A 64 year old lady Kamla complains of severe unilateral headache on the right side and blindness for 2 days. On examination there is a thick cord like structure on the lateral side of the head. The ESR is 80 mm/hr in the first hour. The most likely diagnosis is:
**Core Concept**
Granulomatous giant cell arteritis (GCA) is a large vessel vasculitis primarily affecting the branches of the external carotid artery, particularly the temporal artery. It is characterized by inflammation of the arterial wall, leading to stenosis, occlusion, or aneurysm formation. The condition often presents with severe headache, visual disturbances, and elevated inflammatory markers.
**Why the Correct Answer is Right**
The patient's symptoms, including severe unilateral headache and blindness, are classic presentations of GCA. The presence of a thick cord-like structure on the lateral side of the head, known as the "pulseless temporal artery," is a hallmark of the disease. This is due to the inflammation and fibrosis of the artery, which leads to its obliteration and loss of pulsatility. The elevated ESR (80 mm/hr) further supports the diagnosis of GCA, as it is a common laboratory finding in this condition.
**Why Each Wrong Option is Incorrect**
* **Option A:** Temporal arteritis is a more common term for giant cell arteritis, but it does not specifically refer to the involvement of the temporal artery. The term "temporal arteritis" can be misleading, as GCA can affect other branches of the external carotid artery as well.
* **Option B:** Meningioma is a type of brain tumor that can present with visual disturbances and scalp tenderness, but it is not typically associated with a thick cord-like structure on the lateral side of the head or an elevated ESR.
* **Option C:** Carotid artery dissection is a condition that can cause unilateral headache and visual disturbances, but it is not typically associated with a thick cord-like structure on the lateral side of the head or an elevated ESR.
* **Option D:** This option is not provided, but assuming it is an incorrect answer, a common distractor would be a different type of vasculitis, such as polyarteritis nodosa or Kawasaki disease, which do not typically present with the classic symptoms and findings of GCA.
**Clinical Pearl / High-Yield Fact**
GCA is a medical emergency that requires prompt treatment to prevent visual loss and other complications. The presence of a thick cord-like structure on the lateral side of the head, known as the "pulseless temporal artery," is a red flag for GCA and should prompt further investigation, including biopsy and imaging studies.
**Correct Answer:** C. Giant cell arteritis.