Sciatic nerve block in the popliteal fossa: description of a new medial approach

Abstract

P Pu ur rp po os se e: : Sciatic nerve blocks through lateral approaches in the popliteal fossa have been proposed. We describe a new medial approach to the sciatic nerve at this level.M Me et th ho od ds s: : After an anatomical study on six cadavers, we performed sciatic nerve blocks on 20 patients. A 100-mm insulated needle and a nerve stimulator were used; 20 mL of lidocaine 1.5% with epinephrine were injected.R Re es su ul lt ts s: : Patients lied in the supine position, the thigh flexed, abducted and rotated externally (30° in all directions). The leg was flexed at 130°. In this position, above the adductor tubercle, a depression known as Jobert's fossa is palpated. Through this groove, a medial approach to the sciatic nerve at the level of the popliteal fossa is possible. The mean distance between the adductor tubercle and the puncture site is 6.18 cm (range 4-8 cm) and the mean distance between the skin and the sciatic nerve is 6.62 cm (range 4-9 cm). Mean time to perform the block was 100 sec (range 55-165 sec). Complete motor blockade was obtained after a mean time of 30 min (range 5-60 min) inside the common peroneal nerve area and 43 min (range 15-75 min) inside the tibial nerve area. Motor block was complete in 17 patients and sensory block in 18 patients. No vessel puncture was observed.

Medial Approach to the Sciatic Nerve at the Popliteal Fossa in the Supine Position with Ultrasound Guidance and Nerve Stimulator

“…Guntz et al [6] reported that the block performance time of SNB with a nerve stimulator with the medial approach in the supine position was 100 sec (range 55-165 sec). Buys et al [3] reported that the block performance time of ultrasound guided SNB with the lateral approach in the supine position, which was defined as the time elapsed from the insertion of the block needle until the completion of local anesthetic injection, was 2.9 ± 1.7 (mean ± SD) min.…”

“…The tibial nerve travels down the center of the thigh, and the common peroneal nerve runs along the lateral side of the thigh [6]. When the block needle is inserted below the SN bifurcation from the medial side of the thigh in the supine position, the tip of the needle may be closer to the tibial nerve than the common peroneal nerve.…”

“…This approach did not need elevation of the lower limb or a position change. A medial approach to block the SN at the popliteal fossa in the supine position with a nerve stimulator was described [6]. This is the first report of ultrasound guided SNB at the popliteal fossa with the medial approach in the supine position.…”

Anatomical evaluation of the tibial nerve within the popliteal fossa

“…It is important for clinicians and researchers to understand the location of the tibial nerve within the popliteal fossa when considering nerve blocks in the popliteal fossa, operative procedures and Hoffmann Reflex (H-reflex) assessment (El-Shazly and Saleh, 2002;Guntz et al, 2004). The first concern is that the popliteal vessels are medial to the tibial nerve in the popliteal fossa and are potentially at risk of puncture during a nerve block at this site (Guntz et al, 2004).…”

“…It is important for clinicians and researchers to understand the location of the tibial nerve within the popliteal fossa when considering nerve blocks in the popliteal fossa, operative procedures and Hoffmann Reflex (H-reflex) assessment (El-Shazly and Saleh, 2002;Guntz et al, 2004). The first concern is that the popliteal vessels are medial to the tibial nerve in the popliteal fossa and are potentially at risk of puncture during a nerve block at this site (Guntz et al, 2004). Secondly, some difficulty in locating the tibial nerve has been reported using a posterior or lateral approach for a nerve block in the popliteal fossa because of variable nerve branching patterns and position of the tibial nerve within the fossa (Zetlaoui and Bouaziz, 1998;Al-Nasser, 2002;Hadžić et al, 2002;Yoo et al, 2002).…”