7 Common Causes of Fluid on the Brain in Adults (Hydrocephalus)

Last Updated on November 27, 2025 by Bilal Hasdemir

Hydrocephalus is when too much cerebrospinal fluid (CSF) builds up in the brain’s ventricles. This can cause the brain to swell, leading to high pressure inside the skull. This condition, also known as fluid on the brain, can seriously affect a person’s health and quality of life.

At Liv Hospital, we take hydrocephalus very seriously. We use the latest treatments to help our patients. Our team is committed to giving you the best care possible, with support for patients from all over the world.

Key Takeaways

• Hydrocephalus is a condition where CSF abnormally accumulates in the brain’s ventricles.
• Increased intracranial pressure is a possible problem with hydrocephalus.
• Liv Hospital offers advanced care for adults with hydrocephalus.
• Spotting hydrocephalus early is key to treating it effectively.
• Our focus is on you, our patient, at Liv Hospital.

Understanding Hydrocephalus in Adults

Hydrocephalus involves cerebrospinal fluid (CSF), a clear liquid around our brain and spinal cord. To understand hydrocephalus, we must first know about CSF and how it moves.

What Is Cerebrospinal Fluid (CSF)?

Cerebrospinal fluid (CSF) is a clear liquid in the brain and spine. It’s made in the brain’s ventricles and helps protect the brain. Recent studies show CSF is key to the brain’s health.

How CSF Normally Circulates

CSF moves through the brain and spinal cord. It’s always being made and absorbed, keeping a balance. CSF flows from the brain’s ventricles into the spinal cord and is then absorbed into the blood.

What Happens in Hydrocephalus

In hydrocephalus, CSF flow is blocked, causing fluid buildup in the brain. This can increase pressure and harm brain tissue. It can be caused by blockages, poor absorption, or too much CSF.

Learning about CSF and its flow helps us understand hydrocephalus. This knowledge is vital for diagnosing and treating it in adults.

Types of Hydrocephalus in Adults

Adult hydrocephalus comes in several types, each with its own causes and traits. Knowing these differences is key for the right diagnosis and treatment.

Obstructive (Non-communicating) Hydrocephalus

Obstructive hydrocephalus happens when fluid in the brain can’t move because of a blockage. This blockage stops the fluid from flowing, causing it to build up and increase pressure in the brain.

Common causes of obstructive hydrocephalus include:

• Tumors or cysts in the brain’s ventricles
• Birth defects, like aqueductal stenosis
• Scarring from infections or inflammation

Communicating Hydrocephalus

In communicating hydrocephalus, the fluid in the brain can move but can’t be absorbed. This problem usually happens at the arachnoid villi, where fluid is supposed to be absorbed into the blood.

Factors contributing to communicating hydrocephalus include:

1. Subarachnoid hemorrhage
2. Meningitis or other infections affecting the meninges
3. Trauma or conditions causing scarring around the brain

Normal Pressure Hydrocephalus (NPH)

Normal Pressure Hydrocephalus is a special type of hydrocephalus. It’s marked by problems walking, thinking, and controlling urine. Despite its name, it can sometimes have high pressure in the brain.

Key features of NPH include:

• Walking problems, often feeling magnetic or apractic
• Decline in thinking, sometimes mistaken for Alzheimer’s
• Urinary incontinence, usually appearing later

It’s vital for doctors to understand these types of hydrocephalus. This knowledge helps them diagnose and treat the condition properly.

What Causes Fluid on the Brain in Adults?

Understanding hydrocephalus in adults is key to proper treatment. This condition can stem from many causes. Knowing the cause is vital for managing it.

Acquired vs. Congenital Causes

Hydrocephalus in adults can be either acquired or congenital. Acquired hydrocephalus develops over time due to injury, infection, or other medical issues. Congenital hydrocephalus is present at birth and often diagnosed in infancy or early childhood. But, some cases of congenital hydrocephalus are not diagnosed until adulthood.

Causes include brain tumors, subarachnoid hemorrhage, and meningitis. These conditions block the flow of cerebrospinal fluid (CSF), causing it to build up in the brain.

Risk Factors for Developing Hydrocephalus

Several factors increase the risk of hydrocephalus in adults. These include:

• Age: The risk grows with age.
• Head trauma: Traumatic brain injury can cause hydrocephalus.
• Brain tumors: Tumors can block CSF pathways.
• Infections: Meningitis and other infections can cause inflammation that blocks CSF flow.
• Bleeding: Subarachnoid hemorrhage can lead to hydrocephalus.

Knowing these risk factors is important for early detection and management.

How Increased Intracranial Pressure Develops

Increased intracranial pressure (ICP) is a complication of hydrocephalus. When CSF builds up in the brain, it increases pressure in the skull. This can damage brain tissue and cause symptoms like headache, nausea, and vomiting.

The development of increased ICP depends on how fast CSF accumulates and the brain’s ability to handle it. Sometimes, the body can manage the increased pressure. But, in other cases, intervention is needed to reduce pressure and prevent further damage.

Cause	Description	Effect on CSF Flow
Brain Tumors	Tumors can obstruct CSF pathways.	Obstruction of CSF flow.
Subarachnoid Hemorrhage	Bleeding into the space surrounding the brain.	Inflammation and obstruction of CSF flow.
Meningitis	Infection causing inflammation of the meninges.	Inflammation obstructing CSF flow.

Cause #1: Head Trauma and Brain Injury

Head trauma can lead to hydrocephalus, a condition where too much cerebrospinal fluid (CSF) builds up in the brain. This happens when head injuries disrupt how CSF moves and is absorbed. As a result, CSF can build up.

How Trauma Leads to Hydrocephalus

Head trauma can damage the brain’s ability to move and absorb CSF. This damage can cause inflammation and scarring. These can block the flow of CSF, leading to a buildup and increased brain pressure.

Key mechanisms by which trauma leads to hydrocephalus include:

• Direct damage to CSF pathways
• Inflammation and scarring
• Subarachnoid hemorrhage
• Intraventricular hemorrhage

Types of Injuries Most Commonly Associated

Several head injuries can increase the risk of hydrocephalus. These include:

1. Severe concussions: High-impact injuries that can cause significant brain disturbance.
2. Penetrating head injuries: Injuries where an object penetrates the skull, potentially damaging brain tissue and CSF pathways.
3. Subdural hematomas: Bleeding into the space between the brain and the skull, which can compress brain tissue and disrupt CSF circulation.

Recovery and Prognosis

Recovery from trauma-induced hydrocephalus varies. It depends on the injury’s severity, treatment effectiveness, and individual factors. Treatment often involves a shunt to manage excess CSF. Rehabilitation helps patients regain lost functions and adapt to changes.

Factors influencing recovery include:

• The severity of the initial head trauma
• The presence of other injuries or health conditions
• The effectiveness of treatment and rehabilitation

Cause #2: Brain Tumors and Cysts

Brain tumors and cysts can cause hydrocephalus in adults. They block the flow of cerebrospinal fluid (CSF). This leads to a buildup of CSF and increased pressure inside the skull.

How Tumors Obstruct CSF Flow

Tumors can block CSF flow by physically blocking narrow passages. For example, a tumor near the aqueduct of Sylvius can stop CSF from moving from the third to the fourth ventricle. This causes CSF to build up in the ventricles.

Common locations for tumors to cause obstruction include:

• The third ventricle
• The aqueduct of Sylvius
• The fourth ventricle

Common Tumor Types That Cause Hydrocephalus

Many types of brain tumors can lead to hydrocephalus. Some of the most common include:

Tumor Type	Description	Association with Hydrocephalus
Meningioma	A tumor arising from the meninges, the protective membranes of the brain.	Can cause obstruction by compressing CSF pathways.
Glioma	A type of tumor that originates from the brain’s glial tissue.	Can obstruct CSF flow depending on its location.
Medulloblastoma	A malignant tumor mainly found in children but can also occur in adults.	Often obstructs the fourth ventricle.

It’s important to understand how brain tumors and hydrocephalus are linked. Knowing the type of tumor and its effect on CSF flow helps doctors create better treatment plans. This approach helps manage both the tumor and the hydrocephalus.

