Overview of Temporal Artery Biopsy
Giant cell arteritis, which was previously known as temporal arteritis, is a condition where inflammation affects medium to large-sized arteries, which are blood vessels that carry blood from the heart to the rest of the body. This condition usually affects the branches of the carotid artery, which is a major blood vessel in the neck that supplies blood to the brain, neck, and face. However, the disease process is not limited to the temporal artery, which is an artery that can be felt just in front of the ear.
If you have giant cell arteritis, you might have symptoms like headaches in the temple area, scalp pain, jaw pain when chewing, and changes to your vision. Sometimes, these vision changes could lead to blindness if not treated. This illness is often linked with polymyalgia rheumatica, which is another inflammatory condition that causes muscle pain and stiffness, most commonly in the shoulders.
Speaking in scientific terms, giant cell arteritis is a form of arteritis where certain types of white blood cells, specifically mononuclear cells and giant cells, infiltrate the vessel wall, leading to inflammation. If doctors take a biopsy, or a small sample of the superficial temporal artery (the artery just in front of the ear), and find these specific changes, it confirms the diagnosis of giant cell arteritis.
Anatomy and Physiology of Temporal Artery Biopsy
Understanding the structures of certain parts of your head, such as the superficial temporal fascia, superficial temporal artery, and the temporal branch of the facial nerve, is important for safely doing a procedure called a temporal artery biopsy.
The superficial temporal artery is a blood vessel that comes up just in front of the tragus, which is a small pointed part of your outer ear. This artery comes off a main artery in your neck. It quickly branches into the middle temporal artery, which plays a key role in supplying blood to your ears and surrounding areas. Then, it divides further into the frontal and parietal branches, each branching off into smaller vessels.
In the majority of people, these arteries branch off higher on the ear. However, in a smaller portion of the population, the arteries branch off lower, near the tragus. This is significant because when the arteries branch off lower, the temporal branch of the facial nerve is closer to the artery, increasing the risk of damage during the biopsy.
Now, let’s talk about the relationship between the superficial temporal artery and the temporal facial nerve. The superficial temporal fascia, also known as temporoparietal fascia, is a layer of tissue that rests just below the fatty tissue of the scalp. This tissue connects with other facial tissues below and others toward the top of the head. The superficial temporal artery moves up within this tissue before splitting into the frontal and parietal branches.
The temporal branch of the facial nerve exits near the ear, making its way to the forehead and eye area to control the muscles for expressions. It is safer to perform a temporal artery biopsy, where a small piece of the artery is cut out, in the areas where the nerve is not present, i.e., above the hairline on the forehead side. But in areas that lack muscles, like the temples, the nerve is more prone to damage.
When planning for a biopsy, the dangerous and safe zones are outlined to avoid any nerve damage. Certain areas near the outer edge of the eye and ear are considered safe zones, while the area between the highest crease of the forehead and earlobe to the eyebrow is considered a danger zone. Other surgeons recommend taking the biopsy from the main trunk of the superficial temporal artery, while some suggest doing it on a branch of the artery to keep the risk to the facial nerve to a minimum.
Why do People Need Temporal Artery Biopsy
Giant cell arteritis is a condition that can lead to sudden vision problems, including temporary or permanent blindness. The early diagnosis of this condition is very important. Symptoms like pain in the head or neck, pain while chewing or talking, muscle aches, tenderness in the temple area, and increased levels of inflammation markers in the blood can indicate giant cell arteritis. However, these symptoms alone won’t certainly confirm the disease, as no single sign or symptom is completely accurate at identifying it.
Because of its high accuracy, conducting a temporal artery biopsy (TAB), which is a test that involves taking a small piece of the blood vessel from the side of your head for examination, is considered the gold standard for diagnosing giant cell arteritis. So, if there’s a suspicion of this disease, TAB should be considered. Importantly, a treatment with anti-inflammation medicines called corticosteroids should not be delayed until after the TAB results are in. This is because starting steroids within 10 days of the biopsy won’t significantly change the results, and starting the treatment early can help reduce the severity of the disease.
