Sciatic Nerve Block

Quick Answer

Sciatic nerve block targets the sciatic nerve (L4-S3) providing anesthesia/analgesia to the posterior thigh, knee (except medial), entire lower leg below knee (except medial strip via saphenous), foot, and ankle. Three primary approaches: (1) Subgluteal (classic Labat approach): patient lateral/prone, needle insertion at 6-8 cm from midline at level of greater trochanter/ischial tuberosity midpoint; (2) Popliteal: patient prone or supine with leg elevated, ultrasound-guided at popliteal fossa where tibial and common peroneal nerves diverge; (3) Anterior: patient supine, needle insertion below femoral crease, medial to femoral vessels (ultrasound essential). Coverage: Entire foot, ankle, posterior leg, lateral leg. Combinations: Always combine with saphenous/femoral for medial coverage (complete lower limb block) or for knee/ankle surgery. Volume: 15-30 mL depending on approach. Duration: 8-16 hours (long-acting LA). Complications: LAST (high volume), vascular puncture, nerve injury, hematoma, urinary retention (subgluteal - pudendal spread). [1-20]

Anatomy

Sciatic Nerve Origin and Course

Origin:

• Formed from: L4-S3 nerve roots (sacral plexus)
• L4 contribution: From lumbar plexus via lumbosacral trunk
• Sacral contributions: L5, S1, S2, S3 ventral rami unite in greater sciatic foramen
• Formation: Within pelvis, anterior to piriformis muscle in 85% of population; posterior/inferior to piriformis in 12%; pierces piriformis in 3%

Pelvic Course:

• Exits pelvis: Greater sciatic foramen, inferior to piriformis
• Relations: Anterior to piriformis, posterior to internal pudendal vessels and vessels supplying hamstrings
• Gluteal region: Descends deep to gluteus maximus muscle

Thigh Course:

• Passes: Between ischial tuberosity (medial) and greater trochanter (lateral)
• Relations: Deep to hamstring muscles (long head biceps femoris, semimembranosus, semitendinosus)
• Position: Posterior thigh, then lateral to mid-thigh

Terminal Division:

• Location: Varies from pelvis to popliteal fossa (typically 4-10 cm proximal to popliteal crease, but highly variable)
• Tibial nerve: Continuation of medial component; medial popliteal fossa; supplies posterior leg, plantar foot
• Common peroneal nerve: Continuation of lateral component; lateral popliteal fossa; winds around fibular neck; supplies anterior/lateral leg, dorsal foot
• Divisions: Usually occur 4-10 cm above popliteal fossa, but can be as proximal as sciatic notch or remain undivided in popliteal fossa

Detailed Anatomy by Approach

Subgluteal Approach Anatomy:

Landmarks:

• Greater trochanter: Lateral bony prominence of proximal femur
• Ischial tuberosity: Medial bony prominence ("sit bone")
• Posterior superior iliac spine (PSIS): Reference point for triangle of Landau
• Sacral hiatus: Inferior margin of sacrum

Triangle of Landau (Classic):

• Apex: Point between greater trochanter and ischial tuberosity
• Base: Line between PSIS and greater trochanter
• Posterior margin: Sacral hiatus to ischial tuberosity
• Needle entry: Perpendicular to skin at apex or 4-6 cm along perpendicular from midpoint of line between trochanter and ischial tuberosity

Deep Structures:

• Superficial: Gluteus maximus (must penetrate)
• Intermediate: Quadratus femoris, inferior gemellus, obturator internus (pierce or deep to)
• Deep: Sciatic nerve, posterior cutaneous nerve of thigh, inferior gluteal vessels
• Nerve depth: 6-8 cm from skin in adults (deeper in obese)

Popliteal Approach Anatomy:

Popliteal Fossa Boundaries:

• Superior: Biceps femoris (lateral), semimembranosus/semitendinosus (medial)
• Inferior: Gastrocnemius heads (medial and lateral)
• Floor: Popliteal surface of femur, posterior knee joint capsule, popliteus fascia
• Roof: Skin, superficial fascia, popliteal fascia

Contents of Popliteal Fossa:

• Popliteal artery: Central, deepest structure
• Popliteal vein: Superficial to artery
• Tibial nerve: Superficial and lateral to vessels (most superficial of neurovascular bundle)
• Common peroneal nerve: Lateral and superficial, diverges from tibial nerve proximally
• Nerve relationship: Initially tibial and common peroneal travel together as sciatic nerve, then diverge in proximal popliteal fossa

Ultrasound Anatomy:

• Popliteal artery: Pulsatile, round/oval, anechoic, non-compressible
• Popliteal vein: Compressible, oval, medial/superficial to artery (may be collapsed in supine)
• Tibial nerve: Superficial to vessels, hyperechoic, round/comma-shaped
• Common peroneal nerve: Lateral to tibial nerve, often diverging proximally
• Biceps femoris tendon: Lateral superior border, hyperechoic linear structure
• Semi-membranosus/semitendinosus tendons: Medial superior border

Anterior Approach Anatomy:

Surface Landmarks:

• Femoral crease: Groin crease at inguinal ligament
• Femoral pulse: Identify femoral artery
• Needle insertion: Approximately 6-8 cm distal to femoral crease, along line between anterior superior iliac spine and pubic tubercle

Deep Structures:

• Rectus femoris/vastus lateralis: Penetrate quadriceps muscle
• Adductor magnus: Deep to quadriceps
• Sciatic nerve location: Posterior to adductor magnus, lateral to lesser trochanter
• Landmark: Lesser trochanter (identifiable on ultrasound lateral to femoral vessels deep)
• Depth: 6-10 cm from skin (ultrasound essential)

Sensory Distribution

Sciatic Nerve Provides Sensation To:

Posterior Thigh:

• Posterior cutaneous nerve of thigh (from sacral plexus, often blocked with sciatic)
• Sensation: Posterior thigh skin

Knee:

• Posterior knee joint capsule (tibial nerve contribution)
• Lateral knee (common peroneal nerve)
• Note: Medial knee (saphenous/femoral nerve) NOT covered

Lower Leg:

• Posterior leg: Tibial nerve (sural nerve, medial/lateral plantar nerves)
• Lateral leg: Common peroneal (superficial peroneal nerve)
• Anterior leg: Common peroneal (deep peroneal nerve)
• Medial leg: Saphenous nerve (NOT sciatic) - separate block needed

Foot:

• Plantar surface: Tibial nerve (medial and lateral plantar nerves)
• Dorsal surface: Common peroneal (deep peroneal - first web space; superficial peroneal - remainder)
• Medial arch: Saphenous nerve (NOT sciatic) - separate block needed

Complete Foot Coverage Requires:

• Sciatic block (posterior, lateral, anterior foot except medial)
• Saphenous/adductor canal block (medial foot, medial ankle, medial leg)
• Together provide complete foot anesthesia (common for ankle/foot surgery)

Motor Distribution

Sciatic Nerve Innervates:

Posterior Thigh (Hamstrings):

• Biceps femoris (long head)
• Semimembranosus
• Semitendinosus
• (Short head biceps femoris from common peroneal branch)
• Action: Knee flexion, hip extension

Lower Leg:

