Paediatric Neurosurgery and Congenital Anomalies
Paediatric questions test timing of intervention, associated anomalies you must look for, and age-specific tumour behaviour.
Congenital anomalies
- Myelomeningocele: cover the placode, give antibiotics, nurse prone and close within 24 to 48 hours. Hydrocephalus develops in 80 to 90 percent. Chiari II is almost universal, with a small posterior fossa, tectal beaking and corpus callosum dysgenesis. Use latex precautions from birth.
- Chiari I: tonsils more than 5 mm below the foramen magnum, often with a syrinx and Valsalva-induced headache; decompress with duroplasty if symptomatic or if a syrinx is present.
- Tethered cord: conus below L2, filum thicker than 2 mm, fatty filum; release when symptomatic or with neurogenic bladder.
- Dandy-Walker: cystic fourth ventricle with vermian hypoplasia and hydrocephalus; treat with ETV or a shunt.
- Craniosynostosis: scaphocephaly with sagittal synostosis, trigonocephaly with metopic, unicoronal plagiocephaly with nasal root deviation, brachycephaly with bicoronal. Operate between 3 and 12 months.
Tumours
- Posterior fossa tumours dominate. Medulloblastoma arises in the vermis, shows restricted diffusion and drops metastases, so image the whole neuraxis and send CSF cytology. Pilocytic astrocytoma is a cyst with a mural nodule and a BRAF fusion. Ependymoma arises from the fourth ventricle floor and squeezes through the foramina of Luschka. Diffuse intrinsic pontine glioma is H3K27M mutated and not routinely biopsied.
- Supratentorial: craniopharyngioma, optic pathway glioma in NF1, germ cell tumour with pineal or suprasellar location, choroid plexus papilloma causing hydrocephalus by overproduction.
- Avoid radiotherapy under 3 years of age where possible.
Hydrocephalus in children
Increasing head circumference, bulging fontanelle, sunsetting eyes and engorged scalp veins. Treat with ETV with choroid plexus cauterisation in infants, or a shunt. Shunt malfunction presents with vomiting, headache and drowsiness.
Worked example
A 6-month-old with a rapidly enlarging head and a full fontanelle has a midline posterior fossa mass with restricted diffusion. This is medulloblastoma until proven otherwise. Complete neuraxis MRI and CSF cytology, then resect and treat by molecular subgroup with craniospinal radiotherapy.
Traps
- Omitting spine imaging in medulloblastoma or ependymoma.
- Operating before tumour markers in suspected germ cell tumour.
- Ignoring an associated syrinx in Chiari I.
- Missing a Chiari II while closing a myelomeningocele.