Temporal (giant cell) arteritis is a chronic inflammatory process that occurs as a result of a malfunction of one’s own immune system, affecting various arteries. Another name for this disease is Horton's disease. It received this name thanks to the doctor who described the pathology in detail.
The exact cause of temporal arteritis is currently unknown. But there is an opinion that its appearance is facilitated by the aging of the body. The fact is that with age, the walls of the temporal and ophthalmic arteries and veins become less elastic, which is why immune inflammation occurs. Since this disease affects the visual system, in rare cases, lack of treatment can cause complete blindness.
Also, according to some experts, Horton's disease has some genetic predisposition. Most often women are susceptible to it.
The disease has two forms - primary and secondary. In primary temporal arteritis, it occurs independently. This form develops due to age-related changes, usually in people over 50-60 years old. The secondary form indicates the occurrence of another disease, which is a catalyst for inflammation. Most often this concerns infectious diseases in a severe stage. The most dangerous among such infections are Staphylococcus aureus and the hepatitis virus.
Causes
Not a single theory of the origin of the disease has been reliably confirmed.
Presumably, the infectious factor plays an important role in its development. There is often a natural connection between the occurrence of arteritis and previous influenza and group B hepatitis. The genetic programming of pathology also has its supporters. Cases of this rather rare disease have been observed in close relatives and identical twins. The leading role in the formation of inflammation of the vascular wall belongs to immunological disorders, and this is recognized by adherents of all etiological concepts. With temporal arteritis, the immune system reacts inadequately to its own tissues - the process proceeds as an autoimmune one.
Pros and cons of ultrasound compared to other diagnostic methods
Compared to other imaging methods, ultrasound can be performed by a physician directly during a clinical examination. Ultrasound is widely available and inexpensive, and most arteries can be easily examined. Ultrasound provides the highest resolution of all imaging modalities. Thus, it is especially useful for small vessels such as the temporal arteries.
Ultrasound vs BVA
In centers with experienced staff, clinical examination and ultrasound will clearly confirm or rule out a suspected diagnosis of GCA in most patients. BVA may be used if results are unclear, especially in patients who have negative ultrasound findings and who have been treated with glucocorticoids for a long time. If the arteries are small or deep, the segment to be biopsied can be marked using ultrasound. However, a prospective study comparing ultrasound-guided BVA with standard BVA found that ultrasound-guided BVA did not improve sensitivity. Thus, only a select few patients with a localized halo may benefit from ultrasound-guided BVA.
Many studies have shown that BVA is less sensitive than ultrasound, primarily because in generalized disease only a small anatomical area is assessed. Ultrasound may give a false-negative result in patients with localized adventitial vasculitis and vasculitis limited to the vasa vasorum of the temporal arteries. However, the main advantages of ultrasound over BVA are time and cost. Biopsy results can take 2 weeks or more to obtain and a recent publication showed that the cost of temporal and axillary artery ultrasound was reduced by £485 in favor of temporal and axillary artery ultrasound compared with BVA. Thus, new classification criteria for GCA will likely include ultrasound in addition to BVA.
Ultrasound vs MRI, CT and PET
Imaging techniques such as MRI, CT, and PET combined with CT (PET-CT) provide improved visibility of the large vessels and allow better visualization of the thoracic aorta compared with ultrasound. However, these imaging modalities are more expensive than ultrasound and may be unnecessary except in those few patients in whom the thoracic aorta is exclusively affected. In addition, radiation exposure is especially high with CT and PET scans. The use of angiography is also limited by radiation exposure and invasiveness; as a result, it plays no role in the diagnosis of GCA and should only be used when surgical intervention is necessary.
Several studies have been published that directly compare ultrasound with other imaging modalities. Available data indicate that ultrasound correlates well with PET, although PET may be slightly more sensitive in the vertebral arteries, whereas ultrasound may detect less changes in the axillary arteries. Ultrasound of the temporal and extracranial arteries also correlates well with MRI.
