If a patient has uneven pupils, what condition might this indicate?

Uneven pupils, also known as anisocoria, can be indicative of several neurological conditions, but a subarachnoid hemorrhage is particularly notable for causing this symptom. A subarachnoid hemorrhage occurs when there is bleeding in the space between the brain and the tissues covering it, often due to trauma or the rupture of an aneurysm. This bleeding can increase intracranial pressure and disrupt the normal functioning of cranial nerves, particularly the oculomotor nerve, which controls pupil response. As a result, unequal pupil sizes can manifest in patients experiencing this condition.

Subdural hematomas, brain tumors, and cerebral edema can also lead to changes in pupil size, but the immediate presentation of unequal pupils is more characteristically associated with a subarachnoid hemorrhage. The presence of other neurological symptoms would help clarify the diagnosis further, but the acute onset of unequal pupils in a patient with a sudden headache or signs of neurological compromise raises the suspicion for a subarachnoid hemorrhage as a critical condition requiring prompt medical evaluation.