Background and objectives:
The posterior approach to the brachial plexus--or cervical paravertebral block--has advantages over the anterolateral interscalene approach, but concerns regarding "blind" needle placement near the neuraxis have limited the acceptance of this useful technique. We present a technique to place an interscalene perineural catheter that potentially decreases neuraxial involvement with the use of ultrasound guidance.
Methods:
A 55-year-old man scheduled for total shoulder arthroplasty underwent placement of an interscalene perineural catheter. The posterior approach was selected to avoid the external jugular vein and anticipated sterile surgical field. Under in-plane ultrasound guidance, a 17-gauge insulated Tuohy-tip needle was inserted between the levator scapulae and trapezius muscles, and guided through the middle scalene muscle, remaining less than 2 cm below the skin throughout. Deltoid and biceps contractions were elicited at a current of 0.6 mA, and a 19-gauge stimulating catheter was advanced 5 cm beyond the needle tip, without a concomitant decrease in motor response.
Results:
The initial 40 mL 0.5% ropivacaine bolus via the catheter resulted in unilateral anesthesia typical of an interscalene block; and subsequent perineural infusion of 0.2% ropivacaine was delivered via portable infusion pump through postoperative day 4.
Conclusions:
Continuous interscalene block using an ultrasound-guided posterior approach is an alternative technique that retains the benefits of posterior catheter insertion, but potentially reduces the risk of complications that may result from blind needle insertion.