An interscalene block is an anesthetic technique. It’s used as a regional anesthetic, and may be combined with a general anesthetic, to block sensations in the shoulder and upper arm before, during, and after surgery. Many anesthesiologists like using interscalene blocks because they provide a faster recovery time, reduce post-surgical pain, and have fewer side effects than general anesthesia.

However, not all people are candidates for this procedure. If you are allergic to certain medications, are currently using blood thinners, or are pregnant, you would not be a candidate for this procedure.

Those in need of shoulder or upper arm surgery are typical candidates for an interscalene block. Some procedures that commonly require an interscalene block include:

As with any procedure, an interscalene block carries its own set of risks. Some common complications of an interscalene block include:

  • recurrent laryngeal nerve blockade, or blocking the feeling of a significant nerve in the airway
  • allergic reaction
  • Horner syndrome, a rare condition that causes disruption of nerve pathways from the brain to the face and the eyes
  • hematoma, or an abnormal collection of blood outside of the blood vessels

Other rare but severe interscalene block complications include:

  • permanent brain damage
  • bradycardia, or slow heartbeat
  • pneumothorax, or a collapsed lung
  • severe hypotension, or low blood pressure
  • carotid artery puncture, or putting a hole in the artery that leads to the head

A nurse will complete a presurgical evaluation and give you specific information on how to prepare for the procedure. On the day of the procedure, the nurse will use an IV to administer fluids and medication. You will be lightly sedated and positioned flat on your back with your head facing away from the side of your body that is to be operated on. This allows the surgeon and the anesthesiologist better access to the correct side of the neck.

You will be awake while the doctors administer your interscalene block. This is to ensure the procedure occurs safely.

The interscalene block is meant to target the brachial plexus, a network of nerves sectioned between two scalene muscles. These nerves send signals from the spine to the shoulder, arm and hand. To identify the area, the anesthesiologist will trace your nerves with a marker on your skin. Once they identify the nerves, they will attach a small needle to a handheld nerve stimulator in order to guide the numbing medication to the brachial plexus nerves.

The handheld stimulator will cause a slight muscle contraction in the biceps or shoulder once the nerve has been activated. This muscle twitch does not cause any pain. When the needle is in the appropriate position, the anesthesiologist will administer the numbing medication and remove the needle. If additional doses of medication are needed, a small catheter may be left in place and removed after it’s no longer needed.

Some anesthesiologists use ultrasound to help guide placement of the needle. In these cases, a small amount of gel is placed on the skin and a transducer, or wand, is moved over the area. There is no discomfort; the only sensation is that of the transducer moving over the skin.

You will first notice a numbing sensation in the arm, shoulder, and fingers. The interscalene block will begin to take effect anywhere from 5 to 30 minutes after being administered, depending on the numbing medication used. The two common medications used are lidocaine, which is used for its quicker effect, and bupivacaine, which is used to prolong the numbing effect.

Children under the age of 18 will need parental or guardian consent to have an interscalene block. However, your doctors will not give you this procedure if they feel it’s risky based on your medical history. The patient also must agree to the procedure, meaning a parent cannot decide to have this done without the child approving.

Numbing effects from the interscalene block will still be present up to 24 hours after your surgical procedure. Don’t be alarmed if you can’t move your arm during this time; it’s not uncommon for patients to have little to no mobility in their upper extremities.