Peripheral Nerve Blocks: A Color Atlas, 3rd Edition

48. Sciatic Nerve Blocks

Giorgio Ivani

Valeria Mossetti

A. Posterior Approach

Patient Position: The child is placed in the lateral position, hip flexed at 120°, knee flexed at 90°, or both knees against the abdomen.

Indications: Anesthesia and postoperative analgesia for foot, ankle, and knee. In combination with femoral nerve block for surgery on the whole leg.

Needle Size: A 22-gauge, 50- to 100-mm, insulated beveled needle.

Volume: Ropivacaine 0.2% for children up to 7 years, levobupivacaine 0.5% for older children, 0.5 to 0.7 mL/kg.

Anatomic Landmarks: The great trochanter, the coccyx, the ischial tuberosity

Approach and Technique: Many approaches have been described but the easiest way, by Dalens, is to mark a line from the skin projection of the great trochanter to the coccyx; the point of insertion of the needle is the midpoint of this line, perpendicular to the skin, pointing to the ischial tuberosity. Since the sciatic nerve is too deep it is impossible to detect it via transcutaneous stimulation. Therefore, insert the needle connected to the nerve stimulator set at 1 mA and 2 Hz, and advance it until the motor response of the foot and toes is elicited (dorsiflexion of the toes and foot or eversion following stimulation of the common peroneal nerve, or plantar flexion of the toes and foot or inversion following stimulation of the tibial nerve). Adjust the position of the needle to maintain the appropriate muscle response with a current of 0.4 to 0.5 mA. Then, after negative aspiration, slowly inject the local anesthetic solution.

 

Tips

1.   There are no particular contraindications or side effects except the vessel puncture of the inferior gluteal artery.

2.   A potential error could be the local anesthetic injection upon stimulatory response from the gluteal muscles.

3.   A combined sciatic and femoral or saphenous nerve block can be used for most lower extremity surgeries. In this case the total dose of local anesthetic must be reduced for each block.

Suggested Reading

Dalens B, Tanguy A, Vanneuvile G. Sciatic nerve block in children: a comparison of the posterior, anterior and lateral approaches in 180 paediatric patients. Anaesth Analg 1990;70:131.

B. Gluteal Approach

Patient Position: Very easy to perform in small children, supine with both the leg maintained flexed on the abdomen at 90° and the knee flexed at 90° helped by a nurse.

Indications: Anesthesia and immediate postoperative analgesia for foot, ankle, and knee. In combination with femoral nerve block for surgery on the whole leg.

Needle Size: A 22- to 25-gauge, 50- to 100-mm, insulated beveled needle.

Volume: Ropivacaine 0.2% for children up to 7 years, levobupivacaine 0.5% for older children, 0.5 to 0.7 mL/kg.

Anatomic Landmarks: The greater trochanter of the femur and the ischial tuberosity (Fig. 48-1).

Approach and Technique: The shorter distance from skin to nerve compared with the posterior approach allows the use of nerve mapping, then insert the needle perpendicular to the skin in the midpoint of the line joining the greater trochanter with the ischial tuberosity. Connect to the nerve stimulator set at 1.5 mA and 2 Hz, and advance it until the motor response of the foot and toes is elicited (dorsiflexion of the toes and foot or eversion following stimulation of the common peroneal nerve, or plantar flexion of the toes and foot or inversion following the stimulation of the tibial nerve). Adjust the position of the needle to maintain the appropriate muscle response with a current of 0.4 to 0.5 mA. Then, after negative aspiration, slowly inject the local anesthetic solution.

Figure 48-1. Gluteal approach anatomic landmarks.

Tips

1.   There are no particular contraindications or side effects except the vessel puncture of the inferior gluteal artery.

2.   A potential error could be the local anesthetic injection upon stimulatory response from the gluteal muscles.

3.   A combined sciatic and femoral or saphenous nerve block can be used for most lower extremity surgeries. In this case the total dose of local anesthetic must be reduced for each block.

4.   In older children this block can be performed placing the patient in lateral position with the same landmarks.

Suggested Readings

Dalens B, Tanguy A, Vanneuvile G. Sciatic nerve block in children: a comparison of the posterior, anterior and lateral approaches in 180 paediatric patients. Anaesth Analg 1990;70:131.

