Secondary Logo

Journal Logo

Letters to the Editor: Letters & Announcements

Obturator Nerve Block: From Anatomy to Ultrasound Guidance

Anagnostopoulou, Sofia, MD, PhD; Kostopanagiotou, Georgia, MD, PhD; Paraskeuopoulos, Tilemachos, MD; Alevizou, Anastasia, MD; Saranteas, Theodosis, MD, DDS, PhD

Section Editor(s): Saidman, Lawrence

Author Information
doi: 10.1213/01.ane.0000297272.42192.70
  • Free

To the Editor:

Recently, Fujiwara et al.1 described the use of ultrasound imaging in the identification and block of the obturator nerve. Despite the clinical relevance of the study, we have some concern about the anatomy of the obturator nerve at the inguinal region level.

The obturator nerve, as it exits the pelvis and at the level of the obturator externus, divides into an anterior branch, which is located superficially, and a posterior branch, which is situated at a deeper anatomic level.2 Cadaveric studies have also confirmed a large degree of anatomic variability in the obturator nerve anatomy, such that in 50% of individuals the common obturator nerve divides into superficial and deep branches at the level of the obturator foramen whereas in the majority of others a multiple branching pattern occurs throughout its anatomic course.3–5

In the report by Fugiwara et al.,1 the authors suggest that the common obturator nerve is located in between three muscles including the adductor longus (anteriorly), adductor brevis (posteriorly), and pectineus muscle (laterally). However, this description seems not to be anatomically correct since at this point the nerve has been already bifurcated into anterior and posterior branches and possibly into further divisions.6 Thus, the authors more likely identified and blocked one of the obturator nerve branches and not the common obturator nerve. Additionally, according to the images provided, the anatomic location of the common obturator nerve seems to be very superficial, approximately 1–2 cm from skin surface. Those images are possibly in contrast with the location of the common obturator nerve, that anatomically lies at a deeper level, in a very close relationship to the obturator externus muscle.5

We conclude that, due to complicated anatomy and the high anatomic variability of the obturator nerve, additional studies are needed to delineate the precise ultrasound anatomy of this nerve.

Sofia Anagnostopoulou, MD, PhD

Department of Anatomy

School of Medicine

University of Athens

Georgia Kostopanagiotou, MD, PhD

2nd Department of Anesthesiology

School of Medicine

University of Athens

Attikon Hospital

Tilemachos Paraskeuopoulos, MD

Department of Anatomy

School of Medicine

University of Athens

Anastasia Alevizou, MD

Department of Anesthesiology

General State Hospital of Athens

Athens, Greece, EU

Theodosis Saranteas, MD, DDS, PhD

2nd Department of Anesthesiology

School of Medicine

University of Athens

Attikon Hospital

Athens, Greece, EU

saranteas@ath.forthnet.gr

REFERENCES

1. Fujiwara Y, Sato Y, Kitayama M, Shibata Y, Komatsu T, Hirota K. Obturator nerve block using ultrasound guidance. Anesth Analg 2007;105:888–9
2. Kahle W, Leonhardt H, Platzer W. Nervous system and sensory organs. 4th ed. Stuttgart: Georg Thieme Verlag, 1993:84–5
3. Harvey G, Bell S. Obturator neuropathy: an anatomic perspective. Clin Orthop Relat Res 1999;363:203–11
4. Moghaddam TC. Variations in the Obturator nerve and the accessory obturator nerve. Anat Anz 1963;31113:1–18
5. Katritsis E, Anagnostopoulou S, Papadopoulos N. Anatomical observation on the accessory Obturator nerve (based on 1000 specimens). Anat Anz 1980;148:440–5
6. Bannister LH, Berry MM, Collings P, Dyson M. Gray’s anatomy. 38th ed. New York: Churchill Livingstone, 1995:1980–1
© 2008 International Anesthesia Research Society