Klinik ve Deneysel Araştırmalar Dergisi / P. Kırdemir et al. Obturator nerve block 2011; 2 (2): 149-151149 Journal of Clinical and Experimental Investigations ORIGINAL ARTICLE / ÖZGÜN ARAŞTIRMA

Does obturator nerve block always occur in 3-1 block? Obturator sinir 3-1 blok ile her zaman bloke olur mu?

Pakize Kirdemir1, Ayhan Comert2, Simel Kendir2, İbrahim Tekdemir2, Alaittin Elhan2

1Medical Faculty of Suleyman Demirel University, Department of Anesthesia and Reanimation, Isparta-Turkey 2Medical Faculty of Ankara University, Department of Anatomy, Ankara-Turkey

ABSTRACT ÖZET Objective: In the femoral “3-in-1 block”, obturator nerve Amaç: Femoral “3-1 blok” uygulamalarında obturator si- block is routinely unsuccessful. Anatomical studies are not nir bloğu genellikle başarısız olmaktadır. Obturator sinir available to explain why blockade of obturator nerve or veya lomber pleksus bloğunun niçin oluşmadığını açıkla- lumbar plexus does not occur. The aim of this study was yıcı yeterli sayıda anatomi çalışması bulunmamaktadır. Bu to examine the effectiveness of femoral “3-in-1 block” ob- çalışmanın amacı, femoral 3-1 obturator sinir bloku etkin- turator nerve block on a cadaver model. liğini bir kadavra modeli üzerinde incelemektir. Materials and methods: Totally, 12 mature adult human Gereç ve yöntem: Toplam 12 erişkin insan kadavrası seçil- cadavers were selected. Methylene blue dye (30 ml) was di. Sekiz kadavraya 30 ml metilen mavisi iliak fasiya altına injected under the iliaca in eight cadavers and into ve dört kadavraya da femoral sinir kılıfı içerisine enjekte the sheath in four cadavers. Careful bilat- edildi. Daha sonra dikkatli bilateral disseksiyon yapıldı. eral dissections were performed following dye injections. Bulgular: Femoral kılıfın lateraline metilen mavisi enjekte Results: It was seen that the dye did not spread to the edilen sekiz kadavrada metilen mavisinin psoas major ka- medial part of the and the obtura- sın medialine yayılmadığı ve obturator sinire ulaşmadığı tor nerve was not stained with the dye in eight cadav- görüldü. Femoral sinir kılıfı içine metilen mavisi enjekte ers in whom dye was injected laterally into the femoral edilen dört kadavrada ise metilen mavisinin psoas kasının sheat. In four cadavers in whom dye was injected into the altından fasialar arasında yayıldığı ve obturator siniri bo- femoral nerve sheat, metylene blue spread through fascial yadığı görüldü. Bu noktada obturator sinir psoas fasiyası- layers in the plane under the psoas muscle and stained nı delerek ekstrafasiyal olarak psoas kasının orta ve derin the obturator nerve just before emerging medially from kenarında ilerlemektedir. Bu alanda obturator sinirin üst the fascia psoas. At this point, the obturator nerve pierced bölümü de boyandı. the psoas fascia and extended extrafascially in the medial Sonuç: Sonuç olarak başarısız obturator sinir bloğunun and deep borders of the psoas muscle. In this area, the buradaki fasiya anatomisine bağlı olarak gelişiyor olabilir. upper section of the obturator nerve was found also to be Femoral ve lateral femoral kutanöz sinir subfasiyaldir ve stained with the dye. bu iki sinir fasiya iliaka alanında kolaylıkla bloke olmakta- Conclusion: We concluded that the cause of an unsuc- dır, ancak obturator sinir bu bölgede ekstrafasiyal alanda cessful obturator nerve block might be the fascial anat- bulunduğu için bloke olmamaktadır. Klin Deney Ar Derg omy of this region. The lateral cutaneous femoral nerve 2011;2(2):149-51 and the femoral nerve easily can be blocked in the fascia Anahtar kelimeler: Obturator sinir, femoral sinir, sinir kı- iliaca compartment, but the obturator nerve block fails lıfı, anestezik teknikler. because of its being extrafascial in this region. J Clin Exp Invest 2011;2(2):149-51 Key words: Obturator nerve, femoral nerve, nerve sheath, anesthetic techniques.

