11.3 Hydrocephalus & Congenital Neurological Abnormalities

Hydrocephalus — Pathophysiology in Children

Hydrocephalus is abnormal CSF accumulation that enlarges ventricles and threatens cerebral perfusion. CSF is produced mainly by the choroid plexus, circulates through the ventricular system, and is absorbed largely via arachnoid granulations. Obstruction anywhere along that path (obstructive / noncommunicating) or impaired absorption (communicating) raises ventricular pressure. Pediatric causes include congenital aqueductal stenosis, Chiari-associated obstruction, post-hemorrhagic hydrocephalus of prematurity, meningitis-related adhesions, and tumor masses.

In infants, rising ventricular volume stretches the skull: accelerating occipitofrontal circumference, a bulging fontanelle, frontal bossing, and sunsetting eyes appear. In older children with fused sutures, headache, vomiting, papilledema, and declining school performance dominate — similar to other ICP crises. Untreated progressive hydrocephalus risks herniation, vision loss, and developmental injury.

CSF Shunts and External Drains

Most chronic hydrocephalus is managed with a ventriculoperitoneal (VP) shunt: a proximal ventricular catheter, valve, and distal catheter into the peritoneal cavity. Alternatives include ventriculoatrial or ventriculopleural shunts when the abdomen cannot be used. In acute PICU care, a temporary external ventricular drain (EVD) may control ICP and allow CSF sampling.

Shunt malfunction is a neurosurgical emergency until disproven. A child with a shunt who develops headache, repeated vomiting, lethargy, irritability, bradycardia, new seizures, or sunsetting eyes needs rapid assessment, NPO status in anticipation of operative revision, and imaging/neurosurgery involvement per protocol. Do not assume “gastroenteritis” in a shunted child with vomiting. Palpate the reservoir only if trained and ordered — pumping is not a casual nursing habit and can worsen obstruction or inject debris.

For EVDs, level the transducer at the prescribed landmark (often external auditory canal/tragus approximating the foramen of Monro), maintain a closed sterile system, and report unexpected drainage stops, bloody CSF, or ICP spikes. Never raise or clamp an EVD without a clear order — clamping can precipitate herniation in dependent patients.

Myelomeningocele and Related Congenital Lesions

Myelomeningocele is an open neural-tube defect in which spinal cord and meninges herniate through a vertebral defect, usually lumbosacral. Almost all children with myelomeningocele have a Chiari II malformation (downward displacement of cerebellar vermis and brainstem through the foramen magnum) and a high rate of hydrocephalus requiring shunting. Prenatal or early postnatal repair closes the defect; lifelong issues include:

• Motor and sensory deficits below the lesion level
• Neurogenic bladder and bowel with infection and renal injury risk
• Orthopedic deformities (scoliosis, clubfoot, hip dislocation)
• Learning and brainstem/Chiari-related apnea or swallowing dysfunction
• Latex allergy risk — use latex-free equipment from the start

Preoperative newborn priorities (when unrepaired) include prone or side positioning to protect the sac, sterile moist dressings per protocol, infection surveillance, and early neurosurgical planning. Postoperative and chronic care emphasize skin integrity over anesthetic pressure points, clean intermittent catheterization teaching, bowel programs, and vigilance for shunt failure or Chiari crisis (stridor, apnea, opisthotonus, weak cry).

Other congenital concepts tested at the CCRN Pediatric level include encephalocele, anencephaly (usually incompatible with prolonged survival), and Chiari I (cerebellar tonsillar herniation that may present later with headache or syringomyelia). Know the associations rather than rare surgical minutiae.

Cerebral Arteriovenous Malformations

A brain arteriovenous malformation (AVM) is a congenital tangle of arteries feeding directly into veins without a normal capillary bed, creating high-flow, low-resistance shunting and fragile vessels. Children may present with intracerebral or intraventricular hemorrhage, seizures, progressive headache, or incidental imaging findings. Acute hemorrhage produces sudden focal deficits, declining LOC, or herniation signs identical to other ICH — airway, BP/CPP support, coagulopathy correction, and emergent imaging/neurosurgery are the priorities.

After known AVM diagnosis, new thunderclap headache, seizure, or neurologic drop should be treated as possible rebleed until proven otherwise. Definitive therapies (microsurgery, embolization, radiosurgery) are specialty decisions; nursing contributions are neuro checks, seizure precautions, blood-pressure parameters, and family preparation for interventional procedures.

Nursing Priorities Across Congenital Neuro Care

Anchor every shift in ICP surveillance tailored to age: fontanelle and OFC in infants; symptom and pupil/motor trends in older children. Prevent infection at CSF device sites with meticulous hub care. Apply latex-free standards for myelomeningocele and many repeatedly instrumented children. Support nutrition and skin because immobility and sensory loss create pressure injury. Teach families the “call now” list for shunt failure — vomiting, severe headache, personality change, redness along the tract, or fever — because many malfunctions declare after discharge.

Coordinate with neurosurgery, urology, and rehabilitation early. Developmental follow-up is part of outcome, not an afterthought: protecting the brain from secondary injury during PICU crises preserves long-term function. On exam items, expect a shunted toddler with vomiting and bradycardia, a myelomeningocele infant needing latex-free suction catheters, or an AVM child with sudden unilateral weakness — choose the action that protects airway and cerebral perfusion while mobilizing neurosurgery.