4 Anesthesia Considerations for Cosmetic Facial Surgery

Local Anesthesia for Cosmetic Facial Surgery

No one can argue that one of greatest medical advances in the history of mankind was the discovery of local anesthetic agents. Virtually no other single innovation has done so much so safely to mitigate human suffering. Local anesthetics are agents that reversibly block nerve conduction in a limited area when injected or topically applied ¹ and exhibit their effect by blocking noxious stimuli from reaching the brain.²

Proficiency in local anesthetic techniques is extremely important for a successful cosmetic practice. It is vital from a patient-care standpoint to ensure painless treatment with predictable outcomes (having to rush a procedure because of inadequate pain control is a bad experience for both surgeon and patient and can effect surgical outcomes). From a marketing and practice-growth standpoint, a gentle, painless doctor will get many word-of-mouth referrals. Surgeons who are rough or fail to utilize pain-control techniques will lose patients. Most doctors receive formal training in local anesthetic techniques, but a review of common anatomy and techniques by both the novice and seasoned cosmetic surgeon is in the best interests of patient care.

Although some patients requesting small-needle techniques such as neurotoxins and injectable fillers ask for topical or injectable anesthetic augmentation, most patients “grin and bear it.” Vanity seems to have a significant impact on analgesia!

Many nonablative resurfacing and skin-tightening techniques are being developed and utilized. Pain control for these procedures does not require general or intravenous (IV) anesthesia but is frequently beyond the effects of topical anesthesia. As these new techniques and fillers become available, surgeons will doubtless be refining their local anesthetic techniques; augmentive pain control will be required. Once mastered, local anesthetic techniques can assist cosmetic surgeons far beyond the scope of injectables. They can be used for lesion removal, facial implant placement, resurfacing, intense pulsed light (IPL), and hair-removal procedures as well as a host of other uses to obtund pain associated with cosmetic procedures of the head and neck.

Mechanism of Action of Local Anesthetics

Local anesthetics block the sensation of pain by interfering with the propagation of impulses along peripheral nerve fibers without significantly altering normal resting membrane potentials.³ Local anesthetics depolarize nerve membranes and prevent achievement of a threshold potential. A propagated action potential fails to develop, and conduction blockade is achieved. This occurs through the interference of nerve transmission by blocking the influx of sodium through the excitable nerve membrane.⁴

Sensory Anatomy of the Head and Neck

The main sensory innervation of the face is derived from cranial nerve V (trigeminal nerve) and the upper cervical nerves (Figure 4-1).

FIGURE 4-1 Sensory innervation of the head and neck is derived from the trigeminal and upper cervical nerves.

Trigeminal Nerve

The trigeminal nerve is the fifth of the 12 cranial nerves. Its branches originate at the semilunar ganglion (gasserian ganglion) located in a cavity (Meckel’s cave) near the apex of the petrous part of the temporal bone. Three large nerves, the ophthalmic, maxillary, and mandibular, proceed from the ganglion to supply sensory innervation to the face (Figure 4-2).

FIGURE 4-2 Main branches of the trigeminal nerve supplying sensation to the respective facial areas. Inset shows the trigeminal ganglion with the three main nerve branches.

Often referred to as the great sensory nerve of the head and neck, the trigeminal nerve is named for its three major sensory branches. The ophthalmic nerve (V1), maxillary nerve (V2), and mandibular nerve (V3) are literally “three twins” (trigeminal) carrying sensory information of light touch, temperature, pain, and proprioception from the face and scalp to the brainstem. The commonly used terms V1, V2, and V3 are shorthand notation for cranial nerve V, branches one, two, and three, respectively. In addition to nerves carrying incoming sensory information, certain branches of the trigeminal nerve also contain nerve motor components. (The ophthalmic and maxillary nerves consist exclusively of sensory fibers; the mandibular nerve is joined outside the cranium by the motor root.) These outgoing motor components include branchial motor nerves (nerves innervating muscles derived embryologically from the branchial arches) as well as “hitchhiking” visceral motor nerves (nerves innervating viscera, including smooth muscle and glands). The trigeminal nerve exits the trigeminal ganglion and courses backward to enter the mid-lateral aspect of the pons at the brainstem.⁵

The ophthalmic nerve (V1) leaves the semilunar ganglion through the superior orbital fissure, the maxillary nerve (V2) leaves the semilunar ganglion through the foramen rotundum at the skull base, and the mandibular nerve (V3) leaves the semilunar ganglion through the foramen ovale at the skull base ⁵ (see Figure 4-2, inset). The remainder of this chapter will only discuss the sensory components of this nerve system as they relate to local anesthetic blocking techniques for cosmetic facial procedures.

