Ultrasound-guided root/trunk (interscalene) block for hand and forearm anesthesia

Area of Science:

• Anesthesiology
• Regional Anesthesia
• Ultrasound-Guided Procedures

Background:

• The anterolateral interscalene block is a common technique for shoulder surgery.
• Historically, this block has shown limited success in providing anesthesia to the hand and forearm.
• The efficacy of targeting the seventh cervical root or inferior trunk for hand and forearm anesthesia remains unclear.

Purpose of the Study:

• To evaluate the effectiveness of an ultrasound-guided interscalene brachial plexus block in achieving surgical anesthesia of the hand and forearm.
• To determine if anesthetic deposition near the deepest brachial plexus roots/trunks reliably anesthetizes the hand and forearm.

Main Methods:

• Ultrasound guidance and a posterior approach were used to position a needle between the deepest and next-deepest brachial plexus roots/trunks.
• Mepivacaine (1.5%) was injected, and grip strength and cutaneous electrical current tolerance were measured for 30 minutes.
• The primary endpoint was at least 90% decrease in grip strength and hand/forearm anesthesia within 30 minutes.

Main Results:

• All 55 subjects achieved shoulder block.
• Only 15% (5 of 33) of subjects demonstrated surgical block of the hand and forearm within 30 minutes.
• Block failures were primarily due to inadequate anesthesia in the ulnar, median, and radial nerve distributions.

Conclusions:

• The interscalene brachial plexus block, as performed in this study, does not reliably provide surgical anesthesia to the hand and forearm.
• The findings do not support the hypothesis that this technique is equivalent to other brachial plexus block approaches for hand and forearm anesthesia.