Giant cell arteritis – Diagnostics – Overview of Information and Clinical Research

Giant cell arteritis is a disease that demands swift recognition and urgent action to protect a person’s vision and prevent serious complications.

Introduction: Who Should Seek Diagnosis

Giant cell arteritis, also known as temporal arteritis, is a condition that requires immediate medical attention. Anyone over the age of 50 who experiences new, persistent headaches—especially around the temples—should consider seeking medical evaluation. This is particularly important if the headache is severe, unusual, or different from headaches experienced in the past.^[1]

The need for prompt diagnosis becomes even more urgent when certain warning signs appear. If you notice jaw pain while chewing, tenderness on your scalp when brushing your hair or sleeping, or any changes in your vision such as blurriness, double vision, or temporary vision loss, you should contact a healthcare professional immediately. These symptoms could indicate that the blood vessels supplying your eyes and head are inflamed, which can lead to permanent vision loss if not treated quickly.^[4]

People who already have a condition called polymyalgia rheumatica—which causes pain and stiffness in the shoulders, hips, and thighs—should be especially watchful. This condition often occurs together with giant cell arteritis. Between 40 and 60 percent of people with giant cell arteritis also have polymyalgia rheumatica, and about 5 to 15 percent of people with polymyalgia rheumatica will eventually develop giant cell arteritis.^[3]

The disease predominantly affects women more than men, and it is most common in people of Northern European descent, particularly those of Scandinavian heritage. The average age when symptoms begin is around 70 years, though it can occur any time after age 50. While it is rare in people of African or Asian descent, it can affect individuals of any race or ethnicity.^[2]

⚠️ Important

Vision loss from giant cell arteritis can occur suddenly and is almost always irreversible, even with treatment. Approximately one-third of patients who lose vision experience temporary vision loss in one eye 7 to 10 days before permanent vision loss occurs. If the condition is not recognized and treated promptly, the second eye will lose vision within 7 to 10 days in 70 percent of cases. This is why early diagnosis and immediate treatment are absolutely critical.^[4]

General symptoms that might prompt someone to seek diagnosis include feeling unusually tired, having a fever without an obvious cause, losing appetite, or experiencing unintentional weight loss. These symptoms can feel similar to having the flu, which is why giant cell arteritis can sometimes be overlooked initially. However, when these general symptoms occur alongside headaches or jaw pain in someone over 50, they should raise concern.^[1]

Classic Diagnostic Methods

Diagnosing giant cell arteritis involves several steps, beginning with a careful review of symptoms and a physical examination. When a doctor suspects this condition, they will pay particular attention to the temporal arteries—the blood vessels that run along the temples on each side of the head. During the examination, the doctor may gently feel these arteries. In someone with giant cell arteritis, the temporal artery often feels hard, like a cord, and may be tender to touch. The pulse in the artery might be reduced or absent.^[10]

Blood Tests for Inflammation

Blood tests play an important role in identifying inflammation in the body, which is a hallmark of giant cell arteritis. The most commonly used test is the erythrocyte sedimentation rate, often called the “sed rate” or ESR. This test measures how quickly red blood cells settle to the bottom of a test tube. When inflammation is present in the body, red blood cells settle more rapidly than normal. Almost everyone with giant cell arteritis has an elevated sed rate.^[3]

Another important blood test measures C-reactive protein, or CRP. This is a substance produced by the liver when inflammation occurs anywhere in the body. An elevated CRP level provides additional evidence of inflammation and helps support the diagnosis. However, it is important to understand that these blood tests alone cannot definitively confirm giant cell arteritis, since other conditions can also cause inflammation and raise these values.^[10]

A complete blood count, or CBC, is also typically performed. Most patients with giant cell arteritis have a slight anemia, meaning their red blood cell count is lower than normal. This finding, combined with elevated inflammatory markers, strengthens the suspicion of giant cell arteritis.^[4]

People with normal blood test results are much less likely to have giant cell arteritis, though there are exceptions. Some patients with the disease do not show elevated inflammatory markers, so a doctor may still pursue further testing if the symptoms strongly suggest giant cell arteritis.^[4]

