**Question:** Headache with bitemporal hemianopia with 6/6 vision seen with:

A. Vasospasm
B. Migraine
C. Intracranial mass lesion
D. Carotid artery dissection

**Core Concept:** Bitemporal hemianopia refers to the loss of visual field in both temporal quadrants of each eye. This condition can be seen in various neurological disorders.

**Why the Correct Answer is Right:** The correct answer is migraine (option B) because migraine is a type of headache that can present with visual disturbances like bitemporal hemianopia, which is a temporary loss of visual field in both temporal quadrants. Migraine is characterized by the typical "4-phase" pattern (premonition, aura, headache, and post-dromal symptoms). In this case, the headache and visual disturbance occur together, but the vision is normal (6/6) during the attack.

**Why Each Wrong Option is Incorrect:**

A. Vasospasm (option A) is a constriction of blood vessels, typically seen in the context of subarachnoid haemorrhage or aneurysm rupture. In this case, the headache and visual disturbance would not be simultaneous, and the visual acuity would likely be compromised.

C. Intracranial mass lesion (option C) can cause headache and visual disturbances, but the presence of normal visual acuity (6/6) would make this less likely.

D. Carotid artery dissection (option D) can lead to headache and visual disturbances, particularly a hemianopia (loss of visual field in one hemifield). However, the normal visual acuity (6/6) in this case would make this less likely.

**Clinical Pearl:** While migraine is a common cause of headache and visual disturbances, it is essential to consider other potential causes like subarachnoid haemorrhage or aneurysm rupture (option A) when evaluating patients with headache, visual disturbances, and normal visual acuity. A detailed neurological examination, including visual field testing, is crucial for accurate diagnosis and appropriate management.