Hydrocephalus & Congenital

Epidemiology

Incidence

Approximately 1 per 1,000 live births for congenital hydrocephalus; substantially higher when post-haemorrhagic and post-infectious cases are added.

Age peak

Bimodal; congenital (presenting in infancy) and acquired (any age).

Location

Lateral ventricles, third ventricle, and fourth ventricle, with the site of CSF-pathway obstruction (where present) determining the pattern.

Clinical Presentation

• Infants (open fontanelles, before sutural fusion): progressive head enlargement crossing percentiles, bulging anterior fontanelle, splayed sutures, distended scalp veins, 'sun-setting' eyes (Parinaud-like upgaze paresis), irritability, poor feeding, and developmental delay.
• Older children (closed sutures): morning headache, vomiting (often without nausea), papilloedema, sixth-nerve palsy, declining school performance, drowsiness, and gait disturbance.
• Acute decompensation: depressed consciousness, bradycardia and hypertension (Cushing's response), pupillary changes, a neurosurgical emergency.

Imaging

• First-line: cranial ultrasound through the anterior fontanelle in infants; MRI in children with closed fontanelles (CT only when MRI is not available or when speed is critical).
• Key MRI sequences: T1 sagittal (aqueduct and tonsils), T2 axial (ventricular size and trans-ependymal flow), heavily T2-weighted CISS / FIESTA / 3D-DRIVE (membranes, aqueductal patency), and phase-contrast cine (aqueductal flow).
• Look beyond ventricular size: trans-ependymal CSF on FLAIR, effacement of cortical sulci, depression of the third-ventricle floor, and morphology of any obstructing lesion.

Pathology & Molecular

Histology. Not a histological diagnosis; hydrocephalus is a clinical-radiological syndrome.

Molecular. Selected congenital forms have monogenic causes: X-linked hydrocephalus due to L1CAM mutation (the classical 'HSAS' phenotype with adducted thumbs), and CCDC88C, MPDZ, and other recessive forms. Genetic testing is increasingly considered in syndromic or familial cases.

Management

Surgery. The two principal options for permanent treatment are: (1) CSF shunt (most commonly ventriculo-peritoneal), and (2) endoscopic third ventriculostomy (ETV), with or without choroid plexus cauterization (CPC) particularly in infants. Choice between them is guided by aetiology, age, anatomy, and the ETV Success Score (see dedicated entry). Temporising procedures (ventricular access device, external ventricular drain, sub-galeal shunt, ventriculo-subgaleal shunt) are used in pre-term infants and in selected acute settings.

Adjuvant therapy. Treatment of the underlying aetiology (resection of obstructing tumour, treatment of CNS infection) may obviate or modify the need for permanent CSF diversion.

Considerations. Always consider the long-term trajectory: paediatric shunts carry a lifetime burden of revisions; ETV failures cluster in the first 6 months but late failures occur and require lifelong surveillance.

Outcomes

Long-term outcome depends primarily on the underlying aetiology and any associated parenchymal injury, not on hydrocephalus per se. Shunted infants with congenital uncomplicated hydrocephalus have generally favourable neurocognitive outcomes; outcomes are worse with post-haemorrhagic, post-infectious, or syndromic forms.

Classification of hydrocephalus; anatomical and aetiological

Clinical features by age; what to look for at the bedside

Epidemiology

Incidence

Accounts for a substantial fraction of congenital hydrocephalus; exact figures vary by source.

Age peak

Often diagnosed antenatally on routine obstetric ultrasound or in early infancy; later presentation occurs with partially compensated forms.

Location

Cerebral aqueduct (between third and fourth ventricles), midline at the level of the midbrain tectum / tegmentum.

Clinical Presentation

• Antenatal: ventriculomegaly on routine second-trimester ultrasound prompts dedicated fetal MRI for confirmation and exclusion of additional anomalies.
• Infants: enlarging head, bulging fontanelle, sunsetting eyes (compression of dorsal midbrain).
• Late presentation: slowly progressive headache, gait disturbance, cognitive changes; the upper midbrain compression may produce Parinaud syndrome (upgaze palsy, convergence-retraction nystagmus, light-near dissociation).

Imaging

• MRI is the diagnostic modality of choice: triventricular hydrocephalus with a normal fourth ventricle; sagittal T2/CISS shows the obstructed aqueduct, often with a 'thin' membrane or web.
• Phase-contrast cine MRI confirms absent or reduced aqueductal flow.
• Always inspect carefully for a tectal-plate glioma, which can present as 'apparent aqueductal stenosis' but requires different management.

