What are the symptoms of measles central nervous system (CNS) involvement in an older child?

Measles CNS Involvement in Older Children: Clinical Manifestations

Yes, measles CNS involvement in an older child would absolutely produce symptoms—most commonly presenting as acute encephalitis with fever, altered mental status, and seizures occurring approximately 1 per 1,000 measles cases. 1, 2

Acute CNS Manifestations

When measles virus enters the CNS during acute infection, symptomatic encephalitis develops with recognizable clinical features:

• Fever is typically present and often high-grade 1, 2
• Altered mental status ranging from confusion to coma develops as a cardinal feature 2, 3
• Seizures occur frequently and may be the presenting neurological sign 2, 3
• Behavioral changes and personality alterations can manifest 2
• Focal neurological deficits may appear depending on the extent of CNS involvement 2

The timing is predictable: neurological symptoms typically appear during or shortly after the acute measles illness, with onset around 10 days after initial infection. 2

Critical Prognostic Considerations

The mortality and morbidity burden is substantial:

• Death occurs in 1-2 per 1,000 measles cases in the United States, with encephalitis being one of the two leading causes of death (along with pneumonia) 4, 1, 2
• Permanent brain damage is a realistic outcome for survivors of measles encephalitis, including mental retardation and persistent neurological impairment 2, 5
• The case-fatality rate can reach 25% in developing countries, though this reflects overall measles mortality rather than encephalitis specifically 4, 1

Late-Onset CNS Disease: SSPE

Beyond acute encephalitis, measles can cause subacute sclerosing panencephalitis (SSPE), a devastating delayed complication:

• SSPE appears years after the initial measles infection (median latency 9.5 years, range 2.5-34 years) with insidious onset 2, 6
• Clinical presentation includes progressive personality changes, intellectual decline progressing to dementia, myoclonic jerks with characteristic EEG findings, motor deterioration, coma, and invariably death 2
• Risk is approximately 4-11 per 100,000 measles-infected individuals, with higher risk for those infected at younger ages 2
• SSPE occurs even in immunologically normal individuals and represents persistent mutant measles virus in the CNS 2, 7

The California data from 1998-2015 revealed SSPE incidence of 1:1,367 for children under 5 years and 1:609 for infants under 12 months at time of measles infection—substantially higher than previously estimated. 6

Clinical Recognition Algorithm

For acute CNS involvement during measles illness:

1. Monitor for fever onset beginning around day 10 of illness 2
2. Assess for altered consciousness including confusion, lethargy, or decreased responsiveness 2, 3
3. Evaluate for seizure activity which may be generalized or focal 2, 3
4. Document any behavioral changes or personality alterations 2

For delayed SSPE consideration:

1. Maintain suspicion in any patient with progressive neurological deterioration and history of measles infection, even without documented measles history 2, 6
2. Obtain CSF for measles-specific antibody testing showing intrathecal synthesis to confirm diagnosis 2

Important Clinical Pitfalls

The absence of typical measles rash does not exclude CNS involvement—immunocompromised patients may develop severe measles with CNS complications without the characteristic rash. 4, 1

SSPE can occur even in older patients with no specific documented history of measles infection, as many measles cases are subclinical or forgotten. 6 Clinicians should maintain awareness of SSPE in compatible presentations regardless of age or recalled measles history.

The mechanisms of CNS entry remain incompletely understood—neural cells do not express the known measles receptors (CD46 and SLAM), yet CNS infection clearly occurs. 7, 8 This underscores that symptomatic CNS disease represents a real and serious complication despite incomplete mechanistic understanding.

Management Considerations

For acute measles with CNS involvement:

• Vitamin A supplementation is recommended: 200,000 IU orally for children over 12 months, repeated on day 2 for complicated measles 1, 2
• Supportive care with treatment of secondary bacterial infections is essential 2, 5
• Aggressive fever management with acetaminophen or ibuprofen 2
• Standard anticonvulsant protocols for seizure control 2

For SSPE, treatment options are extremely limited—intrathecal ribavirin has been attempted with minimal success, and the condition remains invariably fatal. 2