Sciatic Nerve Block - Subgluteal Region
- The subgluteal region is a convenient location for catheter placement and continuous sciatic nerve block. The nerve is more superficial at this location than the gluteal region and the catheter is easily anchored with less risk of dislodgment.
- The principles of catheter placement in this location are the same as those general principles described on Catheter Technique. The procedures for patient position, skin preparation and sterilization, and transducer selection (2-5 MHz) are identical.
- With the patient lying lateral decubitus, insert a 8 cm 17 G insulated needle using the out of plane approach.
- Needle to nerve contact is indicated by nerve movement (+/- nerve stimulation). Then inject 5-10 mL of local anesthetic or D5W (if nerve stimulation is desired) to distend the perineural space.
- A 20 G catheter is then inserted often without real time ultrasound guidance unless an assistant is available to hold the ultrasound transducer in place.
- Aim to advance the catheter 3-5 cm into the perineural space with or without nerve stimulation guidance.
- After the needle is withdrawn, real time assessment of local anesthetic spread during injection through the catheter helps to check if the catheter tip is located in the optimal position. Circumferential local anesthetic indicates optimal catheter location.
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A. Patient in semi-prone position.
GT = greater trochanter
IT = ischial tuberosity |
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B. Out of plane needle approach. |
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C. Catheter is advanced with the help of an assistant. |
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D. Transverse scan of the nerve after hydro dissection.
Arrowhead = nerve
NT = needle tip
GT = greater trochanter |
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E. Transverse scan showing catheter & local anesthetic (LA).
Arrowhead = nerve |
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F. Longitudinal scan showing catheter & local anesthetic (LA).
Arrowhead = nerve |
1. Local Anesthetic Spread Around the Sciatic Nerve
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A. Pre-injection
The sciatic nerve is predominantly hyperechoic and elliptical in this transverse view.
Arrowhead = sciatic nerve |
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B. Post-injection
The sciatic nerve is now surrounded by a hypoechoic collection of local anesthetic (LA). The nerve is now round in shape. Local anesthetic spread is not circum-ferential.
Arrowhead = sciatic nerve |
2. Apparent Nerve Enlargement After Local Anesthetic Injection
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The nerve diameter is noted to be wider after injection suggesting some degree of unintentional intraneural injection.
Arrowhead = sciatic nerve
LA = local anesthetic |
3. Poor Nerve Visualization
The subgluteal sciatic nerve may not be clearly visualized (up to 30% in |
Pre-injection
GMM = gluteus maximus muscle
GT = greater trochanter
IT = ischial tuberosity |
The sciatic nerve (arrowhead) is now visualized after local anesthetic |
Post-injection
GMM = gluteus maximus muscle
GT = greater trochanter
IT = ischial tuberosity |
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Note: When nerve visualization is difficult, it is extremely helpful to combine nerve stimulation with ultrasound for nerve localization. The sciatic nerve is expected to lie deep to the gluteus maximus muscle (GMM) and between the greater trochanter (GT) and ischial tuberosity (IT). |
4. A Thick Adipose Layer
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Arrows = thickness of the adipose tissue
Arrowhead = sciatic nerve |
Subgluteal Sciatic Nerve Block (Out of Plane Approach)
Subgluteal Sciatic Nerve Block (Out of Plane Approach) 2
Subgluteal Sciatic Local Anesthetic Injection Long Axis View
- Saranteas T, Chantzi C, Paraskeuopoulos T, Alevizou A, Zogojiannis J, Dimitriou V, Kostopanagiotou G: Imaging in Anesthesia: The Role of 4 MHz to 7 MHz Sector Array Ultrasound Probe in the Identification of the Sciatic Nerve at Different Anatomic Locations. Reg Anesth Pain Med 2007; 32: 537-8
- Chantzi C, Alevizou A, Saranteas T, Zogogiannis J, Iatrou C, Dimitriou V: Usefulness of the two to 5 MHz ultrasound probe in examination and block of the sciatic nerve in orthopedic trauma patients: a preliminary study. J Clin Anesth 2007; 19: 486-8
- Chan VW, Nova H, Abbas S, McCartney CJ, Perlas A, Quan XD: Ultrasound Examination and Localization of the Sciatic Nerve: A Volunteer Study. Anesthesiology 2006; 104: 309-14
- Graif M, Seton A, Nerubai J, Horoszowski H, Itzchak Y: Sciatic nerve: sonographic evaluation and anatomic-pathologic considerations. Radiology 1991; 181: 405-8
- Hullander M, Spillane W, Leivers D, Balsara Z: The use of Doppler ultrasound to assist with sciatic nerve blocks. Reg Anesth. 1991; 16: 282-4