Pathology & Molecular

Histology. Simple congenital stenosis is anatomical narrowing without identifiable lesion; gliotic forms show astrocytic scarring (often after intra-uterine haemorrhage).

Molecular. L1CAM mutation (X-linked hydrocephalus with stenosis of the aqueduct of Sylvius; HSAS) is the prototypical monogenic cause; affected males may have adducted thumbs and corpus callosum abnormalities.

Management

Surgery. Endoscopic third ventriculostomy (ETV) is the first-line treatment in suitable children and is highly successful in this anatomical pattern. CSF shunt remains an alternative or salvage option.

Adjuvant therapy. Where a tectal lesion is identified, management is directed by tumour biology (most tectal-plate gliomas are indolent and require only CSF diversion plus surveillance imaging).

Considerations. Children under one year have lower ETV success in pure aqueductal stenosis than older children; the ETV Success Score should be applied in counselling.

Outcomes

ETV in older children with isolated aqueductal stenosis has high long-term success; long-term neurocognitive outcome is generally favourable in the absence of associated parenchymal injury.

Epidemiology

Incidence

Approximately 25-30% of very-low-birth-weight (<1,500 g) infants develop IVH; progressive post-haemorrhagic ventricular dilatation (PHVD) occurs in a significant fraction of grade III/IV cases.

Age peak

First weeks of life in the neonatal intensive care unit.

Location

Bilateral lateral ventricles initially; obstruction of the aqueduct or basal cisterns may produce a non-communicating component.

Clinical Presentation

• Often clinically silent in the ventilated pre-term infant; surveillance by serial cranial ultrasound through the open fontanelle is the standard.
• When clinical signs appear: rapid head-circumference growth, apnoea/bradycardia, full or bulging fontanelle, splayed sutures, feeding intolerance.
• Late: developmental delay, motor impairment (especially with parenchymal grade IV injury).

Imaging

• Serial cranial ultrasound is the workhorse: ventricular index, anterior horn width, and thalamo-occipital distance trended against published nomograms.
• MRI in older or larger infants for anatomy and prognostication; rapid-MRI protocols avoid sedation.
• Imaging biomarkers (ventricular size, white-matter signal) inform but do not replace clinical trends.

Pathology & Molecular

Histology. Initial IVH from rupture of the fragile germinal-matrix vasculature; subsequent organisation produces obliterative arachnoiditis and aqueductal scarring in many cases.

Molecular. Inflammatory cascades driven by iron and free haem within CSF are implicated in subsequent fibrosis and impaired CSF absorption, the rationale for clearance-based strategies.

Management

Surgery. Initial temporising measures (used to delay permanent CSF diversion until the infant is large and stable enough for shunting or ETV): repeated lumbar/ventricular taps; ventricular access device (VAD or reservoir) with intermittent CSF withdrawal; ventriculo-subgaleal shunt. Definitive options when the child reaches an appropriate size and stability: ventriculo-peritoneal shunt or, in selected anatomies, ETV ± CPC. Neuro-endoscopic ventricular lavage (NEL) (endoscopic clearance of intraventricular haematoma and fibrinous debris) is increasingly performed at selected centres and is the subject of active comparative research, including the historical DRIFT trial (drainage, irrigation and fibrinolytic therapy).

Adjuvant therapy. Comprehensive neonatal neurodevelopmental care, including early intervention services, is central to long-term outcome.

Considerations. Shunt complications are particularly frequent in this population (high CSF protein, frequent infections, small babies); the decision tree should be made in close collaboration with neonatology.

Outcomes

Long-term outcome is dominated by the parenchymal injury sustained at the time of IVH rather than by the success of CSF diversion alone. Children with isolated grade III IVH and well-controlled hydrocephalus can have favourable cognitive and motor outcomes; grade IV with periventricular haemorrhagic infarction has substantial risk of cerebral palsy.

Epidemiology

Incidence

Practice patterns vary widely between centres; ETV is now the default in older children with aqueductal stenosis, intermediate-grade posterior-fossa obstruction, and selected fourth-ventricle outlet obstruction.

Age peak

Any age; success rates are significantly age-dependent.

Location

Floor of the third ventricle (between mammillary bodies and infundibular recess), penetrating into the interpeduncular cistern (anterior to the basilar artery and its perforators).

Clinical Presentation

• Procedural anatomy: rigid or flexible endoscope through a coronal pre-coronal burr hole, through the lateral ventricle, foramen of Monro, into the third ventricle; the floor is fenestrated bluntly anterior to the basilar tip.
• Intra-operative confirmation: pulsatile flow through the stoma; visualisation of the prepontine cistern and basilar artery; balloon dilatation may be used to enlarge the stoma.
• CPC is performed by bipolar cauterization of the choroidal villi in both lateral ventricles, accessed via the same or a separate trajectory.

Imaging

• Pre-operative MRI essential: confirm anatomy, identify the position of the basilar artery and any thickened/atypical third-ventricle floor.
• Post-operative MRI: phase-contrast cine through the stoma confirms flow; reduction in ventricular size on follow-up is variable and may lag the clinical response.

Pathology & Molecular

Histology. Not applicable, a procedure rather than a pathology.

Molecular. Not applicable.

Management

Surgery. ETV ± CPC is the alternative to shunting for selected paediatric hydrocephalus. Failure (most often clinical recrudescence of raised ICP, sometimes with re-expansion of ventricles) typically occurs within the first 3-6 months but late failures occur. Salvage options include re-ETV (if scarring/closure of the stoma is identified), CSF shunt insertion, or both.

Adjuvant therapy. None.

Considerations. Counsel families that ETV is not 'one and done'; lifelong surveillance for delayed failure is appropriate, especially in young children and those with complex hydrocephalus.

Outcomes

Highly aetiology- and age-dependent. Older children with isolated aqueductal stenosis: ETV success rates well above 70%. Infants with aqueductal stenosis: lower success with ETV alone; ETV+CPC improves outcomes in this group as demonstrated by Warf and colleagues.

ETV Success Score (Kulkarni et al., 2010); points by patient feature

Epidemiology

Incidence

Hundreds of thousands of paediatric shunt insertions and revisions globally each year.

Age peak

Any age, with a heavy weighting toward infancy.

Location

Most commonly right occipital or right frontal entry; distal end in peritoneum.

Clinical Presentation

• Acute obstruction: features of raised ICP; headache, vomiting, irritability, drowsiness, sun-setting eyes (in infants), papilloedema (in older children).
• Infection (most often within 3-6 months of surgery): fever, shunt-tract erythema, signs of meningitis, abdominal pseudocyst (with peritoneal end).
• Over-drainage: postural headache, slit-ventricle syndrome (in older children), subdural collections, secondary craniosynostosis in young infants.
• Disconnection / fracture / migration: often a 'silent' radiological finding in growing children, the soft-tissue tract becomes fibrotic and may permit continued (precarious) function.

Imaging

• Shunt-series radiographs to identify disconnection, fracture, or migration.
• CT or rapid-MRI for ventricular size compared with a known baseline (a copy of the child's 'usual' ventricular appearance should be retained in the record).
• Trans-fontanelle ultrasound in infants for serial follow-up.
• When in doubt and the child is unwell, surgical exploration is appropriate; radiological imaging can be normal in early shunt malfunction.

Pathology & Molecular

Histology. Not applicable, a device-related condition.

Molecular. Not applicable.

Management

Surgery. Obstruction: revision of the obstructed component (proximal more common in infants, distal more variable in older children). Infection: external CSF drainage with appropriate antibiotic therapy, followed by re-insertion of a new shunt after culture-confirmed clearance; the standard is removal of the contaminated hardware. Over-drainage: programmable valve adjustment, addition of an anti-siphon device, or revision to a higher-resistance valve.

Adjuvant therapy. Antibiotic-impregnated catheters reduce infection rates in selected series. Strict adherence to a peri-operative shunt protocol (skin preparation, glove change, antibiotic timing, minimal hardware handling) is the most effective infection-prevention measure.

Considerations. Programmable valves are routinely checked after MRI in children with non-MRI-resistant valves; institutional protocols vary.

Outcomes

Approximately half of paediatric shunts require revision within the first 1-2 years after insertion, with a long tail of failures over the lifetime; cumulative revision burden is high.

By molecular subgroup: Highest failure rates in pre-term infants with post-haemorrhagic hydrocephalus and in children with multiloculated hydrocephalus; lowest in older children with simple obstructive hydrocephalus.

