Which conditions should be considered in the differential diagnosis for a child with new focal neurologic deficits and fever?

• A. Meningitis/encephalitis, brain abscess, stroke due to vasculitis or sickle cell disease, tumor, metabolic disease
• B. Migraine and tension headaches
• C. Sinusitis and otitis media
• D. Allergic rhinitis

Answer: (A)

When a child presents with new focal neurologic deficits and fever, the brain or its protective coverings must be considered as the site of illness, and the causes are most concerning when they can cause localized dysfunction plus systemic infection or inflammation. Infections and inflammatory processes that directly involve the brain or its lining—such as meningitis or encephalitis—often present with fever and can produce focal signs depending on which brain areas are affected. A brain abscess is another infectious process that creates a localized lesion with fever and focal deficits. Vascular events that alter blood flow to a specific brain region, such as stroke from vasculitis or in children with sickle cell disease, can present as sudden focal deficits and may be accompanied by fever in the setting of systemic illness. A tumor can cause new focal deficits as it grows and disrupts function, and although fever is not typical, it can occur with associated inflammation or infection. Metabolic diseases or crises can also disrupt function in a way that localizes to certain brain regions, especially in the context of systemic illness or stress.

Other scenarios are less likely to fit the combination of fever and new focal deficits. Migraines and tension-type headaches can have transient neurologic symptoms like aura, but fever is not a defining feature and persistent focal deficits are uncommon outside of a complicated or secondary process. Sinusitis or otitis media may cause fever and pain, but they do not produce true focal neurologic deficits unless a serious complication such as meningitis or a brain abscess develops. Allergic rhinitis typically does not present with fever or focal neurologic signs.

The key takeaway is to keep a broad but urgent differential that centers on infectious, vascular, structural, and metabolic brain processes, since these are the kinds of conditions that explain both fever and localized neurologic findings in a child.