Head Blocks

Indications:
Blocks of the cutaneous nerves supplying the scalp are indicated in the
emergency room and for plastic surgery to avoid tissue distortion.
Blocks of the frontal branch of the supraorbital and infraorbital
nerves are indicated for anesthesia in or around the eye. These blocks
are indicated for blepharoplasty or for other lid procedures, including
traumatic and posttraumatic reconstructive surgical procedures. Blocks
of the auriculotemporal, greater auricular nerves, and minor occipital
nerves are indicated for ear surgery.

Needle Size: 25-gauge, 20-mm needle.

Volume: 1 to 2 mL.

Anatomic Landmarks: Cutaneous nerves supplying the scalp and face (Fig. 23-1):
1, frontal nerve; 2, supraorbital nerve; 3, zygomaticotemporal nerve
(V2); 4, auriculotemporal nerve (V3); 5, greater auricular nerve; 6,
minor occipital nerve; 7, greater occipital nerve; 8, supra- and
infratrochlear nerve; 9, infraorbital nerve; 10, external nasal
branches of the ethmoid nerve; 11, mental nerve.

Approach and Technique:
The appropriate site is identified, and 0.5 to 1.0 mL of 1% lidocaine
with 1/100,000 epinephrine is injected subcutaneously in small
increments up to 2 mL per nerve to obtain adequate anesthesia.

Indications:
Blocks of the facial nerve are indicated when cosmetic procedures are
planned that require the injection of botulin toxin-A to produce nerve
paralysis with subsequent removal of forehead rhytides. It is of utmost
importance to test the effect of blocking the zygomaticotemporal branch
of the facial nerve using a short-acting local anesthetic. If the
botulin injection is not performed correctly, and the botulin toxin is
infiltrated lower, then a paralysis of the eyelids occurs that can last
2 to 3 months (temporary motor denervation). Blocks of the facial nerve
are also used for plastic surgery (to produce a temporary paralysis of
the eyelids when performing CO₂ laser resurfacing or dermabrasion) and for traumatic repairs as well as posttraumatic reconstructive surgery.

Needle Size: 25-gauge, 35-mm needle.

Volume: Up to 2 mL.

Anatomic Landmarks: The orbit.

Approach and Technique:
1% lidocaine with 1/100,000 epinephrine is injected in small increments
(up to 2 mL) along the orbit posterior to the rim, laterally and
inferiorly. The needle can come close to the midline without causing
paralysis and affecting eye closure. The effects are not long lasting
and can be used as a good test prior to injecting the botulin toxin.

The first division of the trigeminal nerve (V1) gives
rise to the supraorbital nerve, which exits the brain through the
supraorbital fissure. This branch gives sensation to the forehead and
parietal scalp. The second division (V2) exits through the infraorbital
fissure to exit into the face through the infraorbital foramen, located
at approximately the midpoint of the infraorbital rim. Figure 23-3 depicts the cutaneous dermatomes associated with the different sensory branches of the trigeminal nerve.

Indications: Plastic, ophthalmologic, and trauma surgery involving the eye and the nose (ethmoid sinus labyrinth).

Needle Size: Variable, depending on the depth.

Volume: Up to 2 mL per nerve.

Anatomic Landmarks:
The ophthalmic nerve cannot be blocked directly because it is posterior
to its branches (the lacrimal, nasociliary, and frontal nerves). The
nasociliary nerve insinuates itself through the annulus of Zinn into
the apex of the orbit and innervates

the
eye. Its two branches, the posterior and anterior ethmoids, leave the
orbital apex and pass into the posterior and anterior ethmoid foramina.
The frontal and lacrimal branches are not accessible to blocks in the
posterior orbital apex because they lie entirely outside of the apex of
the orbital wall.

Approach and Technique:
With a needle pointing to the anterior ethmoid foramen, the anterior
and posterior ethmoid nerves are blocked, which innervates the
conjunctiva. Up to 2 mL of 1% lidocaine with 1/100,000 epinephrine is
then injected near the superior orbital fissure. With the insertion of
the needle, the globe elevates as digital pressure increases. With a
needle pointing to the posterior ethmoid foramen, the frontal and
lacrimal nerves are blocked by injecting up to 2 mL of the same local
anesthetic solution. The frontal nerve may be blocked forward, above
the bulb.

Indications:
For incision and drainage of dental abscesses in the outpatient
setting, to remove hardware used in repairing maxillofacial fractures,
and, occasionally, in sinus surgery in the elderly and in closed
reduction of nasal fractures. Palatal blocks are also indicated to
excise cysts, small benign tumors, and bony exostoses. They are also
occasionally used as a conduit to the pterygopalatine foramen either to
block V2 at the foramen rotundum or to therapeutically obtain
hemostasis in posterior nosebleeds by placing the internal maxillary
artery in spasm and using the hydrostatic pressure for vessel
compression against the bony canal. Blocking the sphenopalatine
ganglion is also valuable in evaluating contact neuralgia (Sluder type)
prior to any definitive surgical procedure.

Needle Size: 22-gauge, 89-mm spinal needle.

Volume: 2 to 5 mL per nerve depending on the nerve.

Anatomic Landmarks: Anatomy—main trunk (V2) intraoral and infraorbital branches (Fig. 23-3).