Cause #3: Subarachnoid Hemorrhage

Subarachnoid hemorrhage is a serious condition where blood bleeds into the space around the brain. It’s a major reason for hydrocephalus in adults. This bleeding can mess up the flow and absorption of cerebrospinal fluid (CSF). This leads to a buildup of CSF and higher pressure inside the skull.

Mechanism of Hemorrhage-Induced Hydrocephalus

Subarachnoid hemorrhage causes hydrocephalus through several ways. Blood in the subarachnoid space blocks CSF flow through the ventricles. This makes it hard for CSF to get absorbed into the bloodstream. As a result, CSF builds up, causing hydrocephalus.

• Blood and inflammatory substances can block the arachnoid granulations, making CSF absorption harder.
• The blood can also cause inflammation and scarring. This can block CSF pathways for a long time.

Acute vs. Delayed Hydrocephalus After Bleeding

Hydrocephalus from subarachnoid hemorrhage can happen quickly or later. Acute hydrocephalus happens right after the bleeding, needing quick action. Delayed hydrocephalus can show up weeks or months later, needing ongoing watch.

Treatment Considerations

Treating hydrocephalus from subarachnoid hemorrhage means fixing the bleeding and the hydrocephalus. Treatment strategies include:

1. Emergency steps to fix the hemorrhage, like clipping or coiling an aneurysm.
2. Putting in a ventricular drain or shunt to manage pressure and hydrocephalus.
3. Keeping an eye on the patient for signs of delayed hydrocephalus or shunt problems.

Understanding the link between subarachnoid hemorrhage and hydrocephalus helps doctors treat it better. This can lead to better outcomes for patients.

Cause #4: Infections of the Central Nervous System

Infections of the central nervous system can cause hydrocephalus in adults. This is a serious condition that needs quick treatment. These infections can damage the brain and block the flow of cerebrospinal fluid (CSF).

Bacterial Meningitis

Bacterial meningitis is a severe infection that affects the brain and spinal cord. It can block the flow of CSF, leading to hydrocephalus. We will look at how bacterial meningitis causes hydrocephalus and its effects on adults.

The main way bacterial meningitis causes hydrocephalus is by blocking CSF pathways. It can also cause scarring in the brain, making it harder for CSF to move.

Viral Encephalitis

Viral encephalitis is an inflammation of the brain tissue caused by a viral infection. It can lead to hydrocephalus by damaging brain tissue and blocking CSF pathways.

Viral encephalitis can cause serious problems, including hydrocephalus. The inflammation can lead to long-term brain damage.

Fungal and Parasitic Infections

Fungal and parasitic infections can also cause hydrocephalus in adults. These infections can cause inflammation and scarring, blocking CSF flow.

For example, cryptococcal meningitis, a fungal infection, can cause hydrocephalus in people with weakened immune systems. Parasitic infections like neurocysticercosis can also lead to hydrocephalus by blocking CSF pathways with cysts or causing inflammation.

It’s important to know about the different infections that can cause hydrocephalus. This knowledge helps in diagnosing and treating the condition effectively. The table below summarizes the different types of infections and their mechanisms leading to hydrocephalus.

Infection Type	Mechanism Leading to Hydrocephalus	Common Causative Agents
Bacterial Meningitis	Inflammation and scarring in CSF pathways	Streptococcus pneumoniae, Neisseria meningitidis
Viral Encephalitis	Inflammation and damage to brain tissue	Herpes simplex virus, Enteroviruses
Fungal Infections	Granulomatous inflammation and scarring	Cryptococcus neoformans
Parasitic Infections	Obstruction by cysts or inflammation	Taenia solium (neurocysticercosis)

In conclusion, infections of the central nervous system are a major cause of hydrocephalus in adults. Knowing about the different infections and how they work is key to finding effective treatments.

Cause #5: Complications from Brain Surgery

Brain surgery can lead to hydrocephalus, affecting patient outcomes. It’s a risk when treating neurological conditions. This can happen due to complications after surgery.

Post-Surgical Inflammation and Scarring

Inflammation and scarring after brain surgery can block cerebrospinal fluid (CSF) flow. This blockage causes CSF to build up, leading to hydrocephalus. Post-surgical inflammation is a natural response but can cause problems.

