**Abstract**

Giant cell arteritis (GCA) is a primary vasculitis that affects especially extracranial medium-sized arteries, such as superficial temporal arteries (TAs). Three findings are important for the ultrasound (US) diagnosis of TA: "dark halo" sign, which represents vessel wall edema, stenosis, and acute occlusions. US has a high sensitivity to detect vessel wall thickening in the case of large vessels GCA. The eye involvement in GCA is frequent and consists in arteritic anterior ischemic optic neuropathies or central retinal arterial occlusion, with abrupt, painless, and severe loss of vision of the involved eye. Because findings of TAs US do not correlate with eye complications in GCA, color Doppler imaging of the orbital vessels is of critical importance (it reveals low end diastolic velocities, and high resistance index), in order to quickly differentiate the mechanism of eye involvement (arteritic, versus non-arteritic). The former should be treated promptly with systemic corticosteroids to prevent further visual loss of the fellow eye.

**Keywords:** giant cell arteritis (GCA), temporal arteries (TAs), temporal artery biopsy (TAB), "dark halo" sign, ultrasonography (US), arteritic anterior ischemic optic neuropathies (A-AION), central retinal artery occlusion (CRAO), color Doppler imaging (CDI) of the orbital vessels, end diastolic velocities (EDV), resistance index (RI)

## **1. Introduction**

Giant cell arteritis (GCA) is a primary (non-necrotizing granulomatous) vasculitis of autoimmune etiology, which especially affects extra cranial medium-sized arteries (branches of the external carotid arteries-ECAs-particularly the superficial temporal arteries-TAs) and sometimes large-sized arteries (aorta and its major branches). It is also recognized as Horton, temporal, or granulomatous arteritis. It causes narrowing of the artery, leading (by wall thickening) to partial (stenosis) or complete obstruction (occlusion) of local arterial blood flow, its clinical manifestations being expressed by signs of local ischemia [1–6].

GCA is the most common form of vasculitis that occurs in adults and in the elderly, being diagnosed over the age of 50's. Women are two to three times more affected than men. It is well known that the disease can occur in every racial group but is most common in Caucasians, especially people of northern European descent, and others in northern latitudes [1–6].

According to Hunder [7], and Jennette [8] a complete diagnosis of GCA requires the presence of American College of Rheumatology (ACR) classification modified criteria:


Several imaging techniques may be suitable in the diagnosis of GCA [9]. Compared to other imaging techniques, US is considered to be the most suitable in the evaluation of GCA patients, therefor it can easily be performed by the clinician (immediately after the general examination of patient), and it is significantly shortening the waiting period until another investigation is performed [9–16].

#### **Figure 1.**

*Giant cell arteritis (GCA) of the left superficial temporal artery (TA) shows a prominent, tender and nodular artery, that is also hypo pulsating on palpation [9].*

*An Integrated Approach to the Role of Neurosonology in the Diagnosis of Giant Cell Arteritis DOI: http://dx.doi.org/10.5772/intechopen.96379*

#### **Figure 2.**

*The histopathological examination of the left superficial temporal artery biopsy (TAB) noted [10]. (A) Thickened vascular wall with inflammatory infiltration of multinucleated giant cells, (B) epithelioid cells and (C) dissolution of the internal elastic lamina (H&E stain).*