Temporal Artery Biopsy

The definitive way to diagnose giant cell arteritis is through a temporal artery biopsy. This procedure involves removing a small segment of the temporal artery from beneath the skin on the temple and examining it under a microscope. A pathologist looks for specific changes in the artery wall, including inflammation and the presence of large cells called “giant cells,” which give the disease its name.^[7]

The temporal artery biopsy is typically an outpatient procedure that takes less than an hour. It is performed using local anesthesia—the same type of numbing medication a dentist uses—so the patient remains awake but feels no pain in the area. Most people experience very little discomfort during or after the procedure, and it usually leaves little or no visible scar. The biopsy can be performed within 7 to 10 days after starting treatment with steroids and will still show the characteristic changes of the disease.^[7]

It is important to know that giant cell arteritis does not affect every part of every temporal artery uniformly. The inflammation can “skip” certain sections of the artery. This means that occasionally, a biopsy may come back negative even when the person has the disease. When one biopsy is negative but suspicion remains high, doctors may recommend biopsying the temporal artery on the opposite side of the head to increase the chance of finding the characteristic changes.^[7]

Imaging Tests

In addition to blood tests and biopsy, several imaging tests can help diagnose giant cell arteritis and assess the extent of blood vessel involvement. These tests create pictures of the blood vessels and can show areas of inflammation or narrowing.

Doppler ultrasound uses sound waves to create images of blood flowing through the vessels. This test can reveal changes in the temporal arteries that suggest inflammation. It is non-invasive, meaning it does not require needles or surgery, and causes no discomfort. In some cases, ultrasound may be used instead of or in addition to a temporal artery biopsy.^[10]

Magnetic resonance angiography, or MRA, combines magnetic resonance imaging with a contrast material injected into a vein. This produces detailed images of blood vessels throughout the body. Because the test is performed inside a tube-shaped machine, people who feel uncomfortable in confined spaces should let their doctor know beforehand. MRA can be particularly useful for detecting inflammation in larger blood vessels, such as the aorta and its branches.^[10]

Positron emission tomography, called a PET scan, may be recommended if the doctor suspects that giant cell arteritis has affected large arteries beyond just the temporal arteries. This test uses a small amount of radioactive tracer solution injected into a vein. The tracer accumulates in areas of inflammation, allowing doctors to see which blood vessels are affected. PET scans are especially helpful in identifying involvement of the aorta and other major blood vessels.^[10]

⚠️ Important

If a doctor suspects giant cell arteritis, treatment with high-dose corticosteroid medication should begin immediately, even before the temporal artery biopsy is performed. Waiting for biopsy results before starting treatment can increase the risk of serious complications, including permanent blindness. The biopsy can still confirm the diagnosis if it is performed within the first week or so of starting treatment.^[3]

Additional Diagnostic Evaluations

For patients who experience vision problems, a comprehensive eye examination by a specialist called a neuro-ophthalmologist is essential. This doctor has specific training in diagnosing and managing vision problems related to giant cell arteritis. The examination includes testing central and peripheral vision, assessing color vision, checking eye movements, and performing a dilated eye exam where drops are placed in the eyes to widen the pupils so the doctor can examine the back of the eye.^[4]

Additional eye tests may include taking photographs of the retina, performing optical coherence tomography (OCT) which creates detailed images of the layers of the retina, and conducting a visual field test to map peripheral vision. Some patients may also undergo fluorescein angiography, where a special dye is injected into a vein and photographs are taken as the dye travels through the blood vessels in the eye.^[4]

Diagnostics for Clinical Trial Qualification

When researchers conduct clinical trials to test new treatments for giant cell arteritis, they use specific diagnostic criteria to ensure that participants truly have the disease. These criteria help researchers select the right patients and compare results across different studies.

