Hydrocephalus is a condition caused by an imbalance in the production and absorption of CSF in the ventricular system. When production exceeds absorption, CSF accumulates, usually under pressure, producing dilation of the ventricles.
It is a term derived from the Greek words “hydro” meaning water, and “cephalus” meaning head, and this condition is sometimes known as “water on the brain”.
People with hydrocephalus have abnormal accumulation of cerebrospinal fluid (CSF) in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head, convulsion, and mental disability.
Usually, hydrocephalus does not cause any intellectual disability if recognized and properly treated. A massive degree of hydrocephalus rarely exists in typically functioning people, though such a rarity may occur if onset is gradual rather than sudden.
Hydrocephalus occurs with a number of anomalies, such as NTD’s.
Congenital hydrocephalus usually results from defects, such as Chairi malformations. It is also associated with spina bifida.
Acquired hydrocephalus usually results from space-occupying lesions, hemorrhage, intracranial infections or dormant development defects.
Hydrocephalus can be caused by impaired cerebrospinal fluid (CSF) flow, reabsorption, or excessive CSF production.
- The most common cause of hydrocephalus is CSF flow obstruction, hindering the free passage of cerebrospinal fluid through the ventricular system and subarachnoid space (e.g., stenosis of the cerebral aqueduct or obstruction of the interventricular foramina – foramina of Monro secondary to tumors, hemorrhages, infections or congenital malformations).
- Hydrocephalus can also be caused by overproduction of cerebrospinal fluid (relative obstruction) (e.g., papilloma of choroid plexus).
Based on its underlying mechanisms, hydrocephalus can be classified into communicating, and non-communicating (obstructive). Both forms can be either congenital, or acquired.
· Communicating hydrocephalus, also known as non-obstructive hydrocephalus
· It is caused by impaired cerebrospinal fluid resorption in the absence of any CSF-flow obstruction.
· It has been theorized that this is due to functional impairment of the arachnoid granulations, which are located along the superior sagittal sinus and is the site of cerebrospinal fluid resorption back into the venous system.
· Various neurologic conditions may result in communicating hydrocephalus, including subarachnoid/intraventricular hemorrhage, meningitis, Chiari malformation, and congenital absence of arachnoidal granulations (Pacchioni’s granulations).
- Normal pressure hydrocephalus (NPH) is a particular form of communicating hydrocephalus, characterized by enlarged cerebral ventricles, with only intermittently elevated cerebrospinal fluid pressure. The diagnosis of NPH can be established only with the help of continuous intraventricular pressure recordings (over 24 hours or even longer), since more often than not, instant measurements yield normal pressure values. Dynamic compliance studies may be also helpful. Altered compliance (elasticity) of the ventricular walls, as well as increased viscosity of the cerebrospinal fluid, may play a role in the pathogenesis of normal pressure hydrocephalus.
- Hydrocephalus ex vacuo also refers to an enlargement of cerebral ventricles and subarachnoid spaces, and is usually due to brain atrophy (as it occurs in dementias), post-traumatic brain injuries and even in some psychiatric disorders, such as schizophrenia. As opposed to hydrocephalus, this is a compensatory enlargement of the CSF-spaces in response to brain parenchyma loss – it is not the result of increased CSF pressure.
Non-communicating hydrocephalus, or obstructive hydrocephalus, is caused by a CSF-flow obstruction (either due to external compression or intraventricular mass lesions).
- Foramen of Monro obstruction may lead to dilation of one or, if large enough (e.g., in colloid cyst), both lateral ventricles.
- The aqueduct of Sylvius, normally narrow to begin with, may be obstructed by a number of genetically or acquired lesions (e.g., atresia, ependymitis, hemorrhage, tumor) and lead to dilatation of both lateral ventricles as well as the third ventricle.
- Fourth ventricle obstruction will lead to dilatation of the aqueduct as well as the lateral and third ventricles.
- The foramina of Luschka and foramen of Magendie may be obstructed due to congenital failure of opening (e.g., Dandy-Walker malformation).
- The subarachnoid space surrounding the brainstem may also be obstructed due to inflammatory or hemorrhagic fibrosing meningitis, leading to widespread dilatation, including the fourth ventricle.
