Efficacy of the C8 Nerve Root Block During Interscalene Block for Anesthesia of the Posterior Aspect of the Shoulder

This study evaluates the effects of selective 8th cervical nerve root block during interscalene brachial plexus block on the relief of pain intensity upon the introduction of a posterior portal during arthroscopic shoulder surgery. The 5th to 7th cervical nerve roots will be blocked in half of participants, while the 5th to 8th cervical nerve roots will be blocked in the other half.