Guardini R, Waldron BA, Wallace WA. Sciatic nerve block: a new lateral approach. Acta Anaesthesiol Scand 1985;29:515–519.

C. Lateral Approach

Patient Position: The patient is supine, with the leg in a neutral position or rotated slightly inward.

Indications: Anesthesia and postoperative analgesia for foot, ankle, and knee.

Needle Size: A 22-gauge, 50- to 100-mm, insulated beveled needle.

Volume: Ropivacaine 0.2% for children up to 7 years, levobupivacaine 0.5% for older children, 0.5 mL/kg.

Anatomic Landmarks: The greater trochanter of the femur (Fig. 48-2).

Approach and Technique: Find and mark the lateral skin projection of the greater trochanter of the femur. The site of introduction of the needle is 1 to 3 cm below the greater trochanter. Since the sciatic nerve is too deep it is impossible to detect it via transcutaneous stimulation. Therefore insert the needle connected to the nerve stimulator set at 1 mA and 2 Hz, just below the trochanter perpendicular to the skin and advance it, passing below the femur, until the motor response of the foot and toes is elicited (dorsiflexion of the toes and foot or eversion following stimulation of the common peroneal nerve, or plantar flexion of the toes and foot or inversion following the stimulation of the tibial nerve). Adjust the position of the needle to maintain the appropriate muscle response with a current of 0.4 mA. Then, after negative aspiration, slowly inject the local anesthetic solution.

Figure 48-2. Lateral approach anatomic landmarks.

Tips

1.   Lateral sciatic nerve block is effective, safe, and simple and there is no need to mobilize the child. Since children are often sedated during the performance of the block, with this approach the child is in spontaneous ventilation and can breathe properly.

2.   There are no particular contraindications or side effects.

3.   If a femur contraction occurs, the insertion of the needle is too ventral; remove the needle and insert it slightly below.

4.   A combined sciatic and femoral or saphenous nerve block can be used for most lower extremity surgeries. In this case the total dose of local anesthetic must be reduced for each block.

Suggested Readings

Dalens B, Tanguy A, Vanneuvile G. Sciatic nerve block in children: a comparison of the posterior, anterior and lateral approaches in 180 paediatric patients. Anaesth Analg 1990;70:131.

Gardini R, Waldron BA, Wallace WA. Sciatic nerve block: a new lateral approach. Acta Anaestesiol Scand 1985;29:515.

Ichikiyanagi K. Sciatic nerve block: lateral approach with the patient supine. Anaesthesiology 1959;20:601.

Ivani G, Tonetti F. Postoperative analgesia in infants and children: new developments. Minerva Anestesiol 2004;70(5):399–403. Review.

D. Posterior Popliteal Approach (Common Peroneal and Tibial Nerve Blocks)

Patient Position: The patient is in the prone position.

Indications: Anesthesia and postoperative analgesia for lower extremity surgery, especially for ankle and foot, except for the medial aspect of the thigh, supplied by the saphenous nerve.

Needle Size: A 22-gauge, 50- to 100-mm, insulated beveled needle.

Volume: Ropivacaine 0.2% for children up to 7 years, levobupivacaine 0.5% for older children, 0.5 mL/kg.

Anatomic Landmarks: The popliteal fossa, the tendons of the biceps femoris and semitendinosus muscle, the medial and lateral epicondyle of the femur.

Approach and Technique: Find and mark the bisector of the angle created by the summit of the popliteal fossa, formed by the tendons of the biceps femoris and the semitendinosus. The point of puncture is located 1 cm lateral to this bisector at the junction of the upper one-third with the lower two-thirds of the line extending from the apex of the popliteal fossa to the intercondylar line. Set the nerve stimulator at a frequency of 2 Hz and a current of 2.5 mA. Connect this to the pen dedicated for the transcutaneous technique (instead of the pen it is possible to use the negative electrode of the ENS) and point it to the skin cranially with a 30° angle direction until a motor response of the foot and toes is elicited (dorsiflexion of the toes and foot or eversion following stimulation of the common peroneal nerve, or plantar flexion of the toes and foot or inversion following stimulation of the tibial nerve). Then insert the needle connected to the nerve stimulator set at 1 mA and 2 Hz, exactly at the point evidenced via transcutaneous in a cranial direction until the motor response is again elicited. Adjust the position of the needle to maintain the appropriate muscle response with a current of 0.4 to 0.5 mA. Then, after negative aspiration, slowly inject the local anesthetic solution.