Lastly, people aged 50 years or older who have higher than normal levels of inflammation markers in their blood (for example, C-reactive protein levels equal to or more than 25 mg/L or erythrocyte sedimentation rate equal to or more than 50 mm/h), and experience at least one of the following symptoms such as new or unusual headaches, new vision changes, and pain in the jaw or tongue while chewing or talking, should be highly suspected of having giant cell arteritis.
When a Person Should Avoid Temporal Artery Biopsy
There aren’t many reasons why a doctor might choose not to perform a temporal artery biopsy, or TAB – this is a procedure that lets doctors examine a blood vessel at your temple to look for signs of certain diseases.
However, medical experts can’t seem to agree on whether or not it’s a good idea to do a TAB after a patient has been taking corticosteroids for a long time. Corticosteroids are a type of medication that can treat a variety of conditions, but they can also affect medical tests. According to some, these medications don’t really change the outcome of the TAB. Others, however, believe that taking these medications for two to four weeks can significantly alter the results of the biopsy.
Also, if a patient has already had a TAB which didn’t show any signs of a condition called giant cell arteritis, some doctors may see this as a reason not to perform another biopsy on the other side. This is mainly because only around 2-3% of patients end up testing positive in these circumstances.
Equipment used for Temporal Artery Biopsy
When getting a temporal artery biopsy, which is a medical procedure to remove a small piece of tissue from the artery near your temple, the following equipment is used:
The preparation stand, which is not required to be sterile, helps to hold all the necessary tools. Doctors use a Doppler ultrasound, a device that uses sound waves to image blood flow, along with a water-based gel to ensure the ultrasound works properly. A marking pen is used to make a visible note on the skin where the biopsy will be taken. Cooling, absorbent dressings known as 4×4 gauze are used, along with a numbing cream containing 4% lidocaine.
The actual biopsy procedure involves Lidocaine with epinephrine, a type of local anesthetic mixed with a drug that narrows blood vessels to reduce bleeding, to numb the area. Hypodermic needles of differing sizes (18-gauge and 27-gauge) are used, along with a specific syringe for applying local anesthesia. An electric hair clipper might be needed to cut away any hair around the biopsy area. The sample collected during the biopsy is placed in a special container with formalin, a solution to keep the tissue sample preserved.
A sterile Mayo stand is used to hold surgical instruments and supplies during the procedure. The scalpels (sharp surgical knives), forceps (tool for grasping) and scissors are used to cut and hold the tissue. Certain suction tips and clamps are used to help the surgical process. Needle holders are used for stitching, and retractors are used to hold the tissue apart.
There are also specific tools to stop bleeding (cautery tools) and different types of sutures (stitches), which are made from different materials and have different qualities. The procedure concludes with a dressing of ointment, tape, and gauze to protect the biopsy site.
Who is needed to perform Temporal Artery Biopsy?
A temporal artery biopsy is a procedure carried out by a specialized surgeon who has the necessary skills and experience. Usually, this surgeon is an eye specialist, known as an ophthalmologist. They will be assisted by a nurse who will lend a helping hand during the procedure and also keep a close eye on you after the procedure to make sure everything is okay.
Preparing for Temporal Artery Biopsy
Choosing the right place for a biopsy, a small tissue sample, is crucial for diagnosing a condition known as giant cell arteritis. This condition can cause symptoms like visual disturbance, headaches, or tenderness in an artery. These symptoms help guide the doctor to determine which side of the head to take the biopsy from. However, a physical exam doesn’t always clearly show the best spot for a biopsy.
To find the best place, doctors commonly use a tool called a Doppler ultrasound. This tool helps identify a safe spot on the forehead branch of the temporal artery – an artery on the side of the head. This spot is usually just behind the front hairline, which is a good location because it allows any scarring to blend in with the hair.
During the procedure, the patient lies back in a semi-reclined position. The surgeon marks out two spots: a 5-centimetre (about two inch) length of the artery and a separate 3-4 centimetre (about one and a half inch) incision spot. They choose this length because the disease can affect different segments of the artery. This way, the doctor can get a better idea of what’s happening inside the body.
How is Temporal Artery Biopsy performed
The following steps describe a surgical procedure for taking a sample of a blood vessel called the temporal artery, which travels across the side of the head.
