Overview of Infraorbital Nerve Block
Nerve blocks are a type of pain relief that numbs a specific area of the body. They work by using less anesthetic than traditional pain relief methods, which helps to reduce the swelling of the tissues around the area, especially in places like the face. Nerve blocks can be particularly useful for tasks such as closing wounds, dental procedures, treating severe face pain known as trigeminal neuralgia, and other similar procedures on the middle of the face, and are often used when people can’t have general anesthesia.
However, if a wound is located in an area controlled by several nerves, nerve blocks might not be as effective.
A specific type of nerve block, the infraorbital nerve block, works on the infraorbital nerve. This nerve gives feeling to the lower eyelid, the side of the nose, the upper lip, and certain teeth. This nerve block could be particularly useful for procedures that involve the skin between the lower eyelid and upper lip, as well as dental procedures.
To achieve an infraorbital nerve block, pain medication is applied where the infraorbital nerve exists in the bone of the upper jaw, known as the maxilla bone. This can be done in two ways: from outside the mouth (extraoral approach) or from inside the mouth (intraoral approach), with the second option being more common. If going for the intraoral approach, the pain medication is injected into the inner cheek lining, opposite the upper second tooth from the back, roughly 0.5 cm from the inner cheek surface in adults. If going for the extraoral approach, the pain medication is injected into the tissues surrounding the small hole where the infraorbital nerve exists, known as infraorbital foramen. Proper care must be taken to avoid injecting the medication into a blood vessel.
Anatomy and Physiology of Infraorbital Nerve Block
The infraorbital nerve is one of the branches of the maxillary nerve, which is the second part of the trigeminal nerve. This nerve leaves a cavity in the skull called the pterygopalatine fossa and travels through another opening, the inferior orbital fissure. It then goes along the floor of the eye socket as the infraorbital nerve. This nerve is responsible for feeling in the lower eyelid, the side of the nose, the upper lip, the front teeth (incisors and canines), premolars, and the root of the first molar on the same side of the face.
The infraorbital nerve block is a procedure where anesthesiology numbs the infraorbital nerve and others such as the anterior and middle maxillary alveolar nerves, inferior palpebral, lateral nasal, and superior labial nerves. People will also feel numbness in the upper incisors, canines, and premolars. The hard tissues that support these teeth and cover them also numb along with the roots of the maxillary first molar. Certain areas along the side of the nose and inside the nasal cavity also numb using this method. But the vertebral nerve responsible for feeling in the molars, known as the posterior superior alveolar nerve, is not affected by this anesthetic.
To use anesthesia correctly, doctors look for certain markers or “landmarks” on the skull. Two crucial landmarks are the nasospinale and jugale. These landmarks determine the location of the infraorbital foramen to be used in the procedure. The nasospinale is the crossing point of an imaginary middle line of the body and the bottom of the nasal opening. The jugale is situated where the bone on the side of the skull (the zygomatic bone) meets the frontal bone of the forehead. The infraorbital foramen, the specific point where the doctor will numb the nerve, is found halfway between these two landmarks.
However, differences in how nerves supply sensation among people may impact how effective nerve blocking is. Some studies show that up to 54% of people have a middle superior alveolar nerve that exits from the groove in the infraorbital area, while 18% do not have this nerve, and the remaining 28% are varied. That’s why some medical professionals suggest a molar approach to infraorbital blocking.
In short, an infraorbital nerve block numbs certain nerves:
- The infraorbital nerve, including branches such as the Inferior palpebral branch, Lateral nasal branch, and the Superior labial branch
- The anterior superior alveolar nerve
- The middle superior alveolar nerve
The infraorbital artery and vein are near the nerve, which means the doctor needs to be careful not to inject the numbing medicine into these blood vessels.
Why do People Need Infraorbital Nerve Block
Nerve blocks are medical procedures used to reduce or completely take away pain in a specific area of the body. This is done by targeting a certain nerve or group of nerves. This can be used in a hospital during surgery, or in a doctor’s office for less major procedures. For example, when a patient is having surgery involving the upper lip (like repairing a cleft lip), nasal septum, the floor of the eye socket, or lower eyelid, a nerve block called an infraorbital nerve block is often used. This type of nerve block can also be used for less major procedures in a doctor’s office, like cleaning a wound, draining an abscess, or stitching a facial wound. It can also be used to manage pain conditions involving the infraorbital nerve, and for various dental and cosmetic procedures.
