Care and management of the child with shunted hydrocephalus.
The term hydrocephalus is derived from the Greek, hydor (water) and kephale (head). Hydrocephalus is an accumulation of cerebrospinal fluid (CSF) in the ventricles, which results in dilatation of the ventricles (see Figure 1). As fluid volume increases, pressure increases within the intracranial vault. CSF serves many functions: (a) it buffers the brain to protect it from normal movements of the head, (b) it helps maintain normal chemical balance, and (c) it assists in the maintenance of the blood-brain barrier.
[FIGURE 1 OMITTED]
Physiology. CSF is formed and secreted by the choroid plexus, the highly vascular lining of the ventricles, at a rate of approximately 500 cc per day in the adult. Newborns produce approximately 25 cc. per day, and children will range on a continuum between the adult and newborn rate (Greenberg, 2001).
CSF is secreted by the choroid plexus and circulates through the intracranial vault and spinal column in a predictable pathway (see Figure 2). From the lateral ventricles CSF travels through the Foramen of Monro to the third ventricle, then through the Aqueduct of Sylvia to the fourth ventricle. The fluid then flows through the Foramen of Luske and Magendie to cisterns and to the arachnoid space of the cerebral and cerebellar hemispheres as well as the thecal sac. A small amount of CSF also flows through the central canal of the spinal cord. After completing its flow through the central nervous system, the CSF is absorbed by the arachnoid villi in the subarachnoid space. There also is speculation that some CSF is drained via the lymphatic system. This is based on clinical observations that some children with shunt obstruction develop nasal congestion and facial swelling (McLaurin, Venes, Schut, & Epstein, 1989).
[FIGURE 2 OMITTED]
Causes of hydrocephalus. Hydrocephalus develops when there is impedance to CSF flow or absorption. Rarely hydrocephalus will occur due to the overproduction of CSF, as in choroid plexus papilloma. During the neonatal and early infancy period the most common causes of hydrocephalus are due to congenital anomalies, including aqueductal stenosis, Chiari I and II malformation, and Dandy-Walker malformation. Acquired hydrocephalus problems in infancy are most commonly secondary to intraventricular hemorrhage due to prematurity (G reenberg, 2001). Infections in utero also are a factor in some cases of neonatal hydrocephalus, and are caused by viruses or bacteria. Guinea pigs, rabbits, and cats are known to be vectors for viruses that can cause asymptomatic infection in pregnant women. However, the virus crosses the placenta to cause potentially catastrophic neurologic problems in the developing fetus (Wright et al., 1997). Therefore, pregnant women should be counseled to avoid exposure to these animals.
Other causes of hydrocephalus that occur in any age group include masses such as tumors, vascular malformations or cysts, and hematoma secondary to trauma. Infectious processes such as meningitis can impede reabsorption of CSF at the level of the arachnoid villi resulting in hydrocephalus (Greenberg, 2001).
Symptoms. Regardless of the cause of hydrocephalus, the symptoms are classic and consistent with increased intracranial pressure (ICP). In infancy indications of raised ICP are enlarging occipito-frontal head circumference that either crosses more than 2 percentile lines or increases out of proportion to previous measurements (Brann & Schwartz, 1992). Premature infants will have greater head growth as compared to term infants; therefore, their measurements are plotted on growth charts especially developed for premature infants.
Initially in developing hydrocephalus the infant's skull sutures will move to allow for intracranial expansion, and the infant may be asymptomatic. With progression of intracranial pressure the infant may exhibit irritability, emesis, a full, bulging fontanel and neurologic symptoms such as 6th nerve palsy or "setting sun eyes," which is an upward gaze palsy. An infant may also develop irregular respirations with apneic periods and splaying of the cranial sutures. In adults and older children, symptoms of hydrocephalus include headache, papilledema, nausea and vomiting, lethargy or irritability, worsening school performance, gait disturbances, and 6th nerve palsy, as well as other abnormalities in the neurologic exam (McLone, 2001).
The treatment of symptomatic hydrocephalus may initially include the temporary use of medications to decrease CSF production, such as acetazolamide. Decadron may be administered to decrease edema secondary to increased ICP. Definitive management is surgical intervention, either via a shunt system or third ventriculostomy procedure (Drake & Lantosca, 2001).
