Introduction

An interscalene brachial plexus block uses injected medication to numb the shoulder and upper arm prior to surgical procedures or repositioning (reduction) of a dislocated shoulder. An interscalene brachial plexus block delivers numbing medication to nerves in the shoulder and arm. It may be used for hand and wrist surgery as well, but additional medication is usually required. The nerve block is temporary, lasting up to several hours. Following the operation, the medication wears off and the sense of feeling returns.

Anatomy

Your spine is made up of small bones called vertebrae. The scalene muscles connect select vertebrae at the neck (cervical spine) and upper body (thoracic spine) to the upper ribs on both your right and left sides. Nerves extend from the spinal cord, through the anterior and middle scalene muscles, and form branches or networks of nerves called the brachial plexus. The brachial plexus then becomes the nerves that supply muscles and skin in the chest, shoulders, and arms.

Causes

An interscalene brachial plexus block is primarily used to temporarily numb or “turn off” the nerves responsible for feeling in the shoulder and upper arm before surgery or other medical procedures are performed. This technique can also be used to alleviate various painful conditions affecting the shoulder and upper extremity.

Treatment

The interscalene brachial plexus block takes place prior to your surgery or procedure to numb your shoulder and upper arm. You will wear a gown for your procedure and lay on your back on a surgical table. Your head will be turned away from the side that will receive the nerve block, as this helps identify neck muscles and other anatomical landmarks. Your doctor may feel your neck muscles to find a landmark called the interscalene groove. The interscalene groove is the site where the injection is given.

The area is sterilized and draped. A local anesthetic is delivered to the injection site. The brachial plexus nerves are located using ultrasound or electrical nerve stimulation. The area below the shoulder will twitch when the correct nerve is stimulated. Once identified, the injection needle is carefully directed to the brachial plexus. The anesthetic medication is delivered and the needle is removed.

The interscalene brachial plexus block will numb the upper arm and shoulder for several hours to allow surgery or a medical procedure to take place without you feeling any pain. Following your surgery, your arm may be placed in a sling to protect it until your sense of feeling returns. Your doctor will prescribe pain medication for you to use after the block has worn off.