Nerve blocks are a widely used procedure in anesthesia and pain management, offering local anesthesia and pain relief for patients before, during, and after surgical procedures. Performed by trained medical professionals, nerve blocks are generally safe and effective. However, there is an incidence of 0.22% for block-related neural complications for all nerve blocks (Watts & Sharma, 2007). One of the risks of nerve block is nerve palsy, a condition characterized by weakness or paralysis in the area targeted by the nerve block. It can impact a patient’s recovery, and depending on severity, impact their quality of life.
The incidence of nerve palsy following nerve block procedures varies depending on factors such as the type of nerve block, the experience of the practitioner, and the health status of the patient. Some equipment-related factors that may affect peripheral nerve injury include bevel type and needle size. For example, sharper needles with longer bevels are more likely to pierce peripheral nerve fascicles (O’Flaherty et al., 2018).
There are various mechanisms by which nerve palsy can occur after a nerve block. One of the most common causes is mechanical trauma during needle insertion. If the needle directly injures the nerve or if the anesthetic solution is injected into the nerve instead of around it, the patient can experience temporary nerve dysfunction (Landgraeber et al., 2012). The employment of ultrasound guided nerve block can help mitigate this risk by providing better visualization, though it has its own limitations (O’Flaherty et al., 2018). Ischemic injury can also occur if the blood supply to the nerve is compromised during the procedure (Landgraeber et al., 2012). This can happen when there is prolonged pressure on the nerve or vasoconstrictive agents are used in the anesthetic solution. Additionally, chemical toxicity can cause nerve palsy, as some anesthetic agents can be neurotoxic if they come into direct contact with nerve tissue. While all local anesthetics have the potential to be neurotoxic, ester local anesthetics seem to be more toxic than amide local anesthetics (O’Flaherty et al., 2018).
The presentation of nerve palsy after a nerve block can vary from mild symptoms such as numbness, tingling, or weakness in the affected area, to more severe symptoms, including complete paralysis or severe pain in the affected area. Mild cases typically resolve within a few hours or days. More severe cases of nerve palsy can persist for weeks or months (Landgraeber et al., 2012). While most cases of nerve palsy are temporary and resolve without long-term consequences, permanent nerve damage can occur.
Management of nerve palsy after a nerve block involves supportive care and rehabilitation. Transient nerve palsy may delay same-day discharge in ambulatory surgeries or cause a patient to be admitted (Udo et al., 2018). Physical therapy can play a crucial role in maintaining muscle strength and preventing joint stiffness as the nerve heals (O’Flaherty et al., 2018). Early diagnosis and management are critical to improving outcomes for patients experiencing nerve palsy after a nerve block.
In conclusion, while the incidence of nerve palsy after a nerve block is relatively low, it remains a significant concern due to the potential for lasting nerve damage. Understanding the risk factors and causes of nerve palsy, coupled with careful procedural techniques and thorough patient monitoring, can help mitigate these risks and improve patient outcomes. As research and technology evolve and advance, further reductions in the incidence of this complication are likely, which will improve the safety and effectiveness of nerve blocks in medical practice.
References
Landgraeber, Stefan et al. “Delayed appearance of hypaesthesia and paralysis after femoral nerve block.” Orthopedic reviews vol. 4,1 (2012): e8. doi:10.4081/or.2012.e8
O’Flaherty, D et al. “Nerve injury after peripheral nerve blockade-current understanding and guidelines.” BJA education vol. 18,12 (2018): 384-390. doi:10.1016/j.bjae.2018.09.004
Udo, Isaac Assam et al. “Transient Femoral Nerve Palsy Following Ilioinguinal Nerve Block for Inguinal Hernioplasty.” Nigerian journal of surgery : official publication of the Nigerian Surgical Research Society vol. 24,1 (2018): 23-26. doi:10.4103/njs.NJS_20_17
Watts, S A, and D J Sharma. “Long-term neurological complications associated with surgery and peripheral nerve blockade: outcomes after 1065 consecutive blocks.” Anaesthesia and intensive care vol. 35,1 (2007): 24-31. doi:10.1177/0310057X0703500103