- The cranial bones fuse by the end of the third year of life. For head enlargement to occur, hydrocephalus must occur before then. The causes are usually genetic but can also be acquired and usually occur within the first few months of life, which include 1) intraventricular matrix hemorrhages in premature infants, 2) infections, 3) type II Arnold-Chiari malformation, 4) aqueduct atresia and stenosis, and 5) Dandy-Walker malformation.
- In newborns and toddlers with hydrocephalus, the head circumference is enlarged rapidly and soon surpasses the 97th percentile. Since the skull bones have not yet firmly joined together, bulging, firm anterior and posterior fontanelles may be present even when the patient is in an upright position.
- The infant exhibits fretfulness, poor feeding, and frequent vomiting. As the hydrocephalus progresses, torpor sets in, and the infant shows lack of interest in his surroundings. Later on, the upper eyelids become retracted and the eyes are turned downwards (due to hydrocephalic pressure on the mesencephalic tegmentum and paralysis of upward gaze). Movements become weak and the arms may become tremulous. Papilledema is absent but there may be reduction of vision. The head becomes so enlarged that the child may eventually be bedridden.
- About 80-90% of fetuses or newborn infants with spina bifida—often associated with meningocele or myelomeningocele—develop hydrocephalus.
- This condition is acquired as a consequence of CNS infections, meningitis, brain tumors, head trauma, intracranial hemorrhage (subarachnoid or intraparenchymal) and is usually extremely painful.
- Abnormal rate of head growth
- Bulging fontanelle
- Tense anterior fontanelle (often bulging and nonpulsatile)
- Dilated scalp veins
- Macewen’s sign (“cracked pot”)
- Frontal bossing
- Setting sun sign
- Sluggish and unequal pupils
- Irritability and lethargy with varying LOC
- Abnormal infantile reflexes
- Possible cranial nerve damage
Manifestations in children include possible signs of increased ICP, which include headache on awakening with improvement following emesis, papilledema, strabismus, ataxia, irritability, lethargy, apathy and confusion.
Laboratory and Diagnostic Study Findings:
- Level II ultrasonography of the fetus will allow a prenatal diagnosis. (Transuterine placement of ventriculoamniotic shunts during late pregnancy is still being developed as a treatment modality).
- CT scan will diagnose most cases postnatally.
- MRI can be used if a complex lesion is suspected.
1. Teach the family about the management required for the disorder
a. Treatment is surgical by direct removal of an obstruction and insertion of shunt to provide primary drainage of the CSF to an extracranial compartment, usually peritoneum (ventriculoperitoneal shunt)
1. The major complications of shunts are infections and malfunction
2. Other complications include subdural hematoma caused by a too rapid reduction of CSF, peritonitis, abdominal abscess, perforation of organs, fistulas, hernias and ileus.
b. A third ventriculostomy is a new nonshunting procedure used to treat children with hydrocephalus.
2. Provide preoperative nursing care
a. Assess head circumference, fontanelles, cranial sutures, and LOC; check also for irritability, altered feeding habits and a high-pitched cry.
b. Firmly support the head and neck when holding the child.
c. Provide skin care for the head to prevent breakdown.
d. Give small, frequent feedings to decrease the risk of vomiting.
e. Encourage parental-newborn bonding.
3. Provide Postoperative nursing care (nursing interventions are the same as those for increased ICP)
a. Assess for signs of increased ICP and check the following; head circumference (daily), anterior fontanelle for size and fullness and behavior.
b. Administer prescribed medications which may include antibiotics to prevent infection and analgesics for pain.
c. Provide shunt care
1. Monitor for shunt infection and malfunction which may be characterized by rapid onset of vomiting, severe headache, irritability, lethargy, fever, redness along the shunt tract, and fluid around the shunt valve.
2. Prevent infection (usually from Staphylococcus epidermis or Staphylococcus aureus)
3. Monitor for shunt overdrainage (headache, dizziness and nausea). Overdrainage may lead to slit ventricle syndrome whereby the ventricle become accustomed to a very small or slitlike configuration, limiting the buffering ability to increased ICP variations.
4. Teach home care
a. Encourage the child to participate in age-appropriate activities as tolerated. Encourage the parents to provide as normal lifestyle as possible. Remind both the child and parents that contact sports are prohibited.
b. Explain how to recognize signs and symptoms of increased ICP. Subtle signs include changes in school performance, intermittent headache, and mild behavior changes.
c. Arrange for the child to have frequent developmental screenings and routine medical checkups.