Lower extremity anatomy and Peripheral nerve blocks

Lower Extremity Anatomy and Peripheral Nerve Blocks John D. Hermann D.O. Director of Regional Anesthesia Wilford Hall Medical Center Lackland Air Force Base, Texas JDH 1 JDH 2 Objectives  Review the cadaver anatomy of the anterior lower extremity that correlates with successful peripheral nerve blockade. Discuss Anterior lower Extremity block techniques based on anatomical findings. 3  JDH Key Peripheral Nerve Blocks         Lumbar Plexus Block Femoral Nerve Block & “3 in 1 Block” Fascia Iliaca Block Lateral femoral Cutaneous Block Obturator Block Saphenous Nerve Block Genitofemoral Nerve Block Iliohypogastric and Ilioinguinal Nerve block 4 JDH JDH 5   Iliohypogastric Nerve – L1 Ilioinguinal Nerve – L1 Genitofemoral Nerve – L1, L2 Lateral Femoral Cutaneous Nerve – L2,L3 Obturator Nerve – L2,3,4 Femoral Nerve – L2, L3, L4 Saphenous Nerve – distal branch of Femoral n. 6      JDH JDH 7 JDH 8 JDH 9 Iliohypogastric and Ilioinguinal  Sensory nerves of the inguinal region and superiomedial aspect of the thigh Both are derived from Ventral Rami L1 Superio-medial to the ASIS the nerves lie between the transversus abdominus and the internal oblique. After transversing inferio-medial to the ASIS the nerve pierces the Internal oblique and lies between the Internal and external oblique muscles. 10    JDH Iliohypogastric and Ilioinguinal Nerve Block Internal Oblique M External Oblique M Iliohypogastric Nerve Ilioinguinal Nerve JDH 11 Iliohypogastric and Ilioinguinal Nerve Block     Indication : Any somatic procedure of the lower abdominal wall or inguinal region. Does not provide visceral block for intra-perotineal work Several techniques: ASIS and understanding of muscle layers are the keys to success. Techniques – 2cm lateral and 2 cm superior to ASIS  My technique combines the best of two different techniques, always use 22 g Blunt needle, Infiltrate 3-5 cc increments, always aim to enter fasica between the External and internal oblique JDH 12 JDH 13 Lumbar Plexus Anatomy     The lumbar plexus is formed between the Psoas Major and quadratus lumborum muscle. The ventral rami of L2,3,4 pass anterior to the transverse processes of the lumbar vertebrae . Divides into ant and posterior divisions Posterior division of L2-4 forms Femoral n. and runs inferiolateral to psoas and superior to the iliacus down to the inguinal ligament  Obturator L2, 3,4 ant div and leaves the medial border of the psoas at the pelvic brim. 14 JDH JDH 15 JDH 16 Image from NYSORA website JDH 17 Lumbar Plexus Block    Indication: Lower extremity fractures of the upper thigh but will not provide complete anesthesia for major surgery without an accompanying sciatic nerve block Techniques: Can be nerve stimulation or loss of resistance. Local anesthetic spread is through the psoas muscle and around lumbar branches, will not spread below the sacral promontory and will not get sciatic nerve distribution. JDH 18 Lumbar Plexus Block     Lateral Position with affected side up Landmarks: Iliac crest and spinous process (midline) 22g 10 cm long stimulating needle Several techniques described:   4 cm lateral of midline and level of iliac crest 2 finger breadths lateral (4 cm) and 3 cm inferior to intercrestal line. JDH 19 Lumbar Plexus Block   Provide adequate sedation and pain relief Advance until adequate quadriceps twitch is obtained. Paraspinous muscle twitch – too shallow Hamstring twitch – too caudal & medial Flexion at thigh – psoas stimulation/too deep Bony contact – transverse process     JDH 20 JDH 21 FEMORAL NERVE BLOCK    Indications: Surgery on the anterior thigh and superficial surgery on medial aspect of