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

Measles CNS Involvement in Infants: Clinical Manifestations

Yes, if measles enters the CNS in a baby, there will be symptoms—most commonly fever, altered mental status, seizures, and behavioral changes, occurring in approximately 1 per 1,000 measles cases as acute encephalitis. 1, 2

Acute CNS Manifestations

Encephalitis presents during or shortly after the acute measles illness, typically around 10 days after initial infection, with the following symptoms: 2

• Fever (often high-grade, ≥103°F/39.4°C) 2
• Altered mental status ranging from confusion to coma 1, 2
• Seizures (both focal and generalized) 1, 2
• Behavioral changes and agitation 2
• Progressive neurological deterioration with potential for permanent brain damage 1, 2

The CDC reports that encephalitis occurs in approximately 1 per 1,000 measles cases, with a case fatality rate of 1-2 per 1,000 overall measles cases in the United States. 1, 2 Survivors of measles encephalitis frequently experience permanent CNS impairment, including mental retardation and lasting neurological deficits. 2

Age-Specific Considerations for Infants

Infants face particularly high mortality risk from measles and its complications compared to older children. 1 The clinical presentation in babies may include:

• More severe systemic illness with the typical prodrome of fever, cough, coryza (runny nose), and conjunctivitis preceding neurological symptoms 1
• Koplik spots (pathognomonic white spots on red background inside the mouth) may appear before the rash 1
• Maculopapular rash beginning on the face and spreading downward, though immunocompromised infants may develop severe infection without typical rash 1

Late CNS Complication: SSPE

Beyond acute encephalitis, measles can cause subacute sclerosing panencephalitis (SSPE), a rare but invariably fatal late complication appearing years after initial infection. 1, 2 This is particularly relevant for infants, as:

• Risk is highest when measles infection occurs at young ages (approximately 4-11 per 100,000 measles-infected individuals) 2, 3
• SSPE typically presents 6-8 years after the initial measles infection, with onset generally between ages 5-15 years 3
• Clinical manifestations include insidious personality changes, intellectual decline progressing to dementia, myoclonic jerks with characteristic EEG findings, motor deterioration, coma, and death 2

Critical Clinical Algorithm

When evaluating a baby with measles, monitor for: 2

1. Fever with altered mental status during or shortly after acute measles illness
2. Seizure activity (any type)
3. Focal neurological signs or behavioral changes
4. Progressive neurological deterioration in any patient with history of measles infection (even years later for SSPE consideration)

Management Approach

For acute measles with suspected CNS involvement: 1

• Vitamin A supplementation is mandatory: 100,000 IU orally for infants under 12 months 1
• Repeat dose on day 2 for complicated measles 1
• Supportive care with aggressive fever management 2
• Anticonvulsants for seizure control using standard protocols 2
• Antibiotics for secondary bacterial infections, particularly pneumonia 1

Prevention: The Only Effective Strategy

Measles vaccination remains the only effective prevention for both acute encephalitis and SSPE. 1, 3 The CDC recommends:

• First MMR dose at 12-15 months (at exactly 12 months in high-risk areas) 3
• Second dose at 4-6 years 3
• Post-exposure prophylaxis with MMR within 72 hours of exposure may provide protection 1

Vaccination has essentially eliminated SSPE in highly vaccinated populations, demonstrating that prevention through immunization is far superior to managing the devastating neurological complications of measles infection. 1, 2, 3

Common Pitfall

Do not assume that lack of rash means lack of CNS involvement—immunocompromised infants may develop severe, prolonged measles infection without the typical rash but still experience neurological complications. 1