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**
The question is testing the clinical diagnosis of a patient presenting with severe unilateral headache, blindness, and a palpable cord-like structure on the lateral side of the head. This presentation is suggestive of a serious underlying condition that requires prompt recognition and treatment.
**Why the Correct Answer is Right**
The patient's symptoms and signs, particularly the presence of a thick cord-like structure on the lateral side of the head, are classic for a **temporal arteritis** (also known as giant cell arteritis). This condition is an inflammatory disease of the blood vessels, specifically the medium and large arteries, including the temporal artery. The inflammation causes thickening and narrowing of the artery, leading to ischemia of the surrounding tissues, including the optic nerve, which explains the patient's blindness. The elevated ESR (erythrocyte sedimentation rate) of 80 mm/hr further supports this diagnosis, as ESR is a marker of inflammation.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the patient's presentation. While a **stroke** can cause unilateral headache and blindness, it does not typically present with a palpable cord-like structure on the lateral side of the head.
**Option B:** **Migraine** can cause unilateral headache, but it is not typically associated with blindness or a palpable cord-like structure on the lateral side of the head.
**Option C:** **Carotid artery aneurysm** can cause unilateral headache and blindness, but it is not typically associated with a palpable cord-like structure on the lateral side of the head.
**Option D:** **Sphenoid sinusitis** can cause unilateral headache, but it is not typically associated with blindness or a palpable cord-like structure on the lateral side of the head.
**Clinical Pearl / High-Yield Fact**
Temporal arteritis is a medical emergency that requires prompt treatment with corticosteroids to prevent vision loss and other complications. It is essential to consider this diagnosis in patients over 50 years of age presenting with unilateral headache, blindness, and a palpable cord-like structure on the lateral side of the head.
**Correct Answer: C. Carotid artery aneurysm**