• Tibial branch: Posterior compartment (gastrocnemius, soleus, plantaris, popliteus, tibialis posterior, flexor digitorum longus, flexor hallucis longus) - plantarflexion, toe flexion
• Common peroneal branch: Anterior compartment (tibialis anterior, extensor hallucis longus, extensor digitorum longus, peroneus tertius) - dorsiflexion; Lateral compartment (peroneus longus/brevis) - eversion

Foot:

• Intrinsic foot muscles via tibial nerve

Clinical Significance:

• Complete sciatic block → foot drop (cannot dorsiflex or plantarflex)
• Patient unable to ambulate without assistance
• Weight-bearing precautions required until motor block resolves

Indications and Contraindications

Indications

Surgical Indications:

Foot and Ankle Surgery:

• Ankle fracture ORIF (open reduction internal fixation)
• Ankle arthroscopy
• Triple arthrodesis
• Achilles tendon repair
• Bunionectomy (hallux valgus correction)
• Forefoot reconstruction
• Toe amputations
• Plantar fascia release
• Tarsal tunnel release

Lower Leg Surgery:

• Tibia/fibula fracture fixation
• Fasciotomy (compartment syndrome)
• Soft tissue tumor excision
• Skin grafting

Knee Surgery:

• Total knee replacement (posterior component only - rarely used alone)
• ACL reconstruction (hamstring harvest site analgesia)
• Popliteal cyst excision

Combined Procedures:

• With saphenous/femoral: Complete lower limb anesthesia below knee (below-knee amputation, combined foot/knee procedures)
• With lumbar plexus: Complete lower limb (hip down) for total knee, combined knee/foot procedures

Pain Management:

• Chronic pain: Complex regional pain syndrome (CRPS) of lower limb
• Neuropathic pain: Sciatica, post-herpetic neuralgia
• Cancer pain: Infiltration of sciatic nerve by tumor
• Acute pain: Lower limb trauma, postoperative analgesia

Specific Advantages:

• Avoids general anesthesia in high-risk patients
• Superior postoperative analgesia vs systemic opioids
• Reduces opioid requirements and side effects
• Earlier mobilization with catheter techniques
• Outpatient surgery facilitation (single-shot popliteal)

Contraindications

Absolute Contraindications:

• Infection at injection site: Cellulitis, abscess over injection site
• Patient refusal: Inability to obtain informed consent
• Allergy to local anaesthetics: True allergy (rare)
• Local anaesthetic toxicity: Current or recent

Relative Contraindications:

Anticoagulation Concerns (ASRA Guidelines):

• Warfarin: INR <1.5 required
• Therapeutic heparin: Hold 4-6 hours, check aPTT
• LMWH (prophylactic): No restriction
• LMWH (therapeutic): Delay 12-24 hours
• DOACs (apixaban, rivaroxaban): Hold 2-3 days (longer if CrCl <30)
• Fondaparinux: Avoid or extreme caution
• Antiplatelets: Generally safe (aspirin, clopidogrel - continued)
• Specific to sciatic: Subgluteal approach higher bleeding risk due to depth and gluteal vessels

Anatomical Concerns:

• Previous surgery in region: Hip arthroplasty, femur fixation (subgluteal), popliteal surgery (popliteal approach), knee replacement (anterior approach)
• Severe obesity: Deep block, difficult landmarks
• Pre-existing sciatic neuropathy: Document carefully (diabetic neuropathy, peripheral vascular disease)
• Spinal stenosis/cauda equina: Relative - monitor for increased block height

Medical Concerns:

• Severe respiratory disease: Prone positioning (popliteal/subgluteal) may compromise breathing
• Significant cardiac disease: Prone positioning concerns
• Contralateral limb amputation: Difficulty positioning
• Pregnancy: Prone positioning concerns (popliteal/subgluteal)
• Morbid obesity + prone: Consider anterior approach or alternative anesthesia

Specific Approach Contraindications:

• Subgluteal: Inability to lie lateral/prone (hip fractures, severe arthritis), obesity with depth >10 cm
• Popliteal: Popliteal fossa surgery/infection, unable to flex knee 90°
• Anterior: Severe quadriceps weakness pre-existing, prior femoral/vascular surgery

Technique

Pre-Block Assessment

Mandatory Checks:

1. Informed consent: Procedure, alternatives, risks explained (LAST, nerve injury, failure, vascular puncture, hematoma)
2. Medical history: Previous blocks, neuropathy, bleeding disorders, medications (especially anticoagulants)
3. Physical examination: Baseline motor and sensory function documented in distribution of sciatic nerve
4. Site inspection: No infection, skin integrity intact
5. Monitoring: ECG, NIBP, SpO2 established
6. IV access: Patent intravenous cannula (minimum 20G)
7. Resuscitation equipment: Lipid emulsion 20% immediately available, airway equipment, emergency drugs
8. Allergies: Checked and documented

Positioning Requirements:

• Assistant: Helpful for positioning (especially prone/lateral)
• Padding: Pressure points protected (lateral decubitus - axilla, fibular head; prone - breasts, genitals, face, knees)
• Comfort: Position sustainable for 20-30 minutes if needed

Subgluteal Approach (Classic Labat)

Indications:

• Surgery on posterior thigh, hip (posterior), combined procedures requiring high sciatic
• When popliteal block would be too distal (hamstring harvest for ACL)

Contraindications:

• Inability to position lateral or prone
• Severe obesity (depth >10 cm makes block technically difficult and potentially less safe)
• High INR/anticoagulation (deeper block, larger vessels)

Patient Positioning:

• Lateral decubitus: Operative side up, lower leg flexed at hip and knee (stabilizing), upper leg extended (target)
• Prone: Pillows under hips/ankles to facilitate knee flexion if needed
• Sims position: Hybrid (lateral with upper knee flexed toward chest)

Landmark Technique (Historical - Ultrasound Preferred):

1. Greater trochanter identified and marked
2. Ischial tuberosity palpated medially (approximately 10 cm medial to greater trochanter)
3. Line drawn between trochanter and ischial tuberosity
4. Entry point: 4-6 cm along perpendicular line from midpoint of trochanter-ischial line, directed perpendicular to skin
5. Needle: 100-150 mm, 22G (length depends on patient habitus)
6. Depth: 6-10 cm until nerve stimulation or paresthesia
7. Stimulation: Plantarflexion (tibial) or dorsiflexion/eversion (common peroneal) at 0.3-0.5 mA

Ultrasound-Guided Subgluteal:

• Probe: Curved array (2-5 MHz) due to depth
• Position: Transverse in gluteal fold region
• Identify: Ischial tuberosity (medial, hyperechoic), greater trochanter (lateral, hyperechoic), sciatic nerve (between, hyperechoic oval)
• Approach: In-plane from lateral to medial (avoids medial vessels)
• Depth: 6-10 cm typical
• Volume: 20-30 mL

Complications Specific to Subgluteal:

• Pudendal nerve block: Urinary retention (10-20% incidence with large volumes)
• Inferior gluteal artery puncture: Hematoma risk
• Posterior cutaneous nerve of thigh block: Posterior thigh numbness
• Gluteal vessel injury: Significant hematoma in obese patients

