What is a Interscalene Block?

Interscalene blocks explained by Denver, Golden, Aurora, Boulder, Broomfield, Jefferson, and Littleton Colorado’s top pain doctors

Interscalene Nerve Block DiagramShoulder surgery is an invasive and potentially painful procedure. Patients are given general anesthesia in order to prevent pain during surgery, but without additional treatment, the pain following the surgical procedure can make for a difficult recovery. To make this process easier, many physicians perform nerve blocks to ease the pain during surgery and to allow for a more comfortable recovery for the patient. A nerve block is a procedure that essentially blocks the function of specific nerves, particularly when those nerves would cause severe pain to a patient.

In an interscalene block, a local anesthetic is delivered to the brachial plexus, the network of nerves that travel from the spine into the neck and arm area. Specifically, this nerve bundle is located in the space between the anterior and middle scalene muscle. This procedure temporarily disables feeling in and movement of the shoulder and upper arm. This type of nerve block is usually administered to provide pain relief during or immediately after upper extremity surgery on the shoulder or arm.

How is an Interscalene Block Performed?

An interscalene block can be performed with varying levels of anesthesia or sedation. The physician will review a patient’s medical history and specific condition to determine the necessary level of anesthesia and whether the treatment will require the presence of an anesthesiologist. Some level of sedation is often helpful for maintaining blood pressure and heart rate in addition to preventing restlessness and excessive bleeding during surgery. Excessive sedation is typically avoided so that the patient can communicate with the physician as they are asked to perform landmark assessments as the procedure progresses.

To prepare a patient for an interscalene block, the physician thoroughly cleans the neck area with an antiseptic solution and carefully determines the precise block injection point. At this point, the patient will be seated or lying prone, with the back slightly elevated and the head turned to clearly expose the injection site. Fluoroscopic (X-ray) or ultrasonic (sonogram) guidance is often used by the physician to ensure a safe and accurate injection. The needle is then inserted into the injection site and a local anesthetic is administered, numbing the entire neck and shoulder area.

The effects of an interscalene block will persist beyond the end of the surgical procedure, resulting in temporary paralysis of the arm and shoulder. For an average of 24 hours post-surgery, the patient may have limited feeling and mobility of their upper extremity.

Interscalene blocks are relatively safe and routinely administered preceding or following upper extremity surgery. As with any procedure, some side effects may occur. Reported side effects include skin discoloration, infection, hematoma, hoarseness, mild soreness, allergic reaction, anesthetic toxicity, and, in very rare cases, short-term paresthesia or pneumothorax. Following the procedure, the patient will be given instructions on the amount of activity allowed depending on the specific surgical procedure performed.

Conditions Related to Interscalene Blocks 

Left Shoulder PainPhysicians regularly recommend an interscalene block to any patient undergoing painful surgery to the arm or shoulder areas. Administering a local anesthetic into the area of the brachial plexus immobilizes the arm and shoulder during surgery, allowing the patient to experience a more comfortable surgical procedure and reducing complications arising from limb restlessness. An interscalene block is also helpful following upper extremity surgery, since many patients experience extreme pain during recovery and rehabilitation.


For patients undergoing surgery of an upper extremity such as the arm, elbow, or shoulder, their physician will frequently schedule an interscalene block to assist with analgesia and inflammation before or after the surgery. An interscalene block is often administered with a mild sedative to help keep the patient’s blood pressure and heart rate steady. Administration of a sedative can also help the patient to be calmer and more relaxed during the interscalene block and the surgical procedure. The effects of an interscalene block may persist for up to 24 hours after the surgical procedure. For postoperative pain, further injections may be recommended to assist with analgesia during rehabilitation.

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