Imaging examinations should always be performed by a trained professional using appropriate equipment, operating procedures, and settings. The minimum training requirements of the European Federation of Societies for Ultrasound in Medicine and Biology for rheumatologists performing ultrasound of the musculoskeletal system include performing a minimum of 300 ultrasound scans to achieve level I competence.
Symptoms
The disease has no characteristic onset. Several options are possible: acute, subacute, but more often with a long period of precursors, which can last several weeks or more than one month.
The set of symptoms preceding the height of the disease and united under the general name polymyalgia rheumatica includes the following manifestations:
• general malaise;
• slight increase in body temperature within 37.2–37.5°C;
• excessive sweating, especially at night;
• aching joints;
• pain in the muscles;
• sleep disorders;
• weight loss.
Later, vascular disorders come to the fore; their nature and severity depend on the location and degree of damage to the artery. More than half of patients suffer from vision impairment. Patients note:
• headache of varying intensity, often sudden, in various areas (temporal, frontal, parietal, less often - occipital);
• hyperesthesia (increased sensitivity) of the scalp, making it difficult to comb and wear a hat;
• transient pain and numbness in the tongue and lower jaw, which intensifies when talking and chewing;
• painful, stringy compaction along the inflamed artery;
• visual impairment (decreased visual acuity, diplopia (double image), blindness);
• neurological, mental disorders.
When the aorta, coronary, renal, and mesenteric arteries are involved in the pathological process, which happens in severe untreated variants of the disease, the development of aneurysm, angina pectoris and heart attack, impaired blood supply and kidney and intestinal function are possible.
Eye damage
The most common manifestation is anterior ischemic neuropathy, a condition in which the blood supply to the arteries supplying the optic nerve in the immediate vicinity of the eyeball is disrupted. This is manifested by a sharp decrease in vision, loss of areas in the visual field (deterioration of peripheral vision), and in 30% of cases there is bilateral vascular damage with bilateral decrease in vision.
Less common:
- Occlusion of the central retinal artery (impaired blood circulation in the artery supplying the retina, with a sharp and sudden decrease in vision up to complete loss).
- Circulatory disorders in the branches of the central retinal artery (in this case, there is a loss of vision and a decrease in visual acuity, which depends on the area of the retina in which the blood circulation is impaired).
- Paralysis of the oculomotor nerve (as a result of which the movement of the eyeball is impaired, double vision occurs).
- Ocular ischemic syndrome, which occurs due to gradually deteriorating blood flow in the ophthalmic artery that supplies the eye.
In this case, various changes are observed: retinal edema, retinal hemorrhages, increased intraocular pressure, cataracts.
According to a number of studies, in more than 20% of cases, in the presence of signs of arteritis from the eye, general symptoms of the disease may be absent. Thus, if there are characteristic vascular diseases of the eyes in a patient over 50 years of age, it is necessary to exclude temporal arteritis as the main cause.
Diagnostics
The diagnosis of arteritis can be established by performing a histological examination of a section of the superficial temporal artery obtained by biopsy. The sample collection is carried out under local anesthesia and is not difficult. The detection of granulomatous inflammation of the vascular wall with the presence of giant cells is indisputable evidence of this pathology.
But histologists are able to identify typical changes only in half of the cases. The fragmentary nature of the lesion does not always allow for successful selection of the segment for biopsy. However, a negative result does not mean the absence of the disease, since the main criterion for diagnosing Horton’s disease is the totality of clinical manifestations.
Criteria have been formulated and generally accepted to recognize temporal arteritis. The diagnosis is reliable if three or more of the following factors are present:
• age over 50 years;
• headaches with severe intensity;
• vision problems;
• presence of complaints characteristic of polymyalgia rheumatica;
• decrease in the number of red blood cells and hemoglobin level in the blood, increase in ESR.
Sphygmography, rheovasography, and Dopplerography of the affected arteries are of auxiliary value for differential diagnosis. For the same purpose, the presence of C-reactive protein and the level of sialic acid and fibrinogen in the blood are determined.
Technical requirements
Modern, high-resolution linear Doppler probes should be used, especially for the study of the temporal arteries. Ultrasound resolution increases with increasing frequency, and tissue penetration increases with lower frequencies. Probes with frequencies >=15 MHz should also be used to examine the temporal arteries for mild wall thickening. Transducers with frequencies >20 MHz are increasingly available and allow clear visualization of normal temporal artery IMT.