Popliteal Approach (Most Common)

Indications:

• Foot and ankle surgery (most common indication)
• Distal tibia/fibula surgery
• Analgesia for below-knee procedures

Advantages:

• Easiest approach to sciatic nerve (most superficial, reliable ultrasound image)
• Good for outpatient surgery (single-shot)
• Excellent catheter placement site for continuous infusion
• Lower volume required (15-20 mL)
• Less risk of pudendal block than subgluteal

Patient Positioning:

Option 1 - Prone (Traditional):

• Patient prone with feet off end of bed
• Knee flexed 20-30° (pillow under ankle)
• Popliteal fossa accessible

Option 2 - Lateral:

• Operative side up, lower leg flexed for stability
• Upper leg extended or slightly flexed
• Access to popliteal fossa from posterior

Option 3 - Supine (Elevation):

• Patient supine
• Assistant elevates leg, flexing knee 90°
• Foot resting on bed/table (operator sits at foot of bed)
• Patient may hold leg with strap/assistance

Ultrasound Technique:

Equipment:

• Probe: High-frequency linear (10-15 MHz) for superficial, curved (5-8 MHz) if deep/obese
• Needle: 80-100 mm, 22G, echogenic
• Volume: 15-20 mL

Scanning:

1. Locate popliteal crease: Skin crease behind knee
2. Probe position: Transverse, 5-10 cm proximal to popliteal crease
3. Identify artery: Pulsatile, round, anechoic (depest structure)
4. Identify vein: Medial/superficial to artery (compressible)
5. Identify tibial nerve: Superficial to artery, hyperechoic
6. Identify common peroneal nerve: Lateral to tibial, often diverging
7. Trace proximally: Find where two nerves coalesce (sciatic nerve proper) - usually 4-10 cm above crease

Optimal Injection Site:

• Above nerve division: Single injection blocks both branches
• Circumferential spread: Aim for spread around sciatic nerve
• Beneath nerve: Inject deep to nerve within popliteal fossa (between nerve and artery) produces best spread

Needle Insertion:

• In-plane approach: Lateral to medial (most common)
  • Entry: Lateral popliteal fossa
  • Visualise entire needle shaft
  • Target: Beneath sciatic nerve (between nerve and artery)
• Out-of-plane approach: Cephalad to caudad
  • Entry: Proximal to probe
  • More technically challenging
  • Higher risk of vascular puncture

Injection:

1. Aspiration: Before every 3-5 mL (vascular proximity)
2. Test dose: 2-3 mL, observe spread
3. Optimal spread: Nerve lifts off posterior structures, local anaesthetic surrounds nerve circumferentially
4. Total volume: 15-20 mL (lower than subgluteal)
5. Catheter option: Insert catheter 3-5 cm beyond needle tip for continuous infusion

Common Peroneal vs Tibial Block:

• If nerves already divided at injection site, may need separate blocks
• Tibial: Plantar foot, posterior leg
• Common peroneal: Dorsal foot, anterior/lateral leg
• Most foot surgery requires both (usually achieved with proximal popliteal injection)

Anterior Approach

Indications:

• Patient cannot lie prone or lateral (severe obesity, respiratory compromise, bilateral procedures)
• Postoperative analgesia when patient remains supine (e.g., after total hip replacement)
• Fractured hip/contralateral limb issues preventing positioning

Contraindications:

• Prior femoral vascular surgery
• Prior femoral artery catheterization (groin hematoma, pseudoaneurysm risk)
• Severe quadriceps weakness (block exacerbates)
• Morbid obesity with depth >10 cm

Patient Position:

• Supine: Leg extended or slightly externally rotated
• Expose: Anterior thigh from inguinal crease to mid-thigh

Ultrasound Technique:

• Probe: Curved array (2-5 MHz) - depth 6-10 cm
• Position: Transverse, approximately 6-8 cm distal to inguinal crease, along line between ASIS and pubic tubercle
• Identify landmarks:
  • Femoral vessels (medial, avoid)
  • Femur (deep, hyperechoic with shadowing)
  • Lesser trochanter (lateral to vessels, medial to femur)
  • Sciatic nerve: Deep, posterior to adductor magnus, often difficult to visualize (fat/muscle interface)

Needle Insertion:

• In-plane: Lateral to medial
• Deep penetration: Through quadriceps, then adductor magnus
• Target: Deep to adductor magnus, lateral to lesser trochanter
• Nerve stimulation: May be helpful adjunct (plantar/dorsiflexion)

Challenges:

• Depth: Often 8-12 cm in average adults
• Visualization: Sciatic nerve may be difficult to see (isoechoic to surrounding tissue)
• Vascular: Must avoid femoral vessels (medial)
• Femur: Bony shadowing can obscure view

Volume: 20-30 mL (deeper block, need adequate spread)

Local Anaesthetic Selection and Dosing

Single-Shot Block

Recommended Regimens by Approach:

Additives:

Maximum Doses (mg/kg):

• Ropivacaine: 3 mg/kg (max 225 mg without epinephrine)
• Bupivacaine: 2 mg/kg (max 150 mg without epinephrine)
• Levobupivacaine: 2 mg/kg (max 150 mg without epinephrine)
• Lidocaine: 4.5 mg/kg (max 300 mg without epinephrine)
• With epinephrine: Can increase by 30-50%

Continuous Catheter Techniques

Indications for Catheter:

• Major foot/ankle surgery (ORIF ankle, triple arthrodesis, Achilles repair)
• Complex regional pain syndrome
• Postoperative pain >24-48 hours
• Patient-controlled regional analgesia (PCRA)

Technique:

• Popliteal approach preferred: Easiest catheter placement
• Catheter type: 19-20G, multi-orifice, 40-60 cm length
• Insertion: Through-needle or over-needle technique
• Securement: Subcutaneous tunneling (3-5 cm) + adhesive dressings (StatLock, Dermabond)
• Testing: Prior to infusion (5 mL test dose)

Infusion Regimens:

Catheter Duration:

• Typical: 2-5 days
• Maximum: Up to 7-14 days with meticulous care
• Discontinuation criteria: Oral analgesia adequate, infection signs absent, surgery-specific pain resolved

Pharmacological Considerations

Ropivacaine vs Bupivacaine:

• Ropivacaine: Less cardiotoxic (safer profile), more motor-sparing at low concentrations, suitable for ambulatory patients
• Bupivacaine: Longer duration, more dense block, higher cardiotoxicity risk
• Clinical choice: Ropivacaine for outpatients/day surgery; bupivacaine when long duration required

Concentration Selection:

• 0.5% Ropivacaine/0.375-0.5% Bupivacaine: Dense surgical anesthesia, complete motor block
• 0.375% Ropivacaine/0.25% Bupivacaine: Sensory block with partial motor sparing (better for mobilization)
• 0.2% Ropivacaine/0.125% Bupivacaine: Analgesia with minimal motor block (continuous infusions)

Specific Clinical Scenarios:

Outpatient Foot Surgery:

• Popliteal approach, ropivacaine 0.5% 15 mL
• Onset 20-30 minutes, duration 8-12 hours
• Patient discharged once motor block partially resolved

Inpatient Major Ankle Surgery:

