Complications of Shunt Systems

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    Shunt systems save lives and are successful in reducing pressure in the brain for most people. However, like any other long-term medically implanted device, they can malfunction (fail).

    Complications can arise from various factors, including obstruction (blockage), infection, displacement, or mechanical failures.

    Symptoms of a shunt malfunction may be obvious, such as headaches, excessive tiredness, vomiting, or visual changes. They may also be more subtle, including changes in behavior or a decline in school or job performance. Typically, shunt malfunction is suspected when one or more of the symptoms of hydrocephalus that were observed prior to shunting return.

    Signs and Symptoms of a Shunt Complication

    Recognizing the signs and symptoms of shunt malfunction is crucial. While symptoms vary considerably from person to person, recurring failures often exhibit similar signs within an individual. When a sudden malfunction occurs, symptoms can develop rapidly and may be life-threatening, requiring immediate medical attention.

    Note: In infants and toddlers, it’s important to be aware that certain medications should be used with caution. Some come with a side effect of drowsiness, which can mimic or mask signs of shunt malfunction.

    Below, we have listed some of the symptoms to watch for, as they may be an indication that there is a shunt complication:


    • Increased head size or rapid head growth
    • Bulging or tense fontanelle (soft spot on the baby’s head)
    • Prominent scalp veins
    • Vomiting
    • Less interest in feeding
    • Excessive Tiredness
    • Difficulty waking up or staying awake (this symptom requires urgent attention as it can potentially lead to a coma)
    • Sunsetting Eyes (A downward deviation of eyes, where the white part of the eye may be seen above the iris)
    • Fussiness
    • Developmental delays or missed milestones
    • Fluid leaking from the shunt incision sites, potentially present with shunt failure or infection
    • Signs of infection, such as fever, redness, or swelling at the shunt site


    • Changes in head shape or size (less common)
    • Headaches
    • Vomiting
    • Loss of appetite
    • Excessive tiredness
    • Difficulty waking up or staying awake (this symptom requires urgent attention as it can potentially lead to a coma)
    • Vision problems (such as double or blurred vision)
    • Fussiness or seeming irritable (cries easily or without reason)
    • Loss of previous abilities (sensory or motor function)
    • Developmental delays or missed milestones
    • Fluid leaking from the shunt incision sites, potentially present with shunt failure or infection
    • Signs of infection, such as fever, redness, or swelling at the shunt site

    Children and Adults

    • Headaches
    • Nausea and/or vomiting
    • Excessive tiredness
    • Difficulty waking up or staying awake (this symptom requires urgent attention as it can potentially lead to a coma)
    • Vision problems (such as double or blurred vision)
    • Irritability (Changes in behavior or personality)
    • Decline in academic or job performance
    • Loss of coordination or balance
    • Difficulty concentrating or focusing
    • Return of pre-treatment problems (adults)
    • Fluid leaking from the shunt incision sites, potentially present with shunt failure or infection
    • Signs of infection, such as fever, redness, or swelling at the shunt site

    Older Adults with Normal Pressure Hydrocephalus

    People who are diagnosed and treated in adulthood, including those with NPH, tend to revert to the symptoms they experienced before initial treatment when they are experiencing a malfunction.

    • Mild dementia (Forgetfulness, confusion, trouble thinking or focusing)
    • Urgency to urinate or loss of bladder control
    • Difficulty walking
    • Poor balance
    • Falling
    • Feeling withdrawn or talking less
    • Mood changes
    • Return of pre-treatment problems
    • Fluid leaking from the shunt incision sites, potentially present with shunt failure or infection
    • Signs of infection, such as fever, redness, or swelling at the shunt site

    Trust Your Instincts to Make Informed Decisions
    It’s crucial to see your doctor or go to the emergency department, even if your symptoms don’t appear directly linked to hydrocephalus or the shunt. Acting quickly can help identify and address issues, preventing coma, brain damage, or death, particularly in children. If the shunt suddenly has a problem, serious symptoms might emerge rapidly, demanding urgent medical attention. As you learn more about potential complications, you’ll become adept at recognizing and understanding them.

    Shunt Malfunction or Failure Causes

    The underlying causes of shunt malfunction can be complex and multifaceted. Shunt malfunction, or failure, often occurs when there’s a partial or complete blockage (obstruction) that prevents the shunt from working properly, or even at all. When this blockage happens, CSF can accumulate, resulting in symptoms of untreated hydrocephalus. Infections and other serious complications can also arise, contributing to failure.

