Shunt Malfunction: Frequently Asked Questions

Shunt Malfunction (Shunt Failure) Overview: What to Know

Shunt malfunctions (also known as shunt failure) can occur at any age due to various reasons, including blockages, infections, or mechanical failures. Recognizing potential issues early and understanding available diagnostic methods can help individuals and their families seek timely medical care. Here are answers to some of the most frequently asked questions about shunt malfunctions.

What is a Shunt Malfunction (Shunt Failure)?

A shunt malfunction occurs when the shunt system fails to regulate cerebrospinal fluid (CSF) properly, leading to a buildup or improper drainage of fluid. Malfunctions can result from blockages, infections, mechanical failures, or other complications that require medical intervention.

Why do Shunts Malfunction (Fail)?

Shunts malfunction due to a variety of reasons, including:

• Obstruction or blockage: Occurs in any part of the system due to blood, tissue, debris, or bacteria. Both the ventricular catheter (in the brain) and the distal catheter (which drains fluid elsewhere) can become obstructed, leading to increased pressure and potential symptoms.
• Infection: Bacteria can enter or contaminate the shunt system, requiring removal of the shunt system and treatment with antibiotics.
• Overdrainage or underdrainage: If the shunt is draining too much or too little CSF, symptoms may develop that necessitate a revision.
• Shunt disconnection: Occurs when shunt components separate or misalign due to wear, physical trauma, movement, or growth in children, potentially causing malfunction.
• Shunt fracture or breaking: When the tubing or valve mechanism fractures due to trauma, wear, or mechanical stress, it can disrupt fluid flow and add resistance to the system, leading to malfunction.
• Migration of shunt components: Occurs when parts of the shunt move from their original placement, such as catheters shifting out of the ventricle or the distal end moving away from its drainage site.
• Shunt kinking or becoming compressed: Happens when the tubing severely bends, twists, or is pressed upon, blocking CSF flow.
• Shunt material degradation: Over time, the materials used in the shunt system can deteriorate, or the surrounding tissues can react to the tubing. However, the shunt tubing design has been changed, greatly reducing the possibility of this.
• Shunt valve failure: Is infrequent, but the valve can obstruct due to the accumulation of proteins and debris, or the valve can allow too much CSF to flow. This can impede the valve’s capacity to maintain appropriate CSF flow regulation.

Other complications that can be associated with a shunt and present like a shunt malfunction include:

• A subdural hematoma: This occurs when blood becomes trapped between the brain and skull due to pressure changes, leading to headaches, confusion, or dizziness.  This can result from overdrainage of fluid
• Multiloculated hydrocephalus: Inflammation or infection can lead to scarring that causes isolated CSF compartments to form in the brain, and if they do not connect to the part of the ventricle drained by the shunt, they can enlarge.  This can require surgical intervention.
• Abdominal complications: arise from the peritoneal (abdominal) end of the shunt and include issues such as infection, fluid collections, or obstruction.
• Shunt size or location complications due to patient growth: In children, as they grow, the tubing may become too short (in the brain or distal end) and need to be replaced.
• Rare complications: These include the intestine wrapping around the tubing in the abdomen (intestinal volvulus ), or the shunt catheter getting tied around the intestine.  There can be the formation of trapped CSF compartments form in the abdomen/peritoneal cavity.

For detailed explanations about the different types of shunt malfunctions, click here.

What are the Symptoms of a Shunt Malfunction (Shunt Failure)?

Recognizing the symptoms of a failing shunt is crucial for timely intervention. While symptoms can vary based on age and the underlying cause, there are common warning signs to be aware of.

Signs of Shunt Malfunction Can Vary but May Include:

• In infants and toddlers: Increased head size or rapid head growth, bulging fontanelles (soft spots), irritability, vomiting, poor feeding, and developmental delays. For a comprehensive list of symptoms of hydrocephalus in infants and toddlers, click here.
• In children and adolescents: Headaches, nausea, fatigue/sleepiness, vision changes, poor appetite, changes in personality, and/or more irritability than normal, and school performance may decline. For a comprehensive list of symptoms of hydrocephalus in children and adolescents, click here.
• In adults: Headaches, nausea, vision changes, cognitive and memory problems, balance and coordination issues, excessive tiredness, and disturbances in gait (trouble walking). For a comprehensive list of symptoms of hydrocephalus in adults, click here.