Approach and Technique:
To provide a complete block of the region it is necessary to block the
peripheral branches of the second division of the trigeminal nerve (the
infraorbital and superior, posterior, and medial alveolar nerves). The
infraorbital nerve is approached by introducing the needle directly to
the midpoint of the inferior orbital rim and infiltrating the area with
approximately 1 to 2 mL of 1% lidocaine with 1/100,000 epinephrine.
This block produces anesthesia of the lower eyelid, the upper lip, a
large part of the nose, a part of the skin and mucosa of the cheek, the
anterior portion of the superior alveolar process and its periosteum,
the anterior wall of the maxilla, and the upper central and lateral
incisors.

Anesthesia of the second division of the trigeminal
nerve (V2) may be carried out externally by passing a 22-gauge, 89-mm
spinal needle just below the zygomatic arch along the posterior surface
of the ascending ramus of the mandible into the most superior portion
of the pterygopalatine fossa. The point of insertion of the needle lies
immediately behind the lower palpable angle of the malar bone (Fig. 23-4).
First, a small amount of 1% lidocaine with 1/100,000 epinephrine is
injected into the skin itself. From this point, the needle is pressed
inward and upward. Its point passes through the masseter muscle until
it comes in contact with the superior maxillary tubercle, and it is
slid along this surface. Occasionally, the point of the needle strikes
the wing of the sphenoid, in which case, the direction of the needle is
changed, or, if necessary, withdrawn altogether, and another point of
entrance made just posterior to the midpoint of the zygomatic arch. The
appropriate location is assumed once the needle suddenly passes deeper
into the pterygopalatine fossa and reaches the nerve at an approximate
depth of 5 to 6 cm. Once the needle is in the appropriate position, the
patient complains of radiating pain in the face. The needle is then
withdrawn slightly, and 5 mL of 1% lidocaine with 1/100,000 epinephrine
is injected, moving the needle back and forth.

Indications:
Anesthesia of the lower third of the face. Mostly used by dentists and
maxillofacial surgeons in the emergency room setting for repair of
facial lacerations, animal bites, incision and drainage of dental or
salivary gland abscesses, probing of salivary gland ducts, or in
radiology. Indications also include biopsies of the tongue, labiodental
sulcus, or inner table of the mandible, manipulation of the mandible in
cases in which mandible fractures are suspected and the patient is
uncooperative to intraoral exam because of pain, and in removal of
hardware inserted for repair of Le Fort fractures. It is also useful in
performing a number of cosmetic procedures on the lower third of the
face.

Needle Size: 22-gauge, 89-mm spinal needle.

Volume: 5 to 10 mL per nerve.

Anatomic Landmarks: Shown in Figure 23-3.

Approach and Technique: There are two standard access routes to anesthetizing the third division of the trigeminal nerve (V3).

The first method consists of injecting the inferior
alveolar and lingual nerves intraorally by injecting the inner surface
of the ascending ramus of the mandible into the region of the lingula.
This route is the one most commonly performed. The second method is by
directly blocking the nerve trunk in the foramen ovale.

For the intraoral approach (inferior alveolar and
lingual nerve blocks), the index finger is passed intraorally until it
touches the ascending ramus of the mandible. At about 1.5 cm lateral to
the third molar, the sharp edge of the coronoid process can be
palpated. This runs inferiorly along the side of the third molar and
becomes lost in the oblique line. Medially, from this edge, there is a
small, concave bony area, with three corners, directed forward and
inward and medially bounded by a bony ridge. This area is occasionally
referred to by head and neck surgeons as the retromolar trigone.
With the mouth closed, this area lies to the inner side of the third
molar. With the mouth open, it lies laterally to the upper and lower
teeth and is easily accessible. The lingual nerve lies immediately
under the mucosa, and the inferior alveolar nerve is 1.5 cm in back of
this point. A long 22-gauge, 89-mm spinal needle is introduced
intraorally and is directed from opposite the lateral incisors toward
the point of injection and held parallel to the biting surface of the
lower teeth. The needle is then inserted 1 cm above and lateral to the
biting surface of the last molar, into the retromolar trigone. The bone
should be immediately felt. If this is not the case, then the point of
the needle is too far from the median line, in which case the needle
must be directed more to the median line until the border is felt. The
needle is passed along the inner surface of the ascending ramus of the
mandible into the deeper parts for approximately 2.0 to 2.5 cm. Once
the needle is proximate to the lingual nerve, about 5 to 10 mL of 1%
lidocaine with 1/100,000 epinephrine is injected. A long needle is
always used so that the injection site is under direct visualization at
all times.

The foramen ovale approach (block of the main trunk of
the trigeminal nerve) has the advantage of providing a complete block
of the branches originating from the main trunk of the trigeminal
nerve, except for the lingual nerve. For the external approach to the
foramen ovale, once again a long spinal needle is used. The point of
injection is chosen

by
marking the inferior border of the zygomatic arch at its midpoint, and
the needle is inserted almost in transverse fashion. At a depth of 4 to
5 cm, the end of the needle touches the pterygoid process. In this
injection, the needle is approximately 1 cm anterior to the foramen
ovale. The depth is then marked on the needle. The needle is then
withdrawn to the subcutaneous tissue and is once again passed medially
at a slight posterior angle and to the same depth or a few millimeters
more. The characteristic radiating pains will then occur. At this
point, the needle is withdrawn a few millimeters and the injection
proceeds by instilling approximately 5 to 10 mL of 1% lidocaine with
1/100,000 epinephrine (Fig. 23-5).