Hydrocephalus & Macrocephaly: Clinical Case Discussion & Key Points
Model Case Presentation
Patient Demographics
Name: Master Arjun, Age: 6 months, Gender: Male, Informant: Mother (Reliable)
Chief Complaints
- Progressively increasing head size since birth – 6 months
- Irritability and high-pitched cry – 2 months
- Vomiting, especially in the morning – 6 weeks
- Poor feeding and developmental delay
History Summary
Mother noticed the head growing disproportionately large compared to body since 2 months of age. The child has persistent irritability, high-pitched cry, and projectile vomiting predominantly in the morning. Excessive sleepiness noted over the last month. No seizures. Poor head control for age; not yet smiling consistently (delayed social milestones). Eyes appear to look downward (sunset sign noted by the mother).
Born at term via NVD, did not cry immediately (delayed cry), required brief resuscitation. Birth weight 3.1 kg. Antenatal USG at 28 weeks showed ventriculomegaly. No maternal fever/rash in first trimester. Non-consanguineous marriage. No family history of hydrocephalus. Immunizations up to date.
Examination Summary
| Parameter | Finding | Significance |
|---|---|---|
| Head Circumference | 48 cm (+3 SD above mean for age) | Macrocephaly — significant |
| HC Growth Rate | Crossing centiles upward | Progressive — pathological |
| Weight | 6.8 kg (25th centile) | Normal |
| Anterior Fontanelle | Bulging, tense, non-pulsatile | Raised ICP |
| Sutures | Widely split cranial sutures | Raised ICP — Craniosynostosis excluded |
| Scalp Veins | Dilated, prominent | Raised ICP with venous obstruction |
| Eyes | "Sunset sign" — downward deviation of eyes | Pressure on tectal plate (Parinaud phenomenon) |
Neurological: Hypotonia. Brisk DTRs in lower limbs. Head control absent (delayed milestone). Macewen's sign (cracked-pot sound on skull percussion) — positive.
Transillumination: Negative (rules out benign extra-axial fluid collections/subdural).
Fundus: Bilateral papilledema (raised ICP confirmed).
✅ Complete Diagnosis
Congenital Hydrocephalus (Obstructive/Non-communicating) — likely due to Aqueductal Stenosis, presenting with Macrocephaly, Raised Intracranial Pressure, and Global Developmental Delay.
📝 History — Exam Q&A
Macrocephaly is defined as a head circumference (HC) measuring more than 2 standard deviations (SD) above the mean for age and sex (i.e., >98th percentile).
Normal HC at birth: ~33–35 cm. HC grows approximately 2 cm/month in the first 3 months, 1 cm/month from 3–6 months, and 0.5 cm/month from 6–12 months. At 1 year: ~47 cm.
💡 Key Distinction
It is not just the absolute value but the rate of growth (HC crossing centiles upward) that matters. A single large measurement may be familial; serial measurements crossing percentiles indicate pathology.
| Category | Causes |
|---|---|
| CSF-related (most common) | Hydrocephalus (obstructive or communicating), Benign Enlargement of Subarachnoid Space (BESS/Benign external hydrocephalus) |
| Brain parenchyma enlargement (Megalencephaly) | Metabolic (Alexander disease, Canavan disease, MPS), Hemimegalencephaly, Sotos syndrome, Fragile X syndrome |
| Subdural collections | Subdural hematoma (NAI), Subdural hygroma, Empyema |
| Thickened skull | Rickets, Thalassemia (extramedullary hematopoiesis), Fibrous dysplasia |
| Familial/Constitutional | Autosomal dominant benign macrocephaly (measure parents' HC) |
Hydrocephalus is an abnormal accumulation of cerebrospinal fluid (CSF) within the ventricular system, resulting in ventricular enlargement and/or raised intracranial pressure (ICP).
Pathophysiology: CSF is produced by the choroid plexus (~500 mL/day in adults; ~25 mL/day in neonates). It flows: Lateral ventricles → Foramen of Monro → 3rd ventricle → Aqueduct of Sylvius → 4th ventricle → Foramina of Luschka and Magendie → Subarachnoid space → Absorbed at arachnoid granulations into venous sinuses.
Hydrocephalus results from: (1) overproduction of CSF (rare – choroid plexus papilloma), (2) obstruction to flow, or (3) impaired absorption.
| Classification | Type | Description |
|---|---|---|
| By CSF communication | Non-communicating (Obstructive) | Obstruction within the ventricular system — ventricles do not communicate with subarachnoid space. LP not helpful for drainage. |
| Communicating | Obstruction outside the ventricular system (at arachnoid granulations or in basal cisterns). Ventricles communicate with subarachnoid space. LP may temporarily help. | |
| By onset | Congenital | Present at or before birth |
| Acquired | Develops after birth (post-meningitis, post-hemorrhage, tumors) | |
| By pressure | High-pressure hydrocephalus | Most common type in children |
| Normal pressure hydrocephalus (NPH) | Rare in children; classic triad: dementia, gait apraxia, urinary incontinence (mainly adults) |
- Aqueductal stenosis — Most common cause (~50% of congenital HC). Narrowing of aqueduct of Sylvius. May be X-linked (L1CAM gene mutation).
- Arnold-Chiari malformation — Especially Type II (associated with myelomeningocele). Downward displacement of hindbrain obstructs CSF flow.
- Dandy-Walker malformation — Absent/hypoplastic cerebellar vermis + large posterior fossa cyst + non-communicating hydrocephalus.
- Post-infectious — In utero TORCH infections (Toxoplasmosis, CMV) causing ependymitis and aqueductal scarring.
- Holoprosencephaly
- Vein of Galen malformation — AV malformation causing external compression
- Post-meningitis — most common cause of acquired HC in developing countries (Tuberculosis meningitis, bacterial meningitis). Fibrosis at basal cisterns → communicating HC.
- Intraventricular hemorrhage (IVH) — especially in preterm neonates. Blood clots obstruct CSF pathways → post-hemorrhagic hydrocephalus.
- Intracranial tumors — Medulloblastoma (posterior fossa), Ependymoma, Craniopharyngioma. Account for ~20% of childhood HC.
- Brain abscess
- Head trauma
- Choroid plexus papilloma — rare; causes overproduction of CSF
- Antenatal USG: Ventriculomegaly (lateral ventricle width >10 mm at 15–40 weeks is abnormal; >15 mm = severe)
- Maternal infections: TORCH – Toxoplasmosis (cat contact), CMV, Rubella (rash + vaccination status), Syphilis
- Prematurity: IVH risk → post-hemorrhagic hydrocephalus
- Perinatal asphyxia: IVH in term neonates
- Family history: X-linked hydrocephalus (L1CAM) — males affected; female carriers. Ask about brothers/maternal uncles.
- Consanguinity: Autosomal recessive causes (Walker-Warburg)
| Feature | Infant (open sutures) | Older Child (closed sutures) |
|---|---|---|
| Head | Rapidly enlarging, crossing percentiles | No change in HC |
| Fontanelle | Bulging, tense, non-pulsatile | Closed — not applicable |
| Pain | Irritability, high-pitched cry | Headache (worse in morning, on bending/coughing) |
| Vomiting | Projectile vomiting (morning) | Projectile vomiting (morning, without nausea) |
| Eyes | Sunset sign | Papilledema, diplopia (6th nerve palsy) |
| Sensorium | Lethargy, poor feeding | Altered consciousness, behavioral change |
| Tone | Spasticity (lower limbs) | Spasticity, ataxia |
Arrested (compensated) hydrocephalus is a state where ventricular enlargement is present but ICP has returned to normal (self-limited balance between CSF production and absorption). The child has large ventricles and possibly a large head, but is otherwise neurologically stable with no progressive symptoms.
Important: These children can decompensate suddenly (e.g., during a minor head injury or fever). Serial monitoring is essential.
| Feature | Dandy-Walker Malformation (Classic) | Dandy-Walker Variant |
|---|---|---|
| Cerebellar vermis | Complete agenesis | Partial hypoplasia (inferior vermis) |
| Posterior fossa cyst | Large cyst continuous with 4th ventricle | Small/moderate cyst |
| Posterior fossa | Markedly enlarged | Mildly enlarged or normal |
| Hydrocephalus | Present in ~80% | Less common |
| Prognosis | Poor (cognitive deficits) | Better |
BESS (also called Benign External Hydrocephalus or Benign Idiopathic Macrocephaly) is characterized by accumulation of CSF in the subarachnoid spaces over the frontal lobes, with mildly enlarged ventricles, in an otherwise normal infant.
| Feature | BESS | True Hydrocephalus |
|---|---|---|
| HC growth | Rapid rise then follows centile | Continuously crossing centiles upward |
| Fontanelle | Full but soft/pulsatile | Bulging, tense, non-pulsatile |
| Sunset sign | Absent | Present (in significant HC) |
| Development | Normal | Often delayed |
| Transillumination | Positive (frontal) | Negative |
| MRI | Enlarged subarachnoid space, normal/mildly enlarged ventricles | Markedly dilated ventricles |
| Family history | Often positive (parents have large heads) | May or may not |
| Resolution | Self-resolves by 2–2.5 years | Does not resolve without treatment |
🩺 Examination — Exam Q&A
Use a non-stretchable measuring tape. Measure the occipitofrontal circumference (OFC) — place the tape just above the supraorbital ridges (glabella) anteriorly and over the most prominent part of the occiput posteriorly. Take the largest of three measurements. Plot on a gender-specific growth chart (WHO standards).
Normal HC: Birth ~33–35 cm | 3 months ~40 cm | 6 months ~43 cm | 1 year ~47 cm | 2 years ~49 cm | Adult ~55 cm.
- Macrocephaly — HC >98th centile
- Bulging anterior fontanelle — tense, non-pulsatile, not subsiding on sitting up
- Widely split cranial sutures — palpable gaps between bones
- Prominent scalp veins — due to venous hypertension from raised ICP
- Thin, shiny, translucent scalp skin
- Frontal bossing — prominent forehead
- "Setting sun" (Sunset) sign — downward deviation of the eyes with sclera visible above the iris
- Macewen's sign — "cracked-pot" sound on skull percussion (positive when sutures are split)
The sunset sign (also called "setting sun phenomenon") refers to sustained downward conjugate gaze in which the irises are pushed downward so that the white sclera is visible between the upper eyelid and the iris. Eyelid retraction (Collier's sign) may also be present.
Mechanism: Raised ICP causes pressure on the periaqueductal gray matter and tectal plate (dorsal midbrain). This impairs the upgaze pathway (supranuclear), causing Parinaud syndrome or partial dorsal midbrain syndrome.
Note: The sunset sign can be transient and normal in premature or newborn infants. It is pathological when persistent.
Macewen's sign: On percussion of the skull near the junction of the frontal, temporal, and parietal bones, a hollow resonant "cracked-pot" sound is heard (like tapping a cracked clay pot). Normal skull gives a dull sound.
Significance: Indicates widely split sutures due to raised intracranial pressure (hydrocephalus, subdural collections). Also positive over brain abscess. Valid only when cranial sutures are not yet fused (i.e., in infants).
In a completely dark room, a bright, small, rubber-tipped light source (transilluminator/flashlight) is pressed firmly against the infant's skull at various points. The area of light transmission beyond the edge of the light source is measured.
Normal: Slight glow ≤2 cm frontally, ≤1 cm occipitally.
Positive (abnormal): Glow >2 cm frontally/occipitally, or bright transmitted light across the entire skull (like a "lighted bulb").
Indicates: Subdural hygroma, subdural hematoma, BESS, porencephalic cyst, hydranencephaly (entire skull lights up). NOT positive in typical hydrocephalus (which has brain tissue between fluid and skull).
- Spastic diplegia (lower limbs more than upper) — due to stretching of periventricular pyramidal fibers (which represent lower limbs) by the dilated ventricles
- Brisk DTRs in lower limbs ± Babinski sign
- Unsteady/ataxic gait — in older children
- 6th nerve palsy (false localizing sign) — bilateral lateral rectus weakness; due to raised ICP stretching 6th nerve over the petrous bone
- Papilledema — on fundoscopy; may progress to optic atrophy if untreated
- Failure of upward gaze (Parinaud syndrome)
- Intellectual disability / developmental delay
The 6th cranial nerve (abducens) has the longest intracranial course of all cranial nerves. It runs from the pons, over the petrous part of the temporal bone, through the cavernous sinus to the lateral rectus muscle. In raised ICP, the brainstem is displaced downward (caudal herniation), stretching the 6th nerve over the petrous ridge. This causes bilateral 6th nerve palsy, presenting as convergent squint and failure of abduction — not due to a lesion at the site of the 6th nerve nucleus, hence "false localizing."
