Infraorbital Nerve Block for Upper Lip Laceration Repair
For a laceration involving the right upper lip and vermilion border, the infraorbital nerve block is the definitive choice for regional anesthesia, as the infraorbital nerve provides sensory innervation to the superior lateral lip. 1
Anatomic Rationale
The superior lateral lip receives its sensory innervation from the infraorbital nerve, a terminal branch of the maxillary division of the trigeminal nerve. 1 This makes the infraorbital nerve block the most appropriate regional anesthetic technique for upper lip lacerations, particularly those involving the vermilion border. 1
The other nerve blocks listed are inappropriate for this anatomic location:
- Inferior alveolar nerve block anesthetizes the lower teeth and lower lip, not the upper lip 2
- Mental nerve block provides anesthesia to the lower lip and chin region 2
- Supraorbital nerve block anesthetizes the forehead and anterior scalp 2
Recommended Technique: Intraoral Approach
The intraoral approach to the infraorbital nerve block is preferred over the percutaneous approach because it provides:
- Longer duration of anesthesia (1.6 hours vs 0.9 hours) 3
- Higher success rate for achieving upper lip anesthesia (100% vs 75% success) 3
- Subjectively less painful administration when combined with topical anesthesia 3
Step-by-Step Procedural Technique
Preparation:
- Apply topical anesthetic (viscous lidocaine) to the oral mucosa for 1 minute prior to injection 3
- Prepare the injection site with antiseptic solution 1
- Use a 27-gauge needle with 2.5 mL of 2% lidocaine (buffered if available) 3
- Warm the anesthetic solution to room temperature or slightly above to reduce discomfort 1
Injection technique:
- Locate the infraorbital foramen at the intersection of a vertical line through the pupil (in neutral position) and a horizontal line through the ala of the nose 4
- For the intraoral approach, retract the upper lip and insert the needle through the mucosa in the upper buccal sulcus 3
- Aspirate before injection to ensure the needle is not intravascular—this is mandatory to prevent systemic toxicity including seizures, cardiovascular collapse, and respiratory arrest 1, 5
- Inject slowly over 20 seconds to minimize discomfort and tissue trauma 1, 3
- Deposit 2 mL near the infraorbital foramen, then inject additional 1 mL medially toward the ala and 2 mL caudally into the lip 4
Timing:
- Allow 20-30 minutes for adequate onset before proceeding with repair 1
- Inadequate waiting time is a common cause of perceived block failure 1
Critical Safety Considerations
Resuscitative equipment must be immediately available before performing any regional nerve block, including oxygen, airway management equipment, and lipid emulsion for treatment of local anesthetic systemic toxicity (LAST). 5
Maximum dosing:
- Lidocaine without epinephrine: 4.4 mg/kg 6
- Lidocaine with epinephrine: 7.0 mg/kg 6
- Calculate maximum allowable dose before administration 6
Early warning signs of systemic toxicity include restlessness, anxiety, tinnitus, dizziness, blurred vision, tremors, depression, or drowsiness. 5 If these occur, stop injection immediately, support airway and circulation, and administer lipid emulsion per LAST protocol. 6
Common Pitfalls to Avoid
- Failing to aspirate before injection—this can result in intravascular injection and severe systemic toxicity 1, 5
- Proceeding too quickly after injection—allow full 20-30 minutes for onset 1
- Using cold anesthetic solution—this increases injection pain 1
- Inadequate topical anesthesia before intraoral approach—reduces the comfort advantage of this technique 3
Special Considerations for Vermilion Border Repair
Lacerations involving the vermilion border require precise alignment to avoid permanent cosmetic deformity. 7 The infraorbital nerve block provides superior anesthesia compared to local infiltration because it: