Signs of Hydrocephalus in Babies
The short answer
Hydrocephalus occurs when cerebrospinal fluid accumulates in the brain ventricles, causing increased pressure. In babies, the most noticeable sign is rapidly increasing head circumference (head growing faster than expected). Other signs include a bulging or tense fontanelle, prominent scalp veins, downward gaze of the eyes ("sunsetting"), irritability, vomiting, and developmental delays. Treatment typically involves surgical placement of a shunt or endoscopic third ventriculostomy to drain excess fluid.
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By Age
What to expect by age
Hydrocephalus may be detected prenatally or at birth. In young babies, the skull sutures have not fused, so the head can expand to accommodate extra fluid. Regular head circumference measurements at well visits are crucial for early detection. A head that crosses percentile lines upward rapidly is a key warning sign.
Signs include rapidly increasing head size, bulging fontanelle when the baby is upright and calm, prominent veins on the scalp, and sunsetting eyes (the iris appears to be pushed downward by the upper eyelid). Vomiting, irritability, and sleepiness may indicate increasing pressure. An ultrasound through the fontanelle can diagnose hydrocephalus.
If a shunt has been placed, watch for signs of malfunction: increasing irritability, vomiting, sleepiness, bulging fontanelle, and rapid head growth. Shunt malfunction is a medical emergency. For babies with mild ventriculomegaly being monitored, regular imaging ensures the condition is stable.
As the fontanelle closes (usually by 18 months), signs of increased pressure change: headache (shown as irritability), vomiting, sleepiness, and personality changes become more prominent. Children with shunts need lifelong monitoring for malfunction.
Ongoing monitoring for children with treated hydrocephalus. Developmental follow-up ensures appropriate services are in place. Many children with hydrocephalus develop normally with proper treatment, though some may have learning differences that benefit from educational support.
What Should You Do?
When to take action
- Your baby's head circumference is tracking along a consistent percentile curve
- The fontanelle is soft and flat when your baby is calm and upright
- Your baby is meeting developmental milestones
- Your baby's head seems to be growing faster than expected
- The fontanelle seems fuller or more prominent than before
- Your baby with a shunt has subtle changes in behavior or appetite
- Rapidly increasing head size with bulging fontanelle, vomiting, sunsetting eyes, or extreme lethargy
- A child with a shunt showing sudden vomiting, severe headache, lethargy, or personality change (possible shunt malfunction - seek emergency care)
Sources
Related Resources
Trust your instincts. If something feels wrong, reach out to your pediatrician.
Worrying about your baby means you care. That is a good thing.
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When Should My Baby See a Pediatric Neurologist?
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My Baby's Head Shape Looks Abnormal
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Achondroplasia (Dwarfism) in Babies
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Adenoid Hypertrophy and Breathing
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