Hydrocephalus and VP shunts

Description
In hydrocephalus excess cerebrospinal fluid (CSF) accumulates in and around the brain and spinal cord causing potentially harmful pressure on those tissues. This results from an imbalance between production and absorption of CSF, usually through an obstruction in the typical pattern of flow, sometimes due to decreased absorption, and very rarely due to increased production. Hydrocephalus may be congenital or acquired. Causes of hydrocephalus include:

• damage to the developing brain (e.g., associated with spina bifida and Dandy-Walker malformation);
• genetic defects (e.g., aqueductal stenosis); and
• injury (e.g., accumulation of blood clots after intraventricular hemorrhage).
  

Hydrocephalus ex vacuo results from injury, often to the blood vessels supplying the brain resulting in poor brain growth and/or atrophy of the brain. The CSF then increases in volume to fill the empty space. Hydrocephalus may be a primary cause of CP and/or developmental delay or an associated condition. Many causes of CP may result in hydrocephalus, including intrauterine infection, intracranial bleed, and brain malformations.

Prevalence
Hydrocephalus may affect up to 1 in 500 children. See Hydrocephalus information from the NIH.

Signs and Symptoms
Initial signs of hydrocephalus in infants, which may be subtle, include sleepiness, irritability, vomiting, sunsetting eyes, and seizures, as well as a large and/or rapidly increasing head circumference. In children whose skull bones have already fused, nausea, headache, sunsetting eyes, seizures, and visual disturbances, such as diplopia and blurred vision, may develop. Hydrocephalus that is slowly developing may cause more subtle changes, such as a plateau or regression in developmental milestones, new learning problems, such as memory loss and difficulty concentrating, and personality changes. In a child with CP, these complaints should lead to imaging for possible hydrocephalus.

Treatment
If hydrocephalus is present, the child with CP will usually have a shunt placed by a neurosurgeon. The most typical arrangement is a ventriculo-peritoneal shunt. Risks of VP shunts Include shunt malfunction, obstruction, or overdrainage, abdominal complications, and infection. Infection is more common in the first few months after shunt placement and is most often due to Staphylococcus epidermis. Shunt obstruction may result from growth of the child, requiring replacement with a longer catheter. Families and providers for children with VP shunts should be alert to the primary signs of shunt obstruction and infection, including headaches, vomiting, and drowsiness. Slowly progressing shunt malfunctions may present with progressively worsening headaches, loss of developmental milestones, falling asleep in school, personality changes, and new learning problems. These signs should prompt evaluation by the neurosurgeon or local emergency room. X-rays of the shunt (commonly called a "shunt series") and a CT scan of the head may be indicated, along with, if infection is a concern, a shunt tap to examine the CSF. A small percentage of patients with hydrocephalus will be treated with a third ventriculostomy in which small holes are made in the floor of the third ventricle to allow the CSF to escape the ventricular system to the space surrounding the brain, thus bypassing the obstruction.

Prognosis
The prognosis for hydrocephalus is related to its underlying causes and associated conditions. Many children with hydrocephalus will benefit from early intervention, rehabilitation, and educational interventions.