Common shunt complications; recognition and response

Epidemiology

Incidence

Estimated 1% prevalence on routine paediatric MRI; the clinically meaningful subset is substantially smaller.

Age peak

Throughout childhood; symptomatic presentation often in school-age children and adolescents.

Location

Craniocervical junction; cerebellar tonsils, cisterna magna, upper cervical canal.

Clinical Presentation

• Often asymptomatic; discovered incidentally on imaging performed for unrelated reasons.
• When symptomatic: occipital / sub-occipital cough headache (exacerbated by Valsalva); lower cranial-nerve symptoms; cerebellar signs; long-tract symptoms in the context of syringomyelia; rarely sleep-disordered breathing or central apnoea (particularly in infants and syndromic patients).
• Syringomyelia (in roughly half of symptomatic patients): segmental dissociated sensory loss, weakness, scoliosis (occasionally the only presentation).

Imaging

• Sagittal T1/T2 MRI: tonsils ≥5 mm below McRae's line; pointed (rather than rounded) tonsillar morphology; crowded cisterna magna.
• Whole-spine MRI to look for syringomyelia; essential in symptomatic patients.
• Phase-contrast cine MRI at the craniocervical junction in selected cases to assess CSF flow and inform surgical decision-making.

Pathology & Molecular

Histology. Not a histological diagnosis.

Molecular. Most are sporadic; rarely associated with syndromic conditions (skeletal dysplasias, hydrocephalus-related forms).

Management

Surgery. Symptomatic patients (especially those with syringomyelia, cough headache, or progressive neurological deficit): suboccipital decompression. Approaches vary by surgeon and centre; bony decompression alone, bony decompression with duraplasty (autologous or substitute graft), and bony decompression with intradural exploration (tonsillar shrinkage / lysis of arachnoid adhesions / arachnoid plasty) are all described, with no single approach proven uniformly superior. The minimum intervention that resolves symptoms is the goal.

Adjuvant therapy. Persistent or recurrent syringomyelia after decompression may require further procedures (syringo-subarachnoid or syringo-pleural shunt), rarely needed if decompression is adequate.

Considerations. Incidentally discovered, asymptomatic Chiari I without syringomyelia is generally observed; surgical decision-making should be conservative.

Outcomes

Symptomatic resolution of cough headache is reported in the great majority of well-selected patients after decompression; syringomyelia regression is more variable and may take months.

Epidemiology

Incidence

Co-extensive with myelomeningocele; modified in prevalence and severity by folate supplementation and by prenatal repair.

Age peak

Identifiable antenatally on imaging; the clinical burden begins in infancy.

Location

Posterior fossa and cervico-medullary junction, with extensive supratentorial associations.

Clinical Presentation

• Infants: lower brainstem dysfunction; stridor, feeding difficulty, apnoea, weak cry, aspiration; these are the most life-threatening features and demand urgent assessment.
• Older children: signs of associated hydrocephalus (almost universal), syringomyelia, scoliosis, and lower-cranial-nerve dysfunction.
• Adolescents and adults: persistent headache, syrinx-related symptoms, neuropathic bladder management issues, the adult-life consequences of childhood myelomeningocele are substantial.

Imaging

• MRI of brain and entire spine is the standard: cerebellar tissue descent into the cervical canal, medullary kink, tectal beaking, small posterior fossa, and frequently dysgenesis of the corpus callosum.
• Cervical syringomyelia is common; supratentorial findings include nodular grey-matter heterotopia, hypoplastic falx, and stenogyria.
• Hydrocephalus is essentially universal; shunt malfunction in a Chiari II patient may precipitate or worsen brainstem symptoms.

Pathology & Molecular

Histology. Not a histological diagnosis.

Molecular. As for neural tube defects in general; folate-pathway gene variants and other multifactorial contributors; specific monogenic forms are uncommon.

Management

Surgery. Hydrocephalus management as for any infant. Symptomatic infant brainstem dysfunction is an indication for urgent assessment of shunt function and consideration of posterior-fossa decompression where appropriate. In older children, decompression for cervico-medullary symptoms or syringomyelia follows similar principles to Chiari I but with greater anatomical complexity.

Adjuvant therapy. Long-term multidisciplinary care (urology, orthopaedics, rehabilitation, developmental paediatrics) is central.

