Differential Diagnosis for Fever and Severe Headache
Single Most Likely Diagnosis
- Viral Meningitis: This is often the most common cause of fever and severe headache in patients, especially if they are otherwise healthy. Viral meningitis is usually self-limiting but can be severe and requires prompt diagnosis to rule out bacterial causes.
Other Likely Diagnoses
- Bacterial Meningitis: Although less common than viral meningitis, bacterial meningitis is a serious and potentially life-threatening condition that presents with fever, headache, and stiff neck. It requires immediate medical attention.
- Sinusitis: Infections of the sinuses can cause severe headaches and fever, especially if the infection spreads to involve other structures.
- Tension Headache or Migraine: While not typically associated with fever, severe tension headaches or migraines can sometimes present with systemic symptoms including fever, especially if there is an underlying infection.
Do Not Miss Diagnoses
- Subarachnoid Hemorrhage: A life-threatening condition that requires immediate intervention. Although it typically presents with a "thunderclap" headache, fever might not be a primary symptom, but it could be present if there's an associated infection or reaction to the bleed.
- Encephalitis: Inflammation of the brain tissue, usually due to viral infections, which can present with fever, headache, and altered mental status. It's critical to diagnose and treat promptly to prevent long-term neurological damage.
- Brain Abscess: A rare but potentially deadly condition where an abscess forms in the brain, often as a result of a bacterial or fungal infection. Symptoms can include fever, headache, and focal neurological deficits.
Rare Diagnoses
- Cerebral Vasculitis: Inflammation of the blood vessels in the brain, which can cause a variety of symptoms including fever and headache. It's rare and often associated with systemic diseases.
- Neurosyphilis: A complication of untreated syphilis infection that can cause a range of neurological symptoms, including fever and headache, although it's relatively rare in areas with access to modern healthcare.
- West Nile Virus or Other Arboviruses: These can cause encephalitis or meningitis and present with fever and headache, among other symptoms. Their incidence varies by geographic location and time of year.