The Cushing Triad indicates severe, life-threatening raised ICP:
- Hypertension (widened pulse pressure)
- Bradycardia
- Irregular/slow respirations (Cheyne-Stokes or apnea)
Other signs: Fixed dilated pupils, decerebrate posturing, rapidly falling consciousness (GCS). This is a neurosurgical emergency requiring immediate management (head elevation, mannitol, hyperventilation, urgent neurosurgery).
| Feature | Papilledema (Raised ICP) | Papillitis (Optic Neuritis) |
|---|---|---|
| Visual acuity | Normal (until late) | Reduced (early) |
| Pain on eye movement | Absent | Present |
| Disc swelling | Bilateral, symmetric | Usually unilateral |
| Pupil | Normal | RAPD (relative afferent pupillary defect) |
| Colour vision | Preserved | Impaired |
🔬 Investigations — Exam Q&A
Cranial Ultrasonography (USG) through the anterior fontanelle is the first-line investigation in infants with an open fontanelle. It is bedside, radiation-free, and can be repeated serially.
It can assess: Ventricular size, presence of blood (IVH), periventricular leukomalacia, and progression of hydrocephalus. However, it provides limited information about the posterior fossa and cortical detail.
MRI Brain (with and without contrast) is the gold standard. It provides:
- Exact size and morphology of ventricles
- Site of obstruction (aqueductal stenosis, tumor)
- Brain parenchyma and cortical detail
- Periventricular edema (transependymal CSF seepage — T2 hyperintensity)
- Associated anomalies (Chiari, Dandy-Walker)
- No radiation exposure
CT brain is preferred in acute/emergency settings (faster, no sedation needed) to assess ventricular size quickly before intervention.
- Dilated lateral ventricles (temporal horns >2 mm)
- Ballooning of the third ventricle (normally slit-like)
- Evans' ratio > 0.3 — ratio of maximum frontal horn diameter to maximum intracranial biparietal diameter (normal ≤0.3)
- Enlarged frontal or occipital horns (ballooning)
- Periventricular edema (transependymal CSF seepage) — T2/FLAIR hyperintensity around ventricles on MRI; indicates active/acute hydrocephalus
- In aqueductal stenosis: small/absent 4th ventricle with markedly enlarged 3rd and lateral ventricles
- In communicating HC: all ventricles dilated including 4th ventricle
💡 Evans' Ratio
Evans' Ratio = Maximum frontal horn width ÷ Maximum inner skull biparietal diameter. Ratio >0.3 suggests hydrocephalus. It is the standard radiological index used.
- Increased skull size (macrocephaly)
- Thinning of skull bones (due to chronic raised ICP)
- Widened sutures (separated cranial sutures — >3 mm is abnormal after infancy)
- "Beaten silver" or "Copper-beaten" appearance — gyral markings impressed on inner surface of skull from chronically elevated ICP (seen in older children with closed sutures)
- Erosion of dorsum sellae — in chronic raised ICP
X-ray skull is largely replaced by CT/MRI but may be seen as a finding in exam cases.
Indications:
- Communicating hydrocephalus — LP can temporarily reduce ICP and may be diagnostic (post-meningitis, post-IVH)
- Suspected meningitis as the cause
- Normal pressure hydrocephalus — large-volume LP (tap test) assesses reversibility
Contraindications:
- Non-communicating (obstructive) hydrocephalus — LP is absolutely contraindicated; can precipitate acute tonsillar herniation (coning) by suddenly reducing pressure below the obstruction
- Coagulopathy, local skin infection at LP site
🚨 Danger
NEVER perform LP in non-communicating hydrocephalus or when fundoscopy shows papilledema without first doing a CT/MRI to rule out an obstructive lesion or mass.
Antenatal USG can detect hydrocephalus prenatally from as early as 15–20 weeks of gestation.
- Ventriculomegaly: Lateral ventricle atrial width >10 mm (mild: 10–12 mm; moderate: 12–15 mm; severe: >15 mm)
- Associated abnormalities may be detected: Dandy-Walker, neural tube defects (spina bifida), agenesis of corpus callosum, TORCH features
- Fetal MRI is done for better anatomical characterization if anomaly is suspected
Parents should be counseled regarding prognosis, associated anomalies, genetic testing (TORCH titers, chromosomal microarray), and options including termination of pregnancy in severe cases.
