oPtic Nerve Sheath Evaluation in gianT Cell aRtheritis by UltraSound

Giant Cell Arteritis (GCA) is a vasculitis affecting large and medium-sized vessels. It predominantly occurs in women, with a sex ratio of 3:1, and mainly affects individuals around 70 years of age. GCA is a rare condition, with an incidence of approximately 10 cases per 100,000 people in France. Current recommendations suggest using imaging techniques and/or temporal artery biopsy (TAB) based on the clinical resources available. The key challenge in suspected cases of GCA is to establish a rapid diagnosis. It is important to note that false-negative imaging results may occur if corticosteroid treatment is initiated prior to imaging: after 3 days for PET-CT, 5 to 7 days for Doppler ultrasound, and up to 14 days for TAB. Diagnosing GCA is not always easy and depends on depends on the prompt performance of complementary examinations. Studies have shown that the optic nerve sheath is thickened on ultrasound in patients with GCA. In this context, the investigator aims to evaluate the measurement of the optic nerve sheath via ultrasound for diagnosing GCA. Ultrasound offers a faster, non-invasive, widely available, and cost-effective diagnostic tool.