• Popliteal catheter with ropivacaine 0.2% infusion
• Provides 48-72 hours analgesia
• Reduced opioid requirements, earlier mobilization

Combined Saphenous-Sciatic for Total Knee:

• Saphenous/adductor canal: Ropivacaine 0.5% 10-15 mL (motor sparing)
• Sciatic (popliteal): Ropivacaine 0.5% 15 mL (posterior knee/leg)
• Provides complete knee coverage without quadriceps weakness (preserves mobilization)

Complications and Management

Local Anaesthetic Systemic Toxicity (LAST)

Incidence: 0.01-0.05% with ultrasound guidance [41-50]

Risk Factors Specific to Sciatic Block:

• High volumes (20-30 mL vs 10-15 mL for other peripheral blocks)
• Vascular injection (gluteal, popliteal, femoral vessels depending on approach)
• Absence of ultrasound guidance
• Obesity (high local anaesthetic dose relative to lean body weight)
• Elderly (reduced metabolism, reduced protein binding)
• Hepatic impairment (reduced amide metabolism)
• Cardiac disease (reduced clearance, increased sensitivity)

Prevention:

• Ultrasound guidance: Reduces LAST by 50-70%
• Incremental injection: 3-5 mL aliquots with frequent aspiration
• Epinephrine: Added to local anaesthetic (early warning of intravascular injection - tachycardia)
• Dose calculation: Based on lean body weight in obese patients
• Patient monitoring: Continuous observation during and after injection

Recognition (Progressive Signs):

Central Nervous System (Early):

• Metallic taste, tinnitus
• Perioral numbness, tongue numbness
• Lightheadedness, dizziness
• Confusion, agitation, anxiety
• Muscle twitching, tremors

Central Nervous System (Severe):

• Generalized tonic-clonic seizures
• Loss of consciousness
• Respiratory arrest (post-ictal or direct effect)

Cardiovascular System (Late, Severe):

• Hypertension and tachycardia (early) progressing to hypotension
• Ventricular arrhythmias (ventricular tachycardia, fibrillation)
• Bradycardia, asystole
• Cardiovascular collapse (bupivacaine particularly cardiotoxic)

Management (ASRA LAST Checklist):

Immediate Actions:

1. Call for help: Alert additional personnel immediately
2. Airway management: 100% oxygen, support ventilation (prevent hypercapnia which worsens toxicity)
3. Stop injection: Maintain needle position if possible (prevents further spread)
4. Seizure control: Benzodiazepines (midazolam 2-5 mg IV, or diazepam 5-10 mg IV)
   • Avoid: Propofol (cardiac suppression), thiopental (cardiac suppression)
   • Acceptable if no benzodiazepines: Low-dose thiopental (50-100 mg)

Specific Antidote - Lipid Emulsion 20% (Intralipid):

• Bolus: 1.5 mL/kg IV over 1 minute (approximately 100 mL for 70 kg adult)
• Infusion: 0.25 mL/kg/min (approximately 500 mL over 20 minutes for 70 kg)
• Repeat bolus: If cardiovascular instability continues, repeat bolus up to 3 times
• Increase infusion: If no response, increase to 0.5 mL/kg/min
• Total dose: Maximum 12 mL/kg (approximately 840 mL for 70 kg)

Cardiovascular Support:

• Advanced cardiac life support (ACLS) modifications:
  • Reduced epinephrine doses: 10-100 mcg IV (not standard 1 mg) for bradycardia/hypotension
  • Avoid vasopressin, calcium channel blockers, beta-blockers
  • Amiodarone for ventricular arrhythmias (avoid lidocaine)
• Prolonged CPR: May be required (bupivacaine highly protein bound, prolonged resuscitation may be needed)
• ECMO: Consider early if available and refractory cardiac arrest

Post-Resuscitation:

• Monitoring: ICU admission, continuous monitoring 12-24 hours
• Lipid emulsion levels: Can cause interference with laboratory tests (lipemia)
• Repeat lipid: May need continued infusion if recurrent toxicity

Success Rates:

• With prompt lipid emulsion: >90% survival from severe LAST
• Delayed treatment: Higher mortality and neurological morbidity

Nerve Injury

Incidence: 0.1-1% temporary neuropathy, 0.01-0.1% permanent [51-60]

Mechanisms of Injury:

1. Direct needle trauma: Intrafascicular injection, nerve laceration
2. Intraneural injection: High-pressure injection into nerve fascicles
3. Neurotoxicity: Local anaesthetic toxicity to nerve tissue
4. Ischemia: Pressure effects, vascular compromise
5. Stretch: Patient positioning (hip flexion, extension)

Risk Factors:

• Patient factors: Pre-existing neuropathy (diabetes, chemotherapy, peripheral vascular disease), female gender, young age
• Technical factors: Intraneural injection, high injection pressure (>15 psi), multiple attempts, nerve stimulator current <0.2 mA with motor response (indicates intraneural needle)
• Surgical factors: Tourniquet time >2 hours, tourniquet pressure >300 mmHg, retractor placement

Prevention:

• Ultrasound guidance: Visualize needle tip, avoid nerve penetration
• No intraneural injection: Perineural spread adequate; never target nerve fascicles
• Low pressure injection: Use pressure monitoring or tactile feedback (stop if high resistance)
• Short-bevel needles: Less likely to penetrate fascicles (30° vs 15° bevel)
• Avoid multiple attempts: Limit to 2-3 needle insertions; change approach if difficult
• Document pre-existing deficits: Essential for medicolegal protection

Recognition:

• Immediate: Severe pain on injection ("electric shock"), motor response at <0.2 mA
• Early: Persistent numbness beyond expected block duration (12-16 hours)
• Late: Motor weakness, neuropathic pain, complex regional pain syndrome

Management:

• Immediate: If pain on injection or high pressure - stop injection, withdraw needle
• Short-term observation: Most injuries resolve spontaneously over 3-6 months
• Neurology referral: EMG at 3-4 weeks if persistent symptoms (distinguishes axonotmesis vs neuropraxia)
• Physical therapy: Maintain range of motion, prevent contractures
• Pain management: Neuropathic pain medications (gabapentin, TCAs, SNRIs)
• Surgical exploration: Rarely indicated (neurolysis, repair)

Prognosis:

• Neuropraxia (conduction block): Recovery days to weeks
• Axonotmesis (axon injury): Recovery weeks to months
• Neurotmesis (complete transection): May not recover, surgical repair needed

Vascular Puncture and Hematoma

Incidence: 2-5% with ultrasound, 10-15% landmark-based [61-65]

Risk Factors:

• Anticoagulation (warfarin INR >1.5, therapeutic heparin, DOACs)
• Coagulopathy (liver disease, thrombocytopenia)
• Multiple attempts
• Deep block (subgluteal > popliteal)
• Obesity (difficult compression)

Clinical Presentation:

• Immediate: Blood return through needle, hypotension (if significant bleed)
• Early: Pain at injection site, swelling, bruising
• Late: Large hematoma, compartment syndrome (rare but serious in thigh)

Management:

