatic nerve block in 90% of DPN patients. The MELAV90 was calculated using isotonic regression and a 95% confidence interval bootstrapping method.Results:The study included 53 patients to obtain 45 successful blocks. The MELAV90 of 0.5% bupivacaine was obtained at 5.85 ml (95% confidence interval, 5.72 to 6.22 ml). Eight patients needed supplemental anaesthesia to complete the surgery. No other complications were noted.Conclusion:For patients with diabetic peripheral neuropathy undergoing below-knee surgery, the MELAV90 of 0.5% bupivacaine for subparaneural popliteal sciatic nerve to achieve surgical anaesthesia was 5.85 ml.