Considerations. An infant with myelomeningocele who develops new stridor, swallowing difficulty, or apnoea has a shunt problem until proven otherwise.

Outcomes

Long-term outcome depends primarily on the level of the spinal lesion (motor and bladder function), the trajectory of hydrocephalus, and brainstem symptoms, not on Chiari II per se. Survival into adulthood is now the rule; the medical, urological, and orthopaedic burden across the lifespan is substantial.

Epidemiology

Incidence

Approximately 0.3-2 per 1,000 live births globally; markedly reduced in populations with effective peri-conceptional folate supplementation.

Age peak

Antenatal diagnosis is now standard in most regions; closure is performed prenatally (in selected cases meeting MOMS criteria) or postnatally in the first 24-72 hours of life.

Location

Most commonly lumbo-sacral, but can occur anywhere along the spinal axis.

Clinical Presentation

• Antenatal: ventriculomegaly and lemon/banana sign on second-trimester ultrasound; confirmed by detailed ultrasound and/or fetal MRI; elevated maternal serum AFP.
• At birth: exposed neural placode, CSF leakage, lower-limb deficit (level-dependent), neuropathic bladder, anorectal dysfunction, and Chiari II.
• Across the lifespan: orthopaedic deformity, neurogenic bladder with renal-tract risk, bowel dysfunction, scoliosis, tethered-cord re-presentation, latex allergy, and pressure-area complications.

Imaging

• Pre-operative: MRI of brain and entire spine (anatomy of the lesion, Chiari II features, hydrocephalus).
• Post-operative surveillance: cranial imaging for hydrocephalus; spinal MRI when symptoms suggest tethered cord.

Pathology & Molecular

Histology. Exposed neural placode is the unfused spinal cord; the dorsal aspect is the central canal.

Molecular. Multifactorial; folate-pathway gene variants implicated; specific monogenic forms uncommon.

Management

Surgery. Postnatal closure: meticulous re-creation of the layers; placode tubularisation; reconstruction of the pia/arachnoid; dural closure (with substitute when needed); fascial and skin closure with attention to deep-fascial integrity to reduce dehiscence. Performed within 24-72 hours where feasible to reduce infection. Prenatal closure: performed in selected centres meeting strict MOMS-style criteria (singleton pregnancy, gestational age 19-25 weeks, characteristic spinal lesion, hindbrain herniation, normal karyotype, BMI and obstetric criteria). Hydrocephalus management as a separate decision, often deferred 1-3 months postnatally until the trajectory is clear.

Adjuvant therapy. Multidisciplinary follow-up (urology, orthopaedics, neurology, rehabilitation, developmental paediatrics) is essential lifelong.

Considerations. Latex precautions from birth; bladder management is the single most important long-term determinant of renal outcome.

Outcomes

Survival into adulthood is now the rule; ambulation, continence, and educational outcomes depend on the level of the lesion, the trajectory of hydrocephalus, and the quality of multidisciplinary care.

By molecular subgroup: MOMS trial demonstrated that prenatal repair reduced the need for shunt diversion at 12 months (about 40% vs 82% in the original trial) and reduced hindbrain herniation, at the cost of increased maternal-fetal risks including preterm delivery. Long-term school-age follow-up (Houtrow et al., 2020) confirmed durable benefits on hindbrain anatomy and shunt requirement with mixed motor and cognitive findings.

MOMS trial; selected primary outcomes at 12 months (prenatal vs postnatal repair)

Epidemiology

Incidence

Approximately 1 per 5,000 live births overall, with strong regional variation; basal/frontoethmoidal forms are markedly more common in Southeast Asia.

Age peak

Antenatal diagnosis is common for occipital and parietal lesions; basal lesions may present later with nasal mass, recurrent meningitis, or CSF rhinorrhoea.

Location

Anatomical location is the principal classifier.

Clinical Presentation

• Occipital / parietal: visible swelling at birth, with or without overlying skin; may be small (covered, easily missed) or large (containing significant brain tissue).
• Frontoethmoidal: facial-midline mass, hypertelorism, sometimes with ocular involvement.
• Basal: often hidden; recurrent meningitis, CSF leak, or 'nasal polyp' in an infant should prompt MRI of the skull base before any biopsy.

