Analgesia & Resuscitation : Current ResearchISSN: 2324-903X

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Case Report, Analg Resusc Curr Res Vol: 3 Issue: 1

Continuous Anterior Sciatic Nerve Block: A Case Series

Maged Guirguis1*, Armin F. Deroee2, Sree Kolli2, Alaa A. Abd-Elsayed3 and Sherif Zaky1
1Ochsner health system, New Orleans, Louisiana, USA
2Anesthesiology Institute, Cleveland Clinic, Cleveland, Ohio, USA
3Department of Anesthesiology, University of Cincinnati, Cincinnati, Ohio, USA
Corresponding author : Maged Guirguis
Institute of Anesthesia, Pain management department Ochsner Health System 2820 Napoleon Ave, New Orleans , LA 70115, USA
Tel: 440-321-0525
Fax: 216-444-2294
E-mail: [email protected]
Received: September 29, 2013 Accepted: December 24, 2013 Published: January 03, 2014
Citation: Guirguis M, Deroee AF, Sree K, Abd-Elsayed AA, Sherif Z, (2014) Continuous Anterior Sciatic Nerve Block: A Case Series. Analg Resusc: Curr Res 3:1. doi:10.4172/2324-903X.1000112

Abstract

Continuous Anterior Sciatic Nerve Block: A Case Series

Sciatic nerve block is classically performed through posterior or lateral approaches. With the increased use of ultrasound, the anterior approach has gained popularity. An anterior approach should be considered in patients after trauma and severe postoperative pain where patient positioning can be challenging. The anatomical landmark techniques can be difficult for anterior approach and cannot always be relied on due to inconsistency in extremely obese population. The presence of large blood vessels in the needle path and increasing use of anticoagulants, call for the use of ultrasound guidance for anterior approach to sciatic nerve

Keywords: Sciatic nerve block; Anterior approach; Ultrasound guided; Peripheral nerve catheter; Inguinal crease; External rotation; Lesser trochanter; Curvilinear probe

Keywords

Sciatic nerve block; Anterior approach; Ultrasound guided; Peripheral nerve catheter; Inguinal crease; External rotation; Lesser trochanter; Curvilinear probe

Introduction

Sciatic nerve block may be performed at different anatomical levels starting high up at the pelvis and ending below at the popliteal fossa. Different approaches for blocking the sciatic nerve have been described. The anterior approach, first described by GP Beck in 1963 [1], was less preferred because the sciatic nerve runs along the posterior thigh and behind the femur, an anatomy which makes finding the landmarks technically more difficult and time-consuming [2,3]. In addition, the attempt to find the landmarks may be extremely painful for patients with lower extremity fractures. Nevertheless, the anterior approach offers the main advantage that it avoids positioning the patient, which could pose a challenge in some patients, for instance, trauma patients, patients with chronic regional pain syndrome, and patients experiencing severe postoperative pain. Moreover, with the recent use of ultrasound for peripheral nerve blocks, including its use in performing sciatic nerve block at the subgluteal level [4,5], the anterior approach has become more feasible and less difficult. It has been shown that under ultrasound guidance, the anterior approach to sciatic nerve block is performed as easily and successfully as the posterior approach in patients undergoing knee surgery [6].
With the anterior approach, inserting the sciatic nerve catheter under ultrasound guidance [7,8] is relatively new and potentially less time-consuming, especially if combined with femoral nerve catheters or blocks. This approach is also safer and leads to fewer complications such as infection, catheter kinking or dislodgment [9].
We describe two cases in which an anterior approach was used to place an indwelling sciatic nerve catheter under ultrasound guidance.

Case 1

A 46-year-old female with chronic regional pain syndrome type 1 involving both lower limbs was scheduled for elective right-ankle surgery. Managing the patient’s perioperative pain was challenging, because the patient had very limited movement of her limbs due to excruciating pain. Positioning this patient for the sciatic nerve catheter at the popliteal fossa was nearly impossible; we therefore inserted a sciatic catheter using the anterior approach under ultrasound guidance.

Case 2

The patient was a 66-year-old woman who underwent a right below-knee amputation. She was in severe pain in the post anesthesia care unit and was known to be intolerant to most opiates. Therefore the anterior approach was used to place both femoral and sciatic nerve catheters.
All patients then experienced marked pain relief and a comfortable postoperative period. Case 1 had the continuous nerve block for 4 days and case 2 had the catheter for 3 days postoperatively. Catheters were removed before discharge from the hospital.

