++
Chapter 30. Nerve Blocks of the Face
++
++
++
What of the following statements is true regarding trigeminal nerve block?
++
++
++
A. It is a purely sensory block.
++
++
B. It is the primary therapy for patients with trigeminal neuralgia.
++
++
C. It can be performed distally and proximally.
++
++
D. It carries preganglionic and postganglionic fibers.
+
++
C is correct. The trigeminal nerve block can be performed either distally at the respective exit points from the facial bones (V1–V3) or proximally at their emergence from the cranium (V2–V3).
++
A is incorrect. The trigeminal nerve is a mixed sensory and motor nerve. While it is predominantly sensory, it does also carry the motor fiber for the muscles of mastication in its mandibular branch (V3).
++
B is incorrect. Blockade of the trigeminal ganglion is a treatment for patients with trigeminal neuralgia who failed pharmacological therapy. A blockade with local anesthetic (LA) is typically used as a diagnostic test prior to neurolysis.
++
D is incorrect. The trigeminal nerve is comprised of purely postganglionic fibers. Blockade of the trigeminal ganglion achieves blockade of preganglionic and postganglionic fibers.
++
++
++
What statement is true regarding landmark-based superficial trigeminal nerve blocks?
++
++
++
A. The ophthalmic nerve (V1) enters the orbit and divides into its branches prior to exiting the orbit.
++
++
B. 3–5 mL of local anesthetic (LA) should be injected per nerve.
++
++
C. The terminal branch of V2, the infraorbital nerve, can be blocked both intra- and extra-orally.
++
++
D. The most common complication of the superficial trigeminal nerve block is penetration of the foramen.
+
++
C is correct. In the extra-oral approach, the needle is inserted perpendicular to the skin while palpating the infraorbital foramen until bony resistance is encountered. The needle is then advanced in a caudal and medial direction while keeping a finger on the foramen to prevent cephalad advancement. For the intraoral approach, the target landmark is the intersection of a vertical line through the papilla and a horizontal line through the alae of the nose. The buccal mucosa is entered between the canine and first molar and the needle advanced in an upward and outward direction.
++
A is incorrect. The ophthalmic nerve divides into its three branches (lacrimal, frontal, and nasociliary) prior to entering the orbit.
++
B is incorrect. Only 0.5 mL are necessary to achieve a successful block; 3–5 mL carry a risk of generalized seizures and/or epidural and subarachnoid anesthesia given the proximity of blood vessels.
++