Imaging

• MRI is the modality of choice; defines the size of the bony defect, the brain tissue within the sac (if any), and any associated hydrocephalus or other intracranial anomalies.
• CT for bony anatomy in surgical planning, particularly for skull-base lesions.
• Endoscopic intranasal assessment for suspected basal encephalocele, without biopsy of the lesion.

Pathology & Molecular

Histology. Sac contents range from CSF and meninges alone (meningocele) to dysplastic brain tissue (encephalomeningocele).

Molecular. Most are sporadic; some are syndromic (Meckel-Gruber, Walker-Warburg, etc.).

Management

Surgery. Closure of the defect with reduction or excision of non-functional sac contents, with watertight dural repair and reconstruction. Occipital lesions are usually approached posteriorly; frontoethmoidal and basal lesions often require combined transcranial and endoscopic endonasal approaches with skull-base reconstruction.

Adjuvant therapy. Hydrocephalus management as a separate question (frequent after closure of large occipital lesions).

Considerations. Skin coverage is critical; large defects may require local flaps or staged reconstruction. Basal lesions require collaboration with paediatric otolaryngology / skull-base surgery.

Outcomes

Variable. Small meningoceles with no significant brain tissue in the sac and no associated CNS anomaly typically have favourable neurological outcomes. Encephaloceles with large amounts of dysplastic brain tissue, or with associated CNS anomalies, often carry developmental morbidity.

Epidemiology

Incidence

Approximately 1 per 25,000 to 1 per 30,000 live births.

Age peak

Antenatal diagnosis is common; postnatal presentation is most often with hydrocephalus in infancy.

Location

Posterior fossa; fourth ventricle, vermis, cerebellar hemispheres, with frequent supratentorial associations.

Clinical Presentation

• Antenatal: posterior-fossa cyst with vermian hypoplasia on routine ultrasound, prompting fetal MRI.
• Infants: enlarging occipital prominence, hydrocephalus, developmental delay, ataxia.
• Older children (where the diagnosis is later or milder): chronic headache, learning difficulty, mild cerebellar signs.

Imaging

• MRI is diagnostic: posterior-fossa cyst communicating with the fourth ventricle, vermian hypoplasia (best assessed on midline sagittal images), elevated tentorium and torcula.
• Supratentorial assessment is essential; corpus callosum dysgenesis and other anomalies are frequent.

Pathology & Molecular

Histology. Vermian hypoplasia or aplasia, cystic dilatation of the fourth ventricle, often with abnormal cerebellar foliation.

Molecular. Heterogeneous; multiple syndromic associations described.

Management

Surgery. Hydrocephalus management is the main neurosurgical question and is patient-specific: ventricular shunt, cyst shunt, dual-compartment shunt (Y-connector), or endoscopic third ventriculostomy (with or without cyst fenestration); selection depends on whether the cyst and ventricles communicate.

Adjuvant therapy. Long-term developmental and cognitive surveillance; intervention for associated anomalies as required.

Considerations. Posterior-fossa CSF compartmentalisation can be deceptive; communication between fourth ventricle and cyst on standard imaging does not guarantee functional communication after shunt insertion.

Outcomes

Strongly determined by associated anomalies, particularly supratentorial. Children with isolated mild forms and well-controlled hydrocephalus may have favourable outcomes; those with extensive associated anomalies often have substantial developmental morbidity.

Epidemiology

Incidence

Approximately 1 per 2,000 to 1 per 2,500 live births overall; sagittal is the most common non-syndromic form, followed by coronal and metopic.

Age peak

Most non-syndromic forms present in the first months of life; syndromic forms often have additional craniofacial and digital features identifiable at birth.

Location

Sagittal (scaphocephaly, long, narrow head), unicoronal (anterior plagiocephaly with brow elevation on the affected side), bicoronal (turribrachycephaly), metopic (trigonocephaly, triangular forehead, hypotelorism), unilambdoid (true lambdoid synostosis; rare and often mis-diagnosed as positional plagiocephaly).

Clinical Presentation

• Abnormal head shape on examination, often noted by parents and clinicians in the first months of life.
• Palpable ridge over the affected suture (especially sagittal and metopic).
• Restricted growth perpendicular to the fused suture and compensatory overgrowth in the unrestricted directions.
• Syndromic forms: additional craniofacial features (midface hypoplasia, exorbitism), digital anomalies (Apert, Pfeiffer, Saethre-Chotzen), and increased risk of raised ICP.