Treatment
At the moment, there are two directions in the treatment of temporal arteritis: therapeutic and surgical . Surgical methods are resorted to in the event of the development of complications such as aortic aneurysm and thrombosis of blood vessels, especially those supplying blood to the eyeball.
The basis of treatment for the disease, without which it is impossible to achieve positive results, is the prescription of steroid hormones (prednisolone). There is no alternative to glucocorticoids. They are prescribed as early as possible and taken for a long time. Doses and regimen are selected individually, under constant laboratory monitoring of clinical and biochemical blood parameters. A combination of hormones and drugs that suppress immune responses is possible. Symptomatic treatment is also carried out using anticoagulants, agents that improve microcirculation, and vitamins.
Reliability of ultrasound
The use of ultrasound is increasingly recommended as a first-line diagnostic modality in patients with suspected GCA and can replace temporal artery biopsy (TAB) in most cases. Conversely, questions have been raised regarding the diagnostic performance and reliability of ultrasound and ascertaining the overall clinical utility of ultrasound in GCA.
To address these issues, the OMERACT initiative on ultrasound in videoconferencing was created in 2014; it includes members from Europe and the USA. The OMERACT initiative is designed to achieve consensus on common, consistent definitions that can be used in future clinical trials and to test the reliability of these definitions for image and video interpretation, and for imaging and interpretation in patients. The basis for these determinations was a systematic review of publications on ultrasound and other imaging modalities for the diagnosis of VCS using the Ovid MEDLINE, EMBASE and Cochrane databases up to March 2021. Full research articles of prospective studies involving more than 20 patients with suspected (diagnostic studies) or established (follow-up studies) primary VCS. Case–control studies and studies using continuous wave Doppler and M-mode ultrasound to examine vessel wall pulsatility were excluded because they were not considered relevant to clinical practice. A meta-analysis was also conducted to summarize the data. This work also forms the basis of the EULAR recommendations for imaging in VCS. The EULAR recommendations are expected to be published soon.
Studies that met the selection criteria for the systematic literature review included ultrasound, MRI, CT, and PET; however, the majority of selected studies examined ultrasound. The overall sensitivity and specificity of temporal artery ultrasound were 77% and 96% compared with clinical diagnosis of GCA, with likelihood ratios of 19 and 0.2 for positive and negative ultrasound, respectively. Three older meta-analyses found specificities of 83%, 91%, and 94% for the halo symptom compared with clinical diagnosis. The first meta-analysis described a sensitivity of 55% for the halo symptom, which increased to 87% when accounting for stenosis and occlusion. Another meta-analysis showed a sensitivity of 68% and 75% for the halo symptom. Detection of a bilateral halo sign increased specificity to 100%. In more recent studies, sensitivity has been higher due to improved technology and growing experience; this improvement is reflected in the most recent meta-analysis. A recently published study of 451 patients with suspected GCA, of whom 256 patients had a final diagnosis of GCA, showed a sensitivity of 91.6% and a specificity of 95.8% for ultrasound compared with the final clinical diagnosis. Another recent study (TABUL) examined the diagnostic accuracy and cost-effectiveness of US compared with BVA. In this multicenter study, the sensitivity of ultrasound compared with clinical diagnosis at 6 months was unexpectedly low (54%); however, it was higher than the sensitivity of BVA (39%). It is difficult to determine the gold standard for diagnosing GCA for testing any new diagnostic modality such as ultrasound and other imaging modalities. Despite this caveat, it is clear that BVA is less sensitive than ultrasound in most studies, especially because BVA evaluates only a limited anatomical region in systemic disease.
How reliable is ultrasound? In radiology, it is common practice to evaluate the reliability of image interpretation, but not to simultaneously evaluate image acquisition and interpretation. Although scientific evidence is lacking, ultrasound is highly operator dependent. Solving this problem requires data and interpretation to obtain images. One Spanish study showed very high reliability of image and video interpretation of temporal artery ultrasound. For all scenarios, k-values were >0.8, suggesting almost perfect agreement. In another study, interoperator agreement in the diagnosis of GCA between two sonographers at the same institution assessing the symptom of temporal artery compression was excellent, with the two sonographers disagreeing in only 1 of 60 patients. However, these data need to be confirmed by large-scale international studies.
