The patient is positioned lying supine.

The patient’s head may be placed to rest on a donut.

Each nerve is closely associated with a readily palpable foramen. Figure 15.2 illustrates the cross-sectional anatomy of each respective foramen, captured by Visible Human Visualization Software (VHVS) and MRI.

The nerves are too superficial to visualize well with ultrasound. However, ultrasound can be used to identify the foramina by scanning sagittally in the medial to lateral direction [1]. The foramina create discontinuity in the hyperechoic line of the bone. The absence of hyperechogenic bony structure indicates the position of the foramen (Fig. 15.3). Using this method, the foramina can be landmarked and marked on the skin to facilitate easier identification of the needle insertion site. Color Doppler can also be used to verify the locations of the foramina by imaging the blood vessels associated with each foramen; however, these vessels are small and are often difficult to visualize.

Generally, short, 25G–30G hypodermic needles will be suitable for these blocks, provided that one is not trying to enter the foramen directly since this may require a larger needle for accurate placement. Longer needles are essential for:

Most exiting foramina communicate directly with the inferior orbital fissure. Thus, when using techniques that require injection of local anesthetic into the foramen itself, orbital contents may be injured inadvertently if one is not conscious of the depths and anatomic characteristics of the various canals where the nerves exit the facial skeleton.

Intraforaminal approaches are popular in many countries, but they have been reported to result in a higher incidence of paresthesia. Careful attention to injection pressure is critically important if the needle has entered the infraorbital canal itself. When placing the needle in these small foramina, the injection pressure must not be excessive, thereby minimizing trauma to the nerve. Intraforaminal approaches are not recommended for beginners since the basic approaches, when performed correctly, will provide excellent anesthesia and eliminate any risk of major complications.

When determining the optimal technique for infraorbital nerve block, the choice of an extraoral percutaneous route or an intraoral route (see below) must be made. While many practitioners advocate one technique over the other, either approach is appropriate, provided that the practitioner understands the benefits and limitations of the various approaches:

Before the needle is introduced, the location and anatomic characteristics of the infraorbital foramen and the course of the exiting nerve branches should be studied. Understanding the shape and course of the foramen will help the practitioner decide how best to enter or, in most cases, avoid entering the foramen.

The branches of the infraorbital nerve include the inferior palpebral, external nasal, internal nasal, and superior labial branch (which has a medial and lateral division). Only 40 % of the time do the nerves exit as separate branches [10]; the other 60 % of the time, the nerves exit as a network. Regardless, it is critical to remember that all the nerves travel in a lateral-to-medial direction toward the nasal ala. Successful nerve blockade is achieved when the local anesthesia spread matches these branching patterns. By understanding this principle, one can use visualization to determine when an adequate dose is achieved.

Mark the skin with landmarks: the easiest landmark to identify in almost all ages is a point at the intersection of a line passing through the orbit at the vertical level of the limbic sagittal line and a line drawn from the lateral edge of the orbit to the nasal ala rim. At this point, the infraorbital foramen may be palpated.

Mark the foramen’s location, and place the index finger of the hand contralateral to the side to be blocked on the superior aspect of the eyelid of the side to be blocked (e.g., left index finger on the child’s right eyelid). This will enable the practitioner to hold the syringe like a pencil and perform accurate needle placement. Injection with the non-dominant hand requires practice but is worth the effort to improve accuracy.

With the free hand’s index finger, the patient’s eye can be examined for abnormalities and to confirm that stage 2 anesthesia is not present. Following this, place the index finger below the orbit in the area of the infraorbital notch. Take care not to push the eye as this may cause a bradycardiac response.

Lowering the eyelid and placing the finger on the inferior orbital rim can prevent local anesthetic from spreading in a superior direction, which is not necessary unless blockade of the inferior palpebral branch is needed for surgery. This will also help to prevent spread of local anesthetic to the loose soft tissues of the eye, which may lead to bruising and a black eye.

The needle is inserted in a temporal-to-nasal direction, directly superior and lateral to the marked infraorbital foramen. Entering a small distance away from this mark will help ensure needle contact with the bone in the area of the foramen itself. The goal is to not enter the infraorbital foramen directly but to place the needle in proximity to the infraorbital foramen when contact with the maxilla occurs.

Many authors describe backing the needle off the bone at this point. This is unnecessary but can be done if desired to decrease the risk of nerve injury. After aspiration of the syringe, inject enough local anesthetic to ensure spread to the nasal ala rim, thereby covering all nerve branching patterns. If local anesthetic tracks in any other direction, the block may not be accurate, and the needle should be repositioned.

Advanced extraoral approaches include modifying the above technique and using a needle insertion point either at the infraorbital rim in the area of the infraorbital notch itself or entry of the infraorbital foramen directly. These superiorly based techniques are best performed in older children or adolescents undergoing awake surgery and allow the block to be performed relatively rapidly using small volumes of local anesthetic. This approach can be performed with a smaller volume of a more concentrated local anesthetic solution and may work at volumes of 0.25–1 mL per side to achieve adequate anesthesia. By moving the needle to the area immediately below the foramen, the needle tip can be placed directly under the fascia surrounding the infraorbital nerve as it exits the foramen while using the maxilla as a backstop. When done accurately, local anesthetic will be injected at the under-surface of the foramen, providing consistent and reliable anesthesia. An added benefit is that a gentle and quick injection can gain a scared awake child’s confidence.

Entering the infraorbital foramen is another advanced technique and is best performed if one remembers to change the needle direction to nasal-temporal. The foramen is located 7–8 mm below the orbital rim in adults and older children. When entering from a percutaneous nasal ala approach, a longer needle may be required. Zide [11] suggests to place the needle in the center of an imaginary triangle formed by the nasal labial fold, the nasal ala fold, and the foramen. Using this technique, block success was 100 % in adults when 1 mL local anesthetic was placed directly in the foramen, and no cases of nerve injury were found. To date, no studies have been done in pediatric patients using this technique.

The supraorbital and supratrochlear nerves are the terminal branches of V1 and can be blocked using one needle insertion with redirection (Fig. 15.4). After blocking the supraorbital nerve, the needle is withdrawn and redirected medially toward the supratrochlear foramen, where the supratrochlear nerve can be blocked.