Differential Diagnosis for Mohan's Headache and Fever

Given the symptoms of headache and fever presented by Mohan, a comprehensive differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis
  • Viral upper respiratory tract infection (e.g., common cold, influenza): This is often the most common cause of headache and fever in the general population, typically presenting with additional symptoms such as cough, sore throat, and runny nose.
• Other Likely Diagnoses
  • Sinusitis: An infection or inflammation of the sinuses can cause headache (often localized to the face) and fever, accompanied by nasal congestion and discharge.
  • Meningitis: Although less common, meningitis is a significant consideration, especially if Mohan presents with severe headache, fever, stiff neck, and altered mental status.
  • Tension headache: While not typically associated with fever, if Mohan has a fever from another source, a tension headache could be exacerbated or perceived as worse.
• Do Not Miss Diagnoses
  • Meningitis (as mentioned, but emphasized here due to its severity): Early recognition and treatment of meningitis are crucial to prevent serious complications or death.
  • Encephalitis: An inflammation of the brain, usually caused by viral infections, which can present with headache, fever, confusion, and sometimes seizures.
  • Subarachnoid hemorrhage: Although typically presenting with a sudden, severe headache, fever might not be a primary symptom, but it could be part of the clinical picture in cases of infection or as a reaction to the hemorrhage.
  • Brain abscess: A rare but potentially life-threatening condition that can cause headache, fever, and focal neurological deficits.
• Rare Diagnoses
  • Temporal arteritis (giant cell arteritis): More common in older adults, this condition can cause headache and fever, along with jaw claudication and visual disturbances.
  • Neurosyphilis: A manifestation of late syphilis infection that can cause a variety of neurological symptoms, including headache and fever, depending on the form of neurosyphilis.
  • Cerebral vasculitis: Inflammation of the blood vessels in the brain, which can cause headache, fever, and a range of neurological symptoms depending on the areas of the brain affected.

Each of these diagnoses requires careful consideration of Mohan's full clinical presentation, including any additional symptoms, physical examination findings, and potentially, diagnostic tests such as imaging studies or lumbar puncture, to determine the underlying cause of his headache and fever.