Imaging

• Examination plus careful surface inspection is often sufficient for non-syndromic single-suture forms; low-dose 'sagittal' CT with 3D reconstruction confirms suture fusion when needed for planning.
• MRI to assess for hydrocephalus, Chiari malformation (frequent in syndromic forms), and brain anomalies.
• Plain radiographs are largely historical.

Pathology & Molecular

Histology. Premature ossification of the suture; the molecular biology of suture closure involves FGF, BMP, and other signalling pathways.

Molecular. Syndromic forms have identified genetic drivers: FGFR2 (Apert, Crouzon, Pfeiffer), FGFR3 (Muenke), TWIST1 (Saethre-Chotzen), and others. Genetic testing is appropriate in syndromic and bicoronal cases.

Management

Surgery. Endoscopic strip craniectomy + post-operative orthotic helmet: minimally invasive option performed in early infancy (typically before 3-4 months), with a relatively quick procedure and short hospital stay but a 6-12 month helmet protocol. Suitable for single-suture non-syndromic synostosis, particularly sagittal. Open cranial vault remodelling: typically at 6-12 months of age, offers comprehensive reshaping in one stage, suitable for any suture, multi-suture, and most syndromic cases. Spring-assisted cranioplasty and posterior cranial vault distraction are additional techniques used in selected anatomies and syndromes.

Adjuvant therapy. In syndromic patients, additional craniofacial surgery (midface advancement, monobloc, frontofacial distraction) is staged over childhood. Hydrocephalus, Chiari, and obstructive sleep apnoea require dedicated management.

Considerations. Centre and surgeon experience matters; outcomes correlate with case volume.

Outcomes

Excellent for cosmetic and functional outcomes after non-syndromic single-suture repair in experienced hands. Syndromic patients require staged, multidisciplinary care across childhood with generally good but more complex outcomes.

Craniosynostosis; suture × head-shape correlation

Epidemiology

Incidence

Variable by subtype; collectively common in paediatric neurosurgical practice.

Age peak

Cutaneous stigmata are present from birth and should prompt imaging; clinical tethered-cord syndrome may present at any age, with growth-related deterioration in adolescence a recognised pattern.

Location

Predominantly lumbosacral; cervical and thoracic dermal sinus tracts are uncommon but important.

Clinical Presentation

• Cutaneous markers, the bedside red flags: midline lumbosacral lipoma; deep dermal pit (especially above the sacrum and above the gluteal cleft, which deserve particular attention); hairy patch; haemangioma; skin-tag; appendage; pigmented patch.
• Neurological: lower-limb weakness or asymmetry, sensory loss, foot deformity, gait abnormality.
• Urological: neuropathic bladder (incontinence, retention, recurrent UTIs); often the earliest evidence of tethered cord.
• Orthopaedic: scoliosis, foot deformity, leg-length discrepancy.

Imaging

• MRI of the entire spine is essential whenever the diagnosis is suspected; ultrasound is useful in young infants before sacral ossification, but is not a substitute for MRI when concern is raised.
• Look at the conus level (normal below L2-3 by 3 months of age), filum thickness, presence of intradural lipoma, dermal sinus tract trajectory (which can extend deep into the canal), and split-cord anatomy.

Pathology & Molecular

Histology. Lipomyelomeningocele: intradural lipoma fused to a dysplastic placode. Dermal sinus: epithelial-lined tract from skin to dura ± intradural extension and ± dermoid cyst. Split cord: cord divided by a bony or fibrous septum (Pang type I vs II).

Molecular. Multifactorial; specific monogenic forms uncommon.

Management

Surgery. Symptomatic tethered cord: surgical untethering, division of the filum (when filum-only), or careful microsurgical separation of placode and lipoma (lipomyelomeningocele), is the standard. Dermal sinus tract: excision of the entire tract from skin to its termination, with closure of any dural defect (never just 'tie off' a sinus at the skin. Split-cord: resection of the dividing septum and untethering. Asymptomatic infants with closed dysraphism are an area of practice variation) some centres operate prophylactically, others observe with surveillance for new symptoms.

Adjuvant therapy. Multidisciplinary surveillance, particularly urology and orthopaedics.

Considerations. Re-tethering after initial repair can occur years later, particularly in growing children; long-term follow-up is essential.

Outcomes

Surgery in symptomatic patients arrests progression in most and produces functional improvement in a meaningful subset; reversal of established deficits is incomplete.