What is Hydrocephalus
The word comes from "hydro" (water) and "cephalus" (head). Hydrocephalus is abnormal accumulation of cerebrospinal fluid (CSF) in the brain's ventricles, raising intracranial pressure. It can occur at any age from congenital malformations, infections, tumors, or traumatic brain injury, and is also termed a hydrodynamic CSF disorder.
Classification
In noncommunicating (congenital) hydrocephalus, an obstruction blocks the free circulation of CSF. In communicating hydrocephalus, there is no obstruction between the ventricles and the spinal theca; instead, defective CSF absorption raises pressure on the brain or spinal cord.
Pathophysiology
Normally a delicate balance holds between CSF formation and absorption, and in hydrocephalus that balance is disturbed. CSF is formed mainly in the lateral ventricles by the choroid plexus and absorbed into the venous system through the arachnoid villi, circulating within the ventricles and the subarachnoid space. An obstruction in this free circulation raises pressure on the brain or spinal cord, and the site of obstruction may be the foramen of Monro, the aqueduct of Sylvius, the foramen of Luschka, or the foramen of Magendie. Without obstruction, the cause is defective CSF absorption, which likewise raises pressure on the brain or spinal cord.
Statistics and Incidences
Congenital hydrocephalus affects roughly 1 to 2 per 1,000 live births (about 1 in 500 newborns by one widely cited estimate), with United States and Canada studies reporting closer to 0.7 per 1,000 (systematic review and meta-analysis); the incidence of acquired hydrocephalus is not known exactly because of the variety of disorders that cause it. Shunt dependence occurs in 75% of all treated hydrocephalus cases and in 50% of children with communicating hydrocephalus. Incidence is equal in males and females. The age curve is bimodal, with one peak in infancy tied to congenital malformations, and adult hydrocephalus making up about 40% of total cases.
Causes
The most common problem is partial obstruction of normal CSF flow, either between ventricles or from the ventricles to spaces around the brain. Less common is impaired absorption by the blood vessels, often from inflammation of brain tissue after disease or injury. Rarely, the mechanisms overproduce CSF faster than it can be absorbed.
Clinical Manifestations
Presentation depends on age, cause, location and duration of obstruction, and rapidity of onset. The infant feeds poorly. An excessively large head at birth suggests hydrocephalus. The anterior fontanelle becomes tense and bulging, the skull enlarges in all diameters, and the scalp becomes shiny with dilated veins. As pressure climbs without intervention, the eyes appear pushed downward with sclera visible above the iris, the setting sun sign. Rising ICP also brings a high-pitched cry, irritability, and projectile vomiting.
Assessment and Diagnostic Findings
CT scanning assesses the size of the ventricles and other structures. MRI assesses for Chiari malformation or cerebellar or periaqueductal tumors. Ultrasonography through the anterior fontanelle in infants assesses for subependymal and intraventricular hemorrhage and follows infants for progressive hydrocephalus. Skull radiography detects erosion of the sella turcica or a beaten copper (or beaten silver) cranium, the latter also seen in craniosynostosis, and after shunt insertion confirms correct hardware position. MRI cine measures CSF stroke volume (SV) in the cerebral aqueduct, though such measurements do not appear useful for predicting shunt response. Diffusion tensor imaging (DTI) detects differences in fractional anisotropy and mean diffusivity of brain parenchyma around the ventricles, picking up microstructural periventricular white matter changes too subtle for conventional MRI. Radionuclide cisternography (in NPH) assesses shunting prognosis but is no longer commonly used given its poor sensitivity when the ventricular to total intracranial activity (V/T) ratio is less than 32%.
Medical Management
The goal is to reduce or prevent brain damage by improving CSF flow, which may mean surgical shunting that drains excess fluid from the ventricles to an extracranial space such as the peritoneum or right atrium (in older children), or medications to reduce ICP if progression is slow or surgery is contraindicated.
Pharmacologic Therapy
Acetazolamide (ACZ) and furosemide (FUR) treat posthemorrhagic hydrocephalus in neonates; both are diuretics that also appear to decrease CSF secretion at the choroid plexus. Anticonvulsants interfere with impulse transmission in the cerebral cortex to prevent seizures. Antibiotics, guided by culture and sensitivity, treat shunt infections such as septicemia, ventriculitis, and meningitis, or serve as prophylaxis.
