Overview of Peripheral Nerve Block of the External Ear
People often come to the emergency room with different kinds of ear problems, like injuries, collections of fluid that need draining, or stuck foreign objects. Oral medications (pills you swallow) and parenteral medications (administered through any route other than the digestive tract, typically by injection) usually don’t help enough with the pain for the localized procedures (procedures in a specific area) needed to treat these problems. Using medications to make a patient sleepy (procedural sedation) carries a substantial risk, especially for children. Giving injections directly into the external ear can be painful and can increase the chance of the healthcare provider accidentally sticking themselves with the needle.
But if a larger area of the ear needs to be numbed (anesthesia), a peripheral nerve block can be a good option. This type of procedure numbs a specific nerve, reducing the sensation of pain in the area that nerve controls. Multiple nerves control the external ear; these nerves come from cranial nerves (nerves in your head) and the cervical plexus (a network of nerves in your neck).
In the past, the most common method of peripheral nerve block used to numb the external ear was the ring block. But with the increased availability and usefulness of ultrasound in the emergency room, recent studies suggest that ultrasound can help locate the great auricular nerve and the lesser occipital nerve (two nerves in the neck) for anesthetic blockade (meaning block them with anesthesia). Blocking the auriculotemporal nerve (a nerve in the head) has been shown to be as effective, if not more so, and provides equally good pain control using less anesthesia than the traditional ring block.
Anatomy and Physiology of Peripheral Nerve Block of the External Ear
The outside part of your ear is made up of a few different structures. These include the external auditory canal (the tube that leads to the eardrum), the auricle (or pinna, which is the visible part of the ear) and is made up of the helix, the antihelix, and the lobule), the antitragus, the tragus (the small, pointed piece of cartilage just in front of the ear canal), and the concha (the deepest part of the auricle).
These parts of the ear are supplied by several nerves that carry information between them and the brain. The two main ones are the great auricular and the lesser occipital, which come from the second (C2) and third (C3) branches of the network of nerves in the neck known as the cervical plexus. The auriculotemporal nerve, from the mandibular branch of the trigeminal nerve, and the Arnold nerve (or the auricular branch of the vagus nerve), are also involved.
The great auricular nerve can be found around the muscle on the side of the neck, the sternocleidomastoid. The lesser occipital nerve is also located around the sternocleidomastoid, slightly lower down. The auriculotemporal nerve starts from the mandibular nerve in the jaw and runs upwards in front of the ear. Finally, the auricular branch of the vagus nerve comes out of the skull bone deep to the concha.
The nerves supply different areas of the auricle. The great auricular nerve innervates the helix, concha, and lobule while the antihelix, antitragus, tragus, and concha get nerves from the great auricular nerve, the vagus nerve, and a part of the auriculotemporal nerve. Also, three nerves supply the backside of the auricle: the great auricular nerve, the lesser occipital nerve, and the vagus nerve. Detailed knowledge of the innervation helps doctors anesthetize the right area if an operation on the ear is necessary. If numbing the ear canal close to the eardrum is required, a numbing cream or a small injection might be necessary considering the complex overlap of nerve supply in this region.
Why do People Need Peripheral Nerve Block of the External Ear
In an emergency hospital setting, a doctor might numb the outer part of your ear, a procedure known as a nerve block, for a few different reasons. Here’s why they might do this:
- To manage pain and make a detailed examination of the ear possible
- For patients who cannot have general anesthesia or sedation for a procedure due to certain health conditions
- To drain and then pack an auricular hematoma, which is a collection of blood that forms within the outer part of the ear
- To drain abscesses (pus-filled pockets) and cysts (fluid-filled sacs)
- To repair cuts on the ear
- To remove something foreign that has become lodged in the ear
- To treat red ear syndrome, a condition where the ear becomes red and hot, often with no known cause
- To treat great auricular neuralgia, a condition where you feel pain in the nerve that provides sensation to the ear.
Regardless of the reason, the goal is always to ensure that the patient is as comfortable as possible during the procedure.
When a Person Should Avoid Peripheral Nerve Block of the External Ear
There are certain situations where a doctor wouldn’t give a local anesthetic to numb the external ear, such as:
1. If a person knows they are allergic to the numbing medicine.
2. If a person isn’t able to cooperate during the procedure.
3. If a person has a condition known as coagulopathy, which means they have difficulty stopping any bleeding.
4. If a person has cellulitis (a skin infection) or erythema (reddening of the skin) at the site where the injection would be given. This is because of a risk that the existing infection might spread.
Equipment used for Peripheral Nerve Block of the External Ear
To perform a nerve block on the external ear (which is a way to numb your ear for a procedure), certain tools are necessary. These are:
Requirements for Ring Block
- Clean, sterile gloves for the doctor to wear
- A surgical mask equipped with glasses or goggles for eye protection
- An injection of a numbing agent, which could be either 0.5% bupivacaine or 1% lidocaine, and may or may not include an additive called epinephrine*
- A needle size 25 or 27 in gauge that is 1.5 inches in length
- A 10 mL syringe for the anesthetic
- An antiseptic (a germ-killing solution) that’s either povidone-iodine 7.5% or chlorhexidine 2%**
- A clean, sterile 4 x 4 gauze to clean the area
The tools needed for an ultrasound-guided nerve block on the external ear are mostly the same, but this procedure also requires:
- An ultrasound machine, with a high-frequency linear probe
- Sterile gel for the ultrasound
*Historically, doctors avoided adding epinephrine to the local anesthesia used in the ear due to a perceived risk, but recent studies show it is safe and doesn’t increase the risk of tissue damage from reduced blood flow (ischemic necrosis).
