Pseudocysts in Hydrocephalus: Causes, Symptoms, Treatment

Understanding Pseudocysts in Hydrocephalus: What You Need to Know

Pseudocysts are a potential complication for individuals with hydrocephalus, particularly those with ventriculoperitoneal (VP) or lumboperitoneal (LP) shunts. These fluid-filled collections are not formed by living tissue lining the cysts – hence the name ‘pseudocysts’.  If they form, they may cause complications if left untreated. This article explores what pseudocysts are, why they occur, and how they impact individuals with hydrocephalus.

What Are Pseudocysts?

Pseudocysts are fluid collections that can develop in the peritoneal cavity (the lining of the abdominal cavity). Unlike true cysts, pseudocysts lack an epithelial lining. They can form as a result of the body’s response to the shunt or due to an infection.  They can result in the blockage in the flow of cerebrospinal fluid (CSF) or cause a problem of CSF absorption in the abdomen.

While pseudocysts can remain asymptomatic and not require intervention, they can cause discomfort or complications if they grow or affect the shunt’s function.

Why Do Pseudocysts Form in Shunted Patients?

Pseudocysts occur as a result of the body’s response to an irritation in the abdomen. The most common reasons for their formation include:

1. Infection or Inflammation: Infections or inflammation in the abdomen, or in and around the shunt, can lead to the formation of pseudocysts.  If the fluid builds up around the tip of the shunt, it causes obstruction of the shunt.
2. Body’s Response to Foreign Material: The body may treat the shunt as a foreign object, forming a protective barrier that results in fluid accumulation.

Symptoms of Pseudocysts

Pseudocysts often don’t cause symptoms, especially when small.  Infections causing a pseudocyst may also show symptoms such as fever, redness along the shunt, tenderness at or along the shunt or in the abdomen.  Infections require prompt evaluation and treatment.

However, larger or symptomatic pseudocysts can cause:

• Abdominal Pain: In the case of a VP shunt, a pseudocyst may cause swelling or discomfort in the abdomen. Larger pseudocysts can press against organs, causing pain.
• Distention of the abdomen:  The fluid can collect and enlarge the belly; the accumulation can be quite significant and may not always cause other symptoms.
• Signs of Shunt Malfunction: A pseudocyst that interferes with CSF drainage can cause symptoms of increased intracranial pressure (ICP), such as headaches, nausea, vomiting, and changes in mental status.

Diagnosis of Pseudocysts

Pseudocysts are typically diagnosed through imaging studies such as:

• X-ray: Sometimes done to evaluate the shunt or a distended abdomen, they can show signs of the collection or the fluid buildup.
• Ultrasound: Can be used to detect pseudocysts in individuals with VP shunts; this non-invasive technique can reveal fluid collections in the abdominal area.
• CT Scan or MRI: These imaging methods assess the shunt system, identifying blockages or issues, and confirming the presence and size of pseudocysts.

Treatment Options

If a pseudocyst causes symptoms or affects shunt function, intervention may be necessary. Treatment options include:

• Observation: If asymptomatic, pseudocysts can be monitored with regular imaging to ensure they do not cause further issues.
• Shunt Revision or Drainage: If the pseudocyst is large or causing discomfort, or there are signs of infection or shunt malfunction, surgical intervention may be required. This can involve repositioning or replacing the shunt.  Often, the pseudocyst is drained at the same time to alleviate symptoms and confirm the presence or absence of infection.

Seeking Medical Advice for Pseudocysts

If you experience abdominal pain, swelling, or signs of shunt malfunction (headaches, nausea, vomiting), consult your healthcare team promptly. Early detection and treatment are crucial to prevent complications, particularly if pseudocysts interfere with shunt function or lead to infection.

Regular monitoring and staying in communication with your doctor can help manage pseudocysts and ensure proper shunt function.

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.