Vasculitis: symptoms and causes of Horton's arteritis

By Cristiano Antonino On Sep 23, 2022

Horton’s arteritis is a form of vasculitis: inflammation of the blood vessels, most common in older people with a calculated incidence in the most affected countries of Northern Europe of 17-18 cases per 100,000 over 50

What is Horton’s arteritis

Horton’s arteritis (AH), from the doctor who first described it in 1937, also referred to as giant cell arteritis or temporal arteritis, is an inflammation that affects certain large and medium-sized arteries of the body, in particular, and more frequently, certain arteries that irrigate:

head (temporal arteries);
eyes and eye area (ophthalmic, posterior ciliary);
neck and trunk (vertebral arteries).

The inflammation forms agglomerates (granulomas) composed of various elements, such as immune system cells and connective tissue fragments, which infiltrate mainly the middle layer of the blood vessel (middle tonaca), but can also affect all 3 layers of the artery walls (intima, middle tonaca and adventitia tonaca).

Symptoms of giant cell arteritis

The clinical manifestations of the disease can be varied and diverse, but with a systemic symptomatology found in most patients.

Among the main symptoms of the disease are

headache: approximately 90% of subjects present with an intense headache that can be localised in various areas such as:
temporal area (to the sides of the eyes, in the direction of the ear);
top of the head;
occipital area (the part of the head located above the back of the neck);
pain in the scapular musculature: in 15-30% of cases accompanied by headache and with characteristics superimposed on polymyalgia rheumatica (PMR), an inflammatory disease causing pain and joint stiffness in the neck, shoulder and pelvic girdle area
fever: present in approx. 15% of cases, rarely exceeding 39° C;
pain during chewing (claudication of the masseters), due to ischaemia, i.e. insufficient blood supply to the masticatory muscles. In these cases the pain may radiate to: face; ears; tongue, mouth and oral cavity;
cough of unknown cause;
peripheral arthritis, affecting large joints such as:
knee;
elbow;
ankle;
wrist;
peripheral neuropathies: approx. 15% of patients present with peripheral nerve damage and disorder (multiple mononeuritis, polyneuropathy etc.);
other rare symptoms such as cerebral ischaemia; spinal cord infarction; dementia; scalp necrosis.

On objective examination, about 50 per cent of subjects show pain on touching the temporal artery, which appears thickened and/or with nodules, so that it is often not possible to detect the arterial pulse.

Horton’s arteritis may also present in some cases with ocular symptoms, including:

blindness: the most severe clinical manifestation, which affects about 20 per cent of cases, is the loss of vision on one or both sides, mainly linked to an occlusion of the posterior ciliary arteries. Initially this blindness may be transient and perhaps unilateral, but without appropriate treatment it can become permanent within a few weeks, which unfortunately occurs in about 30% of cases;
double vision (diplopia), in 2-15% of cases;
no ocular manifestation: between 5-40 % of cases, with a significant risk of ocular complications.

The causes of the pathology

The inflammation caused by Horton’s arteritis results from activation of the innate and acquired immune system with triggering causes, however, that are not yet known, as is the case with most vasculitides.

One can speak, however, of a genetic predisposition.

Who it affects

Temporal arteritis appears to affect females 2 to 6 times more than males, with the likelihood of developing the disease increasing with age, so much so that at 90 years of age the risk is 20 times higher than at 50/60 years of age.

The populations of Northern Europe and the United States have the highest number of cases, increasing, according to some data, but this could also be due to an increasing awareness of the disease, which appears to be very rare in Asians and black people.

Diagnosis of giant cell arteritis

In suspected cases of Horton’s arteritis, the doctor prescribes blood tests (ESR and C-reactive protein) to detect the presence or absence of inflammatory markers.

In addition to these, the gold standard for diagnosis to date is the temporal artery biopsy: a sample of at least 2 cm in length taken from the anatomical site where the major disturbances are found.

It is, however, an invasive procedure which, as such, can also carry risks; moreover, a negative result does not completely rule out the presence of the disease.

Ultrasound as the future of diagnosis?

Ultrasound of the temporal arteries could represent an evolution of biopsy, which, especially in acute phases and provided it is performed by experienced personnel, would appear to be particularly sensitive.

Not all the scientific community, however, agrees on this.

To complete the diagnostic picture, PET (positron emission tomography) with fluorodeoxyglucose can also be used to assess the presence or absence of arteritis at the level of the aortic branches.

Treatment for Horton’s arteritis

The therapy for Horton’s arteritis essentially involves the administration of corticosteroids initially in high doses (0.5/1 mg per kg of the subject), decreasing them at the same time as the inflammation decreases.

Within a few months, in most patients there is a good response to the treatment, which may lead to its definitive discontinuation or indefinite, but low-dose maintenance.

In cases where, however, there is no improvement or relapses occur, other therapies include the administration of substances that inhibit the Interluchin 6 receptor; responsible for inflammation, and can therefore allow a remission of the disease as well as limit the use of corticosteroids and the effects of their chronic use.

The importance of timeliness in Horton’s arteritis

Horton’s arteritis is a disease that can nowadays be effectively managed if it is diagnosed early, which is indispensable in order to be able to prevent greater damage such as blindness through medication.

This is why it is of paramount importance to make people aware of the need to see a doctor as soon as possible if they experience symptoms that can be traced back to the one indicated.

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