Meningitis vs Encephalitis
How to tell Meningitis and Encephalitis apart when a board question makes them look alike.
Meningitis: fever and neck stiffness with intact cortical function; encephalitis: fever with altered mental status, seizures, and focal deficits.
Side by side
Meningitis causes fever, headache, neck stiffness, photophobia, meningeal signs, and CSF pleocytosis centered on meningeal inflammation.
Encephalitis causes fever plus altered mental status, personality change, seizures, focal neurologic deficits, or temporal lobe signs from brain parenchymal inflammation.
Infection or inflammation involves meninges and CSF spaces, producing meningeal irritation.
Infection or inflammation involves brain parenchyma, disrupting cortical or subcortical function.
CSF neutrophils with low glucose and high protein support bacterial meningitis; lymphocytes support viral meningitis in the right setting.
CSF lymphocytes with altered mental status, seizures, MRI/EEG temporal abnormalities, or HSV PCR support encephalitis.
The trap
Both can have fever and headache, so altered mental status, seizures, and focal deficits push toward encephalitis.
The repair move
For CNS infection, ask whether the meninges or brain parenchyma is the main problem.
Try a free question
CoreA patient has fever, severe headache, photophobia, neck stiffness, positive Kernig sign, and CSF showing neutrophils, low glucose, and high protein. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Meningitis. Meningeal signs with bacterial CSF pattern support meningitis.
Why the other choices are tempting
- B. Encephalitis requires prominent brain dysfunction such as altered mental status or seizures.
- C. TIA causes transient focal ischemic deficits without CSF inflammation.
- D. Migraine does not cause neutrophilic low-glucose CSF.
- E. Subdural hemorrhage is crescent extra-axial blood, not CSF infection.
Flashcards
Tap a card to flip it.
What symptom cluster points to meningitis?
Fever, headache, neck stiffness, photophobia, and meningeal signs point to meningitis.
What symptom cluster points to encephalitis?
Fever with altered mental status, seizures, personality change, or focal deficits points to encephalitis.
Quick answers
What is the fastest way to tell Meningitis from Encephalitis?
Meningitis: fever and neck stiffness with intact cortical function; encephalitis: fever with altered mental status, seizures, and focal deficits.
What is the key clue for Meningitis?
Meningitis causes fever, headache, neck stiffness, photophobia, meningeal signs, and CSF pleocytosis centered on meningeal inflammation.
What is the key clue for Encephalitis?
Encephalitis causes fever plus altered mental status, personality change, seizures, focal neurologic deficits, or temporal lobe signs from brain parenchymal inflammation.
What is the common trap with Meningitis vs Encephalitis?
Both can have fever and headache, so altered mental status, seizures, and focal deficits push toward encephalitis.