Overview of Supertrochlear Nerve Block
The supratrochlear nerve block is a special medical procedure used to lessen pain in the middle of your forehead. This technique can be used to numb the forehead region for complicated wound repairs and for a facial pain condition known as trigeminal neuralgia, among other things.
This method differs from local infiltration (another way to numb a specific area) because it doesn’t change the shape of the area being treated. It can provide significant pain relief using a minimal quantity of numbing medicine known as a local anesthetic.
The supratrochlear nerve block procedure has some similarities with another procedure called the supraorbital nerve block, in terms of the region of the body it influences and how the procedure is performed. Despite these similarities, the supratrochlear nerve block is its own unique procedure.
This block is often discussed and performed by healthcare providers in emergency and urgent care settings, plastic surgeons, neurologists, and other professionals who treat patients with painful conditions in this specific area of the head and face.
Anatomy and Physiology of Supertrochlear Nerve Block
Doctors need to know the specific anatomy involved to effectively perform a block, a type of medical procedure designed to numb certain parts of your body. One particular nerve involved is the supratrochlear nerve. This nerve is part of the bigger trigeminal nerve, which is an important nerve in the face. The trigeminal nerve splits into three branches: the ophthalmic, maxillary, and mandibular branches.
The ophthalmic branch then further divides into two parts: the supraorbital nerve and the supratrochlear nerve. The supratrochlear nerve is located just 3mm inwards from a vertical line drawn from the peak of the teardrop-shaped notch found in the inner corner of your eye, along the upper edge of your eye socket.
This nerve is responsible for sensation in the area just to the side of the middle of your forehead. Sometimes, it also provides sensation to a part of the eyebrow and the inner corner of your eye socket.
Why do People Need Supertrochlear Nerve Block
A supratrochlear nerve block is a type of medical procedure often used to numb areas of the body for specific treatments or to provide temporary relief from pain. Here are some of the reasons why someone might receive a supratrochlear nerve block:
The first is for migraine headaches. Migraine is a type of severe headache that usually causes an intense throbbing pain on one side of the head. A supratrochlear nerve block can help reduce this pain.
The second is for laceration repairs. If you have a deep cut or wound (called a laceration), doctors could use this procedure to numb the area so you don’t feel pain during the healing process.
Next, it can be used for different types of medical procedures. These could be cosmetic surgeries, procedures to relieve pressure on a nerve (nerve decompression), or treatments for other medical conditions.
Supratrochlear nerve block can also be used to numb the area around burns. Burns can be extremely painful, and this type of block can help manage the pain while the burns heal.
It can also be used for rashes caused by herpes zoster; this is a viral infection that causes a painful rash and is commonly known as shingles.
Finally, supratrochlear nerve block can be used to help relieve the pain of a condition called trigeminal neuralgia. Trigeminal neuralgia is a chronic pain condition that affects the trigeminal nerve, which carries sensation from your face to your brain. If you have trigeminal neuralgia, even mild stimulation of your face, such as from brushing your teeth, might trigger a jolt of excruciating pain.
When a Person Should Avoid Supertrochlear Nerve Block
There are certain conditions that might prevent a doctor from performing a supratrochlear nerve block, which is a medical procedure to numb a specific region of the forehead. Here’s what might get in the way:
If you’re allergic to the medication used to numb the area, then this procedure is not suitable for you.
If the patient, their legal guardian, or their designated healthcare decision-maker refuses the procedure, it cannot be performed.
Also, if the appearance and the shape of the patient’s body in the area where the doctor is supposed to inject the medicine is altered or unusual, the doctor may choose not to do the procedure.
Lastly, if there is a sign of infection, like cellulitis (a common bacterial skin infection), where the injection is supposed to be given, it’s not safe to do the procedure.
Equipment used for Supertrochlear Nerve Block
To perform a nerve block in the area above the knee called the supratrochlear area, the doctor will need certain tools and medications:
- A syringe that holds between 3 to 10 milliliters (a very small amount) of fluid.
- A 25 to 30 gauge hypodermic needle, which is a very thin needle.
