What condition does a headache with altered mental status suggest?

A headache accompanied by altered mental status is highly suggestive of meningitis. This is because meningitis often involves inflammation of the protective membranes covering the brain and spinal cord, which can lead to increased intracranial pressure, resulting in significant neurological symptoms, including changes in consciousness or mental status.

In cases of meningitis, patients may present with a classic triad of symptoms: fever, neck stiffness, and altered mental status, which can range from confusion to coma. These symptoms arise due to the infection and subsequent inflammation, which impact the brain's function and overall mental state.

The other conditions listed, such as migraines, tension headaches, and cluster headaches, typically do not present with altered mental status. Migraines can cause severe pain and might be associated with nausea or visual disturbances, but they don’t usually affect consciousness. Tension headaches are characterized by a dull, aching pain and do not lead to changes in mental status. Cluster headaches, while extremely painful and occurring in cyclical patterns, also do not typically involve altered mental status. Therefore, in the presence of a headache and altered mental status, meningitis is the most concerning and relevant diagnosis that must be investigated.