B

In the subgluteal space the sciatic nerve is sandwiched between the adductor magnus anteriorly and the hamstrings (long head of the biceps femoris laterally and the semitendinosus/semimembranosus medially).

Place the patient in the lateral position

Place the low-frequency curved array probe in the gluteal crease. A linear probe can be used in lean patients

Visualize the target sciatic nerve (see next page)

Insert the needle from the lateral end of the probe with in-plane technique

Advance the needle tip to the target sciatic nerve

Inject 10-15 mL of local anaesthetic until complete perineural spread is obtained

The needle is advanced from lateral to medial while avoiding piercing the posterior femoral cutaneous nerve.

Place the patient supine.

Place the low frequency curved array probe approximately 10 cm below the inguinal ligament in the femoral triangle and visualize the sciatic and saphenous nerves (see second next page).

Insert the needle from the lateral end of the probe. First advance the needle tip to the sciatic nerve and then direct it to the saphenous nerve subsartorially just lateral to the femoral artery (see second next page)

First the needle is advanced to the sciatic nerve between the gluteus maximus and adductor magnus. Then the needle is redirected to the saphenous nerve lateral to the femoral artery below the sartorius muscle in the femoral triangle.

Proximal sciatic nerve block is indicated:

– for surgical anaesthesia with peripheral nerve blocks that includes surgery of the thigh or knee

– for surgical anaesthesia with peripheral nerve blocks that includes a thigh tourniquet

– as an alternative to popliteal sciatic nerve block when that is not feasible

Proximal sciatic nerve blocks are:

– the subgluteal approach

– the anterior approach combined with a saphenous nerve block (SPEDI)

– the parasacral parallel shift approach to block the sacral plexus (as an alternative to subgluteal approach or
SPEDI – single penetration dual injection)

Parras T & Blanco R: Bloqueo pudendo ecoguiado (Ultrasound guided pudendal block). Cirugia Mayor Ambulatoria 18(1): 31-35 (2013)

http://www.asecma.org/attachments/article/162/06_18_1_FC_Parras.pdf

Parras T & Blanco R: Bloqueo perineal guiado con ultrasonidas.
Revista de anestesia regional e terap

The internal pudendal artery can be visualized in transverse view with Color Doppler at the level of the ischial tuberosity.

The needle is inserted with in-plane technique from the medial end of the probe aiming just lateral to the artery. 10 mL of local anaesthetic is injected bilaterally.

The internal pudendal artery can be visualized with Color Doppler in longitudinal view deep to the deep transverse perineal muscle. The artery can be tracked posteriorly towards the ischial tuberosity. The pudendal nerve runs alongside the internal pudendal artery either medial or lateral to the artery.