Ophthalmic Nerve (V1)

The ophthalmic nerve, or first division of the trigeminal, is a sensory nerve. It supplies branches to the cornea, ciliary body, and iris; to the lacrimal gland and conjunctiva; to part of the mucous membrane of the nasal cavity; and to the skin of the eyelids, eyebrows, forehead, and upper lateral nose (see Figure 4-2, V1). It is the smallest of the three divisions of the trigeminal and divides into three branches: the frontal, nasociliary, and lacrimal.⁵ The frontal nerve divides into the supraorbital and supratrochlear nerves, providing sensation to the forehead and anterior scalp.

The nasociliary nerve divides into four branches, two of which supply sensory innervation to the face. These two branches are the infratrochlear nerve, which supplies sensation to the skin of the medial eyelids and side of the nose, and the ethmoidal nerve, which gives off a terminal branch called the external (or dorsal) nasal nerve and innervates the skin of the nasal dorsum and tip. The lacrimal nerve innervates the skin of the upper eyelid.

Maxillary Nerve (V2)

The maxillary nerve, or second division of the trigeminal, is a sensory nerve that crosses the pterygopalatine fossa, traverses the orbit in the infraorbital groove and canal in the floor of the orbit, and appears upon the face at the infraorbital foramen as the infraorbital nerve.⁵ At its termination, the nerve divides into branches which spread out upon the side of the nose, the lower eyelid, and the upper lip, joining with filaments of the facial nerve.⁵ Terminal branches include the following:

The zygomatic nerve arises in the pterygopalatine fossa, enters the orbit by the inferior orbital fissure, and divides at the back of that cavity into two terminal branches, the zygomaticotemporal and zygomaticofacial nerves.

The zygomaticotemporal branch runs along the lateral wall of the orbit in a groove in the zygomatic bone then passes through a foramen in the zygomatic bone and enters the temporal fossa. It ascends between the bone and substance of the temporalis muscle and pierces the temporal fascia about 2.5 cm above the zygomatic arch, where it is distributed to the skin of the side of the forehead (see Figure 4-2, V2).⁵

The zygomaticofacial branch passes along the inferolateral angle of the orbit, emerges upon the face through a foramen in the zygomatic bone, perforates the orbicularis oculi, and supplies the skin on the prominence of the cheek (see Figure 4-2, V2).

As the maxillary nerve traverses the orbital floor and exits the infraorbital foramen, it branches into a plexus of nerves with the following terminal branches:

The inferior palpebral branches ascend behind the orbicularis oculi muscle and supply the skin and conjunctiva of the lower eyelid (see Figure 4-2, V2).

The lateral nasal branches (rami nasales externi) supply the skin of the side of the nose (see Figure 4-2, V2).

The superior labial branches are distributed to the skin of the upper lip, the mucous membranes of the mouth, and labial glands (see Figure 4-2, V2).⁵

Mandibular Nerve (V3)

The mandibular nerve supplies the teeth and gums of the mandible, the skin of the temporal region, part of the auricle, the lower lip, and the lower part of the face (see Figure 4-2, V3). The mandibular nerve also supplies the muscles of mastication and the mucous membrane of the anterior two-thirds of the tongue. It is the largest of the three divisions of the fifth cranial nerve and is made up of a motor and sensory root.⁵

Sensory branches of the mandibular nerve include the auriculotemporal nerve, which supplies sensation to the skin covering the front of the helix and tragus (see Figure 4-2), and the inferior alveolar nerve, the largest branch of the mandibular nerve. It descends with the inferior alveolar artery and exits the ramus of the mandible to the mandibular foramen. It then passes forward in the mandibular canal, beneath the teeth, as far as the mental foramen, where it divides into two terminal branches, incisive and mental nerves. The mental nerve emerges at the mental foramen and divides into three branches; one descends to the skin of the chin, and two ascend to the skin and mucous membrane of the lower lip.⁵ The buccal nerve supplies sensation to the skin over the buccinator muscle.

Local Anesthetic Techniques

Infiltrative Peripheral Anesthesia Versus Regional Nerve Block Anesthesia

Local anesthesia can be effectively obtained by infiltrations and nerve blocks. Infiltrative local anesthesia applies to the injection of the local anesthesia solution in the area of the peripheral innervation distant from the site of the main nerve. An advantage of infiltrative anesthesia is that no specific skill is necessary. Only the selected area of innervation is involved, and vasoconstrictors can improve local hemostasis. A drawback of infiltrative local anesthesia is the distortion of the tissue at or around the site of injection, which may obscure or hamper cosmetic procedures.