The shunt system consists of several parts, a proximal catheter that enters the lateral ventricle, a valve to prevent CSF from being siphoned due to effects of gravity, and a distal catheter that ends in the peritoneal cavity or alternate drainage site (see Figure 3). The distal end of the catheter is most commonly placed in the peritoneum, although the pleural space of the lungs and right atrium of the heart are used less frequently. The advantages of using the peritoneum include easy accessibility and less risk of complications than other sites. The alternative sites of the heart and lung pose complications such as risk of emboli, pleural effusion, pneumothorax, respiratory distress, and endocarditis.
[FIGURE 3 OMITTED]
Several types of valves are available and are selected based on the neurosurgeon's preference and patient physiology. Older types of valves regulate fluid to drain at high, medium or low pressure. The most recent technology is a shunt valve that is programmable, thus allowing the pressure to be adjusted. These valves are programmed non-invasively by use of a magnet. Patients with programmable shunt valves must avoid magnetic forces such as metal detectors and MRI machines, as this can alter the pressure setting. If a patient with a programmable valve requires an MRI, the valve setting is checked at completion of the MRI via plain x-ray. The valve is then reprogrammed to the desired pressure setting (McLone, 2001). There is some evidence that even weaker magnets such as toy magnets, hair dryers, and telephone speakers can alter the pressure setting, thus causing some manufacturers to recommend that the shunt setting be checked regularly (Anderson, Walker, Viner, & Kestle, 2004), which can be costly and time consuming.
A small group of patients may be candidates for a surgical procedure called endoscopic third ventriculostomy (ETV), which is done in lieu of shunt placement. Patients with obstructive hydrocephalus such as aqueductal stenosis or tumor may be considered for this procedure. An endoscope is used to visualize the floor of the ventricle and a fenestration is made that allows CSF to flow around the obstruction (Greenberg, 2001). Complications of ETV include hemorrhage, CSF leak, subdural hematoma, bradycardia, and injury to the periventricular structures such as the hypothalamus, which can result in diabetes insipidus, increased appetite, loss of thirst, and amenorrhea (Walker, 2004). There is also the possibility that the fenestration may close or narrow at any time, resulting in enlarged ventricles and symptoms of increased intracranial pressure. Surgical intervention is warranted in this situation.
Antibiotic-impregnated catheters also are available for use. In our practice we use these in patients at high risk for infection, or those who have had prior shunt infections.
Very small infants who weigh less than 1000 grams and require shunting may undergo a ventriculosubgaleal shunt. CSF is diverted to the subgaleal space where it is absorbed. The shunt is converted to a VP shunt when the infant is older and has less risk of developing surgical complications. On rare occasion we have found that some patients only require the subgaleal shunt as a temporary measure, and may not need conversion to a full VP shunt. The risks of the ventriculosubgaleal shunt are low, but include infection (5.9%) and CSF leak (4.7%) (Tubbs et al., 2005).
Patient Care After Shunt Insertion
Nursing care in the post-operative period includes frequent neurologic assessments and monitoring for infection. The greatest risk for shunt infections occurs within the first three months following surgery. Patients receive perioperative intravenous antibiotics to help prevent the development of infection. Statistically, approximately 3-12% of patients will develop a shunt infection, with premature and low-birth weight infants being at greatest risk (Casey et al., 1997; Davis, Levy, McComb, & Masri-Lavine, 1999). The most common causative organisms of CSF infections in infants and children are the following: staphylococcus epidermidis and staphylococcus aureus. Proprianobacter acne is a slow-growing infection of the CSF found more often in adolescents and adults (Thompson & Albright, 1998).
Signs of shunt infection include: fever, lethargy, irritability, redness along shunt device system, abdominal discomfort, or apnea. The physician will obtain CSF cultures if a patient develops symptoms of infection (Greenberg, 2001).
Abdominal complications may occur on occasion. Bowel perforation, ileus, pseudocyst or abscesses are potential problems. In rare instances catheter migration has been documented to cause bladder perforation or migration into the scrotal sac resulting in a hydrocele (Ward, Moquin, & Maurer, 2001).
It is not unusual for infants and small children to develop a small subgaleal CSF collection that tracks along the shunt tubing. As the surgical site heals the fluid collection will diminish and resolve over time. However, if the collection changes greatly and the child shows signs of increased intracranial pressure, the child should be evaluated for shunt failure (Tubbs et al., 2003).