Surgical Management
Surgery is the only effective way to relieve brain pressure and prevent further tissue damage, and it is the preferred therapeutic option. A ventriculoperitoneal (VP) shunt relieves pressure from fluid accumulation. A ventriculoatrial (VA) shunt lets CSF flow from the ventricular system to the atrium of the heart. A lumboperitoneal shunt is used only for communicating hydrocephalus, CSF fistula, or pseudotumor cerebri. A Torkildsen shunt (rarely used) is effective only in acquired obstructive hydrocephalus. A ventriculopleural shunt is second-line, used when other shunt types are contraindicated.
Nursing Management
Nursing Assessment
Measuring the newborn's head is essential. Obtain accurate vital and neurologic signs before and after surgery. If the fontanelles are not closed, observe them carefully for bulging. Observe, report, and document all signs of increased ICP. If the child has returned for revision of an existing shunt, get a complete history from the caregiver before surgery to establish a behavioral baseline.
Nursing Diagnoses
Risk for injury related to increased ICP. Risk for impaired skin integrity related to pressure from immobility. Risk for infection related to the presence of a shunt. Risk for delayed growth and development related to impaired ability to achieve developmental tasks. Anxiety related to the caregiver's fear of the surgical outcome. Deficient knowledge related to the family's understanding of the condition and home care.
Nursing Care Planning and Goals
Prevent injury, maintain skin integrity, prevent infection, maintain growth and development, and reduce family anxiety.
Nursing Interventions
To prevent injury, monitor the newborn's level of consciousness at least every 2 to 4 hours, check the pupils for equality and reaction, monitor neurologic status for a shrill cry, lethargy, or irritability, measure and record head circumference daily, and keep suction and oxygen equipment at the bedside. To promote skin integrity after shunting, keep the head turned away from the operative site until the physician allows repositioning, reposition at least every 2 hours as permitted, and inspect the dressing over the shunt site immediately after surgery, every hour for the first 3 to 4 hours, then at least every 4 hours. To prevent infection, watch for and promptly report any signs of infection, perform wound care thoroughly as ordered, and give antibiotics as prescribed. To promote growth and development, give the newborn social interaction (talk to, play with, allow activity) and toys suited to mental and physical capacity. To reduce family anxiety, explain the condition and surgical anatomy in plain terms, encourage questions and expression of anxieties, and give accurate, nontechnical answers. For family teaching, demonstrate shunt care and have caregivers return-demonstrate it, provide a list of signs and symptoms to report, and discuss realistic growth and development expectations.
Evaluation
Goals are met by prevention of injury, maintenance of skin integrity, prevention of infection, maintenance of growth and development, and reduction of family anxiety.
Documentation Guidelines
Document individual risk factors including recent or current antibiotic therapy, insertion sites and character of drainage, signs and symptoms of infection, the plan of care, the teaching plan, responses to interventions and teaching, attainment or progress toward outcomes, modifications to the plan of care, and discharge needs.
Frequently Asked Questions
What is hydrocephalus? It is an abnormal buildup of cerebrospinal fluid in the brain's ventricles that raises intracranial pressure and can damage brain tissue. It can occur at any age from congenital malformations, infections, tumors, or traumatic brain injury.
How common is congenital hydrocephalus? It affects roughly 1 to 2 per 1,000 live births, with United States and Canada studies reporting closer to 0.7 per 1,000 (systematic review and meta-analysis). The Hydrocephalus Association describes it as one of the most common conditions affecting brain development in children.
What are the early signs in an infant? Watch for an excessively large or rapidly enlarging head, a tense and bulging anterior fontanelle, a shiny scalp with dilated veins, a high-pitched cry, irritability, and projectile vomiting. The setting sun sign, where the eyes appear pushed downward, is a later sign of rising pressure.
How is hydrocephalus treated? Surgery is the only effective way to relieve the pressure, most often a ventriculoperitoneal shunt that drains excess fluid to the peritoneum. Medications such as acetazolamide and furosemide may slow CSF production when progression is slow or surgery is contraindicated.
What shunt problems should families watch for? Teach families to recognize shunt infection and shunt failure, both of which show up as returning signs of rising intracranial pressure such as headache, vomiting, irritability, lethargy, or fever. Early reporting prevents a crisis.
What is the difference between communicating and noncommunicating hydrocephalus? Noncommunicating (obstructive) hydrocephalus involves a physical blockage of CSF flow, while communicating hydrocephalus has no obstruction and instead results from defective CSF absorption.