Signs of Hydrocephalus in Babies
Medically reviewed by Dr. Michael Okonkwo, MD, FAAP · Board-Certified Neonatologist
Content reviewed against published NIH, AAP, Mayo Clinic guidelines
Last reviewed:
If your baby has been diagnosed with or you suspect signs of hydrocephalus in babies, here is what the evidence says.
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.
Key takeaways
- 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.
- Usually normal when: Your baby's head circumference is tracking along a consistent percentile curve
- Call your doctor if: Rapidly increasing head size with bulging fontanelle, vomiting, sunsetting eyes, or extreme lethargy
- Varies by age — see the age-by-age breakdown below
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What Parents Should Know
According to NIH, AAP, Mayo Clinic guidelines, 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. At 0-3 months, 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. It is generally considered normal when your baby's head circumference is tracking along a consistent percentile curve. However, you should contact your pediatrician promptly if rapidly increasing head size with bulging fontanelle, vomiting, sunsetting eyes, or extreme lethargy.
Normal vs. Concerning
By Age
What to expect by age
0-3 months
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.
3-6 months
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.
6-12 months
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.
12-24 months
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.
2-3 years
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 to Tell Your Pediatrician
- Describe when you first noticed signs of hydrocephalus in babies and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if your baby's head seems to be growing faster than expected.
- Mention if the fontanelle seems fuller or more prominent than before.
- Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
- Bring a list of any questions or observations you want to discuss at the appointment.
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)
What You Can Do at Home
- Keep track of when you notice signs of hydrocephalus in babies — noting the time of day, duration, and any triggers can help your pediatrician.
- Remember that your baby's head circumference is tracking along a consistent percentile curve — this is generally within the range of normal.
- At 0-3 months, focus on observation rather than intervention unless your pediatrician advises otherwise.
- Follow any care instructions from your pediatrician. Keep a written log of symptoms to bring to appointments.
- While monitoring at home, seek immediate care if rapidly increasing head size with bulging fontanelle, vomiting, sunsetting eyes, or extreme lethargy.
Related Conditions
Signs of Chiari Malformation in Babies
Chiari malformation occurs when part of the brain (cerebellar tonsils) extends below the skull base into the spinal canal. In babies, symptoms may include difficulty swallowing, stridor (noisy breathing), weak cry, apnea episodes, arm weakness, and head tilt. Chiari I may be asymptomatic and found incidentally, while Chiari II is associated with myelomeningocele (spina bifida). Symptomatic cases may require surgical decompression. Many children with Chiari I are monitored without surgery if symptoms are mild or absent.
When Should My Baby See a Pediatric Neurologist?
A pediatric neurologist specializes in disorders of the brain, spinal cord, nerves, and muscles in children. Referral is appropriate for seizures, abnormal head size or growth, significant hypotonia or hypertonia, developmental regression, movement disorders, headaches, suspected neuromuscular conditions, and abnormal neurological examination findings. These specialists perform detailed neurological evaluations and may order EEGs, MRIs, and other specialized testing.
Signs of a Tethered Spinal Cord in Babies
A tethered spinal cord occurs when the spinal cord is abnormally attached to the surrounding tissue, restricting its movement as the child grows. Signs include skin markers on the lower back (deep dimple, tuft of hair, skin tag, or hemangioma above the buttock crease), changes in bladder or bowel function, lower extremity weakness or asymmetry, and foot deformities. Diagnosis is made by MRI. Surgical untethering prevents progressive neurological damage.
Related Resources
Frequently asked questions
Is signs of hydrocephalus in babies normal?
When should I call the doctor about signs of hydrocephalus in babies?
When is signs of hydrocephalus in babies normal?
What causes signs of hydrocephalus in babies?
What should I mention to my pediatrician about signs of hydrocephalus in babies?
Is signs of hydrocephalus in babies normal at 0-3 months?
Is signs of hydrocephalus in babies normal at 3-6 months?
Should I go to the ER for signs of hydrocephalus in babies?