• Immediate: Withdraw needle, apply firm pressure 10-15 minutes
• Monitoring: Observe for expanding hematoma, hemodynamic compromise
• Imaging: USS or CT if large hematoma suspected, compartment syndrome concerns
• Surgical: Vascular surgery consult for expanding hematoma, active bleeding
• Anticoagulation: Hold/reverse if significant bleeding

Prevention:

• ASRA guidelines: Follow anticoagulation protocols
• Ultrasound: Visualize vessels, avoid them
• Aspiration: Before every 3-5 mL injection
• Pressure: Apply post-block, especially if blood encountered

Specific Vascular Risks by Approach:

• Subgluteal: Inferior gluteal artery/vein (significant hematoma risk)
• Popliteal: Popliteal artery/vein, genicular vessels
• Anterior: Femoral artery/vein (must be carefully avoided)

Specific Approach-Related Complications

Subgluteal-Specific:

Pudendal Nerve Block:

• Incidence: 10-20% with 30 mL volume
• Mechanism: Local anaesthetic spread through greater sciatic foramen to pudendal canal
• Effects: Urinary retention, saddle anesthesia, erectile dysfunction (temporary)
• Prevention: Limit volume to 20 mL, inject more distally
• Management: Urinary catheter if retention, self-limiting (resolves with block)

Positioning Injuries:

• Lateral decubitus: Axillary neuropraxia (pressure on dependent axilla), peroneal nerve compression at fibular head
• Prone: Pressure injuries to breasts (female), genitals, face, knees, ocular compression (blindness risk - ensure eyes protected)

Popliteal-Specific:

Popliteal Vascular Injury:

• Artery/vein puncture (lower risk than subgluteal gluteal vessels)
• Pseudoaneurysm (rare)
• Arteriovenous fistula (rare)

Thrombosis:

• Deep venous thrombosis from venous injury
• Popliteal artery thrombosis (rare)

Anterior-Specific:

Femoral Vascular Injury:

• Femoral artery/vein puncture (must be carefully avoided with ultrasound)
• Retroperitoneal hematoma (if deep penetration)
• Pseudoaneurysm

Quadriceps Weakness:

• Exacerbates existing weakness
• Prolonged immobilization risk

Other Complications

Infection:

• Incidence: <0.1% single shot, 1-3% catheters
• Risk factors: Catheter duration >3 days, diabetes, immunosuppression, aseptic technique breaches
• Presentation: Fever, erythema, purulent drainage, increasing pain
• Prevention: Chlorhexidine skin prep, sterile technique, antibiotic prophylaxis for high-risk patients
• Management: Remove catheter, culture, antibiotics (cover Staph aureus), surgical drainage if abscess

Failed Block:

• Incidence: 5-15% depending on approach and operator experience
• Causes: Technical failure (poor needle position, inadequate spread), anatomical variation, nerve division proximal to injection
• Management: Repeat block (different approach), alternative anesthesia, convert to general anesthesia

Tourniquet Pain:

• Sciatic block does NOT prevent tourniquet pain on thigh (supplied by femoral, obturator, lateral femoral cutaneous, posterior cutaneous of thigh)
• Consider combined blocks if tourniquet >90 minutes expected

Clinical Scenarios and SAQs

SAQ 1: Sciatic Nerve Anatomy (12 marks)

Question: A 55-year-old man requires sciatic nerve block for foot surgery.

a) Describe the origin and formation of the sciatic nerve (3 marks)

b) Describe the sensory distribution of the sciatic nerve (4 marks)

c) At what anatomical location does the sciatic nerve typically divide into its terminal branches, and what are these branches? (3 marks)

d) Which areas of the lower leg and foot are NOT innervated by the sciatic nerve? (2 marks)

Model Answer:

a) Origin and formation (3 marks):

• Formed from L4-S3 nerve roots via sacral plexus (1 mark)
• L4 joins via lumbosacral trunk; L5, S1, S2, S3 ventral rami unite anterior to piriformis muscle (1 mark)
• Exits pelvis through greater sciatic foramen inferior to piriformis (1 mark)

b) Sensory distribution (4 marks):

• Posterior thigh (via posterior cutaneous nerve of thigh, often blocked with sciatic) (1 mark)
• Posterior knee joint capsule (1 mark)
• Entire lower leg below knee except medial strip: posterior leg, lateral leg, anterior leg (1 mark)
• Entire foot except medial border: plantar surface, dorsal surface (except medial), toes (1 mark)

c) Division location and branches (3 marks):

• Typically divides 4-10 cm proximal to popliteal fossa crease (variable) (1 mark)
• Terminal branches are tibial nerve (medial) and common peroneal nerve (lateral) (1 mark)
• Tibial continues into deep popliteal fossa; common peroneal travels laterally toward fibular neck (1 mark)

d) Areas NOT innervated by sciatic (2 marks):

• Medial aspect of lower leg (saphenous nerve - femoral nerve branch) (1 mark)
• Medial border of foot and medial ankle (saphenous nerve distribution) (1 mark)

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SAQ 2: Approach Selection and Technique (15 marks)

Question: A 45-year-old woman requires foot surgery. She has severe obesity (BMI 42 kg/m²), obstructive sleep apnea, and cannot lie prone due to respiratory compromise.

a) Which sciatic nerve approach would you choose for this patient, and why? (3 marks)

b) Describe the ultrasound probe position and sonographic anatomy for the popliteal approach (5 marks)

c) What volume and local anaesthetic would you use, and why? (3 marks)

d) What are the potential complications of sciatic nerve block, and how would you manage local anaesthetic systemic toxicity if it occurred? (4 marks)

Model Answer:

a) Approach selection (3 marks):

• Popliteal approach with patient supine and leg elevated (or lateral position) (1 mark)
• Rationale: Cannot tolerate prone positioning due to OSA and respiratory compromise (1 mark)
• Popliteal is most superficial and reliable with ultrasound (better than anterior in obesity) (1 mark)
• Accept: Anterior approach if properly justified (supine position, but deep in obesity)

b) Popliteal ultrasound technique (5 marks):

• Patient supine with leg elevated and knee flexed 90°, or lateral decubitus (1 mark)
• High-frequency linear probe (10-15 MHz) or curved (5-8 MHz) if deep (1 mark)
• Probe transverse, 5-10 cm proximal to popliteal crease (1 mark)
• Sonographic anatomy: Popliteal artery (deepest, pulsatile, anechoic), popliteal vein (superficial/medial to artery, compressible), tibial nerve (superficial to vessels, hyperechoic), common peroneal nerve (lateral, diverging) (2 marks)

c) Local anaesthetic selection (3 marks):

• Volume: 15-20 mL (sufficient for popliteal, lower LAST risk than higher volumes) (1 mark)
• Agent: Ropivacaine 0.5% or bupivacaine 0.375-0.5% (1 mark)
• Rationale: Long-acting for postoperative analgesia; ropivacaine preferred in day surgery for earlier motor recovery (1 mark)

d) Complications and LAST management (4 marks):

• Complications: LAST, nerve injury, vascular puncture/hematoma, infection, failed block (1 mark)
• LAST management: Stop injection, call for help, airway/oxygen support (1 mark)
• Lipid emulsion 20%: 1.5 mL/kg bolus then 0.25 mL/kg/min infusion (1 mark)
• Seizure control with benzodiazepines; cardiopulmonary support as needed (1 mark)

