Perineural Block: Definition and Clinical Applications
A perineural block is a regional anesthesia technique that involves injecting local anesthetic around a peripheral nerve or nerve plexus to block pain transmission, providing targeted analgesia for specific body regions without the systemic effects of general anesthesia or opioids. 1
Key Characteristics of Perineural Blocks
- Mechanism of Action: Local anesthetics are injected in close proximity to peripheral nerves, blocking sodium channels and preventing nerve impulse transmission
- Administration: Typically performed under ultrasound guidance to ensure precise placement and reduce complications 1
- Duration: Can provide analgesia for 6-24 hours depending on the local anesthetic used and whether adjuvants are added 2
- Types:
- Single-injection blocks
- Continuous peripheral nerve blocks (using catheters for prolonged analgesia) 3
Common Applications
Surgical Anesthesia and Analgesia
- Orthopedic procedures: Particularly effective for shoulder, upper and lower extremity surgeries 4
- Abdominal surgery: Transversus abdominis plane (TAP) blocks and rectus sheath blocks provide effective postoperative pain control 1
- Trauma management: Provides targeted pain relief for fractures and traumatic injuries 1
Benefits in Clinical Practice
- Opioid-sparing effect: Significantly reduces the need for systemic opioids, minimizing related side effects like respiratory depression and constipation 1
- Improved pain control: Provides superior analgesia compared to systemic medications alone 4
- Reduced complications: Associated with decreased risk of acute confusional states and chest infections in elderly patients 1
- Enhanced recovery: Facilitates earlier mobilization and shorter hospital stays 1
Technical Aspects
Performance Techniques
- Ultrasound guidance: Recommended standard of care to visualize target nerves, surrounding structures, and monitor local anesthetic spread 1
- Nerve stimulation: Sometimes used in conjunction with ultrasound to confirm proximity to target nerve
- Anatomical landmarks: Used in some settings but less precise than image-guided approaches
Continuous Perineural Blocks
- Involve placement of a catheter adjacent to the nerve for prolonged local anesthetic infusion 3
- Can provide analgesia for days or even weeks in certain cases 5
- Particularly valuable for:
- Major surgeries requiring extended pain control
- Trauma patients awaiting definitive treatment
- Rehabilitation requiring pain-free movement 5
Adjuvants and Optimization
- Dexamethasone: Can be added to local anesthetics to prolong block duration by approximately 3-4 hours when administered perineurally with bupivacaine 2
- Multimodal approach: Perineural blocks are most effective when combined with scheduled non-opioid analgesics (acetaminophen, NSAIDs) 1, 4
- Volume considerations: Using the minimum effective volume of local anesthetic reduces risk of complications while maintaining efficacy 1
Safety Considerations
- Complications: Include local anesthetic systemic toxicity, infection, hematoma, and nerve injury, though these are rare with proper technique 1
- Contraindications: Include infection at the injection site, coagulopathy, and patient refusal
- Monitoring: Essential to observe for signs of local anesthetic toxicity and block success before proceeding with surgery 1
Special Populations
Elderly Patients
- Particularly beneficial due to reduced opioid requirements and associated complications 1
- Strong evidence supports implementation of peripheral nerve blocks for managing acute pain associated with traumatic fractures in elderly patients 1
COVID-19 Considerations
- May help avoid general anesthesia and airway manipulation in appropriate cases 1
- Thorough testing for block success is recommended to prevent need for emergency conversion to general anesthesia 1
Perineural blocks represent a cornerstone of modern multimodal analgesia, offering targeted pain relief with minimal systemic effects when performed correctly under appropriate guidance.