Hand and neck blocks can be used to relieve pain and supplement general anesthesia in infants and children undergoing head and neck surgery.1,2 Block selection depends on the surgical approach. Most anesthesiologists have limited opportunity to perform these blocks since major surgery of the face and neck is relatively uncommon and local infiltration is often used for most minor procedures.3,4
Local infiltration provides a circumscribed area of anesthesia in the immediate vicinity of injection and large volumes of local anesthetic may be required. A nerve block on the other hand provides a larger area of anesthesia for a relatively small volume of local anesthetic.
Most children have an inherent fear of needles, particularly around the facial area. This precludes its use in young children (and in some older children!) without sedation or general anesthesia.
The anatomical landmarks are relatively constant in adults but structural changes that occur during growth of a child results in some variability. A thorough understanding of the anatomical relationship of the nerve to be blocked is essential since the anatomy of the head and neck is compact and the cranial and cervical nerves are close to vital structures. Inadvertent injection into these blood vessels carries a significant risk of toxicity.
DEVELOPMENT OF THE SKULL5
A newborn’s facial configuration differs from that of an adult. Ossification is incomplete and many bones are still in several elements united by fibrous tissue or cartilage. The face below the orbits, including the mandible, accounts for about one-half of the skull in adults. In the newborn the air sinuses are rudimentary, the mandible and maxillae are small, the teeth are absent, and thus the face below the orbit makes up only one-eighth of the skull.
The orbit in newborns is large and almost circular. The supra-orbital notch is near the middle of the supra-orbital margin in adults, whereas it lies more medial in the newborn. The maxilla is small, the distance between the alveolar ridges is short, and the infraorbital foramen is millimeters from the inferior orbital ridge.
The mandibular ramus also varies with age. At birth the angle of the mandible is small (obtuse) and develops with progressive growth of the mandible. In the child, before tooth eruption, the mental foramen is closer to the alveolar margin. When the teeth erupt the mental foramen descends to halfway between the margins, and in adults with the teeth preserved, the mental foramen is somewhat closer to the inferior border of the mandible.6
Briefly, the innervation of the head, face, and neck is best understood if one considers the embryological development as the face forms around the primitive mouth or stomodeum. Initially, the stomodeum is surrounded caudally by the mandibular arch (supplied by the mandibular division of the trigeminal nerve), laterally on ...