Headache is usually the first and the most frequently encountered symptom in intracranial infection. It is usually generalized; it may radiate down the neck and back and into the extremities, and it is severe and unremitting. Encephalitis is characterized by headache, fever, alteration of consciousness, focal neurologic deficit, and seizures (usually focal). Because the brain parenchyma has no sensory receptors, the headache of encephalitis and brain abscess may result from the meningeal inflammation that often accompanies these processes, including a nonspecific response to fever, increased intracranial pressure, or a mass-effect producing traction on pain-sensitive intracranial structures. The most common predisposing conditions of brain abscesses are otitis or mastoiditis. Physical signs of meningeal inflammation do not help clinicians rule in or rule out meningitis accurately. The headaches attributed to intracranial infection are further divided into 5 subtypes in International Classification of Headache Disorders, 3rd edition (beta version). Headache remits with resolution of the infection in most cases, and only in a few patients whose headache might persist for more than 3 months after resolution of the causative infection. However, one longitudinal study showed that the 1-year prevalence of headache suffering was not higher amongst patients with prior intracranial infection than in the general population.