Hydrocephalus can be treated with a shunt system, and this treatment often includes complications. An estimated 50% of shunts in the pediatric population fail within two years of placement and repeated neurosurgical operations are often required.
The most common shunt complications are malfunction and infection.
Shunt malfunction is a partial or complete blockage of the shunt that causes it to function intermittently or not at all. When a blockage occurs, CSF accumulates and can result in symptoms of untreated hydrocephalus.
A shunt blockage from blood cells, tissue or bacteria can occur in any part of the shunt. Both the ventricular catheter – the portion of the tubing placed in the brain – and the distal part of the catheter – the tubing that drains fluid to another part of the body – can become blocked by tissue from the choroid plexus or ventricles. The distal part of the catheter is more often blocked in adults.
Shunts are very durable, but their components can become disengaged or fractured as a result of wear or as a child grows, and occasionally they dislodge from where they were originally placed. More rarely, a valve will fail because of a mechanical malfunction.
Shunt infection is usually caused by a person’s own bacterial organisms and isn’t acquired from other children or adults who are ill. The most common infection is Staphylococcus Epidermidis, which is normally found on the surface of a person’s skin and in the sweat glands and hair follicles deep within the skin. This type of infection is most likely seen one to three months after surgery, but can occur up to six months after the placement of a shunt. People with ventriculoperitoneal (VP) shunts are at risk of developing a shunt infection secondary to abdominal infection. Those patients treated with ventriculoatrial (VA) shunts may develop generalized infection, which can quickly become serious.
NOTE: If you suspect an infection, it’s critical to notify your neurosurgeon immediately or go to the emergency room. Shunt infections are serious and require immediate medical attention to avoid life-threatening illness or possible brain damage.
Other Shunt Complications
Over drainage causes the ventricles to decrease in size creating slit-like ventricles as a result of the brain and its meninges pulling away from the skull. Slit-like ventricles, sometimes called slit-ventricle syndrome (SVS), are most commonly a problem in young adults who have been shunted since childhood. A particular symptom of SVS is severe intermittent headaches that are often relieved when lying down. Imaging studies are required to determine SVS, which is typically indicated by smaller than normal ventricles. Most shunt manufacturers have shunt hardware designed to address slit-ventricle syndrome.
Under drainage causes the ventricles to increase in size and can fail to relieve the symptoms of hydrocephalus. To restore a balanced flow of CSF it may be necessary to place a new shunt with a more accurate pressure valve. For those who have externally adjustable or programmable valves, the balance of flow can be restored by re-setting the opening pressure.
Subdural hematoma occurs if blood from broken vessels in the meninges becomes trapped between the brain and skull. This is most common in older adults with normal pressure hydrocephalus (NPH) and requires surgery to correct.
Multiloculated hydrocephalus is a located (isolated) CSF compartment in the ventricular system that is enlarged and not in communication with the normal ventricle. It may be caused by birth trauma, neonatal intraventricular hemorrhage, ventriculitis, shunt related infection, over drainage or other conditions. This complication may be difficult to identify because it is typically seen in infants and children who may be neurologically compromised. Surgical treatments include multiple shunt placement, ventricular catheters with multiple perforations or openings, craniotomy and fenestration (opening) of the intraventricular loculations.
Seizures sometimes occur in people with hydrocephalus. There is no correlation between the number of shunt revisions or the site of shunt placement and an increased risk of developing seizures. Past studies have shown that children with hydrocephalus who have been treated with a shunt and who also have significant cognitive delay or motor disability are more likely to experience seizures than those without cognitive or motor delays. Studies have also indicated that seizures are not likely to occur at the time of shunt malfunction, and that the most likely explanation of seizure disorder is the presence of associated malformations of the cerebral cortex.
Abdominal complications can occur in people with hydrocephalus treated with a shunt. The peritoneum or abdominal area is the most popular site for distal catheter implantation. Although ventriculoperitoneal (VP) shunts do not have fewer complications than ventriculoatrial shunts, the complications are less severe and have a lower mortality rate. Shunt complications that develop in the peritoneum or abdominal area include peritoneal pseudocysts, lost distal catheters, bowel perforations and hernias.