Nerve blocks offer several benefits after surgery. For instance, using an infraorbital nerve block has been shown to lessens the need for pain medications and speeds up the time it takes for infants and children to start eating and drinking by mouth after cleft lip repair surgery.
When a Person Should Avoid Infraorbital Nerve Block
There are several reasons why a person may not able to have an infraorbital nerve block, a type of anesthesia used to numb the lower part of the face:
If a person has an infection in the area where the injection is supposed to be given, they cannot have the anesthetic. Additionally, a person’s refusal to have the anesthetic, or an allergy to the substances used in the anesthetic, are also reasons the procedure cannot be performed.
If the person’s facial structure is not normal or is distorted, it can be difficult to properly administer the anesthetic. Meanwhile, coagulopathy, a condition that prevents blood clotting and can lead to excessive bleeding, also makes the procedure too risky.
Chronic pain syndromes in the injection area or wounds that affect regions controlled by multiple nerves can also prevent the procedure. Doctors need to be extra careful when a patient has facial trauma or injury, as it can make the procedure complicated and increase the chance of complications.
Equipment used for Infraorbital Nerve Block
There are many anesthetic agents, which are medications used to numb a particular area that can be used for nerve blocks, a type of medication that helps reduce pain. These can be grouped into two major types: amino amides and amino esters, primarily differentiated by their chemical structure. Amides are metabolized, or broken down in the liver; this process creates para-aminobenzoic acid, which increases the likelihood of allergic reactions. On the other hand, esters are metabolized in the plasma, specifically by enzymes known as pseudocholinesterases.
Think about it this way, amino amides usually have two “I’s” in their name, for example lidocaine and bupivacaine, while esters, like tetracaine, benzocaine, procaine, and cocaine, don’t pose this rule.
When it comes to an infraorbital nerve block, a method used to numb the area below your eye, the two most commonly used anesthetic agents are lidocaine and bupivacaine. Lidocaine works faster and for a shorter duration compared to bupivacaine. For instance, lidocaine usually begins working within 2 to 3 minutes after it’s given, while bupivacaine might take anywhere from 10 to 20 minutes to kick in. Most of the time, only 1 to 3 mL of either agent is needed, making severe side effects, such as toxicity, unlikely.
As for dosage, the total amount of lidocaine with the addition of epinephrine, a medication that is often mixed with anesthetics to prolong their effect, should not exceed 7 mg/kg, and 5mg/kg without it. Bupivacaine is a good option if you want something that lasts longer, over 12 hours, and studies show that using 0.25% and 0.5% concentrations provides excellent pain relief.
The necessary tools for this procedure include a fine thin needle (27-gauge), a blunt fill needle, gauze, a small syringe (5- to 10- mL), a local anesthetic agent, and both sterile and nonsterile gloves to ensure cleanliness and minimize the likelihood of infection.
Who is needed to perform Infraorbital Nerve Block?
An infraorbital nerve block is a procedure that needs a skilled healthcare provider – like an anesthesiologist, dentist, or doctor. These professionals are trained in a specific type of pain relief called regional anesthesia. This procedure can be done by one doctor, but having additional healthcare staff like a nurse or medical assistant can be really helpful. They can help watch over patient’s vital signs, get the patient ready for the procedure, and assist with the medical equipment.
In some situations, an extra team member might be needed to help keep the patient stable during the procedure or to quickly get important medical supplies. The entire team must make sure that they maintain a clean and sterile environment – this is known as following aseptic techniques. They always need to ensure that the patient is safe and they are prepared to handle any potential problems that might arise.
Preparing for Infraorbital Nerve Block
Getting ready for a procedure called an infraorbital nerve block involves a few very important steps to make sure the patient is safe and the procedure goes as planned. The first thing is to ensure that the patient understands what the procedure is, why it’s being done, and what the risks and benefits are. This is part of giving what’s known as ‘informed consent’, meaning the patient has all the information they need to decide whether to go ahead with the procedure.
Next, the doctor needs to know the patient’s medical history. This includes any allergies they have and any reasons why the procedure might not be safe for them. After that, the doctor marks out on the person’s face the exact spot where the nerve block will be performed. This is done if needed to help guide the procedure.