The patient should be monitored for fluid leak from the incision. If noted, the neurosurgeon should be promptly notified as a persistent leak places the patient at high risk for developing an infection.
Occasionally there can be over drainage of the ventricles. If this occurs, the patient will complain of postural headaches while sitting up, but that resolves when lying down. Rarely, a subdural hematoma may develop if there is rapid decompression of the ventricles. This complication is due to tearing of the bridging veins of the dura as the brain shifts into the space previously occupied by the ventricles (McLone, 2001).
Long-term management of the child with a ventriculoperitoneal (VP) shunt includes attention to developmental needs. Children with shunts should be encouraged to lead as normal a life as possible. Many parents ask if their child will have normal development and brain function. The shunt itself does not cause developmental delays. However, the underlying problem that caused the child to need a shunt will determine the child's deficits, if any. Each case is individual. Children with VP shunts may have normal intelligence and attend college, while other children are severely impaired. Close monitoring of the child's growth and development is important, so that delays and issues may be addressed in a timely manner, and appropriate referrals for Early Intervention programs can be made.
The infant with a larger than average head may find it difficult to support the weight of the head. Rolling over and sitting up may be difficult or delayed. Parents will need explanation and reassurance about the delay. This becomes less of a problem as the child's body grows more in proportion to his head size.
Parents and older children must be taught the signs and symptoms of shunt failure. Persistent headache, emesis, lethargy, change in the neurologic exam, visual changes such as diplopia or loss of conjugate gaze, or swelling or redness along the shunt valve or tubing are indications to take the child for medical evaluation. A head CT, shunt series, and, if warranted, a shunt tap to obtain CSF for culture, are obtained.
Children are counseled to avoid contact sports that may cause injury to the shunt valve or head trauma. Football, lacrosse, or other contact sports are not recommended. Instead, parents are advised to encourage participation in low impact sports such as tennis or swimming. A helmet should be worn for skiing or other sports that may cause head injury.
A child who does suffer head trauma requires close observation for signs of neurologic deterioration. When there is bleeding into the intracranial vault with resultant increased intracranial pressure, the shunt will act to decompress the ventricular system, thus allowing for rapid expansion of a growing hematoma.
In our practice, we discourage patients from wearing purses, shoulder bags, or backpacks on the side where the shunt tubing passes down the neck. Continuous pressure on the tubing may cause a break or kink in the tubing, thus resulting in shunt malfunction.
Patients with VP shunts do not require extra antibiotic prophylaxis prior to dental, gastrointestinal, or genitourinary procedures. However, children with ventriculoatrial shunts do require antibiotic prophylaxis to prevent bacterial endocarditis. Patients are given the American Heart Association bacterial endocarditis prophylaxis cards to share with their dentist or specialist. The cards can be ordered on the internet from the American Heart Association at www.americanheart.org.
A study by Bragg, Edwards-Beckett, Eckle, Principe, and Terry (1994) indicated that constipation might be a factor in the development of shunt malfunction, and anecdotally we have found this to be true in our clinical practice in several instances. It is theorized that increased abdominal pressure due to constipation may result in a decrease in CSF drainage via the VP shunt, thus resulting in increased ventricular size. In their retrospective case review, Bragg et al. found that some children who had signs and symptoms of shunt failure and radiographic evidence of constipation had resolution of symptoms after bowel cleansing. We counsel parents and children to be aware of bowel patterns and recommend use of laxatives and dietary changes as warranted to maintain regular bowel movements.
As patients enter late adolescence, the independence issues of moving into an apartment or going away to college arise. A person with a VP shunt should have a roommate who knows the symptoms of shunt failure and who will obtain emergency medical help if the patient is too ill to do so. A medical alert bracelet is recommended.
In summary, CSF shunting devices save the lives of many children with hydrocephalus. These patients require consistent neurosurgical follow-up throughout their lives. As children grow they and their parents often have questions regarding the shunt and its impact on their lives. It is important that health care providers assist with anticipatory guidance for long-term management issues and respond to questions and concerns that may arise.
Case study: Twin A.