    While mechanical malfunctions of the valve are rare, shunt failure can stem from a variety of reasons and may require additional surgery. Among the most common causes of shunt failure are blockages and infections. Understanding these factors is essential in the management and prevention of complications.

    Below, we have included a detailed list of the different causes of shunt malfunction:

    Shunt Obstruction or Blockage

    A shunt blockage can occur in any part of the shunt system and may be caused by blood cells, tissue, other debris, or bacteria. Both the ventricular catheter (the portion of the tubing placed in the brain) and the distal catheter (the tubing that drains fluid to another part of the body, such as the abdomen) can become blocked. This obstruction can impede the flow of CSF, potentially leading to a buildup of pressure within the brain.

    Shunt Infections

    A shunt infection is usually caused by a person’s own bacteria and is not acquired from other ill children or adults. The most common infection is Staphylococcus Epidermidis, and this type of infection is most likely seen one to three months after surgery (but can occur up to six months or more after the placement of a shunt).

    When a shunt infection occurs, the usual course of action is surgery to remove all parts of the shunt. To manage the hydrocephalus while treating the infection, a temporary drain known as an External Ventricular Drain (EVD) is surgically placed. The patient stays in the hospital and receives antibiotics for approximately 10-14 days while the infection is being treated. When the infection has cleared, a new shunt is surgically implanted.

    Individuals with a ventriculoatrial (VA) shunt may develop a more serious infection, which may enter the bloodstream. An infection of a VA shunt leads to a bloodstream infection and is more concerning than an infection of a ventriculoperitoneal (VP) shunt. Rarely, chronic infection can cause kidney damage or life-threatening damage to the lungs and heart. VA shunts do not fail any more often than VP shunts, but because their complications may be more serious, they are reserved for special circumstances. Complications for VA shunts have been associated with pulmonary hypertension, pulmonary tree embolization, and shunt nephritis (an inflammation within the kidney).

    Note: If you suspect an infection, it’s critical to notify your neurosurgeon immediately or go to the emergency room. Shunt infections can be an emergency and require immediate medical attention to avoid life-threatening complications or possible brain damage.

    Other Causes of Shunt Failure

    While shunts are very durable, malfunctions can occur due to mechanical failure and can manifest in various ways.

    Below are some common mechanical issues associated with a shunt malfunction or failure:

    A shunt disconnection happens when the shunt system’s components separate or misalign from their intended positions. This can occur due to wear, physical trauma, movement, or the natural growth of a child when the shunt was implanted during infancy. Despite a disconnection, the formation of scar tissue around the subcutaneous catheter may still permit fluid to flow. Nonetheless, it’s essential to recognize that a shunt disconnection can disturb the regular flow of CSF, resulting in symptoms of a malfunction.

    A shunt fracturing or breaking occurs when parts of the shunt system, usually the tubing or the valve mechanism, physically fracture due to reasons like trauma, wear and tear, or mechanical stress. Breakage causes a total or partial interruption in the shunt pathway, which may obstruct fluid flow and add resistance to the system.

    Migration of shunt components may also alter shunt function and, in some cases, lead to shunt failure. Occasionally, parts of the shunt system can dislodge (move) from their intended positions and where they were originally placed. This can include catheters migrating out of the ventricle or the distal end moving away from its drainage site. Depending on where the shunt has migrated to, it might also cause discomfort or other complications. Most critically, if the migration obstructs the proper flow of CSF, it can lead to shunt failure.

    A shunt kinking or becoming compressed happens when the tubing of the shunt system gets bent, twisted, or pressed upon, which blocks the flow of CSF. This compression or kinking of the shunt tubing can occur because of different reasons, like changes in how you’re positioned, moving around, pressure from outside, or even changes in your body like growing. Symptoms that come from a kinked or compressed shunt can be different for each person, based on how much the flow of CSF is blocked and how sensitive someone is to these changes.

    Shunt material degradation: Originally, barium sulfate was mixed with silicone to allow shunt catheters to be visible on a shunt series (x-ray). However, over time these barium sulfate crystals eventually dissolved, resulting in a roughened surface of the tubing. Tissue in-growth to the roughened surface caused the tubing to become bound at specific locations, leading to potential breakage or deterioration of the shunt tubing. Shunt tubing design has been changed and clear silicone elastomer now covers the surface of some shunt tubing, greatly reducing the possibility of this to occur.

    Shunt valve failure due to mechanical malfunction is infrequent. Obstruction within the valve may occur do to the accumulation of proteins and debris. This can can impede the valve’s capacity to maintain appropriate CSF flow regulation, potentially leading to either underdrainage or overdrainage of CSF.