- The type of local anesthetic used will depend on how long the doctor wants the area numbed for and whether the patient is allergic to certain medications. This could include drugs like lidocaine, bupivacaine, diphenhydramine, and so on.
- Something to clean the skin before the procedure, which could be a swab soaked in alcohol or chlorhexidine.
- A medication called a lipid emulsion may be on hand as an antidote for a possible overdose of the local anesthetic. However, this is rarely needed because the amount of anesthetic used for this procedure is much less than the amount that usually causes an overdose.
Preparing for Supertrochlear Nerve Block
It’s very important that doctors chat with their patients about the pros and cons of a treatment, and get their approval before proceeding. This approval is often required from an adult who makes decisions for the patient, like their parents or legal guardian, if the patient is unable to make these decisions themselves.
The doctors also need to check they have all the right equipment and medicine nearby before they start. And, if the doctor isn’t very experienced with this type of treatment, they might benefit from taking some time beforehand to plan out how the procedure will go. They could even mark out certain areas on the body before they start, to make sure they’re totally ready to do a great job with the treatment.
How is Supertrochlear Nerve Block performed
A supratrochlear nerve block is a procedure that involves injecting numbing medicine in the forehead area to manage pain. The following is a simpler explanation of the steps that healthcare providers follow when performing this procedure:
The first step involves identifying specific landmarks on your forehead. This helps the doctor proper place the needle. The landmark spot for the supratrachlear nerve block is located 3 mm from a vertical line extending from the corner of your eye (around the area where tears collect) along the browline.
Next, the doctor will clean the area where the needle will be inserted. They do this to prevent any germs from getting into the skin and causing an infection. They might use different types of antiseptic solutions like alcohol, chlorhexidine, or betadine. However, doctors usually avoid using betadine, especially on the forehead, because it can cause more irritation than the other options.
Once the area has been cleaned, the doctor will fill a syringe with a numbing medicine. The size of the needle used varies with patient’s age – a 25 gauge needle for adults and a 30 gauge for children. The usual amount of anesthesia drawn into the syringe is 3 to 5mL, but, if the patient is a child, especially an infant, the dose is based on their weight to avoid possible toxicity.
The doctor then inserts the needle at the identified spot just under the skin. They pull back a little on the syringe to make sure they haven’t punctured any blood vessels. Once they confirm they are at the right spot, they slowly inject a small amount of the medicine, usually between 0.5 to 1mL, leading to a swelling or ‘wheal.’
Beyond that, the needle is pushed a bit further closer to the nerve. The doctor will perform the pull-back test once more to ensure the needle hasn’t punctured a blood vessel before injecting another 1 to 3 mL of the numbing medicine.
Finally, the needle is removed and the doctor applies pressure to the area to prevent any bleeding. They may also lightly massage the area to stop bleeding and help the medicine spread through the area.
Possible Complications of Supertrochlear Nerve Block
After a medical procedure, there can be a few different complications that might occur, though they vary in how frequently they happen.
These complications can include:
- Bleeding or bruising in the treated area
- Infection
- Damaging the supratrochlear nerve or the supraorbital nerve, which are located close to the treatment area
- Experiencing local anesthetic systemic toxicity (LAST) – this is a reaction to the anesthetic. Some of its symptoms can involve changes in the nervous system, irregular heart rhythm, seizures, difficulty breathing, and even a coma
- Having an allergic reaction to the anesthetic used in the treatment.
There is also the chance that the angular vein, a blood vessel near the treated site, could be accidentally punctured causing a hematoma, which is a solid swelling of clotted blood within the tissues. This complication has been mentioned in medical literature before.
What Else Should I Know About Supertrochlear Nerve Block?
Using a special technique called the “supratrochlear nerve block”, doctors can numb a large portion of your forehead. This process avoids causing tissue distortion which could occur with direct numbing. Plus, it offers a substitute to pain medications like opioids.
There’s another technique called the “supraorbital nerve block,” often used to numb the forehead too. This method can numb an even larger part of your forehead, including the outsides of your face. By using a combination of the supraorbital nerve block with the supratrochlear nerve block, doctors can numb one-half of your forehead. Moreover, the numbing effect can even reach the back and the front part of your scalp.
