Pediatric Hydrocephalus and Endoscopic Surgery

What is pediatric hydrocephalus?

A disorder of “fluid circulation” in the brain—not merely a radiological finding.

Hydrocephalus is a condition in which cerebrospinal fluid (CSF)— the clear fluid that surrounds and protects the brain and spinal cord—fails to circulate or be absorbed properly. The result is pathological enlargement of the ventricles and, typically, increased intracranial pressure.

Depending on where CSF flow or absorption is impaired, hydrocephalus is classified as:

• Obstructive (non-communicating) hydrocephalus – there is a “blockage” at a point within the ventricular system (e.g., the aqueduct of Sylvius, outlets of the fourth ventricle).
• Communicating hydrocephalus – the ventricles communicate with one another, but there is impaired CSF absorption at the basal cisterns or arachnoid granulations.

Other terms, such as hydrocephalus ex vacuo (ventricular enlargement due to cerebral atrophy) or external hydrocephalus in infants with familial macrocephaly, do not represent “true” hydrocephalus with raised pressure, but require careful differential diagnosis.

How common is it & what are the main causes?

Two incidence “peaks”: infancy and old age, with different underlying causes.

In developed countries, congenital hydrocephalus occurs in approximately 0.4–0.8 per 1,000 births. The cumulative prevalence of all types of hydrocephalus is higher, as many pediatric patients develop acquired hydrocephalus due to:

• Prematurity & intraventricular hemorrhage (IVH) – approximately 20–25% of cases.
• Spina bifida / myelomeningocele – ~ 15–20%.
• Posterior fossa tumors (cerebellum, brainstem) – ~ 10–12%.
• Aqueductal stenosis – ~ 8%.
• Congenital communicating hydrocephalus – ~ 8%.
• Other brain tumors, cranial malformations, infection, or traumatic brain injury.

More rarely, hydrocephalus is associated with specific genetic syndromes, such as X-linked Bickers–Adams syndrome (aqueductal stenosis, intellectual disability, epilepsy).

From a socioeconomic perspective, pediatric hydrocephalus represents a significant burden on healthcare systems, due to the large number of new shunts, revisions, and shunt infections each year.

What is cerebrospinal fluid & how does it circulate?

The “reservoir” in which the brain floats—CSF production, flow, and absorption.

CSF is produced primarily by the choroid plexus in the lateral, third, and fourth ventricles, as well as by the brain and meninges themselves. In adults, approximately 0.3–0.4 mL/min are produced—about 400–500 mL/day—while the total CSF volume circulating at any time is only 100–150 mL, meaning it is continuously recycled.

The classical CSF pathway is:

1. Production in the lateral ventricles.
2. Flow through the foramina of Monro into the third ventricle.
3. Passage through the aqueduct of Sylvius into the fourth ventricle.
4. Exit via the foramina of Magendie & Luschka into the subarachnoid space.
5. Circulation around the brain & spinal cord within the basal cisterns.
6. Absorption at the arachnoid granulations and return to the venous system.

When the balance between CSF production, flow, and absorption is disrupted, intracranial pressure rises (normally ~ 5–15 mmHg in the supine position), potentially resulting in hydrocephalus.

How does it present at different ages?

Distinct clinical features in infants with open sutures versus older children.

In infants & toddlers with open sutures:

• Rapid increase in head circumference (crossing growth percentiles).
• Full, tense, or bulging anterior fontanelle.
• Widening of cranial sutures, frontal bossing.
• Downward deviation of the eyes (“sun-setting”), rarely sixth nerve palsy.
• Irritability or, conversely, excessive sleepiness and decreased interaction.
• Possible vomiting, feeding difficulties.

In older children & adolescents:

• Headaches—often worse at night or in the supine position.
• Nausea, vomiting, blurred vision, or diplopia.
• Decline in school performance, impaired concentration.
• Behavioral changes, somnolence, or irritability.
• Fundoscopic evidence of papilledema.

Each child may present differently. Any progressive change in head size, vision, behavior, or level of consciousness warrants prompt evaluation by a pediatric neurosurgeon.

How is it diagnosed & what is the role of investigations?

The combination of clinical assessment and imaging is the “key.”

Diagnosis is based on:

• Clinical evaluation – detailed history, neurological examination, head circumference measurement, fontanelle assessment, and fundoscopic examination.
• Transfontanelle ultrasound – in infants with an open anterior fontanelle, a rapid and painless method to assess ventricular size.
• Computed tomography (CT) – demonstrates ventricular dilation, possible hemorrhage, tumor, or other lesions; mainly useful in emergency settings.
• Magnetic resonance imaging (MRI) – the reference standard for detailed assessment of anatomy, etiology of hydrocephalus, and associated abnormalities.

In addition, quantitative measures (e.g., Frontal-Occipital Horn Ratio – FOR) may be used for objective assessment of hydrocephalus severity. Imaging signs of raised pressure include effacement of sulci and transependymal CSF seepage (transependymal edema).

When is urgent treatment required?