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SAQ 3: Continuous Sciatic Catheter Management (10 marks)

Question: A 65-year-old man has undergone ORIF of ankle fracture with popliteal sciatic catheter insertion for postoperative analgesia.

a) What infusion regimen would you prescribe for this patient? (3 marks)

b) How would you monitor this patient for complications related to the catheter? (4 marks)

c) When and how would you discontinue the catheter? (3 marks)

Model Answer:

a) Infusion regimen (3 marks):

• Ropivacaine 0.2% at 5-8 mL/hour basal infusion (1 mark)
• Patient-controlled bolus: 3-5 mL with 20-30 minute lockout (1 mark)
• Alternative: Ropivacaine 0.375% 8-10 mL every 4-6 hours PRN without basal (reduces motor block) (1 mark)

b) Monitoring (4 marks):

• Sensory and motor block assessment: Check dermatome distribution, motor function (foot dorsiflexion/plantarflexion) every 4-8 hours (1 mark)
• Catheter site inspection: Daily for erythema, discharge, dressing integrity (1 mark)
• Pain scores: Document at rest and with movement (1 mark)
• Systemic effects: Signs of LAST, excessive sedation, respiratory depression from opioid sparing (1 mark)
• Accept: Temperature monitoring for infection

c) Catheter discontinuation (3 marks):

• Criteria: Pain controlled with oral analgesics, no signs of infection at site, no ongoing surgical indication (1 mark)
• Procedure: Remove dressing, withdraw catheter gently in one motion, inspect catheter tip integrity (1 mark)
• Post-removal: Apply pressure, sterile dressing, document catheter appearance and length removed, monitor for signs of infection or nerve injury (1 mark)

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SAQ 4: Combined Blocks for Total Knee Replacement (13 marks)

Question: A 70-year-old woman requires total knee replacement. The surgeon requests regional anesthesia with minimal motor block to facilitate early mobilization.

a) Which peripheral nerve blocks would provide complete anesthesia/analgesia for total knee replacement? (4 marks)

b) How would you modify your block technique to preserve quadriceps function while providing adequate analgesia? (4 marks)

c) Describe the sensory distribution of the sciatic nerve at the knee and why it is important for total knee replacement analgesia (3 marks)

d) What are the advantages of saphenous nerve block (or adductor canal block) over femoral nerve block for this patient? (2 marks)

Model Answer:

a) Peripheral nerve blocks for TKR (4 marks):

• Femoral nerve or saphenous nerve (adductor canal) block: Anterior knee, medial knee, medial leg (2 marks)
• Sciatic nerve block (usually popliteal): Posterior knee capsule, lateral knee, entire leg below knee except medial strip (2 marks)
• Note: Obturator and lateral femoral cutaneous may be needed for complete coverage but often not essential

b) Motor-sparing technique (4 marks):

• Use adductor canal block (distal femoral/saphenous) instead of femoral nerve block (1 mark)
• Lower concentration local anaesthetic (0.375% ropivacaine vs 0.5%) (1 mark)
• Adductor canal preserves quadriceps motor function while providing medial/anterior knee analgesia (1 mark)
• Sciatic block at popliteal level with 0.375% ropivacaine (sensory > motor block) (1 mark)

c) Sciatic distribution at knee (3 marks):

• Tibial nerve: Posterior knee joint capsule, popliteal fossa sensation (1 mark)
• Common peroneal nerve: Lateral knee, lateral leg sensation (1 mark)
• Provides pain control for posterior and lateral aspects of knee surgery not covered by femoral/saphenous blocks (1 mark)

d) Saphenous vs femoral block advantages (2 marks):

• Saphenous/adductor canal block preserves quadriceps motor function, allowing safe ambulation (1 mark)
• Reduces fall risk compared to femoral nerve block which causes quadriceps weakness (1 mark)

ANZCA Exam Focus

Written Examination

High-Yield Topics:

1. Anatomy: Origin, course, division, terminal branches (tibial and common peroneal)
2. Sensory distribution: What sciatic covers and what it doesn't (medial leg via saphenous)
3. Approach selection: When to use each approach (popliteal vs subgluteal vs anterior)
4. Combined blocks: Sciatic + saphenous for foot; sciatic + femoral for knee; complete lower limb
5. Complications: LAST management, nerve injury prevention, vascular complications
6. Ultrasound anatomy: Popliteal fossa sonography, nerve identification
7. Pharmacology: Dosing, duration, additives (dexamethasone, epinephrine)

Common Question Formats:

• Anatomy: Drawing/identifying nerve course and branches
• Clinical scenarios: Choosing appropriate block for specific surgery
• Complications: Managing LAST or nerve injury
• Techniques: Describing ultrasound-guided approach
• Dosing calculations: Maximum safe doses, volume selection

Viva Voce Scenarios

Scenario 1: Approach Selection Viva

• Setting: Preoperative assessment clinic
• Patient: 68-year-old for ankle ORIF, obesity (BMI 38), severe COPD
• Task: Explain chosen approach and rationale
• Key points: Popliteal vs anterior vs subgluteal; positioning limitations; ultrasound rationale
• Pass criteria: Appropriate approach selection with justification, safety considerations

Scenario 2: Technical Performance

• Setting: OSCE station
• Task: Perform ultrasound-guided popliteal sciatic block
• Equipment: Ultrasound, sterile prep, needle, local anaesthetic
• Key steps: Probe position, anatomy identification, needle insertion, injection technique, aspiration
• Critical errors: No aspiration, intraneural injection, intravascular injection
• Pass criteria: Sterile technique, anatomical identification, safe injection practice

Scenario 3: Complication Management

• Setting: Crisis scenario
• Situation: Patient seizing during subgluteal sciatic block after 25 mL bupivacaine 0.5%
• Task: Immediate management
• Key actions: LAST recognition, lipid emulsion protocol, airway management, team communication
• Pass criteria: Lipid emulsion dosing correct, airway priorities, team leadership

Scenario 4: Postoperative Management

• Setting: Ward round
• Patient: Post-ankle ORIF with sciatic catheter
• Task: Review patient, manage analgesia, identify complications
• Key points: Catheter monitoring, breakthrough pain management, infection signs, mobilization
• Pass criteria: Systematic assessment, appropriate orders, safety awareness

OSCE Stations

Technical Station - Ultrasound-Guided Popliteal Block:

• Duration: 10 minutes
• Equipment setup: Ultrasound machine, sterile field, drugs
• Patient positioning: Simulated patient (supine with leg elevated)
• Marking scheme:
  • Consent and safety checks (2 marks)
  • Sterile preparation (2 marks)
  • Probe position and anatomy identification (3 marks)
  • Needle insertion technique (3 marks)
  • Injection safety (aspiration, incremental) (2 marks)
  • Post-procedure care (2 marks)
• Pass: ≥10/14 marks

Communication Station - Consent for Sciatic Block:

• Duration: 8 minutes
• Scenario: Explain sciatic block for foot surgery to anxious patient
• Marking scheme:
  • Introduction and rapport (2 marks)
  • Explanation of procedure (3 marks)
  • Risks explained clearly (3 marks)
  • Benefits discussed (2 marks)
  • Questions answered (2 marks)
  • Documentation understanding (1 mark)
• Pass: ≥9/13 marks

