Maxillary Nerve Block

Complete maxillary nerve block is not commonly required (see Indications below). ^{[1, 2, 3, 4]} This is because the wide area of anesthesia resulting from maxillary nerve block (including the dural, temporal, and zygomatic regions; the mucosa of the maxillary sinus; and the maxillary teeth and their soft tissues) is often not needed. Frequently, the area to be blocked is very small (eg, a single tooth), and the appropriate local anesthesia can be achieved by more specific nerve blocks, which also have the advantage of causing less discomfort to the patient.

The indications for complete maxillary nerve block are few and include the following:

• Procedures requiring anesthesia of multiple teeth and surrounding areas: Individual blocks are cumbersome and lead to patient discomfort; multiple blocks may necessitate administering a larger dose of the anesthetic, which may exceed the toxic dose.

• Large canine abscesses: If specific nerve blocks are given, large volumes of local anesthetic may have to be administered; a maxillary nerve block can be performed with a relatively low dose of the drug.

• Failure of local blocks as a result of infection or abscess formation: This may necessitate a maxillary nerve block, which is administered far from the site of infection.

• Surgery on the maxilla, either alone or as a complement to general anesthesia

• Postoperative pain relief after maxillary surgical procedures

• Painful conditions in the maxillary area that do not respond to systemic analgesics

• Some cases of trigeminal neuralgia

Contraindications for maxillary nerve block include the following:

• Infection over the point of injection

• Patients with coagulopathic abnormalities or those who are taking drugs that alter hemostasis

• Patients who refuse the procedure

• Patients with known allergy to local anesthetics

The maxillary nerve arises in the middle cranial fossa as a purely sensory division of the trigeminal ganglion (see the image below). It gives off a branch as it travels forward on the lateral wall of the cavernous sinus.

After leaving the cranium via the foramen rotundum on the greater wing of the sphenoid, the nerve enters the pterygopalatine fossa, which is located posteroinferior to the orbit. Here, it gives off several sensory branches before exiting via the infraorbital fissure and then the infraorbital canal as the infraorbital nerve.

The nerve finally emerges from the infraorbital foramen on the maxillary bone along with the infraorbital artery and vein.

The branches of the maxillary nerve can be divided into the following 4 categories:

• Intracranial branch

• Branches in the pterygopalatine fossa

• Branches in the infraorbital canal

• Branches in the face

The intracranial branch of the maxillary nerve is the middle meningeal nerve, which innervates the dura mater.

The first of the branches in the pterygopalatine fossa to be considered is the pterygopalatine nerve, which contains the postganglionic parasympathetic secretomotor nerve fibers to the lacrimal gland. This nerve serves as a communication between the pterygopalatine ganglion and the maxillary nerve. It gives sensory innervation to the orbit, nose, palate, and pharynx via the following branches:

• Nasopalatine nerve, which provides sensory supply to the premaxillary palatal mucosa

• Greater and lesser palatine nerves, which supply the hard and soft palate

• Orbital branches, which supply the periosteum of the orbit

• Pharyngeal branches, which supply the mucosa of the nasopharyngeal wall

• Nasal branches, which supply the mucosa of the posterior nasal septum, the superior and middle nasal conchae, and the superior ethmoid sinus

The other branches in the pterygopalatine fossa include the zygomatic nerve, which provides sensory supply to the skin over the forehead and cheek via its zygomaticofacial and zygomaticotemporal branches; and the posterior superior alveolar nerve, which supplies the maxillary molar dentition and the periodontal ligaments, gingivae, and pulp of the molars.

The branches of the maxillary nerve in the infraorbital canal include the middle superior alveolar nerve, which innervates the maxillary alveoli, gingivae, and periodontal tissues of the maxillary premolar area, and the anterior superior alveolar nerve, which innervates the maxillary alveoli, gingivae, and periodontal tissues of the central and lateral incisors and the canines.

The branches of the maxillary nerve in the face include the inferior palpebral nerve, which supplies the eyelids; the lateral nasal nerve, which supplies the skin on the nose; and the superior labial nerve, which supplies the upper lip and mucosa.