Peripheral nerve blocks (PNBs) are widely used to provide pain relief during and after surgery, as they offer an effective way to reduce or avoid the use of opioid medications. Although they are generally safe, these nerve blocks can, in rare cases, cause nerve injury. When this occurs, it is essential to monitor the patient closely to detect problems early and guide treatment. Permanent nerve injury is rare, occurring in fewer than 1 in 1,000 cases, but temporary issues, such as numbness or weakness, are more common and require careful follow-up (1). Medical research has helped to develop monitoring guidelines for cases of suspected nerve injury after a nerve block.

Nerve injury from a block can be caused by several factors: direct needle damage, local anesthetic toxicity, reduced blood supply to the nerve, or pressure from a nearby blood clot. Warning signs include unusual numbness, muscle weakness, or pain that lasts longer than expected. It is important to examine the patient once the numbness from the block has worn off and to compare nerve function before and after the procedure. Medical guidelines recommend further testing and monitoring if symptoms of nerve injury last more than 48 hours after the block or worsen (2).

A 2025 study by Chau and colleagues found that delays in recognizing nerve problems, especially in patients who received spinal or epidural anesthesia during childbirth, could lead to slower recovery and an increased chance of long-term pain (3). This highlights the importance of closely monitoring patients, especially those at higher risk, such as trauma or obstetric patients.

If symptoms persist after a nerve block, doctors may order tests such as electromyography (EMG) and nerve conduction studies to evaluate nerve and muscle function. These tests are usually performed two to three weeks after the suspected injury, once physiological changes can be detected. The results help distinguish between temporary nerve blockages and more serious structural damage. Imaging methods, such as ultrasound or MRI, can also be useful for identifying issues like nerve swelling or compression by a hematoma. Although ultrasound is often used during the block to guide needle placement and avoid direct nerve trauma, its diagnostic value afterward is limited. Current best practices emphasize using ultrasound guidance during the procedure, injecting slowly at low pressure, limiting the anesthetic volume, and using pressure-monitoring devices to avoid sensitive nerve structures (Saporito et al., 2025) to minimize the risk of intraneural injection.

In rare cases where nerve function does not recover following a peripheral nerve block, surgical intervention may be considered. Treatment options depend on the type and extent of injury and can include neurolysis (surgical release of the nerve from scar tissue), direct nerve repair, or grafting in cases of structural disruption. According to Brakkee (2022), while most nerve injuries resolve without surgery, persistent pain or sensory loss, especially in superficial nerves, should prompt an early referral to a specialist. Timely surgical evaluation may improve outcomes by preventing long-term complications, such as chronic pain or irreversible nerve degeneration.

If a patient does experience symptoms of nerve injury after a nerve block, it is important to follow up with monitoring and, if needed, referrals to neurologists or pain specialists. Mild injuries often heal in a few weeks, while more serious ones may take months. In the meantime, physical therapy and medications for nerve pain can help patients stay comfortable and regain function.

References

1. Brull R, McCartney CJ, Chan VW, El-Beheiry H. Neurological complications after regional anesthesia: contemporary estimates of risk. Anesth Analg. 2007;104(4):965-974. doi:10.1213/01.ane.0000258740.17193.ec
2. Neal JM, Bernards CM, Hadzic A, et al. ASRA Practice Advisory on Neurologic Complications in Regional Anesthesia and Pain Medicine. Reg Anesth Pain Med. 2008;33(5):404-415. doi:10.1016/j.rapm.2008.07.527
3. Yang T, Chan WS, Chau A. Neuraxial procedures and time to recognition of postpartum lower limb sensorimotor deficit in an obstetric cohort: a retrospective cohort study (2013-2022). Int J Obstet Anesth. Published online July 26, 2025. doi:10.1016/j.ijoa.2025.104740
4. Dossi R, Quadri C, Capdevila X, Saporito A. Real time continuous monitoring of injection pressure at the needle tip is better than ultrasound in early detecting intraneural injection. Reg Anesth Pain Med. Published online January 14, 2025. doi:10.1136/rapm-2024-106086
5. Brakkee EM, Stokvis A, DeVinney E, Ducic I, Coert JH. Surgical Treatment Strategies for Injuries of the “Unforgiving” Superficial Branch of the Radial Nerve. Plast Reconstr Surg. 2022;150(4):845-853. doi:10.1097/PRS.0000000000009523