Before the procedure starts, the area of the face where the injection will be given is cleaned to make sure it’s germ-free to reduce the risk of infection. The equipment needed for the procedure, like a syringe, the correct size needle, and the local anesthetic drug, is prepared and checked to make sure everything is ready. Also, emergency equipment is kept on hand in case there’s an unexpected reaction or problem during the procedure.
How is Infraorbital Nerve Block performed
The infraorbital nerve block is a procedure that numbs your infraorbital nerve, which is located below your eye and above your upper lip. This can be done in two ways: from inside your mouth (intraorally) or from the outside (extraorally).
Intraoral Methods
There are multiple ways to perform an infraorbital nerve block from inside the mouth.
Conventional bicuspid approach: In this method, you will be made to sit in a way that the top of your mouth forms a 45° angle with the ground. A small stick with cotton on the end will be used to apply numbing gel to the area above your canine tooth on the upper jaw. The doctor will find the area that needs to be numbed by having you look straight ahead and visualizing a line moving downwards from your pupil to the lower edge of your eye socket, crossing through certain teeth in the upper jaw.
After the area is located, a needle is inserted into the gums just above your second bicuspid tooth (a tooth towards the back of your mouth), keeping it steady and straight. Before injecting the numbing medication, the doctor makes sure the needle isn’t inside a blood vessel. The medication is then injected, making sure to avoid a small hole (the infraorbital foramen).
Molar approach: In this method, the needle is inserted near your first molar tooth. It is angled at 65º relative to the upper teeth, pointing it upwards and backwards towards the area that needs numbing. This method can be less uncomfortable than others.
Alar base approach: This method can be used if you have missing teeth. The needle is placed inside the mouth, just behind the base of the nostril. When the needle touches the bone, the doctor ensures it’s not in a blood vessel before injecting 1 to 2 ml of numbing medication.
Extraoral Methods
There are two ways to perform an infraorbital nerve block from outside the mouth.
Anatomic approach: Here, the area is located just like in the conventional bicuspid approach. The skin over the targeted area gets cleaned, and the needle is inserted through your skin, fat, and muscle. To avoid hitting a nerve that controls facial movements, the numbing medication used doesn’t contain substances that narrow blood vessels.
Ultrasound-guided approach: A device that uses sound waves to create images (ultrasound probe) is positioned on the lower edge of your eye socket and is moved towards the base of your nose until a dark spot shows up on the screen, indicating the area that needs numbing. The needle is then carefully guided using the ultrasound image, and prior to injection, the doctor makes sure it’s not inside a blood vessel.
Possible Complications of Infraorbital Nerve Block
There can be complications from getting a nerve block, which is a type of anesthesia, in the area below the eye (also known as an infraorbital nerve block). These potential issues may include bleeding, swelling due to blood collecting in an area (hematoma), infection, damage to the artery or vein, unwanted injection of anesthetic into the artery or vein, damage to the nerve, or swelling of the tissues (edema).
On rare occasions, the anesthetic could mistakenly get injected into a blood vessel. If this occurs, a special medication made up of 20% fat particles can be given through the veins. This is usually given quickly, over 2 to 3 minutes, and then given more slowly to help manage the situation.
It’s important to be careful during the procedure. Goods doctors avoid injecting into an area called the infraorbital foramen because it could cause long-term nerve problems due to the nerve getting squeezed, damage to the base of the eye socket (orbital floor), or harm to the eye socket. If there is any worry about damage to the eye, an immediate consultation with an eye specialist is needed.
There could be allergic reactions to the anesthetic during the procedure. How this is managed depends on which part of the body is affected by the reaction. Other possible reactions to the anesthetic might include symptoms relating to the heart and brain. Also, methemoglobinemia – a blood disorder that affects how oxygen gets to your tissues – could occur, depending on the anesthetic used.
What Else Should I Know About Infraorbital Nerve Block?
The infraorbital nerve block is a technique that uses anesthetic medication to numb the area supplied by the infraorbital nerve. This is beneficial for repairing injuries, managing wounds, dental and beauty procedures, and providing pain relief. This method is especially useful for procedures involving the middle part of the face because it reduces swelling and needs less anesthetic compared to other methods.
