Differential Diagnosis for a 16-year-old Girl with Fever, Headache, and Confusion
Single Most Likely Diagnosis
- Herpes Simplex Virus Encephalitis (HSVE): Given the patient's history of Herpes Simplex Virus Type 2 and presenting symptoms of fever, headache, and confusion, HSVE is a strong consideration. It is a medical emergency that requires prompt treatment.
Other Likely Diagnoses
- Bacterial Meningitis: The symptoms of fever, headache, and confusion could also suggest bacterial meningitis, an infection of the protective membranes covering the brain and spinal cord. The high fever and heart rate support this possibility.
- Viral Meningitis: Similar to bacterial meningitis but caused by a virus, this could present with fever, headache, and confusion, although it tends to be less severe than bacterial meningitis.
- Severe Acute Respiratory Syndrome (SARS) or COVID-19: Although less likely given the specific history of HSV-2, these viral infections can cause severe illness with fever, headache, and in severe cases, confusion due to hypoxia or encephalitis.
Do Not Miss Diagnoses
- Subarachnoid Hemorrhage: A life-threatening condition that could present with sudden headache and confusion. Although less likely given the fever, it's crucial not to miss due to its high mortality rate if not promptly treated.
- Brain Abscess: An infection in the brain that could cause fever, headache, and confusion. It requires urgent diagnosis and treatment to prevent serious complications.
- Sepsis: The patient's high fever and heart rate could indicate sepsis, a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs.
Rare Diagnoses
- Autoimmune Encephalitis: A rare condition where the body's immune system attacks healthy brain cells, leading to inflammation of the brain. It can present with fever, headache, and confusion, among other symptoms.
- Cerebral Vasculitis: Inflammation of the blood vessels in the brain, which can cause a variety of symptoms including fever, headache, and confusion. It is rare and often associated with systemic diseases.
- Prion Diseases (e.g., Creutzfeldt-Jakob Disease): Extremely rare, fatal brain disorders that can cause dementia, memory loss, and personality changes, but are less likely to present with fever and headache as primary symptoms.