- TORCH screen (IgM/IgG antibodies): CMV, Toxoplasma, Rubella — if congenital infection suspected
- CSF analysis: In post-meningitis HC — protein levels, glucose, culture
- Genetic testing: L1CAM gene sequencing (X-linked aqueductal stenosis), chromosomal microarray
- Metabolic workup: Urine MPS (mucopolysaccharidosis), lysosomal enzyme assays — if megalencephaly/storage disorder suspected
- EEG: If seizures are present
- Ophthalmology review: Fundus for papilledema/optic atrophy, visual fields assessment
- MRI spine: If Chiari malformation or spinal cord involvement suspected
💊 Management — Exam Q&A
- Treat the underlying cause where possible (e.g., tumor resection, antibiotics for meningitis)
- Medical management — temporizing measures only; not curative
- Surgical management — definitive treatment; either CSF diversion (shunt) or endoscopic third ventriculostomy (ETV)
- Supportive/rehabilitative: Developmental therapy, physiotherapy, regular ophthalmology follow-up
Medical management is temporizing and NOT a definitive treatment. Used to buy time until surgery.
- Acetazolamide (carbonic anhydrase inhibitor) — reduces CSF production by ~30%. Dose: 25–100 mg/kg/day. Rarely used long-term due to side effects (metabolic acidosis, electrolyte imbalance).
- Furosemide — also reduces CSF production; sometimes used in combination with acetazolamide
- Glycerol — osmotic agent; rarely used
- Mannitol — for acute raised ICP emergency (20% solution 0.5–1 g/kg IV over 20–30 min); not for chronic use
- Repeated LP — useful in communicating post-hemorrhagic hydrocephalus of prematurity to remove blood-stained CSF and reduce ICP temporarily
A VP shunt is a surgically implanted device that diverts excess CSF from the cerebral ventricles to the peritoneal cavity for absorption.
Components:
- Proximal catheter (ventricular catheter) — placed in the lateral ventricle (usually right side through a burr hole)
- Valve mechanism — one-way pressure-sensitive valve placed behind the ear (subcutaneously). Regulates flow and prevents over-drainage. Can be fixed-pressure or programmable (adjustable).
- Distal catheter — runs subcutaneously from valve down the neck and chest into the peritoneal cavity
The peritoneal end has extra length (~30 cm in infants) to allow for child's growth without needing revision.
| Shunt Type | Drainage Site | Preferred Use |
|---|---|---|
| Ventriculoperitoneal (VP) | Peritoneal cavity | Most common — first choice in children |
| Ventriculoatrial (VA) | Right atrium of heart | Used when peritoneum unsuitable (adhesions, peritonitis) |
| Ventriculopleural (VPL) | Pleural cavity | Rarely used; risk of pleural effusion |
| Lumboperitoneal (LP) | Peritoneal cavity from lumbar spine | Communicating HC; pseudotumor cerebri |
| Complication | Details |
|---|---|
| Shunt obstruction/malfunction | Most common complication (~50% fail within 2 years). Proximal end blocks with choroid plexus/debris. Presents with return of raised ICP symptoms. |
| Shunt infection | ~5–10% incidence. Most within 2 months of insertion. Organisms: S. epidermidis (most common), S. aureus, Gram negatives. Presents with fever, meningism, shunt failure. |
| Over-drainage (Slit-ventricle syndrome) | Excessive drainage → low ICP → intermittent headaches. Ventricles appear slit-like on CT. |
| Subdural hematoma | Rapid decompression of hydrocephalus → brain shrinks → bridging veins tear. |
| Shunt migration/disconnection | Proximal or distal catheter migrates; may need revision. |
| Abdominal pseudocyst | CSF-filled cyst forms in peritoneal cavity around distal catheter tip. Presents with abdominal pain/mass. |
| Bowel perforation | Rare; distal catheter erodes through bowel wall. |
Clinical features (return of raised ICP): Headache, vomiting, irritability, lethargy, bulging fontanelle (infants), behavioral change, seizures, decline in school performance.
