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Sciatic nerve block Dr. S. Parthasarathy MD., DA., DNB, MD (Acu), Dip. Diab. DCA, Dip. Software statistics PhD (physio) Mahatma Gandhi Medical college and research institute , puducherry India Indications • • • • • one of the largest nerve trunks in the body Combined with other blocks for anaesthesia Analgesia for ankle fractures Transport analgesia Trauma analgesia Volume • • • • 20 – 25 ml is adequate Volume problem ?? But absorption is less quick Motor block – 0.5 % or 0.25 % bupivacaine Anatomy • L 4 to S3 roots • roots of the sacral plexus form on the anterior surface of the lateral sacrum • assembled into the sciatic nerve on the anterior surface of the piriformis muscle • sciatic nerve exits the pelvis, is joined by the posterior cutaneous nerve of the thigh Anatomy • posterior to the obturator internus, the gemelli, and the quadratus femoris. At this point, these nerves are anterior to the gluteus maximus. • equidistant from the ischial tuberosity and the greater trochanter. • continues downward through the thigh to lie along the posteromedial aspect of the femur. At popleteal fossa, divides to tibial and common peroneal nerves Anatomy Anatomy Anatomy – lateral view Classic technique ( Labat ) • The patient is positioned laterally, with the side to be blocked nondependent. • The nondependent leg is flexed and its heel placed against the knee of the dependent leg The anesthesiologist is positioned to allow insertion of the needle Needle Puncture • A line is drawn from the posterior superior iliac spine to the midpoint of the greater trochanter. • Perpendicular to the midpoint of this line, another line is extended caudomedially for 5 cm. • The needle is inserted through this point Technique • 22-gauge, 10- to 12-cm needle is inserted, • The needle should be directed through the entry site toward an imaginary point where the femoral vessels course under the inguinal ligament • Paraesthesia or motor response. • Bone hits . Go towards trochanter but not more than 2 cm Anterior technique( BECK) • supine patient • leg in neutral position • a line should be drawn from the anterior superior iliac spine to the pubic tubercle. Another line should be drawn parallel to this line from the midpoint of the greater trochanter inferomedially, Anterior Approach Technique • At the point,the perpendicular line crosses the more caudal line, • a 22-gauge, 12-cm needle is inserted so that it contacts the femur at its medial border. Once the needle has contacted the femur, it is redirected slightly medially to slide off the medial surface of the femur. • Then paraesthesia , 20-25 ml. Parasacral sciatic nerve block (Mansour): • Line from p.s.i.spine to ischial tuberosity • 6 cm caudad • Perpendicular needle insertion 5-7 cm • Bone , slip caudad, • get nerve stimulation – dorsiflex foot Raj approach • patient supine • hip and knee flexed to 90°, • the greater trochanter and ischial tuberosity are marked. A line is drawn • intermuscular groove between the adductors and the hamstrings marked Ischianagi’s approach, lateral midfemoral • Supine • Posterior to posterior border of greater trochanter • Needle directed medially • Cant position- ideal technique Problems • Dysaesthesias • Failure because of the necessity of combined blocks Ultrasound guided block USG probe USG image USG image Before and after LA Thank you all