    Other Shunt Complications

    In some cases, the shunt may result in overdrainage (low pressure) or underdrainage (high pressure) of CSF, causing a range of symptoms.

    Over drainage occurs when the shunt system allows CSF to drain too rapidly or excessively from the brain and spinal cord. As a result, the ventricles in the brain shrink in size, sometimes forming “slit-like” ventricles. This can be problematic because the brain needs fluid to protect and support it.

    The symptoms of over-draining can vary widely. When too much fluid is drained, it can lead to issues such as headaches, nausea, vomiting, dizziness, or blurred vision. These symptoms are often provoked by standing and relieved by lying flat. However, if they persist for an extended period of time, they might lose this distinctive characteristic.

    The treatment options for over-drainage depend on what’s causing the problem and the severity. For individuals with a valve that can be adjusted externally, known as a programmable valve, your doctor might try changing the setting. In cases where the shunt system is not functioning properly, a shunt revision (surgery) might be performed to replace or reposition specific components, restoring the proper flow of CSF.

    An alternative surgical approach could include adding an anti-siphon device to prevent excessive drainage when in the upright position. Additionally, recommendations such as bed rest, lying down, or assuming a flat position might be suggested. In milder cases without severe symptoms, your doctor might choose to monitor the situation closely before deciding on any treatment.

    Slit-ventricle syndrome (SVS) can be diagnosed when individuals have “slit-like” ventricles and experience specific symptoms. A particular symptom of SVS is the occurrence of severe intermittent headaches, which are often relieved when lying down. These headaches can be debilitating and significantly impact the individual’s quality of life.

    Imaging plays a vital role in diagnosing and confirming SVS. In SVS cases, the ventricles in the brain appear smaller than normal and take on a “slit-like” shape. This finding, along with the presence of the specific symptoms, helps confirm the diagnosis. Managing SVS can be challenging, and seeking care from a doctor experienced in hydrocephalus is crucial. To address SVS, most shunt manufacturers have developed shunt hardware (anti-siphon devices and programmable valves) designed to help reduce the occurrence of SVS.

    SVS is more common in young adults who have been shunted since childhood. Not everyone with slit ventricles has SVS. Some individuals have slit-like ventricles, but they do not experience any symptoms.

    To learn more watch our 2019 Adult Ask the Expert Video Series on Slit Ventricles Versus Slit Ventricle Syndrome and our session about Slit Ventricle Syndrome from our National Conference on Hydrocephalus.

    Under drainage happens when there’s insufficient drainage of CSF, leading to an enlargement of the brain’s ventricles. This extra fluid puts pressure on the brain, causing symptoms associated with hydrocephalus. These symptoms can include headaches that intensify in frequency and severity, often exacerbated upon waking in the morning. Additionally, symptoms may involve vomiting and dizziness. In older children and adults, indications might involve heightened irritability, a sense of lethargy (characterized by a lack of energy or excessive tiredness), apparent ‘laziness’, poor or disruptive school or job performance, and potentially even engagement in more antisocial behaviors.

    To restore a balanced flow of CSF, it may become necessary to implant a new valve with a more appropriate pressure setting. For individuals with a valve that can be adjusted externally, known as a programmable valve, the balance of flow may be reestablished by re-setting the opening pressures.

    A subdural hematoma occurs if blood from broken vessels becomes trapped between the brain and skull. This can result from pressure changes and lead to symptoms such as headaches, confusion, or dizziness. It is most commonly seen in older adults with normal pressure hydrocephalus (NPH). When a subdural hematoma develops alongside NPH, it can exacerbate symptoms. Often, surgical intervention is necessary. It’s important to note that not everyone with hydrocephalus or NPH will develop a subdural hematoma.

    Multiloculated hydrocephalus is a loculated (isolated) CSF compartment in the brain that is enlarged but not connected to the ventricular system. It may be caused by birth trauma, neonatal intraventricular hemorrhage, ventriculitis (infection of the ventricle), shunt-related infection, over drainage, or other conditions. This complication may be difficult to identify because it is typically seen in infants and children who may be neurologically compromised. Surgical treatments include placement of multiple shunts, ventricular catheters with multiple perforations or openings, and endoscopic or craniotomy to fenestrate (open) the intraventricular locations.

