Learning About Interscalene Blocks

An interscalene block is a type of peripheral nerve block. It's a shot of numbing medicine that's injected into a group of nerves (called the brachial plexus) between the spine and shoulder. The shot is usually given in the neck or just above the collarbone. It numbs the shoulder and upper arm. Doctors often use it for shoulder surgeries.

This nerve block is widely used. It's successful in blocking pain in more than 90 out of 100 people who use it. When done with guidance from an ultrasound device, it is successful in about 99 out of 100 people who use it.

The doctor may use ultrasound or another method to help guide the needle that will be used for the nerve block. After the doctor finds the right spot, the skin is cleaned. The doctor uses a tiny needle to numb the skin.

Then the doctor puts the nerve block needle into the area and injects numbing medicine near the brachial plexus.

If you're awake, you may feel some pressure. But you shouldn't feel pain. The interscalene block is often used with general anesthesia or with medicine that makes you feel relaxed or sleepy during the procedure. Or the nerve block may be all that's needed. In that case, you can stay awake without feeling pain.

Problems after an interscalene block are not common. But like all procedures, it carries some risks. Risks include:

• Infection.
• Bleeding.
• The needle hitting a different nerve, causing damage to the nerve.
• An allergic reaction to the injected medicine.
• Horner syndrome. This is damage to the nerves leading to the eye. This can cause a drooping eyelid, a smaller pupil, and less sweating on that side of the face.
• Blocking the wrong nerve, leading to breathing problems or hoarseness.