Tips

1.   A combined sciatic and femoral or saphenous nerve block can be used for most lower extremity surgeries. In this case the total dose of local anesthetic must be reduced for each block.

2.   One complication could be vessel puncture (popliteal artery and vein).

Suggested Readings

Bosenberg AT. Lower limb nerve blocks in children using unsheathed needles and nerve stimulator. Anaesthesia 1995;50:206–210.

Konrad C, Johr M. Blockade of the sciatic nerve in the popliteal fossa: a system for standardization in children. Anesth Analg 1998;87:511–514.

Singelyn FJ, Gouverneur JM, Gribomont BF. Popliteal sciatic nerve block aided by a nerve stimulator: a reliable technique for foot and ankle surgery. Reg Anesth 1991;16(5):278–281.

Tobias JD. Regional anaesthesia of the lower extremity in infants and children. Paediatr Anaesth 2003;13:152–163.

E. Lateral Popliteal Approach (Common Peroneal and Tibial Nerve Blocks)

Patient Position: The patient is supine, with the leg in a neutral position or slightly rotated inward, the leg to be blocked elevated on a pillow at the knee level.

Indications: Anesthesia and postoperative analgesia for lower extremity surgery, especially for ankle and foot.

Needle Size: A 22-gauge, 50- to 100-mm, insulated beveled needle.

Volume: Ropivacaine 0.2% for children up to 7 years, levobupivacaine 0.5% for older children, 0.5 mL/kg.

Anatomic Landmarks: The patellar crest, the vastus lateralis muscle and the tendon of the long head of the biceps femoris muscle (Fig. 48-3).

Approach and Technique: Find and mark the lateral skin projection of the patellar crest, then palpate the biceps femoris tendon. Palpate the inferior border of the vastus lateralis muscle and identify the groove between the tendon and the muscle. Since the sciatic nerve is too deep it is impossible to detect it via transcutaneous stimulation. Therefore insert the needle connected to the nerve stimulator set at 1 mA and 2 Hz, in a horizontal plane with a cephalad angulation and advance it until the motor response of the foot and toes is elicited (dorsiflexion of the toes and foot or eversion following stimulation of the common peroneal nerve, or plantar flexion of the toes and foot or inversion following stimulation of the tibial nerve). At this level both the tibial branch and the peroneal branch are still together because the division of the sciatic nerve into the two branches occurs at about 5 to 8 cm above the crease at the knee so that the insertion of the needle at 7 cm can easily find both twitches. Adjust the position of the needle to maintain the appropriate muscle response with a current of 0.4 to 0.5 mA. Then, after negative aspiration, slowly inject the local anesthetic solution.

Figure 48-3. Lateral popliteal approach anatomic landmarks.

Tips

1.   Lateral sciatic nerve block is effective, safe, and simple and there is no need to mobilize the child. Since children are sedated during the performance of the block it is better to use the lateral approach both at the trochanter level and at the popliteal level, since in this way the child is in the supine position and can breathe properly.

2.   A combined sciatic and femoral or saphenous nerve block can be used for most lower extremity surgeries. In this case the total dose of local anesthetic must be reduced for each block.

3.   A complication could be the vessel puncture (popliteal artery and vein).

Suggested Readings

McLeod DH, Wong DV, et al. Lateral popliteal sciatic nerve block compared with ankle block for analgesia following foot surgery. Can J Anaesth 1995;42:765–769.

Ter Rahe C, Suresh S. Popliteal fossa block: lateral approach to the sciatic nerve. Tech Reg Anesth Pain Manage 2002;6(3):141–143.

Vloka JD, Hadzic A, Kitain E. Anatomic considerations for sciatic nerve block in the popliteal fossa through the lateral approach. Reg Anesth 1997;84:387–390.