Twin A was born at 37 weeks gestation. The infant developed a high fever and was treated for meningitis. Due to rapidly increasing head circumference and increasing fullness of the fontanel, serial head CT's were obtained. Significant findings included intraventricular hemorrhage and increasing ventricle size, particularly the third and lateral ventricles (see Figure 4). Indications for VPS placement and the surgical risks were explained to the parents. They consented to surgery and, at 3 weeks of age, the infant underwent placement of a VPS. The procedure was well tolerated with 1-2 cc blood loss. A post-operative head CT showed good catheter placement and decreased size of the ventricles (see Figure 5). On physical exam the fontanel was soft and fiat, and the head circumference stabilized. Prior to discharge, the parents were educated about the signs and symptoms of shunt failure and infection. The child is now 2 years old, in good health, and reaching developmental milestones.
[FIGURES 4-5 OMITTED]
Anderson, R.C., Walker, M.L., Viner, J.M., & Kestle, J.R. (2004). Adjustment and malfunction of programmable valve after exposure to toy magnets. Case Report. Journal of Neurosurgery, 101(2 Suppl), 222-225.
Bragg, C.L., Edwards-Beckett, J., Eckle, N., Principe, K., & Terry, D. (1994). Ventriculoperitoneal shunt dysfunction and constipation: A chart review. Journal of Neuroscience Nursing, 26(5), 265-269.
Brann, A., & Schwartz, J. (1992). Central nervous system disturbances. In A. Fanaroff, & R. Martin (Eds.), Neonatal-perinatal medicine (pp. 729-753). St. Louis: Mosby.
Casey, A.T., Kimmings E.J., Kleinlugtebeld, A.D., Taylor, W.A., Harkness, W.F., & Hayward, R.D. (1997). The long-term outlook for hydrocephalus in childhood: A ten-year cohort study. Pediatric Neurosurgery, 27(2), 63-70.
Davis S.E., Levy, M., McComb, J.G., & Masri-Lavine, L. (1999). Does age or other factors influence the incidence of ventriculoperitoneal shunt infections? Pediatric Neurosurgery, 30(5), 253-257.
Drake, J., & Lantosca, M. (2001). Management of pediatric hydrocephalus with shunts. In D. McLone (Ed.), Pediatric neurosurgery (pp. 505-522). Philadelphia: W.B. Saunders.
Greenberg, M.S. (2001). Handbook of neurosurgery (5th ed.). New York: Thieme Medical Publishers.
McLaurin, R., Venes, J.L., Schut, L., & Epstein, E (Eds.). (1989). Pediatric neurosurgery (2nd ed.). Philadelphia: WB Saunders Co.
McLone, D.G. (Ed.). (2001). Pediatric neurosurgery (4th ed.). New York: WB Saunders.
Thompson, T., & Albright, A. (1998). Propranobacterium acnes infections of cerebrospinal fluid. Children's Nervous System, 14, 378-380.
Tubbs, R.S., Banks, J.T., Slocum, S.S., Wellons, J.C., Blount, J.P., Grabb, P.A., et al. (2005). Complications of ventriculosubgaleal shunts in infants and children. Child's Nervous System, 21(1), 48-51.
Tubbs, R.S., Smyth, M.D., Wellons, J.C. III, Blount, J.R, Grabb, P.A., & Oakes, W.J. (2003). Alternative uses for the subgaleal shunt in pediatric neurosurgery. Pediatric Neurosurgery, 39(1), 22-24.
Walker, M.L. (2004). Complications of third ventriculostomy. Neurosurgery Clinics of North America, 15(1), 61-66.
Ward, J.E, Moquin, R.R., & Maurer, S.T. (2001). Expanding the differential diagnosis of the acute scrotum: Ventriculoperitoneal shunt herniation. Urology, 58(2), 281.
Wright, R., Johnson, D., Neumann, M., Ksiazek, T.G., Rollin, P., Keech R.V., et al. (1997). Congenital lymphocytic choriomeningitis virus syndrome: A disease that mimics congenital toxoplasmosis or cytomegalovirus infection. Pediatrics, 100(1), E9.
Marianne Chiafery, RN, MS, is Pediatric Nurse Practitioner, Division of Pediatric Neurosurgery, Strong Memorial Hospital, University of Rochester Medical Center, Rochester, NY.
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|Date:||May 1, 2006|
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