For a detailed list of symptoms, please visit our page on shunt complications.

How is a Shunt Malfunction (Failure) Diagnosed?

Doctors use a combination of symptoms and diagnostic tests to determine if a shunt is malfunctioning. These may include.

Imaging of the brain or body, such as:

• Shunt series X-rays: A set of X-rays to examine the entire shunt system to look for breaks, disconnections, or the location of the tubing.
• Ultrasound (US): Used to assess fluid buildup in the head, especially in infants, but also in the abdomen.
• CT scan or MRI: Imaging to check for fluid buildup and shunt placement

Evaluation of the fluids around the shunt – blood or CSF:

• Blood Tests: To check for infections or abnormalities.
• Shunt tap: A procedure where a needle is inserted into the shunt reservoir to test CSF pressure and flow, helping diagnose blockages or infections.
• Lumbar puncture: In some cases, a spinal tap may be used to measure CSF pressure.

Evaluation of the shunt function more directly:

• Shunt flow studies (shuntogram or shunt patency study): A test to evaluate CSF flow through the shunt system.
• Intracranial Pressure Monitoring (ICP): Measures pressure inside the skull to assess for shunt malfunction.
• External Ventricular Drain (EVD): A temporary drainage system used to monitor CSF flow and pressure.

For more information on diagnostic tests, please click here.

What is a Shunt Revision?

A shunt revision is a surgical procedure performed to replace or adjust part or all of a shunt system when it is not functioning properly. This can involve replacing the valve or catheter/tubing to restore proper cerebrospinal fluid (CSF) drainage.

What Happens During a Shunt Revision Surgery?

Shunt revision surgery is typically performed under general anesthesia. The exact procedure depends on the cause of the malfunction, but common steps include:

1. Anesthesia: You will be under general anesthesia to ensure comfort. An anesthesiologist will monitor your vital signs throughout the procedure. You will meet with your anesthesiologist in advance of the surgery to discuss medications and concerns.
2. Surgical Repair or Replacement:
   • The surgeon will identify and address the malfunctioning part of the shunt. This can involve either replacing the valve, catheter, or entire system.
   • Repairs may require accessing both where the shunt begins (head or spine) and the drainage site (abdomen or heart).
   • In some cases, additional adjustments may be needed, such as repositioning the catheter.
3. Functionality Testing:
   • The surgeon will assess the revised shunt system to ensure it is working properly before completing the operation. This may involve flushing the system or monitoring the flow of cerebrospinal fluid (CSF).
4. Closure:
   • Once the shunt system is verified to be functioning, the surgeon will carefully close the surgical sites with a combination of sutures or staples.

The procedure usually lasts several hours, depending on the complexity of the repair. However, the exact duration can vary based on individual circumstances, such as the nature of the malfunction or any complications. You should discuss this with your doctor ahead of time to address expectations for the length of the procedure.

For more information on what to expect with shunt surgery, click here.

What is the Recovery Like After a Shunt Revision?

Recovery varies depending on the individual and the reason for the revision, but typical considerations include:

• Hospital stay of 1-3 days in most cases, longer if complications arise.
• Gradual return to normal activities.
• Monitoring for any signs of shunt failure or infection.
• Regular follow-up with a neurosurgeon for ongoing care.

How Common are Shunt Malfunctions (Shunt Failure)?

Shunt malfunctions are common, with failure rates depending on factors such as age, shunt type, and underlying medical conditions. An estimated 50% of shunts in the pediatric population fail within two to four years of placement, and repeated neurosurgical operations are often required. Many individuals may need multiple revisions throughout their lifetime.

What are the Risks of Shunt Revision Surgery?

Shunt revision surgery, like any surgical procedure, carries risks. Potential complications include infection, bleeding, overdrainage or underdrainage, damage to surrounding tissues, and the possibility of needing further revisions. Success rates depend on the reason for revision and the patient’s overall health.

Information you can trust! This article was produced by the Hydrocephalus Association, copyright 2025. We would like to thank Bruce A. Kaufman, MD, for his valuable contribution and expert input.

This article is designed to provide helpful information on the subjects discussed. It is not intended as a substitute for treatment advice from a medical professional. For diagnosis or treatment of any medical condition, consult your doctor.