A nerve block involves placing local anesthetic solution in a specific location at or around the main nerve trunk or branch, where it will effectively depolarize that nerve and obtund sensation distal to that area. Advantages of nerve blocks include the fact that a single accurately placed injection can obtund large areas of sensation without tissue distortion at the operative site. Disadvantages of peripheral nerve block include the sensation of numbness in areas other than the operative site and the lack of hemostasis at the operative site from vasoconstrictors.

It should be mentioned that individual anatomic variances in patients are responsible for the sometimes unpredictable effect of peripheral nerve block. Foraminal position, nerves crossing the midline, accessory innervation, and nerve bifurcation are just some factors that affect the predictability and success or failure of local anesthetic nerve blocks. Nerves that innervate areas close to the midline may receive innervation from the contralateral side and require bilateral blocks. For the multiple aforementioned reasons, some nerve blocks may require augmentative infiltrative local anesthesia to obtain adequate pain control.

Since many nerves are accompanied by corresponding veins and arteries, aspiration should always be performed to prevent intravascular injection.

Use of Topical Preanesthesia

Any person who has a pain-free dentist more than likely receives topical mucosal anesthesia prior to having a dental block. Topical anesthetics are more effective and faster acting on mucosal surfaces, and some of the effects may be psychological, but all patients appreciate the extra pain-control effort. The use of a topical anesthetic agent on the lip mucosa will definitely augment injections in that area, regardless of the blocking techniques used. In the author’s practice, when a patient is seated for lip augmentation injections, the assistant immediately applies a liberal coating of “BLT” topical anesthesia (20% benzocaine, 6% lidocaine, 4% tetracaine) to the patient’s lips and oral mucosa inside the lips. The topical anesthetic will be in contact with the mucosa for at least 10 minutes preinjection. This product can be made at most local compounding pharmacies. It produces profound anesthesia in some patients and negates the need for further blocking techniques. Some patients will still require blocks, but topical anesthesia will assist by both psychological and physiologic means. Many cosmetic surgeons also use topical agents for cutaneous anesthesia. I always use local infiltration of the perioral region; I believe in a painless procedure. The patient will be happier, and I can personally do a better job on a truly numb patient.

I have been performing local anesthetic blocks of the face for 30 years and initially used them while injecting the newer fillers in the lips. The negative connotation of additional injections and the added time needed for filler injection led me to look at alternatives. After experimenting with various topical and local anesthesia infiltration techniques, I now rarely utilize trigeminal nerve blocks. Instead, I use the “mini block infiltration” technique, which has expedited appointments for lip filler injection and has been a welcomed change on the part of the patient. The technique has proven adequate for 100% of patients’ filler injection in the lips and/or nasolabial folds. The injections are performed quickly and provide excellent local anesthesia for lip and perioral injection.

Technique for Upper and Lower Lip Anesthesia

As soon as the patient is seated in the treatment room, a potent topical anesthesia compound of 20% benzocaine, 6% lidocaine, and 4% tetracaine is applied intraorally in the depth of the anterior maxillary and mandibular vestibule. The vestibule is the sulcus formed at the junction of the attached gingiva and the unattached mucosa. The same topical is applied to the external lip mucosa. A 1-mL syringe of 2% lidocaine, 1 : 100,000 epinephrine, and a 32-gauge needle are used. Injections of 0.2 to 0.3 mL of local anesthetic solution are given in four to five areas between the canine teeth (Figure 4-3, A). The injection is submucosal in the potential space between the mucosa and the periosteum. This is a soft-tissue injection, so the needle need not touch bone. If both lips are to be injected, the same procedure is performed in the lower vestibule as well (see Figure 4-3, B). After several minutes, the lips and perioral areas are adequately anesthetized for filler injection. This infiltration, if done properly, will approach the profound level and extent of anesthesia experienced with bilateral nerve block and is well suited for cutaneous and vermilion filler injection of the lips. The area anesthetized may extend to the nasal tip in the maxilla and to the mentolabial fold in the mandible. Return of sensation generally progresses between 30 and 60 minutes. No significant anatomic structures traverse this area of the vestibule, and the author has experienced no complications with thousands of these injections.

FIGURE 4-3 A, Multiple infiltration technique in the upper lip. B, Same technique for the lower lip.

