Assess for alternative causes of symptoms (e.g. labs to rule out metabolic process, glucose, infectious workup)
MRI brain with contrast
Blood cultures
Definitive diagnosis by culture of surgical specimens
LP NOT helpful and may precipitate herniation
In infants, a<unk>  tap may be diagnostic and may relieve pressure
Subdural empyema
CVA
Brain abscess
Meningitis, encephalitis
Epidural abscess 
Malignancy
Subdural hemorrhage
Intracranial hemorrhage