Infraorbital Nerve Block

Anatomy and Physiology

The infraorbital nerve is a branch of the maxillary nerve, which is the second division of the trigeminal nerve. The maxillary nerve exits the infraorbital foramen, where it terminates as the infraorbital nerve. The infraorbital nerve provides sensory innervation to the lower eyelid, lateral aspect of the nose, upper lip, upper incisor, canine, premolars, and mesiobuccal root of the first molar on the ipsilateral side of the face. The infraorbital nerve block anesthetizes the anterior and middle maxillary alveolar nerves, inferior palpebral, lateral nasal, and superior labial. This also includes the maxillary incisors, canines, and premolars, as well as their vestibular osseous support and the soft tissues which cover them. Finally, it includes the mesiovestibular root of the maxillary first molar, part of the maxillary sinus and nose.[7][8][9]

Indications

Nerve blocks are useful when a wound repair is required over a large area that is innervated by one nerve. They are also useful when local infiltration of the wound may not be possible or could result in tissue damage or distortion. Other indications include wound closure, dental procedures, pain relief, debridement, and contraindication to general anesthesia.

Contraindications

Contraindications include overlying infection at the site of injection, patient refusal, allergy to anesthetic agents, anatomical landmark distortion, and wounds that involve areas innervated by multiple nerves.

Equipment

Several anesthetic agents can be used for a nerve block. Amino amides and amino esters differ by the chemical structure of an intermediate chain between aromatic and hydrophilic segments. Amines are metabolized in the liver and undergo hydrolysis, which produces para-aminobenzoic acid (PABA) that makes amines more likely to produce an allergic reaction than an amino ester. Pseudocholinesterases metabolize esters in the plasma. The easiest way to remember which drugs belong to each group is by recalling that amino acids generally have two “I”s in the spelling. Common amines include lidocaine and bupivacaine. Common esters include tetracaine, benzocaine, procaine, and cocaine.

The two most common anesthetic agents for infraorbital nerve block are lidocaine and bupivacaine. Lidocaine is faster in onset and has a shorter duration than bupivacaine. Lidocaine starts to take effect 2 to 3 minutes after infiltration, whereas bupivacaine can take 10 to 20 minutes to take effect. Typically, only 1 to 3 mL of the agent is needed, so toxicity is rare. The total dose of 1% lidocaine with epinephrine should not exceed 7 mg/kg (0.7 mL/kg) and 4 mg/kg without epinephrine.

Equipment required includes a 27-gauge needle, blunt fill needle, gauze, 5 to 10 mL syringe, a syringe (Luer-lock if available for easier control and administration), anesthetic agent, and sterile and non-sterile gloves.

Preparation

The patient should be educated about the procedure and informed about the risks and benefits. Informed consent should be obtained before the procedure. All equipment should be brought to the bedside.

Technique or Treatment

Intraoral Approach

Place the patient in a seated position so that the maxillary occlusal plane forms a 45-degree angle with the floor. Use a cotton-tipped applicator to apply a topical anesthetic to the oral mucosa of the gum line above the maxillary canine. The infraorbital foramen can be approximated by having a patient look straight ahead and imagining a line down from the pupil to the inferior border of the infraorbital ridge, bicuspid teeth, and mental foramen. Find the inferior orbital rim with the index and middle fingers of the non-injecting hand. Once it is located, the palpating finger should remain in place to prevent losing landmarks and stop the needle from entering the orbit. Retract the cheek with the thumb of the non-injecting hand and then insert the needle into the mucosa above the upper second bicuspid approximately 0.5 cm from the buccal surface. The needle should be directed superiorly and remain parallel to the second bicuspid until it is palpated near the foramen. Before injecting the anesthetic, it is important to aspirate to ensure the needle is not within a vessel. Inject the anesthetic into the space. It is important to avoid injecting the anesthetic into the foramen by keeping firm pressure on the inferior orbital rim with the palpating finger.

Extraoral Approach

The infraorbital foramen can be approximated by having the patient look straight ahead and imagining a line down from the pupil to the inferior border of the infraorbital ridge, bicuspid teeth, and mental foramen. Find the inferior border on the infraorbital rim. Cleanse the skin over the infraorbital foramen with an antiseptic agent and sterile gauze. Insert the needle through the skin, subcutaneous tissue, and muscle. Before injecting the anesthetic, aspirate to ensure the needle is not within a vessel. Inject the anesthetic. Due to the proximity of the facial nerve when the extraoral approach is used, it is best to use an anesthetic agent that does not contain added medication with vasoconstrictor properties. The overlying tissues should appear edematous. Massage the area for 10 to 15 seconds after removing the needle.

Complications

Complications from infraorbital nerve block may include bleeding, hematoma formation, infection, artery or vein injury, unintentional injection of anesthetic into the artery or vein, nerve damage, or edema.[10][11]

It is possible for a patient to develop an allergic reaction to the anesthetic medication used for the procedure. Other reactions to the anesthetic medication include cardiovascular and neurological symptoms. Depending on the anesthetic, methemoglobinemia is also a possible complication.

Clinical Significance

The infraorbital nerve block provides analgesia by introducing anesthetic medication in the distribution of the infraorbital nerve for injury repair, abscess drainage, dental procedures, or pain relief.

Enhancing Healthcare Team Outcomes

The infraorbital nerve block may be performed by the anesthesiologist, dentist, trauma surgeon, facial surgeon and the emergency department physician. A dedicated nurse must be assigned for monitoring the patient. In addition, resuscitation equipment must be in the room before starting the procedure. The infraorbital procedure is relatively easy and safe but an inadvertent injury to the nerve is not uncommon. After the procedure, the patient must be monitored for 30-45 minutes to ensure that there are no complications.

Nursing, Allied Health, and Interprofessional Team Interventions

• Ensure consent is obtained
• Educate the patient about the procedure
• Ensure that the skin site is sterile and appropriately drapped
• Prepare the instrument tray
• Ensure that monitoring and resuscitation equipment is in the room

Nursing, Allied Health, and Interprofessional Team Monitoring

• Monitor the vital signs
• Monitor the patient for bleeding, anxiety, pain