Technique for Nasolabial Fold Anesthesia

Using the 1-mL syringe with a 32-gauge needle, 0.1 to 0.2 mL of local anesthesia is injected deep in the nasolabial fold (so as not to distort the fold and effect filler accuracy) in two to three areas from the nostril to the corner of the mouth (Figure 4-4). Only a small amount of local anesthesia is required to produce acceptable anesthesia. Although many practitioners use no anesthesia for cutaneous injection, I can attest to patient appreciation of this simple technique.

FIGURE 4-4 Deep local anesthesia injection to anesthetize the nasolabial fold region. Generally 0.2 mL of local anesthesia is injected at two to three points along the fold. Deep injection prevents obscuring the fold, which would make the filler injection inaccurate.

These simple techniques of maxillary and mandibular vestibular and mucosal infiltration in conjunction with topical mucosal anesthesia are safe, rapid, and effective ways to provide local anesthesia for the cosmetic injection of fillers in the lips and perioral and nasolabial regions.

Local Anesthetic Techniques for Blocking the Main Sensory Nerves of the Head and Neck

A rudimentary knowledge of the neuroanatomy of the head and neck can enable the cosmetic surgeon to perform painless surgical procedures in this area. When used concomitantly with general anesthesia or intravenous sedation, local anesthetic blocks can decrease the amount of intravenous or inhalation agents needed and provide excellent postanesthetic pain control.

Scalp and Forehead

The frontal nerve exits through a notch (in some cases a foramen) on the superior orbital rim approximately 27 mm lateral to the glabellar midline (Figure 4-5). This supraorbital notch is readily palpable in most patients. After exiting the notch or foramen, the nerve traverses the corrugator supercilii muscles and branches into a medial and lateral portion. The lateral branches supply the lateral forehead, and the medial branches supply the scalp. The supratrochlear nerve exits a foramen approximately 17 mm from the glabellar midline (see Figure 4-5) and supplies sensation to the middle portion of the forehead. The infratrochlear nerve exits a foramen below the trochlea and provides sensation to the medial upper eyelid, canthus, medial nasal skin, conjunctiva, and lacrimal apparatus⁶ (see Figure 4-5).

FIGURE 4-5 The supraorbital nerve (SO) exits about 27 mm from the glabellar midline, and the supratrochlear nerve (ST) is located approximately 17 mm from the glabellar midline. The infratrochlear nerve (IT) exits below the trochlea.

When injecting this area, it is prudent to always use the free hand to palpate the orbital rim to prevent inadvertent injection into the globe! To anesthetize this area, the supratrochlear nerve is measured 17 mm from the glabellar midline, and an injection of 1 to 2 mL of 2% lidocaine, 1 : 100,000 epinephrine is given (Figure 4-6, A). The supraorbital nerve is blocked by palpating the notch (and or measuring 27 mm from the glabellar midline) and injecting 2 mL of local anesthetic solution (see Figure 4-6, B). The infratrochlear nerve is blocked by injecting 1 to 2 mL of local anesthetic solution at the junction of the orbit and the nasal bones (see Figure 4-6, C). In reality, one can block all three of these nerves by simply injecting 2 to 4 mL of local anesthetic solution from the central brow proceeding to the medial brow. Figure 4-7 shows the regions anesthetized by the described blocks.

FIGURE 4-6 Forehead and scalp are blocked by a series of injections form the central to the medial brow.

FIGURE 4-7 Shaded areas indicate anesthetized areas from supraorbital nerve (SO), supratrochlear nerve (ST), and infratrochlear nerve (IT) blocks.

Infraorbital Nerve Block

The infraorbital nerve exits the infraorbital foramen 4 to 8 mm below the orbital rim in an imaginary line dropped from the medial limbus of the iris ⁶ or the pupillary midline. The anterior superior alveolar nerve branches from the infraorbital nerve before it exits the foramen, so some patients will manifest anesthesia of the anterior teeth and gingiva if the branching is close to the foramen. Areas anesthetized include the lateral nose, anterior cheek, lower eyelid, and upper lip on the injected side. This nerve can be blocked by intraoral or extraoral routes. To perform an infraorbital nerve block from an intraoral approach, topical anesthesia is placed on the oral mucosa at the vestibular sulcus just under the canine fossa (between the canine and first premolar tooth) and left for several minutes. The lip is then elevated, and a -inch 27- gauge needle is inserted in the sulcus and directed superiorly toward the infraorbital foramen (Figure 4-8). It is unnecessary for the needle to enter the foramen for a successful block. The anesthetic solution need only contact the vast branching around the foramen to be effective. It is imperative to use the other hand to palpate the inferior orbital rim to avoid injecting the orbit; 2 to 4 mL of 2% lidocaine with 1 : 100,000 epinephrine are injected in this area for the infraorbital block.