In an online test of the reliability of images and videos of the temporal and axillary arteries of GCA patients and controls following the strict ultrasound guidelines associated with OMERACT, the OMERACT ultrasound group also achieved k-values >0.8 for intra- and inter-operator agreement for halo symptoms and compression. The TABUL study used even stricter rules when assessing the reliability of video data from 12 sonographers randomly selected from the study database, regardless of their quality. Reliability was equal to that of the 14 pathologists who described the BVA specimens, with intraclass correlation coefficients of 0.61 and 0.62, respectively. Sonographers in the TABUL study were less experienced than sonographers in the OMERACT study. Both studies show that ultrasound images and videos can reliably confirm the diagnosis of GCA. This allows the use of ultrasound as an inclusion criterion for future studies of GCA, provided that stored ultrasound videos are available for subsequent review.
Reliability has also been tested according to OMERACT guidelines in studies of patients in several other diseases such as RA and gout. This test is difficult to perform in patients with GCA because GCA responds quickly to treatment. However, a recent study was conducted with very good reliability for the overall diagnosis of GCA and moderate to good reliability for the detection of vasculitis in the relevant anatomical segments.
Forecast
Temporal arteritis is a serious disease. If not recognized in a timely manner and treated inadequately, the pathology poses a threat to the health and life of the patient. A timely diagnosis and compliance with doctors’ recommendations avoid complications and make the prognosis favorable.
In our department of vascular surgery, a full examination, qualified interpretation of the results obtained and professional implementation of all types of treatment measures are possible.
Ultrasound for disease monitoring
With treatment, the halo becomes brighter and its diameter decreases. In the temporal arteries, it may resolve from 2 days to many months after the start of treatment. Mild wall thickening may remain visible for many years, especially in patients with a halo or temporal artery occlusion; this can be determined using sensors >20 MHz. The role of temporal artery ultrasound in monitoring disease activity is still unclear, and studies are currently underway to address this issue.
In extracranial arteries, such as the axillary arteries, wall thickening usually persists for months or years, likely reflecting the greater volume of edematous tissue in these arteries. In GCA of large vessels, wall thickness can be measured twice a year. If the IMT increases, this indicates that the patient may not have received proper treatment. However, conventional ultrasound can only monitor damage; but cannot predict disease progression. Neovascularization may be a potential indirect marker of vascular inflammation, and contrast-enhanced ultrasound may reveal small vessels in the arterial wall. One recent study using contrast-enhanced ultrasound showed a correlation between increased vascular flow, disease activity, and positive PET findings. However, further research is needed before this tool can be used in clinical practice.
What is temporal arteritis?
Temporal arteritis , also called Horton's disease, giant cell arteritis , or cranial arteritis, is a rheumatic vascular disease. Large and medium-sized vessels are mainly affected. Most often, the disease occurs on the branches of the carotid artery. These vessels supply blood to the temporal region, the back of the head and the eyes. In approximately every fifth patient, temporal arteritis affects the aorta. In less than one percent of cases, the disease affects blood vessels, arteries of the brain, or other arteries of internal organs.
Temporal arteritis is one of the autoimmune diseases. Because in the affected vessels certain cells of the immune system (granulocytes and lymphocytes) accumulate and form chronic inflammation. Particularly large cells called giant cells . The disease, commonly called giant cell arteritis today, causes cells in the vessel wall to multiply and eventually narrow the affected vessel . As a result, especially during physical activity, the blood supply is no longer sufficient. Depending on the organ affected, corresponding symptoms occur.
Temporal arteritis is also called Horton's disease or Horton's temporal arteritis, according to its discoverer. This is one of the most common rheumatic vascular diseases. The disease mainly affects adults and elderly people aged 50-70 years. Giant cell arteritis affects women about three times more often than men.