Investigations:
- Urgent CT head — compare with previous scans; increase in ventricular size confirms obstruction (but 15% of blockages may NOT show ventricular change)
- Shunt series X-rays — AP and lateral skull, neck, chest, abdomen X-rays tracing the entire shunt catheter for disconnection, kinking, migration
- Shunt tap — neurosurgeon aspirates from the shunt valve; flow of CSF confirms proximal patency; failure to refill after pumping suggests distal obstruction
🚨 Key Point
A child with a known VP shunt presenting with fever + vomiting + irritability = assume shunt malfunction or infection until proven otherwise. Treat as a neurosurgical emergency.
ETV is a minimally invasive endoscopic procedure where a small hole is made in the floor of the 3rd ventricle, creating an alternative CSF pathway from the 3rd ventricle to the prepontine (subarachnoid) cisterns, bypassing the obstruction.
Best suited for: Non-communicating (obstructive) hydrocephalus due to aqueductal stenosis, tectal tumors, or posterior fossa tumors. NOT effective in communicating hydrocephalus.
| Feature | ETV | VP Shunt |
|---|---|---|
| Hardware | No implanted hardware | Foreign body (risk of infection) |
| Long-term reliability | Can fail (stenosis of stoma) | Mechanical failures common |
| Revision surgery | Less likely if successful | ~50% require revision in 2 years |
| Best age | >1 year (success rate drops in infants) | Any age |
| Communicating HC | Not suitable | Suitable |
ETV Success Score (ETV-SS): A scoring tool predicting ETV success based on age, etiology, and previous shunting. Score >80 = high success rate.
- Position: Head elevated 30° (head-up tilt); avoid neck flexion
- Airway/Oxygenation: Ensure adequate oxygenation; if unconscious — intubate
- Hyperventilation (if intubated): Target PaCO2 35–40 mmHg (moderate hypoventilation is harmful; only short-term measure)
- Mannitol 20%: 0.5–1 g/kg IV over 20–30 min — osmotic dehydration. Onset in 15–30 min. Or Hypertonic Saline (3%) 3–5 mL/kg IV bolus (increasingly preferred).
- Dexamethasone: Useful only for vasogenic edema around tumors/abscesses (NOT for hydrocephalus per se)
- Restrict IV fluids to avoid cerebral edema
- Treat seizures: IV lorazepam, levetiracetam
- Urgent neurosurgery: Emergency EVD (External Ventricular Drain) or VP shunt revision
Post-hemorrhagic hydrocephalus (PHH) of prematurity is a common sequela of grade III/IV IVH. Management is stepwise:
- Serial cranial USG monitoring of ventricular index
- Serial LP (lumbar punctures) — may temporarily relieve pressure in communicating PHH
- Ventricular access device (VAD) / Ommaya reservoir — inserted subcutaneously; allows repeated CSF drainage without repeated lumbar puncture. Used as a bridge until infant is large enough for VP shunt.
- VP shunt — definitive treatment. Delayed until: infant weight >2 kg (ideally) and CSF is clear (protein <1–2 g/L, no active infection)
- ETV-CPC (ETV + Choroid Plexus Cauterization) — used in some centers as an alternative to shunting, especially in resource-limited settings (Warf technique)
Prognosis depends on the underlying cause, severity at presentation, and timing of intervention:
- Isolated aqueductal stenosis with early treatment: relatively good outcome; ~50–80% have normal or near-normal intelligence.
- Hydrocephalus with myelomeningocele (Chiari II): ~70% have normal intelligence with appropriate management.
- Post-meningitic HC: Outcome depends on degree of brain damage from meningitis.
- Dandy-Walker: Generally poor — significant cognitive and motor deficits.
- Untreated progressive hydrocephalus: Irreversible cortical damage, blindness, severe intellectual disability, death.
All shunted children require lifelong follow-up. VP shunts are not outgrown and are lifelong devices.
🔭 Recent Advances — Exam Q&A
Programmable valves allow non-invasive adjustment of the shunt opening pressure using an external magnetic device, without the need for surgery. The valve has multiple pressure settings that can be changed by the neurosurgeon at the bedside.
Advantages: Avoids revision surgery for over/under-drainage; allows fine-tuning of CSF drainage as the child grows.
Important note: MRI scanning can alter the valve setting — always check and reprogram the valve after MRI in patients with programmable shunts.
