Giant Cell Arteritis (GCA)

What is Giant Cell Arteritis (GCA)?

Giant cell arteritis (GCA), also called temporal arteritis, is an inflammatory disease of medium and large blood vessels. It predominantly affects people over age 50 and can cause sudden, severe, and permanent vision loss if not treated immediately. GCA causes inflammation in the walls of the arteries — particularly the temporal arteries and the arteries supplying the optic nerves. When blood flow to the optic nerve is blocked by this inflammation, it results in anterior ischemic optic neuropathy (AION) and irreversible vision loss. GCA is a medical emergency, and treatment must begin immediately — even before confirmatory testing — to protect vision in the unaffected eye.

Symptoms

• New, severe headache — especially in the temple region
• Scalp tenderness (pain when combing hair or resting head on a pillow)
• Jaw claudication — pain or fatigue in the jaw muscles while chewing
• Sudden painless vision loss in one eye
• Transient visual obscurations — brief episodes of vision loss as a warning sign
• Fatigue, weight loss, fever, and general malaise
• Pain or stiffness in the shoulders and hips (polymyalgia rheumatica)

Diagnosis

Urgent blood work is the first step — ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein) are typically markedly elevated. A CBC may show anemia and elevated platelets. The definitive diagnostic test is a temporal artery biopsy, which shows characteristic giant cell inflammation in the vessel wall. However, treatment must not wait for biopsy results. Biopsy remains positive for up to two weeks after starting steroids, so there is no reason to delay treatment.

Treatment

Immediate high-dose corticosteroids are the treatment of choice. If vision loss has already occurred or is threatened, intravenous methylprednisolone (1 gram daily for 3 days) is given, followed by high-dose oral prednisone. The goal is to prevent vision loss in the second eye — once vision is lost from GCA, it rarely recovers. Steroids are gradually tapered over months to years while monitoring inflammatory markers. Tocilizumab (Actemra) is an FDA-approved steroid-sparing agent that can help reduce the cumulative steroid dose and its side effects.