An infraorbital nerve block anesthetizes the ipsilateral lower eyelid, upper cheek, side of the nose, and upper lip.
Indications for Infraorbital Nerve Block
- Laceration or other surgically treated lesion of the midface
A nerve block is used instead of local anesthetic infiltration when accurate approximation of wound edges is important (eg, skin repair), because a nerve block does not distort the tissue as does local infiltration.
Contraindications to Infraorbital Nerve Block
- Allergy to the anesthetic agent or delivery vehicle
- Absence of anatomic landmarks needed to guide needle insertion (eg, due to trauma)
- Infection in the path of needle insertion: Use procedural sedation or other anesthesia.
- Coagulopathy*: When feasible, correct prior to procedure.
- Pregnancy: Avoid treatment in the 1st trimester if possible.
*Therapeutic anticoagulation (eg, for pulmonary embolism) increases the risk of bleeding with nerve blocks, but this must be balanced against the increased risk of thrombosis (eg, stroke) if anticoagulation is reversed. Discuss any contemplated reversal with the clinician managing the patient's anticoagulation and then with the patient.
Complications of Infraorbital Nerve Block
- Allergic reaction to the anesthetic
- Toxicity due to anesthetic overdose (eg, seizure, cardiac arrhythmias)
- Intravascular injection of anesthetic/epinephrine
- Spread of infection, by passing the needle through an infected area
- Errant puncture of the infraorbital venous plexus or the globe due to excessive needle insertion.
- Failure to anesthetize
- Needle breakage (rare)
Most complications result from inaccurate needle placement.
Equipment for Infraorbital Nerve Block
- Dental chair, straight chair with head support, or stretcher
- Light source for intraoral illumination
- Nonsterile gloves
- Mask and safety glasses, or a face shield
- Gauze pads
- Cotton-tipped applicators
- Dental mirror or tongue blade
Equipment to do local anesthesia:
- Topical anesthetic ointment* (eg, lidocaine 5%, benzocaine 20%)
- Injectable local anesthetic such as lidocaine 2% with or without epinephrine† 1:100,000, or for longer duration anesthesia, bupivacaine 0.5% with or without epinephrine† 1:200,000
- Dental aspirating syringe (with narrow barrel and custom injectable anesthetic cartridges) or other narrow barrel syringe (eg, 3 mL) with locking hub
- 25- or 27-gauge needle: 3-cm long for nerve blocks
* CAUTION: All topical anesthetic preparations are absorbed from mucosal surfaces and toxicity may result when dose limits are exceeded. Ointments are easier to control than less-concentrated topical liquids and gels. Excess benzocaine rarely may cause methemoglobinemia.
† Maximum dose of local anesthetics: Lidocaine without epinephrine, 5 mg/kg; lidocaine with epinephrine, 7 mg/kg; bupivacaine, 1.5 mg/kg. NOTE: A 1% solution (of any substance) represents 10 mg/mL (1 gm/100 mL). Epinephrine causes vasoconstriction, which prolongs the anesthetic effect. Patients with cardiac disease should receive only limited amounts of epinephrine (maximum 3.5 mL of solution containing 1:100,000 epinephrine); alternatively, use local anesthetic without epinephrine.
Additional Considerations for Infraorbital Nerve Block
- Document any preexisting nerve deficit before doing a nerve block.
- An intraoral or extraoral approach to the infraorbital foramen may be used. The intraoral approach, preferred and discussed here, causes less pain and may provide a longer duration of anesthesia.
- Nerve block may fail if the anesthetic is not placed sufficiently close to the nerve.
- Use a new needle with each attempt (the previous needle may have become blocked with tissue or blood, which would obscure an inadvertent intravascular placement).
- Consider sedation or an alternative method of anesthesia for patients unable to cooperate with procedure.
- Stop the nerve block procedure and find a different method of anesthesia if you are unsure where the needle is or if the patient is uncooperative.
Relevant Anatomy for Infraorbital Nerve Block
- The infraorbital nerve is the termination of the maxillary nerve, which is the 2nd branch of the trigeminal nerve.
- The infraorbital nerve exits the infraorbital foramen, located immediately below the inferior border of the infraorbital ridge, and, via several branches, innervates the ipsilateral midface, lower lid, side of the nose, and upper lip.
- The infraorbital foramen is directly below the pupil when the patient is looking straight ahead and is usually palpable.
Positioning for Infraorbital Nerve Block
- Position the patient inclined, with the occiput supported, and with the neck extended 30 degrees, such that the injection site (upper mucobuccal fold) is accessible.
Step-by-Step Description of Procedure
- Wear nonsterile gloves and a mask and safety glasses, or a face shield.
- Externally palpate the infraorbital ridge, to identify the infraorbital foramen.
- Place and maintain your middle finger over the infraorbital foramen.
- Using your index finger and thumb, grasp and retract the upper lip laterally.
- Use gauze to thoroughly dry the mucobuccal fold adjacent to the 2nd maxillary premolar tooth.
- Apply topical anesthetic with cotton-tipped applicators and wait 2 to 3 minutes for the anesthesia to occur.
Inject the local anesthetic
- Instruct the patient to slightly open the mouth and relax the jaw and lip muscles.
- Retract the upper lip laterally, to delineate the mucobuccal fold.
- Insert the needle into the mucobuccal fold above the 2nd upper premolar tooth, and advance the needle parallel to the long axis of the tooth toward the infraorbital foramen.
- Maintain a shallow angle of insertion and advance the needle cephalad until your middle finger can palpate the needle tip under the skin near the foramen (usually at an insertion depth of about 2.5 cm). A steeper angle of insertion will hit bone before reaching the foramen. A too-shallow angle of insertion will risk inserting too far and entering the orbit.
- Aspirate, to rule out intravascular placement. If aspiration reveals an intravascular placement, withdraw the needle 2 to 3 mm, then re-aspirate prior to injection.
- Slowly inject about 2 to 3 mL of anesthetic adjacent to, but not into, the infraorbital foramen.
- Massage the area externally for about 10 seconds, to hasten the onset of anesthesia.
Aftercare for Infraorbital Nerve Block
- Have the patient rest, with mouth relaxed, while awaiting onset of anesthesia (5 to 10 minutes).
Warnings and Common Errors of Infraorbital Nerve Block
- To minimize the risk of needle breakage, do not bend the needle prior to insertion, do not insert the needle to its full depth (ie, to the hub), and instruct the patient to remain still, with the mouth wide open, and resist grabbing your hand.
Tricks and Tips
- Distraction techniques (eg, talking to the patient or having the patient hold someone else's hand) may help to reduce patient anxiety.
- Inject the local anesthetic solution slowly (30 to 60 seconds) to reduce the pain of injection.
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