CerebroSpinal Fluid (CSF) shunt
Shunt surgery is the primary surgical option of treatment of different types of hydrocephalus. A shunt is a thin tube that is permanently implanted to allow excess fluid to drain away to another part of the body, where it can be absorbed. Depending upon the cause of the hydrocephalus, fluid can either be drained away from the ventricles of the brain (ventricular shunt) or from around the spinal cord in the lower back (lumbar shunt).
There are several types of shunts designed to treat hydrocephalus depending on the types of shunts and the body compartments that the cerebrospinal fluid will diverted to, through the shunt system. When the CSF diverted from the ventricles of the brain to the peritoneal cavity, it called ventriculoperitoneal shunt(VPS), while when the CSF directed from the ventricles of the brain to the venous side of the heart, ventriculoatrial shunt(VAS), from the ventricles to the pleural cavity around the lungs, called ventriculopleural shunt while the shunt that connects the lumbar thecal sac at the lower part of the spine to the peritoneal cavity called lumboperitoneal shunts(LPS). The most common type of them all is the VPS.
The shunt system consist of 3 main parts. The Proximal or ventricular catheter which is inserted in to the ventricular system or lumbar thecal sac. The valve that regulates the flow of CSF along it. And finally, the distal catheter which is inserted in other compartment of the body like, peritoneum of the abdomen, atrium of the heart, or pleura cavity in the chest. Sometimes, a fourth part called anti-siphon device may be needed in a shunt system. This device will prevent over-drainage of the CSF and then lead to uncommon complications of the shunt system called stiff ventricular syndrome, low pressure headache and/or subdural hemorrhage.
There are two types of the valve system that can be used: one with a fixed pressure valve, or an adjustable valve. The adjustable valve allows change of the pressure setting and then the CSF diversion amount according to patient clinical symptoms and need. This can be done after surgery by using a special magnet that will turn a magnet sensitive lever inside the valve and then change the setting pressure.
Benefit of Shunt procedures
Shunt operation is a life saving procedure designed to decrease the fluid pressure inside the brain, depending on the underlying pathology that is causing hydrocephalus. The surgeon should explain the shunt operation, the benefit, risks and alternative.
Risks and complications
- Infection is variable but was reported up to 5-15 percent of shunts will get infected especially in the in initial few months after shunt insertion. It can affect any part of the shunt system. Patient may present with headache, fever, photo phobia, neck pain, redness of the skin around the scars, nausea and vomiting. In addition to the antibiotic treatment, shunt should be removed or converted to external ventricular drain in cases of infection affecting the CSF.
- Shunt malfunction or obstruction which can be serious if it occurs suddenly due to sudden accumulation of the CSF in the ventricles and causing reappearing of the symptoms of hydrocephalus like headache, nausea, vomiting, loss of consciousness etc. Urgent medical attention needed with investigation like CT scan and MRI scans to confirm the diagnosis.
- Bleeding which may lead to hematoma collection and pressure at the brain that may need further surgery.
- Neural tissue injury, which is the the most serious complication may cause life changing consequences in form of weakness or paralysis of legs, sphincters, sensory or sexual changes. The risk is very small and variable according to the area of the brain targeted to insert the ventricular catheter.
- Injury to the blood vessels of the brain leads to stroke with a variable neurological deficit.
- Seizure , either immediately or shortly after surgery.
- Failure to improve symptoms.
- General anesthetic complications (heart attack, stroke)
- Deep venous thrombosis/pulmonary embolism (clots in legs / lungs).
- Small risk to life.