Differential Diagnosis for Fatigue, Headache, Neck Stiffness, and Muscle Aches
Single Most Likely Diagnosis
- Viral Meningitis: This condition is characterized by inflammation of the meninges (the protective membranes covering the brain and spinal cord) due to a viral infection. Symptoms such as fatigue, headache, neck stiffness, and muscle aches are common, especially in the initial stages. The duration of 6 days also fits within the typical timeframe for viral meningitis.
Other Likely Diagnoses
- Influenza: Often presents with sudden onset of high fever, headache, muscle aches, and fatigue. While neck stiffness is not a hallmark symptom, it can occasionally be present, especially if there is a secondary bacterial infection.
- Mononucleosis (Mono): Caused by the Epstein-Barr virus, mono can lead to symptoms like fatigue, headache, and muscle aches. Although less common, neck stiffness can occur, particularly if there is involvement of the central nervous system.
- Strep Throat: While primarily known for causing throat pain, strep throat can also lead to headache, fatigue, and muscle aches. In some cases, especially if the infection spreads, neck stiffness might be observed.
Do Not Miss Diagnoses
- Bacterial Meningitis: A severe and potentially life-threatening condition that requires immediate medical attention. Symptoms can include headache, fever, neck stiffness, and altered mental status. The presence of neck stiffness and headache, even without other classic symptoms like fever or rash, warrants consideration of this diagnosis.
- Subarachnoid Hemorrhage: Although typically presenting with a sudden, severe headache (often described as "the worst headache of my life"), this condition can sometimes have a more gradual onset. Neck stiffness can be a sign of blood in the cerebrospinal fluid.
- Encephalitis: Inflammation of the brain tissue, usually due to viral infections, but can also be caused by bacteria, fungi, or parasites. Symptoms can include fever, headache, confusion, and sometimes neck stiffness.
Rare Diagnoses
- Lymphocytic Choriomeningitis (LCMV): A viral infection that can cause meningitis or encephalitis, often with symptoms like fever, headache, and muscle aches. It's particularly rare and usually associated with exposure to rodents or their droppings.
- West Nile Virus: Primarily transmitted through mosquito bites, West Nile virus can cause a range of symptoms from mild fever to severe neurological diseases like meningitis or encephalitis. Neck stiffness and headache can be part of the presentation, especially in more severe cases.
- Tick-Borne Illnesses (e.g., Lyme Disease, Rocky Mountain Spotted Fever): These can occasionally present with headache, fever, and muscle aches. While neck stiffness is less common, it can occur, particularly if there is central nervous system involvement.