Peripheral nerve blocks are widely used in medical practice to provide pain relief during and after surgical procedures, as well as in the management of chronic pain. They involve the injection of anesthetic near a specific nerve or group of nerves to block sensation in a targeted area of the body 1,2. While peripheral nerve blocks are generally considered safe and effective, they are not without potential downsides. Understanding these limitations is crucial for both healthcare providers and patients when considering this pain management option.
One of the downsides of peripheral nerve blocks is the risk of nerve damage. Although uncommon, improper needle placement or accidental puncture of the nerve can lead to temporary or permanent nerve injury. Symptoms of nerve damage may include numbness, tingling, weakness, or even paralysis in the affected area. In some cases, these symptoms may resolve over time, but in others, they can become permanent, leading to chronic pain or loss of function 3.
Infection is a potential complication of any procedure that involves breaking the skin, including peripheral nerve blocks. If proper sterile techniques are not followed, bacteria can be introduced into the injection site, leading to infection. Symptoms of infection may include redness, swelling, warmth, and pain at the injection site. In severe cases, an abscess may form, requiring further medical intervention. Additionally, there is a risk of hematoma formation, especially if the needle punctures a blood vessel. This can lead to localized bleeding and the development of painful swelling or a bruise 3–5.
Patients may experience allergic reactions to the anesthetic agents used in peripheral nerve blocks. While allergic reactions are rare, they can range from mild (such as itching or rash) to severe (such as anaphylaxis, which is a life-threatening condition). It is important for healthcare providers to thoroughly review a patient’s medical history and any known allergies before administering a nerve block to minimize this risk 6.
While peripheral nerve blocks are generally effective, incomplete or failed blocks—when the anesthetic does not fully numb the intended area—come with several downsides including procedural delays, patient discomfort, and re-attempting the block or changing the anesthetic plan. Failed block can result from several factors, including incorrect needle placement, inadequate dosage of anesthetic, or anatomical variations in the patient. A failed block can lead to inadequate pain control during surgery or post-operatively, necessitating the use of additional pain management techniques, such as general anesthesia or systemic analgesics 3.
Systemic toxicity occurs when the anesthetic used in a nerve block is absorbed into the bloodstream at levels that can affect other parts of the body. This can happen if too much anesthetic is used or if the injection inadvertently enters a blood vessel. Symptoms of systemic toxicity can include dizziness, tinnitus (ringing in the ears), seizures, and cardiac arrest. Although rare, this is a serious complication that requires immediate medical attention 3,6,7.
Peripheral nerve blocks are an important tool in pain management, offering significant benefits for patients undergoing surgery or dealing with chronic pain. However, like any medical procedure, peripheral nerve blocks come with risks and potential downsides. Understanding these risks is essential for making informed decisions about their use.
References
1. Peripheral Nerve Blocks – StatPearls – NCBI Bookshelf. Available at: https://www.ncbi.nlm.nih.gov/books/NBK459210/.
2. Nerve Block Pros and Cons: – Atlas Pain Specialists. Available at: https://atlaspainspecialists.com/nerve-block-pros-and-cons/.
3. Jeng, C. L., Torrillo, T. M. & Rosenblatt, M. A. Complications of peripheral nerve blocks. Br. J. Anaesth. (2010). doi:10.1093/bja/aeq273
4. Nerve Block: What It Is, Procedure, Side Effects & Types. Available at: https://my.clevelandclinic.org/health/treatments/12090-nerve-blocks.
5. Wiegel, M., Gottschaldt, U., Hennebach, R., Hirschberg, T. & Reske, A. Complications and adverse effects associated with continuous peripheral nerve blocks in orthopedic patients. Anesth. Analg. (2007). doi:10.1213/01.ane.0000261260.69083.f3
6. Local Anesthetic Systemic Toxicity and Allergy to Local Anesthetics | Hadzic’s Peripheral Nerve Blocks and Anatomy for Ultrasound-Guided Regional Anesthesia, 3e | AccessAnesthesiology | McGraw Hill Medical. Available at: https://accessanesthesiology.mhmedical.com/content.aspx?bookid=3074§ionid=255807496.
7. Wiederhold, B. D., Garmon, E. H., Peterson, E., Stevens, J. B. & O’Rourke, M. C. Nerve Block Anesthesia. StatPearls (2023).