Method

We used an identical technique for both of the cases to place the sciatic nerve catheter. Standard noninvasive monitoring was used in accordance with ASA guidelines. Patients were positioned supine with some degree of external rotation of the corresponding lower extremity if tolerated. A curvilinear probe (2-5 MHZ) was used to facilitate deep tissue scanning. The ultrasound probe was placed approximately 10 cm distal to the inguinal crease and scanned by sliding and tilting to obtain a clear hyperechoic image of the sciatic nerve, which was identified deep to adductor muscle, posterior and medial to the femur (Figure 1).
Figure 1: Placement of the ultrasound probe.
The skin was sterilized with chlorhexidine prep and standard sterile precautions were followed. After skin infiltration with 1% Lidocaine, a 6-in 17-guage Tuohy needle was inserted in line with the ultrasound probe from anterolateral to posteromedial direction. The needle was advanced slowly under real-time ultrasound guidance avoiding the blood vessels and reaching close to the nerve. In each of the three cases a nerve stimulator was connected and foot plantarflexion or dorsiflexion at 1mA or less was accepted.
A local anesthetic solution of 0.5% Ropivacaine was injected, needle tip manipulated to achieve good spread around the nerve. The indwelling catheter was inserted 5 cm past the needle tip under real-time ultrasound guidance and the position of the catheter tip was confirmed using 2 cc of air. In Case 1, infusion of 0.2% Ropivacaine was started at 8 cc basal rate and 12cc bolus every 60 min. In the second case infusion of 0.1% Ropivacaine was started at 8 cc basal rate.

Discussion

Continuous sciatic nerve blockade can theoretically be achieved at any point along the course of the sciatic nerve. It has been used for analgesia after major foot and ankle reconstruction, ankle fracture fixation, and below-the-knee amputation. It has also been used for knee arthroplasty, though the evidence does not support the need for sciatic nerve blockade beyond the first 24 hrs.
Successful sciatic catheter placement has been reported extensively with both lateral and posterior approaches. The consistent problem reported with popliteal catheters is a high incidence (15%-25%) of kinking or dislodgement. One study [10] comparing the popliteal and subgluteal approaches for catheter placement showed that 13.3% of the catheters in the popliteal group were either occluded or dislodged compared with 6.6% of the catheters in the subgluteal group. The anterior sciatic catheter theoretically is less likely to be kinked, dislodged or infected. In the prospective study by Neuburger et al. [11] of 2,285 peripheral nerve catheters, the anterior proximal sciatic nerve catheters were associated with the lowest risk of inflammation and infection.
The introduction of high quality ultrasound imaging has facilitated easy identification of the sciatic nerve using the anterior approach. With the anterior approach the external rotation of the thigh and the placement of the probe medially and looking posterolaterally resolved the problem of a nerve being behind the femur. It has been demonstrated that the sciatic nerve is better accessed in internal rotation for the landmark techniques at the level of the lesser trochanter [12-14].
Ericksen et al. [15] showed that by going 4 cm below the lesser trochanter, the sciatic nerve is consistently medial to the femoral shaft and thus may be more accessible using an anterior approach. Therefore by inserting the needle 8-10 cm distal to the inguinal crease with the leg externally rotated, it is possible to locate the sciatic nerve accurately and place an indwelling catheter using ultrasound guidance. Anterior sciatic nerve block is a useful method to use in patients who cannot be positioned for the traditional lateral or posterior techniques (Figure 2).
Figure 2: Anatomy of anterior sciatic nerve block under ultra sound.

Conclusion

The anatomical landmark techniques can be difficult with the anterior approach and cannot always be relied on because of their inconsistency, because of an increasingly obese population, the presence of large blood vessels in the needle path, and the increasing use of anticoagulants. All these challenges argue for the use of ultrasound guidance in the anterior approach to the sciatic nerve. The use of ultrasound has made the anterior approach safer and more feasible. The nerve can be visualized using real-time ultrasonography and the catheter can be placed safely, avoiding damage to major blood vessels and to the nerve itself.

Acknowledgment

Work was supported only by institutional financial support. Approval was obtained from the Cleveland Clinic institutional review board (IRB) and that all patients had an informed consent. We thank Mr Jack Vander Beek who kindly granted us the permission to use the figures from his website : www.neuraxiom.com in this manuscript.

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