Trigeminal Nerve Block Medication

Updated: Jul 06, 2016
  • Author: Anusha Cherian, MBBS, MD, DNB; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Medication

Medication Summary

The goals of pharmacotherapy are to reduce morbidity and to prevent complications.

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Local Anesthetics, Amides

Class Summary

Local anesthetics block the initiation and conduction of nerve impulses.They are used to increase patient comfort during the procedure.

Bupivacaine and epinephrine (Marcaine with epinephrine, Vivacaine, Sensorcaine with epinephrine)

This decreases permeability to sodium ions in neuronal membranes, resulting in the inhibition of depolarization, thereby blocking the transmission of nerve impulses. Epinephrine prolongs the duration of the anesthetic effects from bupivacaine by causing vasoconstriction of the blood vessels surrounding the nerve axons.

An 18-gauge needle is introduced medial to the tibialis anterior tendon, and 15-20 mL of saline or 0.25% bupivacaine solution with epinephrine is injected to distend the ankle joint.

Bupivacaine (Marcaine)

Bupivacaine decreases permeability to sodium ions in neuronal membranes, resulting in the inhibition of depolarization, thereby blocking the transmission of nerve impulses.

Lidocaine (Xylocaine)

Lidocaine is an amide local anesthetic used in a 1-2% concentration. The 1% preparation contains 10 mg of lidocaine for each 1 mL of solution; the 2% preparation contains 20 mg of lidocaine for each 1 mL of solution. Lidocaine inhibits depolarization of type C sensory neurons by blocking sodium channels.

To improve local anesthetic injection, cool the skin with ethyl chloride before injection. Use smaller-gauge needles (eg, 27 gauge or 30 gauge). Make sure the solution is at body temperature. Infiltrate very slowly to minimize the pain. The time from administration to onset of action is 2-5 minutes, and the effect lasts for 1.5-2 hours.

Lidocaine and epinephrine (Xylocaine with epinephrine, Lignospan)

Lidocaine inhibits depolarization of type C sensory neurons by blocking sodium channels. Epinephrine prolongs the duration of the anesthetic effects from bupivacaine by causing vasoconstriction of the blood vessels surrounding the nerve axons.

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Neurologics, Other

Class Summary

Neurolytic agents provide a longer duration of pain relief, typically lasting for a few months. They achieve this by causing destruction of nerve fibers and wallerian degeneration of axonal fibers and Schwann cells. The neurons regenerate in 3-5 months. Often, it might take 1-2 weeks before complete pain relief is experienced.

Glycerol

Glycerol is a mild neurolytic agent used for treating trigeminal neuralgia but may cause perineural damage. Glycerol may down-regulate central neuronal hyperexcitability.

Alcohol

Alcohol is used in therapeutic neurolysis; however, because of its high complication rate, it has fallen out of favor. Concentrations of 95% will reliably lyze sympathetic, sensory, and motor components of a nerve.

Phenol

Phenol causes nerve destruction by inducing protein precipitation. It causes a separation of the myelin sheath from the axon and axonal edema. The use of higher concentrations of phenol may predispose to a higher incidence of vascular injury.

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CNS Depressants

Class Summary

For trigeminal nerve block, the patient undergoes mild sedation.

Midazolam

Midazolam increases the presynaptic GABA inhibition and reduces the monosynaptic and polysynaptic reflexes. It suppresses muscle contractions by facilitating inhibitory GABA neurotransmission and other inhibitory transmitters. The patient undergoes mild sedation with midazolam 0.5-1 mg.

Fentanyl (Duragesic, Actiq, Abstral)

Fentanyl citrate is a synthetic opioid that has 75-200 times more potency and a much shorter half-life than morphine sulfate. It has fewer hypotensive effects than morphine and is safer in patients with hyperactive airway disease because of minimal or no associated histamine release. By itself, fentanyl citrate causes little cardiovascular compromise, although the addition of benzodiazepines or other sedatives may result in decreased cardiac output and blood pressure.

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