The standard diagnostic criteria for enrolling patients in clinical trials typically include a combination of clinical symptoms, laboratory findings, and biopsy results. Patients must usually be over 50 years of age, as giant cell arteritis rarely occurs in younger individuals. They must present with characteristic symptoms such as new-onset headaches, particularly around the temples, or jaw pain when chewing.^[6]

Blood tests showing elevated inflammatory markers are usually required. Researchers typically look for an elevated erythrocyte sedimentation rate (ESR) and an elevated C-reactive protein level. These objective measures help confirm that inflammation is present in the body. In many clinical trials, there are specific threshold values that must be met—for example, an ESR above a certain number or a CRP level above a particular value.^[3]

A positive temporal artery biopsy provides the strongest confirmation of diagnosis for clinical trial enrollment. The biopsy must show the characteristic features of giant cell arteritis, including inflammation of the artery wall and the presence of giant cells. However, because biopsy results can sometimes be negative even when the disease is present, some trials may accept patients without a positive biopsy if they have very strong clinical and laboratory evidence of the disease.^[7]

Imaging studies may also be used as part of the diagnostic criteria for clinical trials. Some studies require evidence of large-vessel involvement documented by imaging techniques such as ultrasound, MRA, or PET scan. This is particularly important for trials studying treatments aimed at preventing complications related to inflammation of major blood vessels like the aorta.^[10]

Clinical trials may also assess the severity of the disease at enrollment. Researchers might evaluate whether patients have experienced vision loss, document the extent of their symptoms, and measure the levels of inflammatory markers. This information helps determine whether patients are appropriate candidates for the specific treatment being tested and allows researchers to track how well the treatment works.

Some clinical trials focus on patients who have never been treated before, while others enroll patients who have already received treatment with corticosteroids but continue to have symptoms or have experienced a relapse of the disease. The diagnostic criteria for these different types of trials may vary based on the research questions being asked.

Prognosis and Survival Rate

Prognosis

The outlook for people with giant cell arteritis depends largely on how quickly the condition is diagnosed and treatment is started. With prompt treatment using corticosteroids, most patients experience rapid improvement in their symptoms. Headaches and other symptoms often ease within 72 hours of starting medication, and the inflammatory markers in blood tests typically drop significantly. When treatment begins before any vision loss has occurred, the risk of blindness decreases dramatically from about 20 percent to just 1 percent.^[7]

However, patients who present with existing visual symptoms have a more guarded outlook for their vision. Even with immediate treatment, vision loss that has already occurred is typically severe and almost always permanent. The damage to the optic nerve or retina cannot be reversed. This underscores the critical importance of seeking medical attention at the first sign of symptoms, before vision is affected.^[4]

The disease itself is treatable and often curable with appropriate therapy. Most patients remain on high-dose corticosteroids for about a month, after which the dose is gradually reduced over several months. Many people are able to taper off prednisone completely after one to two years of treatment. The disease can return after treatment is stopped, which is why ongoing monitoring is necessary. However, with proper medical care, giant cell arteritis rarely causes lasting problems aside from vision loss that occurred before treatment began.^[3]

Patients who develop complications such as stroke or damage to major blood vessels like the aorta face more serious long-term challenges. Large-vessel involvement occurs in a significant number of patients and may lead to aneurysms or other vascular problems that require additional treatment. Regular follow-up with healthcare providers helps detect these complications early.^[2]

Survival rate

Giant cell arteritis itself is not typically a fatal disease when properly diagnosed and treated. The condition does not directly affect survival rates in most patients. However, serious complications such as stroke, heart attack, or aortic aneurysm can occur if the disease affects major blood vessels and is not adequately controlled. In severe cases where these complications develop, they can potentially be life-threatening.^[4]

The vast majority of patients with giant cell arteritis who receive appropriate treatment can expect to live a normal lifespan. The main risks to long-term health come from the side effects of prolonged corticosteroid treatment rather than from the disease itself. Long-term use of these medications can lead to bone loss, increased risk of infections, and other health issues. For this reason, doctors work to reduce the steroid dose to the lowest level necessary to control symptoms.^[3]

Patients who experience permanent vision loss face challenges in daily living but can adapt with appropriate support and resources. The loss of vision does not affect survival but significantly impacts quality of life and independence. With early treatment, this outcome can be prevented in the vast majority of cases.^[7]