A shunt is a medical device, typically a system of tubes, surgically placed within the body to redirect fluid. Its primary purpose is to drain excess cerebrospinal fluid (CSF) from the brain, most commonly to treat a condition called hydrocephalus. Hydrocephalus involves an accumulation of CSF, leading to increased pressure within the brain. While shunts are life-saving interventions that effectively manage this pressure, they are medical implants and, like any such device, can experience complications. These potential issues are important to understand for anyone living with a shunt.
Understanding Shunt Malfunction
Shunt malfunction refers to mechanical or functional problems that can prevent the device from working correctly. One common issue is a blockage, where the shunt tubing becomes obstructed. This obstruction can be caused by various materials, including tissue, blood, or protein. Blockages often occur at specific points, such as the ventricular catheter located in the brain or the distal catheter that drains fluid to another body part.
Another type of malfunction involves the physical integrity of the shunt system. Components can experience disconnection or breakage. This can impede the shunt’s ability to regulate pressure effectively.
Shunts can also experience problems with fluid drainage rates, leading to either over-drainage or under-drainage. Over-drainage happens when the shunt drains CSF too quickly from the brain. This rapid drainage can cause complications such as subdural hematomas, which are collections of blood outside the brain, or a condition known as slit ventricle syndrome, where the brain’s ventricles become unusually small. The rate of drainage is often controlled by a valve within the shunt, which can sometimes be adjusted externally to manage over-drainage or under-drainage.
Conversely, under-drainage occurs when the shunt fails to drain enough CSF. This can happen if the shunt is undersized or becomes partially obstructed.
Recognizing Shunt Infection
Shunt infections are typically caused by bacteria. These infections commonly arise from bacteria naturally found on the skin, which can be introduced during the initial surgical placement of the shunt. While most infections occur relatively soon after surgery, often within the first few months, they can sometimes appear years later.
Infections may manifest with localized signs along the path of the shunt. These can include redness, tenderness, and swelling of the skin, or pain along the implanted tubing. A fever is also a common systemic sign of a shunt infection.
Fluid leaking from the surgical incision sites can also indicate an infection or other shunt problem. Shunt infections are serious complications that require prompt medical attention. Depending on the type of shunt, infection can lead to peritonitis if the shunt drains into the abdomen, or systemic signs if it drains into the bloodstream.
Common Symptoms Indicating a Problem
When a shunt is not functioning properly due to malfunction or infection, various symptoms can arise, often reflecting increased intracranial pressure. Headaches are a frequently reported symptom, which can be severe, persistent, or worse in the morning. These headaches may also be positional, worsening when sitting or standing.
Nausea and vomiting are also common indicators of increased pressure within the skull. Vision changes can occur, including blurred or double vision. Some individuals may experience difficulty looking upwards or notice a downward deviation of the eyes, sometimes referred to as “sunsetting eyes,” especially in infants.
Changes in mental status are significant symptoms, ranging from increased drowsiness and lethargy to difficulty waking up or staying awake. Irritability, confusion, difficulty concentrating, and personality changes can also be observed. These cognitive and behavioral changes can sometimes manifest as a decline in school or job performance.
New onset seizures or a worsening of pre-existing seizure activity may indicate a shunt problem. In infants and young children, whose skull bones have not fully fused, specific physical signs are often apparent. These include a rapid increase in head circumference, a bulging or tense soft spot (fontanelle) on the head, and prominent scalp veins. Other symptoms that may occur include neck pain or stiffness, problems with balance, weakness or numbness in the limbs, and difficulty walking.
When to Seek Medical Attention
Any new or worsening symptoms that could be related to a shunt should prompt immediate medical evaluation. Problems with shunts can become serious rapidly, so prompt consultation with a healthcare professional can help identify and address complications early.
During a medical evaluation, healthcare providers will typically conduct a physical examination and may order imaging tests, such as CT scans or MRI scans, to assess the shunt’s function and the brain’s condition.
In some cases, a shunt tap may be performed. This procedure can help diagnose infection or blockage.
Prompt diagnosis and treatment are crucial for managing shunt-related complications. Treatment might involve a shunt revision surgery, which means repairing, replacing, or adjusting components of the existing shunt system. If an infection is present, antibiotics are typically administered, and the shunt may need to be removed and replaced once the infection clears.