Temporal arteritis, also known as giant cell arteritis, is an inflammatory vasculitis of the small and medium arteries that originate from the aortic arch.
It can also involve the larger arteries, including the ascending aorta.
Given the potential for irreversible visual loss if not identified and treated promptly, this diagnosis remains extremely important from both a clinical and legal standpoint.
Pathophysiology of Temporal Arteritis
The pathophysiology of this disease is not well understood.
The leading research suggests that with age, genetic predisposition, and inflammation, the body has a “maladaptive response to endothelial dysplasia (Waickus, 2016), resulting in a subsequent inflammatory response of the intima, media, and advetitia of the artery itself.
Once the inflammatory response begins, the body releases cytokines, macrophages, and multinucleated giant cells, hence the name of the disease.
Risk Factors for Temporal Arteritis
Given the ramifications of missing the diagnosis, temporal arteritis is a commonly tested subject on end of rotation exams and a common board question scenario.
Being able to recognize the characteristics of the disease and initiating treatment is paramount clinically as well, as the lifetime risk for developing temporal arteritis is 1% in women and 0.5% in men, respectfully.
Age, hypertension, ethnicity, particularly Caucasian are risk factors. Advancing age is one of the single most important risk factors. The disease is virtually unheard of in patients under 50 years old. Over 80% of patients with temporal arteritis are greater than 70 years old.
An association with temporal arteritis is that of polymyalgia rheumatica. Polymyalgia rheumatica is another inflammatory disease of the shoulders, neck, and pelvic girdle. It is thought that patients with temporal arteritis have comorbid polymyalgia rheumatica in up to 50% of cases.
Symptoms of Temporal Arteritis
Patients presenting with temporal arteritis can present with a variety of symptoms.Fever, fatigue, weight loss, and other vague symptoms may be all that is present.
A headache may occur in up to two-thirds of patients, making it the most common symptom.
Despite exam questions focusing on temporal headaches, it is important to note that the headache in temporal arteritis can be in the temporal region, diffuse, or anywhere else.
Usually the only important thing about a headache is that it is usually new in onset.
A very important clue in the history is jaw claudication. Up to one half of patients may have new onset jaw claudication. This is due to a disruption in blood flow to the masseter and pterygoid muscles of mastication, resulting from vasculitis of the external carotid artery.
Other, more bizarre symptoms, can even include macroglossia if the tonsillar artery is involved.
Perhaps the most dreaded symptom related to temporal arteritis is visual loss. Amaurosis fugax is a painless, abrupt onset visual loss, most often described as a curtain coming down over the eye.
Diplopia can be present as well. Visual loss can be monocular or binocular.
The Physical Exam in Temporal Arteritis
The first clue to examination in a patient with temporal arteritis is that patients appear systemically ill.
Palpation of the scalp may reveal tenderness. There may be a visible temporal artery prominence and frank tenderness to palpation.
Given that the disease can impact other arteries, a thorough examination of the carotid, temporal, brachial, and radial pulses should be performed.
Cardiac auscultation should check for the murmur of aortic regurgitationm, which can indicate that the ascending aorta is involved. It is important to note that the vasculitis associated with giant cell arteritis may impact more than just the temporal artery
Funduscopic exam should be performed to check for cotton wool spots, edema, and hemorrhages. A comprehensive eye exam may be needed by a trained ophthalmologist.
The Workup for Temporal Arteritis
If the diagnosis is suspected, lab work should be completed to support the diagnosis. Standard lab work includes a CRP, ESR, CBC, and CMP.
The inflammatory markers are key to diagnosis. An ESR greater than 50 mm/hr can be suggestive of the disease, but may be elevated for other reasons. It is important to note that the ESR and CRP can be normal in acute temporal arteritis, but this is very unlikely.
The lab tests should not be used to rule in or rule out the disease, but rather should be used to support the history and physical. A C-reactive protein greater than 2.45 in the setting of symptoms and compatible exam has a 97% sensitivity for the disease.
The gold standard test for temporal arteritis is the temporal artery biopsy. In the setting of time, a color Doppler ultrasound may be used to look for inflammation and edema in the artery, but is operator dependent.
A better alternative is histologic analysis of the temporal artery. The temporal artery is usually chosen because it is easy to access. The sample taken must be at least 2 cm long to be valid. The sensitivity of temporal artery biopsy is 87% (Waickus, 2016).
Biopsy results suggestive of temporal arteritis include inflammation in the artery wall and edema. The classic multinucleated or “giant cells” may only be seen in about 40 to 50% of cases.
Treatment for Temporal Arteritis
The treatment of temporal arteritis is glucocorticoids. The initiation of glucocorticoids should begin as soon as the disease is suspected and should not be delayed for lab work or a temporal artery biopsy.
The chance of visual loss, once steroids are initiated, is very low. Sources suggest giving between 40 and 60 mg of prednisone upon suspicion of the diagnosis. Methlyprednisone may be used as well.
The dosing beyond the first few days can involve a complicated taper which should be performed by a specialist. Most patients with temporal arteritis should start improving within 24 to 48 hours of steroid initiation. If visual loss is present, initially IV steroids are preferred.
Given the complexity of long tapers, there is significant concern for relapse of the disease. The average taper can last from 9 to 12 months, but in some cases, may require years of therapy to avoid recurrence of the disease.
The ESR and CRP can be used as markers of progress and may be drawn to monitor taper progression. Some new studies suggest that aspirin may be helpful long term in temporal arteritis, but data is still being collected.
Summarizing Temporal Arteritis
Temporal arteritis is a very important clinical condition. The diagnosis should be suspected in patients with headache, visual loss, and other constitutional symptoms.
Inflammatory markers such as CRP and ESR are supportive of the diagnosis.
The gold standard diagnosis is via temporal artery biopsy.
Visual loss, the most feared complication of the disease, is unfortunately usually permanent.
However, on a brighter note, if glucocorticoids, which are the hallmark of treatment are initiated prior to visual loss, it is unlikely that the patient will lose their vision.