To begin with, the area where the surgery will take place is prepped. Hair may be trimmed if it’s in the way, and the skin is washed and covered with a sterile cloth (this is called ‘draping’). The surgeon will then apply a local anesthetic to numb the area. This anesthetic also contains a medication called epinephrine, which helps to reduce bleeding during the procedure.
Next, the surgeon makes a small cut with a scalpel on the skin above the artery. They will then use small scissors and hooks to gently pull apart the incision. This reveals a layer of tissue called the superficial temporal fascia, which they’ll hold in place using forceps. After making another small insicion in this fascia, they will be able to see the artery itself. If the surgeon has trouble finding the artery, they can try to feel for its pulse.
The surgeon then needs to remove a small piece of the artery, about 5 centimeters long. This piece will be sent to a lab for testing. To do this, they have to ‘ligate’, or tie off, any small branches coming off the part of the artery they plan to remove. They also ligation the artery above (proximal) and below (distal) the piece they’re removing. This is to prevent bleeding. Some surgeons may also apply a tool which uses electricity to stop any bleeding (this is called ‘electrocoagulation’). After removing the piece of artery, the surgeon will also apply electrocoagulation to the ends left behind.
Once the wound is no longer bleeding, it’s time to close it up. First, the surgeon will stitch together the deeper layer of the skin using a special type of suture that dissolves over time. Then, they’ll use either a skin adhesive (a type of medical ‘glue’) or more sutures to close up the outer layer of the skin.
There are also some helpful tips that surgeons keep in mind during the procedure:
- Drawing a ‘safe zone’ on the skin before starting can guide the surgery and make it easier.
- Blunt dissection (pulling apart tissue using tools rather than cutting) should be used while exposing the artery.
- Additional, deeper cuts should be avoided once the artery is visible.
- It’s important to look for nerves nearby the artery and be careful not to accidentally harm them.
- The frontal branch of the artery is the best place to take the sample from, instead of the main part or the parietal branch which is at the back.
- The surgeon should be gentle when handling the artery.
Possible Complications of Temporal Artery Biopsy
Reading a temporal artery biopsy (TAB), which is a procedure to take a small sample of artery for testing, can be tricky. There’s a chance that the results might miss some important signs of disease. This can happen in 5% to 10% of cases. Part of ensuring accurate results falls on the surgeon. They need to carefully select where to take the sample from, handle the tissue properly, and make sure the sample is big enough. Even then, sometimes the results might show no signs of disease where they do exist. In some situations, doing the procedure on both sides might provide more information and fewer false negatives.
The procedure does carry some risks. The biggest one is temporary or lasting damage to a facial nerve that sits near the temporal artery. To reduce this possibility, doctors can use an ultrasound to identify the artery’s position, make cuts right above the artery to protect the nearby nerve, and use delicate techniques during the procedure. Past studies have found that some samples contained part of this nerve and some patients experienced facial muscle weakness even six months after the procedure.
Besides the common risks associated with any surgery like bleeding, infection, and wound opening, TABs can cause some very rare complications. These include a stroke caused by a blockage in the blood supply to the brain and tissue death in the scalp and tongue. To reduce these risks, some doctors suggest feeling and holding the pulse of the artery for several minutes before starting the procedure. This ensures that other arteries can supply enough blood in case something goes wrong during the TAB.
What Else Should I Know About Temporal Artery Biopsy?
Giant cell arteritis is a condition that causes inflammation in the arteries in your head, especially those in your temples. The most reliable way for doctors to diagnose this conditions is by taking a small sample (biopsy) from one of these arteries. However, even with this method, a negative result doesn’t always mean you don’t have the disease. So doctors may use other clues to help them decide.
For example, doctors can be pretty sure you have this condition if you have three out of these five things:
- You’re 50 years old or older when your symptoms start
- You’ve recently started experiencing headaches
- Your temporal artery (the one running along your temples) is unusually tender or its pulse is not easy to feel
- A blood test called ESR (Erythrocyte Sedimentation Rate) reading is equal or more than 50 mm/hr. This test checks for inflammation in your body.
- The biopsy from your temporal artery shows signs of inflammation, with certain types of immune cells (mononuclear cells or giant cells) or a specific kind of swelling (granulomatous inflammation).
Remember, always consult with your doctor if you’re experiencing any concerning symptoms. It’s important to get diagnosed and properly treated for any condition you might have.
