Normal pressure hydrocephalus (NPH) can be treated with a shunt system, which can include complications resulting from the surgical procedure but more often are issues that occur days or years later.
The most common shunt complications are malfunction and infection as well as subdural hematoma.
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, cerebrospinal fluid (CSF) accumulates and can result in symptoms of untreated normal pressure hydrocephalus.
A shunt obstruction 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. 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.
Subdural hematoma is a blood clot and is one of the more serious complications that can occur following insertion of a shunt. The risk of a subdural hematoma in people with normal pressure hydrocephalus and a shunt is approximately five to ten percent. Because most shunts drain CSF from the center of the brain or the ventricles, this may cause the surface of the brain to pull away from the skull, stretching and tearing blood vessels from the scalp to the surface of the brain. This is sometimes seen on a CT scan as a fluid space between the brain and the skull called a hygroma. Although a hygroma may not have clinical symptoms, it may increase the risk of hematoma.