**Chlorhexidine antiseptic has been less commonly used in head and neck procedures due to concerns about the risk of keratitis (inflammation of the cornea) and ototoxicity (damage to the ear, potentially causing hearing loss). However, it may offer a lower risk of infection after the procedure if applied carefully around the ear area and not in contact with the eardrum (tympanic membrane).
Who is needed to perform Peripheral Nerve Block of the External Ear?
This process needs medical professionals, like doctors or practitioners with advanced skills, who are well-trained in doing a type of nerve numbing procedure known as a “peripheral nerve block”. They also need to be experienced in doing procedures guided by an ultrasound. This ultrasound tool helps the doctor see inside the body to perform the procedure accurately. An additional person, who doesn’t need to be in sterile attire, can also help out whenever necessary.
Preparing for Peripheral Nerve Block of the External Ear
Your doctor may suggest a peripheral nerve block to alleviate your pain. This medical procedure involves numbing a specific area of your body to block pain signals. Before you agree to the procedure, the doctor will explain its pros and cons, risks and benefits. If you understand and agree to go through with it, you’ll sign a document called informed consent, which acknowledges you understand the procedure and its potential outcomes.
During the procedure, you will lie on your side with the painful area facing up. Alternatively, you can lay flat on your back with your head turned away from the doctor, with the area in pain facing upward. The doctor will then clean the areas around and including your ear, as well as your lateral neck along a large muscle known as the sternocleidomastoid muscle. The cleaning solution used depends on the practice, but if 2% chlorhexidine is used, the doctor will wait until it dries entirely before proceeding.
Once the area is prepped and clean, the doctor will cover you with sterile towels, leaving the cleaned area exposed for the procedure. If the doctor uses ultrasound to guide the process, they will set up the ultrasound machine on the side of the bed opposite where they are standing. They will sterilize a probe that gives the ultrasound visual and cover it with a sterile sheath before applying a sterile gel on the skin where the procedure will be done.
The use of ultrasound helps the doctor see the nerves more clearly and accurately deliver the nerve block. This patient-oriented process aims to ensure that the procedure is done safely, effectively, and causes as little discomfort as possible.
How is Peripheral Nerve Block of the External Ear performed
Ring Block
This process involves a medical professional giving you an anesthetic injection around your ear to numb the area. Here are the steps:
1. The doctor will make a small prick with a fine needle under your earlobe, in line with the hole of your ear.
2. The doctor will check to make sure they’re not injecting into a blood vessel.
3. They will then inject a small amount of numbing medicine at the needle entry point.
4. The needle will be slowly moved towards and over the bony bump behind your ear; parallel to the skin surface. While moving the needle slowly back, some more of the numbing medicine will be injected.
5. The needle will not be completely removed at this point.
6. The needle will now be directed towards the front of the ear, towards the area just in front of the small projection from the outer part of your ear. After checking again not to inject into a blood vessel, more of the medicines will be injected while pulling the needle out.
Following this, on the upper part of your ear, the needle will be inserted again and steps 2 through 6 will be repeated.
In total, you’ll be given around 10-12 milliliters of anesthetic medicine. The way they are injected, will kind of make letter V shapes on both lower and upper parts of your ear.
Ultrasound-Guided Great Auricular and Lesser Occipital Nerve Block
This similar process uses an ultrasound machine to improve accuracy:
1. The doctor places an ultrasound probe on your neck muscle.
2. The needle is carefully guided near a nerve under the ultrasound’s guidance.
3. Once the needle is close to the nerve (but not in it), some more numbing medicine is administered.
Auriculotemporal Nerve Block
In this procedure:
1. The needle is inserted just in front of your ear’s small projection (the tragus)
2. They’ll then inject some numbing medicine into this area as well after checking they’re not in a blood vessel.
Helpful Notes
– The “great auricular nerve” – a nerve providing sensation to your ear- can be located easily using certain landmarks on your neck.
– If the doctor wants to numb the entire outer ear, they’ll have to perform all the steps including those in the “ring block” and the “great and lesser occipital nerve block” procedures.
– The “ring block” method usually doesn’t numb the small hollow part of ear or the ear canal.
Possible Complications of Peripheral Nerve Block of the External Ear
An ear nerve block, which is a procedure to lessen pain in the ear, can sometimes come with potential complications. These might include:
– discomfort, or not doing enough to numb the pain
– bleeding from the site where the block was performed
– an infection developing at the same location
– an allergic reaction to the drug used to numb the area
– development of a hematoma, which is a swelling of clotted blood within the tissue
– injury to nearby blood vessels
– an overdose-like reaction to the numbing drug, affecting whole body
– the numbing drug accidentally affecting the facial nerve and causing temporary facial paralysis.
What Else Should I Know About Peripheral Nerve Block of the External Ear?
Blocking the nerves in the outer part of the ear is a widely used method in various places like the surgery room, doctor’s office, and emergency ward. This technique effectively numbs the ear and is relatively quick to perform. It can be used on its own or alongside other pain relief methods.