INTRODUCTION injection. In recent years, this technique has been

1 used as an effective alternative for arthroscopic sur- Block 3 in 1 was described by Winnie in 1973. gery anesthesia and any superficial surgery such as This technique is supposed to block of the femoral, skin harvesting or a biopsy of the quadriceps muscle femoral cutaneous, and obturator nerves by a single

Yazışma Adresi /Correspondence: Doç. Dr. Pakize Kırdemir, Medical Faculty of Suleyman Demirel University, Department of Anesthesia and Reanimation, Isparta-Turkey, Email: [email protected] Geliş Tarihi / Received: 29.07.2010, Kabul Tarihi / Accepted: 09.04.2011 J Clin Exp InvestCopyright © Klinik ve Deneysel Araştırmalarwww.clinexpinvest.org Dergisi 2011, Her hakkı saklıdır / All rightsVol reserved 2, No 2, June 2011 150 P. Kırdemir et al. Obturator nerve block can be done. Winnie, hypothesized that “If a volume served to be comprised of the part above the ingui- of 20 ml or more is utilized, anesthesia of all three nal ligament blending with the iliac and psoas fas- nerves is virtually assured”.1 Ritter indicates that cia. The sections in horizontal plane, examined with “3-in-1 block” probably does not block the lumbar microscopic dissection, support these findings. 2 3 plexus or the obturator nerve. Lonsdale has con- Based on our observations, this sheath cannot 3 firmed Winnie’s anatomical hypothesis. transport the local anesthetic to the lumbar plexus Obturator nerve block is routinely unsuccessful because this sheath covering the femoral nerve is in the femoral “3-in-1 block”. Anatomical studies not thick or strong enough and has a cribriform are not available to explain why blockade of obtura- structure. Cadavers in whom dye was injected in the tor nerve or lumbar plexus does not occur. There- femoral sheath, the lateral femoral cutaneous nerve fore, in this study, we performed an anatomical ca- and the femoral nerve were stained with dye; dur- daveric study to explain the anatomical basis of why ing the dissection, we observed that the part under obturator nerve block does not occur. the psaos was not stained with the dye because the mass of the psoas muscle was pressured where the MATERIALS AND METHODS cross section of this nerve was seen to be flat and somewhat wide. Dye was spread through the fas- Totally, 12 mature adult human cadavers were se- cial layers in the plane under the psoas muscle and lected for the study. Cadavers with a history or evi- the obturator nerve was found to be stained with dence of surgery in the lower , pelvis and dye just before emerging medially from the fascia inguinal regions were excluded. Age, height, and psoas and at that point, the obturator nerve pierced weight were not included as the criteria for selection the psoas fascia and extended extrafascially in the in all of the cadavers. A 15 cm, 22-gauge catheter medial and deep border of the psoas muscle and the was inserted 2 cm distal to the upper section of the obturator nerve was also seen to and 1cm lateral to the at a 30º angle be stained with dye. cephalad and underneath the and . Thirty ml of methylene blue dye was slowly DISCUSSION injected via the catheter. Without disturbing the ad- jacent anatomic structures bilateral dissection was Major potential benefits of peripheral nerve block performed. techniques may include postoperative analgesia, The fascia of the was opened less physiologic derangements, more rapid postop- and the femoral, lateral femoral cutaneus and obtu- erative recovery, avoidance of airway instrumenta- rator nerves were dissected. Sections in horizontal tion, and a reduced incidence of potential compli- planes were made and examined in Department of cations associated with general anesthesia (nausea/ Anatomy with an aid of surgical microscope. In four vomiting, aspiration, inability to ventilate/intubate, 4 cadavers, inguinal section of