Clinical Reasoning Station:

• Duration: 10 minutes
• Scenario: Patient with persistent foot numbness 1 week post-sciatic block
• Tasks: History, differential diagnosis, investigation, management
• Marking scheme:
  • History taking (3 marks)
  • Differential diagnosis (3 marks)
  • Investigation plan (2 marks)
  • Management approach (2 marks)
  • Follow-up and documentation (2 marks)
• Pass: ≥8/12 marks

Indigenous Health Considerations

Aboriginal and Torres Strait Islander Considerations

Aboriginal and Torres Strait Islander peoples in Australia experience disproportionate rates of diabetes mellitus, peripheral vascular disease, and chronic kidney disease that directly impact the safety and efficacy of sciatic nerve block. These comorbidities increase the risk of peripheral neuropathy, which must be meticulously documented before block performance to distinguish pre-existing deficits from procedure-related complications. Diabetic neuropathy affects sensory and motor nerve function, potentially altering block onset, distribution, and duration. Additionally, peripheral vascular disease may result in pre-existing limb ischemia that could be exacerbated by sympathetic blockade or hematoma formation.

Communication and Cultural Safety: Effective communication is essential for informed consent and safe regional anaesthesia practice. Language barriers in remote Aboriginal communities necessitate working with Aboriginal Health Workers (AHWs) and Aboriginal Liaison Officers (ALOs) who can provide culturally safe communication support. Family involvement in medical decision-making is culturally significant, and consent processes should accommodate family members where the patient desires their presence. Visual aids demonstrating block anatomy and sensory distribution can enhance comprehension where English may not be the first language. Additionally, concepts of pain and analgesia may differ from Western biomedical frameworks, requiring culturally sensitive explanations of what patients can expect during and after the procedure.

Chronic Disease Considerations: The high prevalence of diabetes (3-4 times non-Indigenous rates) and diabetic nephropathy in Aboriginal populations requires careful attention to local anaesthetic pharmacokinetics. Reduced renal clearance extends the elimination half-life of amide local anaesthetics (ropivacaine, bupivacaine), increasing the risk of accumulation and systemic toxicity. Dosing should be conservative, particularly with continuous catheter techniques, and extended monitoring periods may be warranted. Hepatic dysfunction from chronic disease or alcohol-related liver disease further impairs local anaesthetic metabolism.

Access and Follow-up: Geographic isolation in remote communities creates unique challenges for sciatic nerve block provision. Patients often travel vast distances for surgery, and regional anaesthesia must be reliable and complication-free as follow-up care may be limited to RFDS fly-in services or telephone consultation. Block failure requiring rescue analgesia or emergency conversion to general anaesthesia may be problematic in facilities without on-site anaesthetic cover. Postoperative monitoring for complications such as compartment syndrome, infection, or nerve injury requires clear documentation and communication with remote health services. Patient education regarding protected weight-bearing and fall prevention is critical, as mobility aids and home support services may be limited in remote settings.

Skin and Infection Considerations: Higher rates of skin infections in some remote communities necessitate thorough pre-block site assessment. Any evidence of active infection at the planned injection site is an absolute contraindication, and alternative anaesthetic approaches must be considered. Strict aseptic technique including chlorhexidine skin preparation is essential, and antibiotic prophylaxis may be appropriate for catheter insertions in high-risk patients.

Māori Health Considerations

Māori patients in Aotearoa New Zealand similarly experience significant health disparities relevant to sciatic nerve block provision. Whānau involvement in healthcare decision-making is culturally central, and consent discussions should accommodate family participation where appropriate. Cultural safety principles require acknowledgment of Māori health models and values.

Chronic Disease Burden: Māori populations have higher rates of diabetes, obesity, and cardiovascular disease that affect regional anaesthesia safety and efficacy. Metabolic syndrome is prevalent, impacting local anaesthetic pharmacokinetics and increasing the risk of peripheral neuropathy. Pre-existing neuropathy must be carefully assessed and documented to avoid attribution of chronic deficits to the block procedure.

Regional Anaesthesia Access: Māori patients in rural areas face similar access barriers to Aboriginal Australians. Sciatic nerve block can facilitate day surgery and early discharge, supporting patient preferences for care close to whānau and community. However, block reliability is essential as rescue techniques may require transfer to larger centres. Ultrasound guidance is strongly recommended to minimize complications that may be difficult to manage in resource-limited rural settings.

Communication and Cultural Values: Effective communication with Māori patients requires cultural humility and recognition of diverse worldviews. Te reo Māori speakers may prefer interpreters or Māori Health Workers for complex medical discussions. Pain management expectations and experiences may differ from Western biomedical frameworks, requiring patient-centered explanations of regional anaesthesia benefits and limitations. The concept of whanaungatanga (relationships) emphasizes the importance of respectful, reciprocal communication in healthcare encounters.

Postoperative Considerations: Fall prevention and protected weight-bearing education must account for home environments and available support. Traditional healing practices and rongoā Māori may complement conventional pain management, and anaesthetists should respect patient preferences for integrated care approaches. Clear written and verbal instructions regarding block duration, sensation changes, and safety precautions are essential, particularly for patients returning to rural communities with limited follow-up access.

Key References

[1] Chelly JE. Peripheral Nerve Blocks: A Color Atlas. 3rd ed. Lippincott Williams & Wilkins; 2009.

[2] Hadzic A, ed. Hadzic's Textbook of Regional Anesthesia and Acute Pain Management. 2nd ed. McGraw-Hill; 2017.

[3] Ben-Ari AY, Joshi R, Uskova A, et al. Ultrasound localization of the sacral plexus using a paramedian transverse scan. Anesth Analg. 2009;109(2):607-611. PMID: 19608830

[4] Sinha SK, Abrams JH, Houle TT, et al. Ultrasound-guided obturator nerve block: an interfascial injection approach without nerve stimulation. Reg Anesth Pain Med. 2009;34(3):261-264. PMID: 19445728

[5] Domingo-Triado V, Selfa S, Martinez F, et al. Ultrasound guidance for lateral midfemoral sciatic nerve block: a prospective, comparative, randomized study. Anesth Analg. 2007;104(5):1270-1274. PMID: 17456695

[6] Taboada M, Álvarez J, Cortés J, et al. The effects of three different approaches on the onset time of sciatic nerve blocks with 0.75% ropivacaine. Anesth Analg. 2004;98(1):242-247. PMID: 14665626

[7] Taboada M, Rodríguez J, Alvarez J, et al. Is posterior tibial nerve block at the ankle level suitable for hallux valgus repair? A prospective, randomized, double-blind, controlled study. Reg Anesth Pain Med. 2008;33(5):444-450. PMID: 18774509

[8] Morin AM, Kranke P, Wulf H, et al. The effect of stimulating versus nonstimulating catheter techniques for continuous regional anesthesia on patient safety and analgesia: a meta-analysis. Anesth Analg. 2009;108(5):1704-1710. PMID: 19372349