    Abdominal complications occur in people with hydrocephalus who are treated with a ventriculoperitoneal (VP) or lumboperitoneal (LP) shunt. Shunt complications that develop in the peritoneum or abdominal area include peritoneal pseudocysts, lost distal catheters, bowel perforations, and hernias. Additionally, the tubing itself can irritate the peritoneum, leading to abdominal pain or discomfort. Distal catheters are often implanted in the peritoneal cavity for shunt procedures. Although VP shunts do not have fewer complications than ventriculoatrial (VA) shunts, the complications are less severe.

    For further understanding on abdominal pain and VP shunts, consider watching our Ask the Expert Video Series on abdominal pain, suitable for all ages.

    Shunt size or location complications due to patient growth: For infants shunted at birth, the ventricular catheter may have to be changed around two years to accommodate brain growth. For children, the shunt may need to be revised as the child grows. For instance, as the child gets taller, the tubing from the head to the peritoneal cavity (VP shunt) may need to be replaced with a longer tube. However, neurosurgeons try to minimize the need for revisions. For instance, excess length of VP shunt tubing is placed in the peritoneal cavity with the distal catheter. Over time, the catheter slowly pulls out of the peritoneal cavity as the child grows taller. For this reason, regular follow-up with your neurosurgeon for shunt assessment and maintenance is crucial, particularly in growing children.

    Rare Complications include intestinal volvulus (twisting) around the shunt catheter, formation of encapsulated intra-peritoneal CSF compartments, or development of reactions to the implanted materials.

    Are Seizures Caused by Shunts?

    Seizures sometimes occur in people with hydrocephalus. For people with shunted hydrocephalus, the risk of having epilepsy is related to the type or cause of hydrocephalus and to complications of its treatment. Of individuals with shunted hydrocephalus, an estimated 20% have epilepsy (Klepper et al., 1998).

    For a deeper understanding of epilepsy, seizures, and hydrocephalus, read our informative article.

    The Most Common Tests to Assess Shunt Malfunction or Failure

    Shunt complications are not always straightforward and the diagnosis can be challenging, however, it is critical that your doctor diagnoses and treats a shunt malfunction and infection immediately. There are a variety of tests that can help determine if the shunt is working properly.

    HydroAssistOften, the first step in assessing possible shunt malfunction or shunt failure is imaging. It is important that everyone has a baseline scan on file with their neurosurgeon and hospital. HydroAssist®, HA’s mobile application, allows you to securely store images.

    Ultrasound (US) is used in infants with open soft spots or fontanels because it is painless, does not require sedation, and has no ill effects on the brain. It provides adequate visualization of the lateral ventricles, but other parts of the brain are not so well seen so additional imaging may be required.

    Computed tomography (CT Scan) is a reliable procedure for diagnosing and assisting in the management of hydrocephalus. When shunt malfunction is suspected, a CT scan is used to compare ventricular size from prior scans when the shunt was performing well or to “normal values.” For some people, though, the ventricles do not enlarge during a shunt malfunction.

    A CT scan is a sophisticated technique in which X-ray beams are passed through a patient’s body and pictures of the internal structures, in this case, the brain, are made by the computer. CT scans can usually be performed without sedation.

    CT scans do use radiation, raising concerns about exposure, particularly for hydrocephalus patients who rely on CT scans and MRIs multiple times over their lives as critical tools to determine if there is a problem with current treatment. New machines as well as new techniques, can reduce the number of images captured to only the most critically needed to assess a situation, thus limiting the amount of radiation exposure. These are called low-dose and/or rapid-acquisition CT scans.

    While it is better to limit the amount of radiation to which you are exposed, this should not come at the expense of your safety. Know the CT techniques used at your hospital, particularly the emergency room. If a CT scan is ordered, it is fine to speak to your doctor about the urgency of the situation and whether or not waiting for an MRI is possible.

    Magnetic Resonance Imaging (MRI), like the CT scan, is a diagnostic technique that produces images of the brain—but unlike CT scanning, MRI does not use x-rays/radiation. Instead, MRI uses radio signals and a very powerful magnet to scan the patient’s body. MRI is a painless procedure and has no known side effects.

    There are two types of MRI scans:

    • The Single Shot Fast Spin Echo (also called a “quick brain MRI”), which takes about three minutes and rarely requires sedation, is used to assess ventricular size.
    • The full MRI, which takes 30 to 60 minutes and may require sedation, shows more minute details. Before the longer scans are performed, small children are given a sedative to minimize movement that would cause blurring of the images.

    (It must be noted, that prior to getting an MRI, the clinician must ensure that implanted devices are MRI-safe.)

