Peripheral Nerve Blocks: A Color Atlas, 3rd Edition

55.Peripheral Nerve Blockade of the Head and Neck

Kristine Henderson

Pediatric patients undergoing many types of head and neck procedures can benefit from peripheral nerve blockade for postoperative analgesia. Common procedures include cleft lip and palate repair, otoplasty, rhinoplasty and septoplasty, mastoidectomy, craniotomy, and ventricular shunt placement.

The scalp is innervated by two groups of nerves: the first division of the trigeminal nerve, which divides into the supraorbital and supratrochlear nerves, and cervical root C2, which gives rise to the occipital nerves. The supraorbital and supratrochlear nerves supply the anterior part of the scalp, and the occipital nerves supply the posterior part of the scalp. These two blocks are often performed together for analgesia of the frontal scalp.

For the first block, the supraorbital notch is palpated. After antiseptic preparation of the skin, a 27-gauge needle is inserted perpendicularly into the notch and 1 mL of bupivacaine (0.25% with 1:200,000 epinephrine) is injected after aspiration to prevent intravascular injection (Fig. 55-1).

To then block the supratrochlear nerve, the needle is withdrawn to the skin level and directed medially toward the tip of the nose; 1 mL of bupivacaine is injected. Gentle pressure should then be applied to the supraorbital area to prevent the dissection of local anesthetic and the formation of ecchymosis (Fig. 55-2).

The greater occipital nerve provides cutaneous innervation to the major portion of the posterior scalp. Blocking this nerve provides relief of occipital pain following posterior fossa surgery and posterior shunt revisions. For this block, the patient's head is turned to one side, or with the patient prone, the occipital artery is palpated at the level of the superior nuchal line. The occipital nerve is located medial to the occipital artery; 1 to 2 mL of bupivacaine (0.25% with 1:200,000 epinephrine) is injected to form a skin wheal. Blockade of these three nerves together can provide effective analgesia for most craniotomies (Fig. 55-3).

The infraorbital nerve is the termination of the second division of the trigeminal nerve. It is entirely sensory. The nerve emerges in front of the maxilla through the infraorbital foramen and divides into four branches, innervating the lower eyelid, lateral inferior portion of the nose and its vestibule, the upper lip, and the vermilion. Blocking this nerve helps provide postoperative pain relief in cleft lip repair, septoplasty, rhinoplasty, and in patients undergoing endoscopic sinus surgery. An intraoral approach or an extraoral approach can be used. The intraoral approach may be more aesthetic, in that any small hematoma that is formed will be less obvious (Fig. 55-4).

 

Figure 55-1. Supraorbital nerve block.

The sphenopalatine ganglion (SPG) appears to be a pain pathway, especially when trigeminal nerve divisions 1 (ophthalmic, sensory) and 2 (maxillary, sensory) are involved. This ganglion is located in the pterygopalatine fossa, behind the middle nasal turbinate under 1 mm of mucous membrane, and anterior to the pterygoid canal. Due to this superficial location, the block can be performed by topical application of local anesthetic or by injection.

The sphenopalatine ganglion is classified as a parasympathetic ganglion because only preganglionic parasympathetic axons appear to synapse within the ganglion. It contains the cell bodies of the postganglionic parasympathetic neurons. However, postganglionic sympathetic neurons as well as somatic sensory afferent branches of the trigeminal nerve also pass through the ganglion (without terminating), all of which may be inhibited by this block.

Figure 55-2. Supratrochlear nerve block.

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Figure 55-3. Greater occipital nerve block.

Postganglionic parasympathetic neurons then distribute to the lacrimal glands, paranasal sinuses, palate, and upper pharynx. They also innervate the major cerebral arteries, along with postganglionic sympathetic fibers. A portion of the pain relief from this block is probably secondary to blocking the parasympathetic contribution to intracranial vasodilation.

The somatic sensory afferent axons traveling through the ganglion arise from the maxillary division of the trigeminal nerve by way of five branches that extend from the nasopharynx, nasal cavity, palate, and orbit.

The simplest, least invasive approach to block this ganglion is via the intranasal approach. The most common technique utilizes 2 cotton applicators soaked with 4% lidocaine placed intranasally until the posterior pharyngeal wall is contacted. This technique can be modified by using an intratracheal cannula to deliver the local anesthetic instead of cotton applicators, in order to deliver a more perfectly weight-appropriate dose, if this is a consideration. The patient is placed supine and a small-gauge intratracheal cannula preloaded with the dose of 4% lidocaine may be inserted into the nose, passing alongside the inferior turbinate and directed posteriorly until the upper posterior wall of the nasopharynx is reached. As you can see in this example, sometimes the intranasal approach is not as feasible.

Figure 55-4. Infraorbital nerve block.

Figure 55-5. Transfacial approach.

The transfacial approach may also be used in the anesthetized child. A 22-gauge B-bevel needle is inserted anterior to the mandible and under the zygoma. The needle is advanced until it contacts the pterygoid plate, and is then withdrawn approximately 1 mm. In Figure 55-5, a spinal needle was used because the oral retractor was in the way. Careful aspiration must confirm that the needle is not intravascular before 1 mL of local anesthetic is injected.

Figure 55-6. Mental nerve block using a transfacial or intraoral approach.

 

Figure 55-7. Greater auricular nerve block.

The mental nerve is easily blocked using a transfacial or intraoral approach. A 25-gauge needle and 0.5 to 2 mL local anesthetic are used. Typically, a slightly greater volume of anesthetic is used with the intraoral approach as there is greater local anesthetic spread in the loose mucosal tissues. This block is useful for plastic surgical procedures or in the emergency room setting.

The intraoral approach is favored by dentists and oral surgeons, but also has the advantage of aesthetics; as with the SPG block discussed previously, any small hematoma formed is less visible. Another advantage is that a small cotton ball soaked with 2% viscous lidocaine can be used to provide topical anesthetic prior to the block. With a helpful parent and the patient's eyes closed, the child may never realize that a needle was used (Fig. 55-6).

The greater auricular nerve, arising from fibers of the 2nd and 3rd cervical nerves, innervates the ear. Blockade of this nerve supplies good postoperative pain relief for otoplasty. It can also be used for pain relief in patients suffering from Ramsay Hunt syndrome, herpetic involvement of the geniculate ganglion.

Palpate the mastoid process. A 25-gauge B-bevel needle is inserted at the level of the mastoid process, then when the periosteum is reached, is redirected toward the earlobe.

Inject a total of 3 mL of local anesthetic in a fan-like pattern, moving medially during injection (Fig. 55-7).