Differential Diagnosis
The patient's symptoms and history suggest a severe and rapidly progressive neurological condition. Based on the information provided, the following differential diagnosis can be considered:
- Single most likely diagnosis
- Rabies: The patient's symptoms, including pharyngeal spasms when drinking water (hydrophobia), hyperactivity, and rapid progression to coma and death, are highly suggestive of rabies. The recent history of exploring caves, where bats may be present, increases the likelihood of exposure to the rabies virus.
- Other Likely diagnoses
- Viral meningitis or encephalitis: The patient's symptoms, such as fever, chills, photophobia, and nausea, could be indicative of a viral infection affecting the central nervous system. However, the presence of hydrophobia and the rapid progression to death are more specific for rabies.
- Brain abscess or empyema: Although the head CT was negative, it's possible that a small abscess or empyema was missed. However, the patient's symptoms and rapid decline are more consistent with a viral or prion disease.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Herpes simplex encephalitis: This condition can present with similar symptoms, including fever, headache, and altered mental status. Although less likely, it's essential to consider and rule out this diagnosis due to its potential for severe morbidity and mortality.
- Tick-borne illnesses (e.g., Rocky Mountain spotted fever, tick-borne relapsing fever): The patient's recent outdoor activities increase the risk of tick exposure. While less likely, these conditions can be severe and require prompt treatment.
- Rare diagnoses
- Prion disease (e.g., Creutzfeldt-Jakob disease): Although rare, prion diseases can present with rapid neurological decline and death. However, the patient's age and lack of family history make this diagnosis less likely.
- Lymphocytic choriomeningitis: This viral infection can cause severe neurological symptoms, but it's relatively rare and typically associated with exposure to rodents or their droppings.
The most specific signs and symptoms for rabies in this patient are:
- Hydrophobia (pharyngeal spasms when drinking water)
- Hyperactivity
- Rapid progression to coma and death
- Recent history of exploring caves, where bats may be present, increasing the risk of exposure to the rabies virus.