Does signs of hydrocephalus in babies go away on its own?
References
- [1]National Institute of Neurological Disorders and Stroke. Hydrocephalus. NIH
- [2]American Academy of Pediatrics. Hydrocephalus. HealthyChildren.org. AAP
- [3]Mayo Clinic. Hydrocephalus. Mayo Clinic
Doctor Visit Checklist
Bring this checklist to your next pediatrician visit to discuss Signs of Hydrocephalus in Babies.
Things to mention
- Describe when you first noticed signs of hydrocephalus in babies and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if your baby's head seems to be growing faster than expected.
- Mention if the fontanelle seems fuller or more prominent than before.
- Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
- Bring a list of any questions or observations you want to discuss at the appointment.
Observations to share
- 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
Urgent signs to report immediately
- 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)
My notes
From ismybabyalright.com — free, evidence-based baby health guides
All content follows our editorial policy and is reviewed against published clinical guidelines.
2,705 evidence-based guides6 authoritative medical sources5 medical advisory board members
Related Resources
Bottom line
Most cases of signs of hydrocephalus in babies are normal. Talk to your pediatrician if rapidly increasing head size with bulging fontanelle, vomiting, sunsetting eyes, or extreme lethargy.
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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Related Medical Concerns
Signs of Chiari Malformation in Babies
Chiari malformation occurs when part of the brain (cerebellar tonsils) extends below the skull base into the spinal canal. In babies, symptoms may include difficulty swallowing, stridor (noisy breathing), weak cry, apnea episodes, arm weakness, and head tilt. Chiari I may be asymptomatic and found incidentally, while Chiari II is associated with myelomeningocele (spina bifida). Symptomatic cases may require surgical decompression. Many children with Chiari I are monitored without surgery if symptoms are mild or absent.
When Should My Baby See a Pediatric Neurologist?
A pediatric neurologist specializes in disorders of the brain, spinal cord, nerves, and muscles in children. Referral is appropriate for seizures, abnormal head size or growth, significant hypotonia or hypertonia, developmental regression, movement disorders, headaches, suspected neuromuscular conditions, and abnormal neurological examination findings. These specialists perform detailed neurological evaluations and may order EEGs, MRIs, and other specialized testing.
Signs of a Tethered Spinal Cord in Babies
A tethered spinal cord occurs when the spinal cord is abnormally attached to the surrounding tissue, restricting its movement as the child grows. Signs include skin markers on the lower back (deep dimple, tuft of hair, skin tag, or hemangioma above the buttock crease), changes in bladder or bowel function, lower extremity weakness or asymmetry, and foot deformities. Diagnosis is made by MRI. Surgical untethering prevents progressive neurological damage.
My Baby's Head Shape Looks Abnormal
Many babies develop temporary head shape irregularities that are completely normal. A cone-shaped head from vaginal delivery reshapes within days. Mild positional flattening (plagiocephaly) from sleeping on the back is very common and usually improves with repositioning and tummy time. However, head shape changes involving ridges, a persistently bulging fontanelle, or rapid head growth changes should be evaluated to rule out craniosynostosis.
Achondroplasia (Dwarfism) in Babies
Achondroplasia is the most common form of short-limbed dwarfism, affecting about 1 in 15,000 to 40,000 births. It is caused by a mutation in the FGFR3 gene and is usually apparent at birth with characteristic features including short limbs, a larger head, and a prominent forehead. Intelligence is normal. With monitoring for specific complications and supportive care, children with achondroplasia lead full, active, and independent lives.
Adenoid Hypertrophy and Breathing
Adenoids are lymphoid tissue located behind the nose that help fight infection in young children. When adenoids become enlarged (adenoid hypertrophy), they can block the nasal airway, causing chronic mouth breathing, snoring, nasal speech, and sleep-disordered breathing. Enlarged adenoids are most common between ages 2-7 and are a leading cause of obstructive sleep apnea in young children. Treatment ranges from watchful waiting and nasal steroids to surgical removal (adenoidectomy) if breathing or sleep is significantly affected.