Shunt Infection (CSF Shunt Infection)

How shunts work

In hydrocephalus, fluid builds up in the brain's ventricles. A shunt drains it through a catheter in the ventricle, a valve under the scalp, and tubing under the skin to another body cavity, usually the abdomen (ventriculoperitoneal or VP shunt), sometimes the heart (ventriculoatrial) or lung lining (ventriculopleural).

How shunt infections happen

• during surgery: skin bacteria contaminate the shunt. This causes most infections, which typically appear within weeks to months
• wound breakdown over the tubing or valve
• from the abdomen: bowel perforation or peritonitis can infect the abdominal end
• from the blood: less common, especially with ventriculoatrial shunts

Risk factors

• young age, especially premature babies and infants under 6 months
• recent shunt surgery or revision
• previous shunt infections
• CSF leak from the wound
• thin or fragile skin over the shunt
• having had an external drain before the shunt

Symptoms

Symptoms vary with age and site of infection:

• fever, often low-grade
• redness, swelling or tenderness along the shunt track, at the valve or wound
• wound drainage or exposed tubing
• abdominal pain, swelling or tenderness, sometimes with a fluid collection around the tip
• signs of raised brain pressure if the shunt blocks: headache, vomiting, drowsiness, irritability, a bulging soft spot in babies, eyes deviating downward
• meningitis or ventriculitis signs: stiff neck, confusion, seizures

Symptoms can be subtle, especially in babies, and overlap with common childhood illnesses.

Shunt infection vs shunt malfunction

Infection is a common cause of malfunction.

Diagnosis

• examination of the shunt track, wound and abdomen
• shunt tap: a sample of CSF drawn from the valve reservoir with a fine needle, tested for cells, glucose, protein and bacteria. This is the key test
• blood tests and blood cultures
• CT or rapid MRI to check ventricle size for blockage
• abdominal ultrasound for fluid collections near the tip
• shunt series X-rays to check for disconnection or breakage

Treatment

• shunt removal is usually needed, because bacteria form a biofilm on the device that antibiotics cannot clear
• an external ventricular drain (EVD) is placed temporarily to drain fluid while infection is treated
• IV antibiotics, often vancomycin plus an agent covering other bacteria, adjusted to culture results, for typically 1 to 3 weeks after CSF is sterile
• antibiotics into the ventricles in some cases
• a new shunt is placed once repeated CSF samples are clear

Prevention

Neurosurgery teams reduce infection rates with strict surgical protocols, preventive antibiotics, antibiotic-impregnated or silver-coated shunt catheters, careful wound closure and minimal handling of the shunt. At home:

• keep the incision clean and dry as instructed
• avoid scratching or picking at the skin over the shunt
• treat constipation and know the signs of shunt problems
• carry information about the shunt type and neurosurgery contact details

Outlook

Most shunt infections are cured with removal, antibiotics and replacement. However, they increase hospital stays and can be associated with seizures, developmental effects in children and future shunt problems. Early recognition improves outcomes.

Frequently asked questions

What are the signs of a shunt infection?

Signs include fever, redness, swelling or tenderness along the shunt tubing or valve, wound drainage, belly pain, and symptoms of raised brain pressure such as headache, vomiting, drowsiness and irritability. In babies, a bulging soft spot is a warning sign.

How common are shunt infections?

Shunt infections occur in a minority of shunt surgeries, with rates reported around 5% to 15% depending on the patient group and protocols. They are most common in the first few months after surgery and in young babies.

How is a shunt infection treated?

Treatment usually involves removing the infected shunt, placing a temporary external drain, and giving IV antibiotics until the brain fluid is clear. A new shunt is then placed. Antibiotics alone rarely clear an infected shunt.

What is the difference between a shunt infection and a shunt malfunction?

A shunt malfunction is a blockage or break that stops drainage, causing raised pressure symptoms such as headache and vomiting. A shunt infection is bacterial contamination of the device, often with fever and redness, and can also cause blockage.

When should I worry about a fever in someone with a shunt?

Any fever in someone with a shunt, especially within 6 months of surgery, should be discussed with the neurosurgery team. Seek emergency care if fever comes with severe headache, vomiting, drowsiness, confusion, seizures or a stiff neck.