Overview
An interscalene nerve block has long been a mainstay of pain control for shoulder surgery. It is used as an adjunct to general anesthesia, not as a replacement for it. Patients still receive general anesthesia and are asleep for the operation, but because the block substantially reduces pain signals from the shoulder, it can often allow the general anesthesia to be lighter.
The block is typically administered by the anesthesia team in the preoperative holding area. Patients are often lightly sedated, and the procedure itself generally takes about 5-10 minutes. A long-acting local anesthetic, such as bupivacaine, is injected around the nerves that supply sensation to the shoulder and arm.
What Does the Block Do?
The major advantage is excellent pain control during surgery and immediately afterward. Instead of awakening from surgery with significant shoulder pain, the shoulder and arm remain numb while the block is working. With the blocks commonly used in my patients, I generally tell patients to expect approximately 10-12 hours of significant pain relief, although the duration varies from person to person and depends on the medication and technique used.
As the block begins to wear off, sensation and discomfort gradually return. This creates an important window for staying ahead of the pain. I generally recommend beginning the prescribed pain medication when the first signs of the block wearing off become apparent rather than waiting until significant pain develops. Once severe pain gets ahead of you, it can be considerably more difficult to regain control.
Are There Risks?
Interscalene blocks are generally very well tolerated, but they are not completely without risk. Because of the location of the nerves being treated, the block can temporarily affect nearby structures. This can include temporary weakness of the diaphragm with some difficulty breathing, hoarseness, or Horner syndrome, which can cause a temporary drooping eyelid. These effects, when they occur, are usually recognized immediately while the patient is still under the direct care of the anesthesia team and can be supported appropriately.
Rarely, patients can experience persistent burning, tingling, or other nerve symptoms in the arm after the block has worn off. In my practice, this has been quite uncommon - typically something I encounter less than once a year - but it is one of the reasons I consider the benefits of the block relative to the operation being performed rather than using it automatically for every shoulder procedure.
When Do I Recommend a Block?
For larger shoulder operations - particularly rotator cuff repair and shoulder arthroplasty - I generally recommend an interscalene block because the benefit in early pain control can be substantial. For smaller procedures, such as arthroscopic debridement, biceps procedures, AC joint procedures, or instability repairs, I use the block more selectively. But if minimizing early postoperative pain is particularly important to the patient, I am more likely to recommend a block. For other patients, proceeding without one is also completely reasonable.
Ultimately, the decision is always the patient's. Having or not having an interscalene block does not change the operation itself or the expected long-term result. Its primary purpose is to change the patient's experience during the hours surrounding surgery - particularly by improving pain control during and immediately after the procedure. Whether the operation is large or small, either choice is acceptable. I will make a recommendation based on the procedure and the individual patient, explain the advantages and potential risks, and let the patient decide which approach they prefer.