Hydrocephalus is not always an emergency, but it can deteriorate rapidly.

The indication for treatment is the presence of ventricular enlargement on imaging together with clinical signs of raised intracranial pressure. Immediate / urgent intervention is required when:

• the child is lethargic, difficult to arouse, or has altered consciousness,
• there are recurrent vomiting, severe headache, or seizures,
• the fontanelle is tense and firm,
• there is papilledema or rapid visual deterioration.

In more chronic, stable forms, treatment can be planned, but is generally not deferred for long, in order to protect the child’s neurodevelopment.

What are the main surgical options?

“Diversion” of flow (shunt) versus restoration of physiological circulation (ETV, ETV-CPC).

The principal strategies are:

• Ventriculo-peritoneal shunt (VP shunt) – a thin catheter that diverts CSF from the ventricle to the abdomen, via a valve that regulates flow/pressure.
• Endoscopic Third Ventriculostomy (ETV) – an endoscopic procedure creating a small opening in the floor of the third ventricle to allow CSF to bypass the obstruction and circulate normally.
• ETV with Choroid Plexus Cauterization (ETV-CPC) – a combination of ETV with extensive cauterization (> 90%) of the choroid plexus in the lateral ventricles to reduce CSF production—particularly useful in infants < 1 year of age.

Method selection depends on the etiology (e.g., aqueductal stenosis, tumor, IVH), the child’s age, whether a shunt is already in place, and overall clinical condition.

How is a shunt (VP shunt) placed and what should I expect?

Small incisions, an internal catheter system, and the need for long-term follow-up.

A standard ventriculo-peritoneal shunt consists of:

• Proximal catheter – a thin tube placed into the lateral ventricle.
• Valve – regulates flow (differential pressure, flow-regulated, with or without programmable mechanisms).
• Distal catheter – typically terminates in the peritoneal cavity (abdomen).

The operation is performed under general anesthesia and usually lasts 60–90 minutes. Most children remain in the hospital for 1–3 days. Thereafter:

• feeding and gradual mobilization begin the following day,
• parents are educated on warning signs of malfunction (return of headaches, vomiting, lethargy, behavioral changes, redness along the shunt tract, etc.),
• regular follow-up is scheduled with clinical assessment and imaging as needed.

Approximately 60% of shunts function without revision in the first two years, while 40% will require some form of reoperation (obstruction, infection, overdrainage, etc.).

What are ETV & ETV-CPC and which patients are candidates?

A strategy aimed at shunt independence. Selection is based on age, etiology of hydrocephalus, and anatomy.

Endoscopic Third Ventriculostomy (ETV) is a neurosurgical procedure in which, through a small burr hole, a thin endoscope is introduced into the third ventricle and an opening is created in its floor toward the prepontine cistern. This allows CSF to circulate without passing through the aqueduct or other obstructed pathways.

The success of ETV depends on:

• Age – higher success in children > 1 year, adolescents, and adults.
• Etiology – high success in aqueductal stenosis, tectal glioma, posterior fossa tumors.
• Prior shunt – “shunt-naïve” patients tend to have better outcomes.

The ETV Success Score (Kulkarni) integrates these factors to provide an individualized estimate of success for each child.

In infants < 1 year, ETV alone has lower success rates (20–45%). The addition of extensive choroid plexus cauterization (ETV-CPC) can increase success to approximately 60–70%, provided that ≥ 90% of the choroid plexus is cauterized.

What is the prognosis & long-term outlook?

With timely treatment, many children lead normal and productive lives.

Long-term outcome depends on:

• the age at onset of hydrocephalus,
• how quickly it was diagnosed & treated,
• the underlying etiology (e.g., tumor-related vs. post-hemorrhagic hydrocephalus),
• the presence of associated brain injury or genetic syndromes.

With appropriate treatment and follow-up, many children:

• achieve normal physical development,
• attend school and participate in age-appropriate activities,
• grow into adulthood with good quality of life, with or without a shunt.

Long-term care includes neurodevelopmental monitoring, ophthalmologic evaluation, possible speech or occupational therapy, and close collaboration among pediatrician, pediatric neurologist, and pediatric neurosurgeon.

What are the risks & potential complications?

No surgery is “zero risk,” but most complications are manageable.

Complications are divided into:

Shunt-related complications

• Malfunction / obstruction – the shunt may become blocked at any point, with recurrence of hydrocephalus symptoms; revision is often required.
• Infection – 4–10% of new shunts become infected within the first year. Management may require removal, intravenous antibiotics, and temporary external drainage.
• Overdrainage – postural headaches, subdural hematomas, or hygromas.

Complications of Endoscopic Third Ventriculostomy (ETV) and ETV-CPC

• Failure or early closure of the stoma, necessitating shunt placement.
• Hemorrhage, injury to major vessels or brainstem (rare but serious).
• With ETV-CPC, risk of focal injury from cauterization if proper technique is not followed.

General surgical complications (bleeding, wound infection, seizures, anesthetic risks) are uncommon in specialized pediatric centers, but are always discussed thoroughly prior to surgery.