Shunt Malfunction
When a brain fluid shunt blocks or stops working
Quick Facts
- Type: Neurosurgical complication
- Affects: People with a shunt for hydrocephalus
- Main risk: Rising pressure in the brain
- Urgency: Can be a medical emergency
Overview
A shunt is a thin tube surgically placed to drain excess cerebrospinal fluid (the fluid that surrounds the brain and spinal cord) away from the brain to another part of the body, usually the abdomen, where it is absorbed. Shunts are commonly used to treat hydrocephalus, a buildup of fluid that raises pressure inside the skull.
A shunt malfunction occurs when the shunt stops working properly. It may become blocked, disconnect, break, drain too much or too little, or become infected. When a shunt fails, fluid can build up again and raise pressure in the brain, which can quickly become dangerous. Recognizing the warning signs and seeking prompt care is essential, because a malfunctioning shunt can be a medical emergency.
Symptoms
Symptoms of shunt malfunction often resemble those of the original hydrocephalus and can develop over hours to days. They include:
- Headache, often worsening
- Nausea and vomiting
- Drowsiness, irritability, or difficulty waking
- Vision changes or trouble looking upward
- Confusion or changes in behavior
- Balance or coordination problems
- Seizures
In infants, signs may include a bulging soft spot, an enlarging head, poor feeding, vomiting, and unusual sleepiness or irritability. Rapidly worsening symptoms, severe drowsiness, or loss of consciousness are emergencies and require immediate care.
Causes
Shunts can fail for several reasons:
- Blockage: The most common cause; the tubing or valve becomes clogged by tissue, cells, or debris.
- Disconnection or breakage: Parts of the shunt may separate, kink, or break, often with growth or movement.
- Infection: An infected shunt can stop working and cause illness; this is more common soon after surgery.
- Over- or under-drainage: The shunt may drain too much or too little fluid.
- Migration: The tubing can shift out of position.
Children may outgrow their shunt tubing as they grow, contributing to malfunction over time.
Risk Factors
- Having a shunt, especially within the first months to year after placement
- Young age, as children may outgrow tubing and have higher revision rates
- Previous shunt infections or multiple shunt surgeries
- Certain underlying causes of hydrocephalus
Shunt malfunction is common over a lifetime, and many people with shunts need one or more revisions.
Diagnosis
When shunt malfunction is suspected, doctors act quickly to confirm it:
- Clinical evaluation: Reviewing symptoms and comparing them to the person's known baseline.
- Brain imaging: CT or MRI scans to check whether the fluid spaces in the brain are enlarging.
- Shunt series X-rays: Images along the path of the shunt to look for breaks, disconnections, or kinks.
- Shunt evaluation: Specialized tests or, in some cases, sampling fluid from the shunt to check for blockage or infection.
Treatment
Treatment depends on the type of malfunction but often requires surgery:
- Shunt revision: Surgery to repair or replace the blocked, broken, or disconnected part of the shunt.
- Treating infection: If the shunt is infected, it may be removed or externalized, antibiotics given, and a new shunt placed once the infection clears.
- Adjusting drainage: Some shunts have valves that can be adjusted to correct over- or under-drainage.
- Emergency measures: Temporary drainage may be needed to relieve dangerous pressure while definitive treatment is arranged.
Prompt treatment of a failing shunt prevents serious harm from rising brain pressure.
When to See a Doctor
Anyone with a shunt and their caregivers should learn the warning signs of malfunction and act quickly. Seek emergency care immediately for:
- Severe or worsening headache, repeated vomiting, or neck stiffness
- Increasing drowsiness, confusion, or difficulty waking
- Vision changes, seizures, or weakness
- In infants, a bulging soft spot, enlarging head, poor feeding, or unusual sleepiness
- Loss of consciousness
A shunt malfunction can become life-threatening within hours, so it is safer to be evaluated urgently than to wait. Bring information about the shunt type when seeking care.
Frequently Asked Questions
What are the warning signs of a shunt malfunction?
Common signs include worsening headache, nausea and vomiting, drowsiness, irritability, vision changes, confusion, and seizures. In infants, watch for a bulging soft spot, an enlarging head, poor feeding, and unusual sleepiness. These warrant urgent medical evaluation.
Is a shunt malfunction an emergency?
It can be. When a shunt fails, fluid and pressure can build up in the brain, which may become life-threatening within hours. If you notice warning signs, seek emergency care right away rather than waiting to see if symptoms improve.
Why do shunts stop working?
Shunts most often fail from blockage, but they can also disconnect, break, become infected, or drain too much or too little fluid. Children may outgrow their tubing. Many people with shunts need one or more revision surgeries over their lifetime.
How is a shunt malfunction fixed?
Treatment usually involves surgery to repair or replace the affected part of the shunt. If infection is the cause, the shunt may be removed, antibiotics given, and a new shunt placed later. Temporary drainage may be used to relieve pressure urgently.
Can a shunt malfunction be prevented?
Malfunctions cannot always be prevented, but knowing the warning signs and seeking prompt care reduces harm. Keeping regular follow-up appointments and information about the shunt type on hand helps the medical team respond quickly if problems arise.
References
- Hydrocephalus Association.
- MedlinePlus, U.S. National Library of Medicine. Hydrocephalus.
- American Association of Neurological Surgeons (AANS).
- National Institute of Neurological Disorders and Stroke (NINDS).