A previously healthy 15-year-old boy with no relevant medical history presented with 3 weeks of severe, persistent, holocephalic pain associated with nausea and vomiting, without fever or alteration of consciousness. A brain MRI including magnetic resonance angiography and magnetic resonance venography (MRV) at a local hospital was normal. A lumbar puncture revealed a CSF pressure of 240 mm H 2 O. An intracranial infection was suspected based on clinical symptoms and signs. He received empiric antiviral therapy and rehydration for 1 week, but there was no relief of symptoms. He was subsequently transferred to our hospital. On admission, the patient endorsed poor spirits and poor dietary intake. He denied any neurologic deficits and his vital signs were normal. The neurologic examination revealed meningeal signs and symmetric hyperactive deep tendon reflexes of both lower extremities. Questions for consideration: 1. What is the differential diagnosis for progressive headache? 2. What tests could help narrow the differential diagnosis for this patient? GO TO SECTION 2