Abstract
Answer D.
This case describes a boy with acute encephalitis. It presents in a similar manner to an abscess with a short history of
headache fever confusion vomiting
Important negative signs are the absence of neck stiffness and photophobia (which are signs of meningeal irritation and therefore meningitis). Similarly, the finding of a petechial rash would not be expected in encephalitis.
Viruses are the most common cause of encephalitis. The principal viral agent is herpes simplex, which affects primarily the temporal lobes to give a bilateral low-density region on computerized tomography (CT) scan.