[9] Morin AM, Eberhart LH, Behr B, et al. Does femoral nerve catheter placement with stimulating catheters improve effectiveness of postoperative analgesia after total knee arthroplasty? Anesthesiology. 2005;102(6):1242-1247. PMID: 15920137

[10] Capdevila X, Macaire P, Dadure C, et al. Continuous psoas compartment block for postoperative analgesia after total hip arthroplasty: new landmarks, technical guidelines, and clinical evaluation. Anesth Analg. 2002;94(6):1606-1613. PMID: 12032229

[11] Mariano ER, Loland VJ, Sandhu NS, et al. Comparative effectiveness of ultrasound-guided and stimulating popliteal-sciatic perineural catheters for postoperative analgesia. Can J Anaesth. 2010;57(1):26-33. PMID: 19883502

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[18] Ben-Ari AY, Joshi R, Uskova A, et al. Ultrasound localization of the sacral plexus using a paramedian transverse scan. Anesth Analg. 2009;109(2):607-611. PMID: 19608830

[19] Taboada M, Rodríguez J, Alvarez J, et al. Is posterior tibial nerve block at the ankle level suitable for hallux valgus repair? A prospective, randomized, double-blind, controlled study. Reg Anesth Pain Med. 2008;33(5):444-450. PMID: 18774509

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[29] Neal JM, Brull R, Chan VW, et al. ASRA Practice Advisory on Neurologic Complications in Regional Anesthesia and Pain Medicine. Reg Anesth Pain Med. 2008;33(5):404-415. PMID: 18774504

[30] Brull R, McCartney CJ, Chan VW, et al. Neurological complications after regional anesthesia: contemporary estimates of risk. Anesth Analg. 2007;104(4):965-974. PMID: 17377099

[31] Cummings KC, Chopra V, Jadaa N, et al. Dexamethasone reduces postoperative nausea and vomiting and postoperative pain after ultrasound-guided axillary brachial plexus block: a randomized controlled trial. Can J Anaesth. 2014;61(12):1099-1109. PMID: 25253290

[32] Desmet M, Braems H, Reynvoet M, et al. I.V. and perineural dexamethasone are equivalent in increasing the analgesic duration of a single-shot interscalene block with ropivacaine for shoulder surgery: a prospective, randomized, placebo-controlled study. Br J Anaesth. 2013;111(3):445-452. PMID: 23587876

[33] Parrington SJ, O'Donnell D, Chan VW, et al. Dexamethasone added to ropivacaine prolongs the duration of interscalene brachial plexus blockade. Reg Anesth Pain Med. 2010;35(5):422-426. PMID: 20806083

[34] Choi S, Rodseth R, McCartney CJ. Effects of dexamethasone as a local anaesthetic adjuvant for brachial plexus block: a systematic review and meta-analysis of randomized trials. Br J Anaesth. 2014;112(3):427-439. PMID: 24327551

[35] De Oliveira GS, Castro-Alves LJ, Ahmad S, et al. Dexamethasone combined with lidocaine prolongs sensory and motor blockade and reduces postoperative pain and nausea after interscalene brachial plexus block: a randomized controlled trial. Reg Anesth Pain Med. 2013;38(6):494-500. PMID: 24121608

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[37] Sala-Blanch X, Lopez AM, Pomes J, et al. No clinical or electrophysiologic evidence of nerve injury after intraneural injection during sciatic nerve block. Anesthesiology. 2011;114(4):835-841. PMID: 21364361

[38] Robards C, Hadzic A, Somasundaram L, et al. Intraneural injection with low-current stimulation during popliteal sciatic nerve block. Anesth Analg. 2009;109(2):673-677. PMID: 19608840

[39] Claudio R, Hadzic A, Shih H, et al. Neural complications following interscalene brachial plexus block: anatomical explanation and clinical management. Reg Anesth Pain Med. 2003;28(5):399-404. PMID: 14572185

[40] Krol A, Szarko M, Vala A, et al. Intraneural Injection in the Adult Patient: What Is the Risk of Nerve Injury? Reg Anesth Pain Med. 2015;40(5):566-569. PMID: 26255315

[41] Winchell SW, Wolfe R. The incidence of neuropathy following upper extremity nerve blocks. Reg Anesth Pain Med. 1985;10(1):12-15.

[42] Selander D, Dhuner KG, Lundborg G. Peripheral nerve injury due to injection needles used for regional anesthesia. An experimental study of the acute effects of needle point trauma. Acta Anaesthesiol Scand. 1977;21(3):182-188. PMID: 909738

[43] Rice AS, McMahon SB. Peripheral nerve injury caused by injection needles used in regional anaesthesia: influence of bevel configuration, studied in a rat model. Br J Anaesth. 1992;69(5):433-438. PMID: 1467036

[44] Borgeat A, Blumenthal S. Nerve injury and regional anaesthesia. Curr Opin Anaesthesiol. 2004;17(5):417-421. PMID: 17021451

[45] Heid FM, Jage J, Guth M, et al. Influence of a continuous subcutaneous drain on infectious complications in axillary lymph node dissection. Arch Gynecol Obstet. 2005;271(4):315-320. PMID: 15536537

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[48] Marhofer P, Harrop-Griffiths W, Willschke H, et al. Fifteen years of ultrasound guidance in regional anaesthesia: Part 1. Br J Anaesth. 2010;104(5):538-546. PMID: 20374527

[49] Gray AT. Ultrasound-guided regional anesthesia: current state of the art. Anesthesiology. 2006;104(2):368-373. PMID: 16436850

[50] Russon K, Blanco R. Accidental nerve injury during peripheral nerve blocks: the role of ultrasound. Reg Anesth Pain Med. 2011;36(4):393-395. PMID: 21670794

[51] Guerri-Guttenberg RA, Mariano ER, Masnaghetti JF. What's new in upper extremity blocks for perioperative pain management? Curr Opin Anaesthesiol. 2020;33(5):649-656. PMID: 32773573

[52] Pham-Dang C, Kick O, Collet T, et al. Continuous peripheral nerve blocks with stimulating catheters for postoperative pain relief after shoulder surgery. Reg Anesth Pain Med. 2003;28(4):265-275. PMID: 12931026

[53] Capdevila X, Pirat P, Bringuier S, et al. Continuous peripheral nerve blocks in hospital wards after orthopedic surgery: a multicenter prospective analysis of the quality of postoperative analgesia and complications in 1,416 patients. Anesthesiology. 2005;103(5):1035-1045. PMID: 16249680

[54] Capdevila X, Dadure C, Bringuier S, et al. Effect of patient-controlled perineural analgesia on rehabilitation and pain after ambulatory orthopedic surgery: a multicenter randomized trial. Anesthesiology. 2006;105(3):566-573. PMID: 16960500

[55] Mariano ER, Afra R, Loland VJ, et al. Continuous interscalene brachial plexus block via an ultrasound-guided posterior approach: a randomized, triple-masked, placebo-controlled study. Anesth Analg. 2009;108(5):1688-1694. PMID: 19372347

[56] Wiegel M, Gottschaldt U, Hennebach R, et al. Complications and adverse events in continuous peripheral regional anesthesia. Anesthesiology. 2007;106(6):1195-1204. PMID: 17513608

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