sábado, 4 de mayo de 2019

What is Frontal Nerve Block?

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By Angela Betsaida B. Laguipo, BSNReviewed by Dr. Jennifer Logan, MD, MPH

The frontal block is used to attain regional anesthesia of the face. It’s usually chosen over local tissue infiltration since it has many advantages.

What is a nerve block?

A group of nerves dubbed as ganglion or plexus causes pain to a particular region or organ in the body. But, an injection of a medication into the specific area, near to the nerves, can reduce pain sensation. The injection of this nerve-numbing substance is called a nerve block.

A nerve block leads to the insensibility of a body part by injecting anesthesia close to the nerves that supply it. Nerve blocks have many purposes, including pain relief, determine sources of pain, examines outcomes of treatment, prevent subsequent pain from a procedure, and to avoid surgery.

What is a frontal nerve block?

The frontal nerve enters the orbit at the superior orbital fissure, and then it divides into the supratrochlear and supraorbital branches. The supraorbital nerve is a terminal branch of the trigeminal nerve. It exits the superior surface of the optical rim. It also goes through the supraorbital foramen. The supratrochlear nerve is located medially through the supraorbital notch. The two branches supply sensation to the forehead and frontal scalp, the root of the nose and the middle part of the upper eyelid.

In the face, doctors commonly anesthetize use the frontal nerve or supraorbital nerve to block pain during procedures involving corresponding areas of the face. Moreover, a nerve block requires a lesser amount of medicine than local infiltration, reducing side effects and prevents tissue distortion. Post-operative pain medication needs may also be reduced by using a frontal block.

What are the advantages of the frontal nerve block?

Nerve blocks, in general, have many advantages over regional or local anesthesia. The frontal block is beneficial for upper eyelid and lower forehead surgery including frontal craniotomies, repair of lacerations, frontal ventriculoperitoneal shunt placement, and cosmetic surgery, excision or anterior scalp pigmented nevus, skin grafting, benign tumor removal, or dermoid cyst excision.

Moreover, a supraorbital nerve block is used for conditions such as supraorbital neuralgia, Swimmer’s headache, supraorbital nerve entrapment, pain secondary to herpes zoster infection or Shingles.

What are the complications of frontal nerve block?

Frontal nerve block complications are rarely reported. But in some cases, it may lead to hematoma, eye globe damage, and intravascular injection.

Also, complications performed under ultrasound guidance are rare. Some patients may develop hypersensitivity to local anesthesia, but it’s uncommon. In some patients, they may experience post-procedural pain flare-up especially if steroids are used in the injection. Lastly, hematoma and post block ecchymosis can occur.

How is a frontal block performed?

A supraorbital nerve block can be done through the injection of local anesthesia and steroid under real-time ultrasound guidance. The doctor will target the supraorbital nerve at the supraorbital notch.

First, the doctor will prepare the site or area of injection. The site should be sterile to prevent infection. The supraorbital nerve supplies most of the forehead whereas the supratrochlear nerve supplies the nose. After preparing the site, the doctor will inject 2 – 3 ml of buffered lidocaine infiltrated with a small needle. The injection site is the eyebrow area in line with the pupil. The doctor injects medially and about 3 to 5 ml is infiltrated in a line horizontally that leads to the contraction of the middle part of the eyebrow.

The nerve is usually blocked by injection about 3 to 5 ml of 1% lidocaine or 2% mepivacaine using a 1-inch x 25G needle. The needle is injected at about 1 cm deep through the supraorbital foramen. But, doctors need to prevent injecting or touching a small blood vessel adjacent to the foramen.