Does obturator nerve block always occur in 3-1 block?

Abstract

Objective: In the femoral "3-in-1 block", obturator nerve block is routinely unsuccessful. Anatomical studies are not available to explain why blockade of obturator nerve or lumbar plexus does not occur. The aim of this study was to examine the effectiveness of femoral "3-in-1 block" obturator nerve block on a cadaver model. Materials and methods: Totally, 12 mature adult human cadavers were selected. Methylene blue dye (30 ml) was in-jected under the fascia iliaca in eight cadavers and into the femoral nerve sheath in four cadavers. Careful bilateral dissections were performed following dye injections. Results: It was seen that the dye did not spread to the medial part of the psoas major muscle and the obturator nerve was not stained with the dye in eight cadavers in whom dye was injected laterally into the femoral sheat. In four ca-davers in whom dye was injected into the femoral nerve sheat, metylene blue spread through fascial layers in the plane under the psoas muscle and stained the obturator nerve just before emerging medially from the fascia psoas. At this point, the obturator nerve pierced the psoas fascia and extended extrafascially in the medial and deep borders of the psoas muscle. In this area, the upper section of the obturator nerve was found also to be stained with the dye. Conclusion: We concluded that the cause of an unsuccessful obturator nerve block might be the fascial anatomy of this region. The lateral cutaneous femoral nerve and the femoral nerve easily can be blocked in the fascia iliaca com-partment, but the obturator nerve block fails because of its being extrafascial in this region.

Keywords

• Obturator nerve, femoral nerve, nerve sheath, anesthetic techniques.

Obturator sinir 3-1 blok ile her zaman bloke olur mu?

Öz

Amaç: Femoral "3-1 blok" uygulamalarında obturator sinir bloğu genellikle başarısız olmaktadır. Obturator sinir veya lomber pleksus bloğunun niçin oluşmadığını açıklayıcı yeterli sayıda anatomi çalışması bulunmamaktadır. Bu çalışma-nın amacı, femoral 3-1 obturator sinir bloku etkinliğini bir kadavra modeli üzerinde incelemektir. Gereç ve yöntem: Toplam 12 erişkin insan kadavrası seçildi. Sekiz kadavraya 30 ml metilen mavisi iliak fasiya altına ve dört kadavraya da femoral sinir kılıfı içerisine enjekte edildi. Daha sonra dikkatli bilateral disseksiyon yapıldı. Bulgular: Femoral kılıfın lateraline metilen mavisi enjekte edilen sekiz kadavrada metilen mavisinin psoas major kasın medialine yayılmadığı ve obturator sinire ulaşmadığı görüldü. Femoral sinir kılıfı içine metilen mavisi enjekte edilen dört kadavrada ise metilen mavisinin psoas kasının altından fasialar arasında yayıldığı ve obturator siniri boyadığı görüldü. Bu noktada obturator sinir psoas fasiyasını delerek ekstrafasiyal olarak psoas kasının orta ve derin kenarında ilerlemek-tedir. Bu alanda obturator sinirin üst bölümü de boyandı. Sonuç: Sonuç olarak başarısız obturator sinir bloğunun buradaki fasiya anatomisine bağlı olarak gelişiyor olabilir. Fe-moral ve lateral femoral kutanöz sinir subfasiyaldir ve bu iki sinir fasiya iliaka alanında kolaylıkla bloke olmaktadır, an-cak obturator sinir bu bölgede ekstrafasiyal alanda bulunduğu için bloke olmamaktadır.

Anahtar Kelimeler

• Obturator sinir, femoral sinir, sinir kılıfı, anestezik teknikler.

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