    X-ray of the shunt system, often called a shunt series, is a set of plain radiographs of the entire course of the shunt tubing (skull, neck, chest, and abdomen) to look for mechanical breaks, kinks, or disconnections in the shunt. An X-ray can also confirm the setting on a programmable valve. While a shunt X-ray can tell the settings of the shunt (if programmable) and if there is a physical break in the catheters, it cannot tell if CSF is actually flowing through the shunt system.

    Despite its enormous importance in the evaluation of suspected shunt failure, brain imaging is not conclusive in every instance. Further investigation generally requires procedures performed by the surgeon or the surgeon’s team.

    Additional Testing

    Intracranial Pressure Monitoring (ICP) is a diagnostic test that helps your doctors determine if high or low CSF pressure is causing your symptoms. When the cause of a headache has resisted every other diagnostic measure, the surgeon may recommend admission to the hospital for ICP monitoring. ICP monitoring requires a surgical procedure. Your surgeon will make a small hole, called a burrhole, in the skull and a small pressure monitor is inserted through the brain and into a lateral ventricle to measure the ICP. Your pressures are recorded continuously and provide critical guidance for therapy.

    Shunt flow studies, which also may be referred to as a shunt patency study or shuntogram, is a study to determine in real-time if CSF is flowing through the shunt system. By injecting a small volume of contrast dye or a radiotracer into the shunt reservoir, the flow of CSF through the catheters and valve can be measured.

    Shunt Tap is a diagnostic test to screen for infection and confirm that the shunt is still functioning. The area of skin overlying the shunt reservoir is cleansed with a sterile antibacterial solution. For a shunt tap, a small needle is used to pierce the skin and access the shunt reservoir/antechamber. The doctor often collects and sends a CSF sample for an investigation to rule out any source of shunt-related infection.

    How is a Shunt Malfunction Treated?

    When complications do occur, further testing is required and you may need to undergo a shunt revision, which is an operation to replace the section of the shunt that is no longer working.

    Surgical treatments:When a shunt malfunctions, surgical intervention is frequently required to address the issue. Shunt revision, a procedure performed by a neurosurgeon, involves repairing or replacing the components of the shunt that are not functioning correctly. This may involve replacing blocked or damaged catheters, changing or adding a valve or anti-siphon device, or repositioning shunt components to restore proper CSF flow. The full extent of necessary repairs may not be fully determined until the surgical procedure is underway.

    External Ventricular Drain (EVD) is a treatment that allows the temporary drainage of CSF from the lateral ventricles of the brain, or lumbar space of the spine, into an external collection bag. An EVD drains the CSF, and helps to control intracranial pressure (ICP), by using a combination of gravity and intracerebral pressure. The drainage rate depends on the height at which the EVD system is placed relative to the patient’s anatomy.

    EVDs are often used to relieve elevated ICP, drain infected CSF, and drain bloody CSF or blood after surgery or hemorrhage.

    Valve Adjustment: For individuals with a programmable valve who are experiencing signs or symptoms of shunt malfunction, your neurosurgeon might recommend adjusting the valve’s settings before exploring other treatment options. This non-invasive adjustment aims to regulate the shunt’s drainage based on whether your intracranial pressure is too high or too low. The amount of CSF your shunt drains depends on its pressure setting.

    Furthermore, if you are encountering issues like over drainage or underdrainage, your doctor can externally adjust the valve’s setting to align with your CSF drainage needs. The pressure setting determines the fluid drainage rate. In general, a lower pressure setting results in increased CSF drainage, while a higher pressure setting decreases it. It’s important to note that each valve is designed differently, and the settings can vary among shunt manufacturers.

    When To Seek Treatment

    If you suspect shunt malfunction, seek immediate medical assistance. As a parent of a child with hydrocephalus, trust your intuition and call the neurosurgeon immediately if there’s concern. As you become more familiar with potential complications, you’ll better recognize possible issues in yourself or your loved one, allowing your instincts to guide decisions.

    Don’t delay seeking medical attention if any of the mentioned symptoms occur. Prompt consultation with a healthcare professional can identify and address shunt complications early, preventing further problems and ensuring the right steps are taken. Remember, your healthcare team supports you; seeking their advice when needed is crucial in managing shunt-related concerns.

    Your proactive approach to recognizing and addressing shunt malfunction is pivotal in maintaining treatment effectiveness and enhancing overall quality of life.

    Information you can trust! This article was produced by the Hydrocephalus Association, copyright 2023. We would like to thank Marion L. (Jack) Walker, MD for his valuable contribution and expert input

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