the leg below the knee Significantly improves postoperative analgesia but must be combined with a sciatic nerve block for anesthesia for surgery on the entire leg or ankle. Considered the block of choice for TKA but patients can complain about burning pain behind the knee 22 JDH FEMORAL NERVE BLOCK      Anterior Rami L2-4, posterior division. Largest Branch of Lumbar Plexus The nerve emerges from lateral border of psoas superior to inguinal ligament. Descends post/lat under the midpoint of the inguinal ligament. Lateral to Femoral Artery (2 cm) Breaks up into several terminal branches, to ant thigh, hip and knee joint and medial foot (saphenous nerve) 23 JDH FEMORAL NERVE BLOCK JDH 24 FEMORAL NERVE BLOCK JDH 25 FEMORAL NERVE BLOCK Three options: Classic approach, 3 in 1 approach and Fascia Iliaca.  Classic –midpoint of inguinal ligament and lateral to the Fem a.  3 in 1 “Winnie”– at inguinal ligament and needle directed 30-45 deg angle cephalad. JDH 26 FEMORAL NERVE BLOCK  Classic and 3 in 1 can be started with the following guidelines       Start at Inguinal crease 2 cm lateral to femoral artery 22 ga x 2 in stimuplex needle Patellar snap- critical 30cc of local anesthesia Unreliable method for other:      LFCN: 15-50% Obturator: Ant about 13-50% Post-0% (Knee) Redirection Clues: Sartorius = too medial and/or superficial Adduction = Pectineus or iliopsoas: stim of ant div or too deep 27 JDH FEMORAL NERVE BLOCK JDH 28 Fascia Iliaca Block  Fascia Iliaca – Block takes advantage of the fascial plane that lies anterior to the femoral nerve. -Alternative to “3 in 1” block -Useful in fracture pt’s and kids -No paresthesia or n.stim necessary 22ga x B bevel ,lateral 1/3 of inguinal ligament, 2 cm below, aim 45 deg cephalad 30 cc of local for adequate spread -“Pop” thru fascia lata, then fascia iliaca, then advance another 2mm         -Femoral 100% -LFCN 92% -Obturator 88% 29 JDH Fascia Iliaca Nerve Block Lateral 1/3 of inguinal ligament ASIS Block Site JDH 30 JDH 31 Lateral Femoral Cutaneous Nerve Block           JDH Anatomy: L2,3 roots, sensory only Exits psoas m. laterally, atop iliacus m., medial to ASIS, under ing.lig Pierces fascia lata below ing lig Branches into ant and post branches Block: 1cm med, 1cm inferior to ASIS 22ga x B bevel (blunt) 5 -10 ml volume infiltrated N. stimulation may be useful 32 Obturator Nerve Block  Indications: Relief of Hip pain and adductor muscle spasm related to CP or paraplegia. May be beneficial in urologic surgery to prevent inadvertent obturator activity during lateral wall cytoscopy (spinal may not prevent spasm).  Anatomy: Provides motor innervation to the adductor of the thigh and a small area of sensory innervation to the medial thigh.  Courses medial to the psoas and very close to the bladder wall. JDH 33 Obturator Nerve Block JDH 34  Technique Site is 2cm lateral & 2cm inferior to pubic tubercle. Stimuplex 21ga x 4in advance to sup. ramus, then walk off 2cm into sup-med Obturator foramen   Infiltrate 10 – 15 ML of local JDH 35 JDH 36 Saphenous Nerve Block   Saphenous is a distal branch of the femoral nerve that course all the way to the medial aspect of the ankle. Travels with the vastus medialis under Sartorius to the knee. Passes down the medial side of the leg with the Saphenous vein.  JDH 37 Saphenous Nerve Block   Trans-sartorial Approach Supine position; active hip flexion with knee extended 18/20 ga Touhy needle w/ LOR Depth 1.5-3.0cm 10-20 cc’s of local anesthesia No quadriceps weakness     JDH 38 Saphenous Nerve Block  Ring Block at the knee and ankle 50% success rate with ring block at the knee Block at the level of medial malleolus is more effective   JDH 39 JDH 40 JDH 41