ETV-CPC is a combined endoscopic procedure where:
- ETV creates an alternative CSF pathway through the 3rd ventricular floor
- Choroid Plexus Cauterization (CPC) reduces CSF production by cauterizing the choroid plexus in both lateral ventricles
Combined effect: Reduces both CSF production and improves drainage, potentially avoiding the need for a shunt.
Popularized by Dr. Benjamin Warf in Uganda for post-infectious hydrocephalus in infants. Shows success rates of 40–73% in infants, avoiding lifelong shunt dependence. Now being used in other resource-limited settings.
Antibiotic-impregnated catheters (AICs) are shunt catheters coated with antibiotics (typically rifampicin + clindamycin or rifampicin + trimethoprim) that are slowly eluted, providing local prophylaxis against biofilm formation and shunt infection.
Multiple studies and meta-analyses show AICs significantly reduce shunt infection rates compared to standard catheters. They are increasingly recommended in pediatric neurosurgical guidelines and are now considered standard of care in many centers.
Recent advances in genomics have identified several genes involved in congenital hydrocephalus:
- L1CAM gene: X-linked hydrocephalus (HSAS syndrome) — aqueductal stenosis, corticospinal tract hypoplasia, thumb adduction deformity in males
- SLC12A6, SLC12A7: Associated with obstructive hydrocephalus
- CCDC39, CCDC40: Ciliopathy genes → defective ependymal cilia → impaired CSF circulation → hydrocephalus
- FOXJ1, DNAI1: Primary ciliary dyskinesia genes causing hydrocephalus
Whole exome sequencing (WES) is increasingly used to identify genetic causes of unexplained congenital hydrocephalus, with a diagnostic yield of ~20–25%, enabling accurate genetic counseling and recurrence risk assessment.
Shunted children with hydrocephalus require frequent cranial CT scans for monitoring (shunt malfunction suspected). CT exposes children to ionizing radiation — a cumulative carcinogenic risk over many scans.
The "Image Gently" campaign promotes reduction of radiation exposure in children by using: low-dose CT protocols ("rapid-sequence CT" with reduced mAs), cranial ultrasound (in infants with open fontanelle), and MRI (preferred, radiation-free) for follow-up. Specific low-radiation CT protocols for hydrocephalus monitoring are now being implemented widely.
⚡ Key Points — Quick Revision
One-Liners for Exam
- Macrocephaly: HC > 2 SD above mean (>98th centile) for age and sex
- Hydrocephalus: Abnormal accumulation of CSF causing ventricular dilatation ± raised ICP
- Most common cause of macrocephaly: Hydrocephalus
- Most common cause of congenital HC: Aqueductal stenosis (~50%)
- Most common cause of acquired HC in India: TBM (post-meningitic)
- Communicating HC: Obstruction outside ventricles (arachnoid granulations); all ventricles dilated
- Non-communicating HC: Intraventricular obstruction; LP contraindicated
- Sunset sign: Downward conjugate gaze → pressure on tectal plate → raised ICP
- Macewen's sign: Cracked-pot sound on skull percussion → split sutures
- Evans' ratio > 0.3: Radiological criterion for hydrocephalus
- Periventricular T2 hyperintensity (MRI): Transependymal CSF seepage = active/acute hydrocephalus
- Transillumination positive: BESS, subdural collections, hydranencephaly — NOT typical hydrocephalus
- BESS: Self-resolves by 2–2.5 years; positive family history; normal development
- LP contraindicated in: Non-communicating hydrocephalus; may cause coning
- Definitive treatment: VP shunt (most common) or ETV (for obstructive HC >1 year of age)
- VP shunt most common complication: Shunt obstruction (~50% fail within 2 years)
- Shunt infection organism: S. epidermidis (most common)
- ETV: best for: Non-communicating HC; NOT suitable for communicating HC
- ETV-CPC: ETV + choroid plexus cauterization; reduces shunt dependency in infants
- Cushing's triad: Hypertension + Bradycardia + Irregular breathing = impending herniation — emergency
- 6th nerve palsy in raised ICP: False localizing sign (longest intracranial course)
- Dandy-Walker: Absent/hypoplastic cerebellar vermis + posterior fossa cyst + HC
- X-linked HC gene: L1CAM mutation; thumb adduction deformity in affected males
- Medical Rx (temporizing): Acetazolamide ± furosemide; mannitol for acute ICP crisis
- Programmable valve: Adjustable non-invasively; reset after MRI scan