the femoral nerve was and malignant hyperthermia). Cauhepe et al. have dissected and a catheter was inserted at a 5° angle reported that the external diffusion of the liquid in and 1 cm thrust into the sheath and 30 ml of dye was front of the iliacus muscle never reached the inter- injected. The abdominal cavity was then opened and nal side of the psoas major muscle, and thus the ob- 4 we observed if the nerves were stained with dye. turator nerve, in their anatomical study. The anatomy literature fails to describe a fascial RESULTS “sheath” around the femoral nerve capable of acting as a liquid to conduit to the lumbar plexus.5-8 In a In eight cadavers where the dye was injected later- study, femoral and lateral femoral cutaneous nerves ally into the femoral sheath, the dye did not spread have been stained following femoral intraneural in- to the medial part of the psoas major muscle and the jection, but the obturator nerve has not been stained. obturator nerve was not stained with the dye. Two Our findings support that the femoral nerve does not other nerves were stained with dye in all cadavers. have a fascial sheath but following our injection, In four cadavers, a part of the femoral sheath under dye was spread posteriorly and cephalad to a point the inguinal ligament was found to be very thick above where the obturator nerve pierces the illiacus and after careful dissection of this region, it was ob- fascia. It has been stated that, this technique anesthe- J Clin Exp Invest www.clinexpinvest.org Vol 2, No 2, June 2011 P. Kırdemir et al. Obturator nerve block 151 sizes only two nerves, and hence should be called a fascia iliaca compartment, but the obturator nerve “2-in-1 block” and others reported that lateral femo- block fails because of its being extrafascial in this ral cutaneous nerve is blocked almost every time, region. but only four patients had abductor paralysis fol- 9,10 lowing the 3-in-1 block. Rosenblatt’s report pre- REFERENCES sented X-ray evidence that a catheter can be placed in the sheath surrounding the femoral nerve.11 Our 1. Winnie AP, Ramamurthy S, Durrani Z. The inguinal para- vascular technic of lumbar plexus anesthesia: the “3-in-1 findings support that liquid cannot spread medially block”. Anesth Analg 1973;52(8):989-96. to reach the obturator nerve because this nerve is 2. Ritter JW. Femoral nerve “sheath” for inguinal paravascular extrafascial on the medial side of the psoas. Having lumbar plexus block is not found in human cadavers. J Clin the anesthetic reach the obturator nerve is possible Anesth 1995;7(4):470-3. because of the relation of the femoral nerve sheath 3. Lonsdale M. 3-in-1block: confimation of Winnie’s anatomi- with the fascial structure of this region. cal hypothesis. Anesth Analg 1988;67(5):601-2. For obturator nerve blockade, the anesthetic 4. Cauhepe C, et al. The “3-in-1” block: myth or reality? Ann Fr Anesth Réanim 1989;8(3):376-8. should be injected in the femoral nerve sheath and 5. Gardner E, Bunge R. Gross anatomy of the perpheral nervous we believe that our method would increase the suc- system. In: Dyck P, Thomas P (eds): Peripheral Neuropathy, cess of this nerve block. In a study, it has been con- 3rd ed. Philadelphia: W.B. Saunders Co., 1993:21-2. cluded that the femoral 3-in-1 block does not block 6. Thomas P, et al. Microscopic anatomy of the peripheral ner- the parent trunk of the obturator nerve, where the vous system. In: Dyck P, Thomas P (eds): Peripheral Neu- obturator nerve block was successful in only one of ropthy, 3rd ed. Philadelphia: W.B. Saunders Co., 1993:21. 26 patients.12 Dupré indicates that “3-in-1” block is 7. Pick TP, Howden R. Muscles and fasciae of the lower ex- supported by the idea of diffusion within a space tremity. In: Pick TP, Howden R, eds. Gray’s Anatomy: The Classic Collector’s Edition. 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