Scarring from surgery can also block CSF flow, leading to hydrocephalus. Managing post-surgical inflammation and scarring is key to preventing this.

Prevention Strategies

To prevent hydrocephalus after brain surgery, several steps can be taken. Surgeons and healthcare teams can:

• Use meticulous surgical techniques to reduce tissue trauma
• Give anti-inflammatory medications to manage inflammation
• Watch patients closely for early signs of hydrocephalus

Managing Post-Surgical Hydrocephalus

If hydrocephalus occurs after brain surgery, managing it is critical. Treatment may include a shunt to divert CSF or other interventions. Timely diagnosis and treatment are key to preventing complications and improving outcomes.

Dealing with post-surgical hydrocephalus is tough for patients and families. Our healthcare team is dedicated to providing full care and support during treatment.

Cause #6: Intraventricular Hemorrhage

Intraventricular hemorrhage is a serious condition where blood bleeds into the brain’s ventricles. This can cause hydrocephalus because of the blood and its breakdown products in the cerebrospinal fluid (CSF) pathways.

Differences from Subarachnoid Hemorrhage

Intraventricular hemorrhage is different from subarachnoid hemorrhage because of where the bleeding happens. Subarachnoid hemorrhage bleeds outside the brain, while intraventricular hemorrhage bleeds into the ventricles. This difference is important because it affects how the cerebrospinal fluid moves and is absorbed, which can lead to hydrocephalus.

The main differences between intraventricular hemorrhage and subarachnoid hemorrhage are:

• Location of Bleeding: Intraventricular hemorrhage bleeds into the ventricles, while subarachnoid hemorrhage bleeds outside the brain.
• Impact on CSF: Both can affect cerebrospinal fluid circulation, but intraventricular hemorrhage directly affects the ventricular system.
• Clinical Presentation: Symptoms can vary, but both can cause sudden headache, changes in consciousness, and neurological problems.

Risk Factors and Outcomes

Several factors can increase the risk of intraventricular hemorrhage, including:

1. Premature Birth: Premature babies are more at risk because their blood vessels are fragile.
2. Trauma: Head injuries can cause intraventricular hemorrhage in anyone.
3. Vascular Malformations: Conditions like arteriovenous malformations can raise the risk of hemorrhage.
4. Bleeding Disorders: People with bleeding disorders are more likely to have intraventricular hemorrhage.

Outcomes can vary a lot. They depend on how severe the hemorrhage is, the patient’s age, and their overall health. Some people might fully recover, while others could face serious brain damage or even death.

Emergency Management

Managing intraventricular hemorrhage in an emergency means stabilizing the patient, controlling brain pressure, and finding the cause of the hemorrhage. Treatment options might include:

• External Ventricular Drainage: To help with hydrocephalus and lower brain pressure.
• Fibrinolytic Therapy: To break up blood clots in the ventricles.
• Surgical Intervention: To fix vascular malformations or remove blood clots.

Quick and effective treatment is key to prevent more brain damage and improve chances of recovery. Understanding intraventricular hemorrhage and its effects is vital for the best care for those affected.

Cause #7: Idiopathic Normal Pressure Hydrocephalus

As we get older, the chance of getting Idiopathic Normal Pressure Hydrocephalus (NPH) goes up. It’s a type of hydrocephalus that happens in older adults, often without a known reason.

Why It Occurs in Older Adults

The exact reason for Idiopathic NPH is not fully understood. But, several things can lead to it in older adults. These include changes in cerebrospinal fluid (CSF), age-related brain changes, and possible genetic factors. Knowing these can help in early diagnosis and treatment.

Classic Symptom Triad

NPH is known for a specific set of symptoms: gait disturbance, dementia, and urinary incontinence. The gait disturbance is often a slow, shuffling walk. This can make moving around hard and increase fall risks. Dementia from NPH can look like other types of cognitive decline, making it hard to tell apart. Urinary incontinence usually shows up later in the disease.

Diagnostic Challenges

Diagnosing Idiopathic NPH is tricky because its symptoms are similar to other diseases like Alzheimer’s and Parkinson’s. MRI scans are key to spotting the enlarged ventricles without much brain shrinkage. A detailed check-up and sometimes tests like a lumbar puncture are needed to confirm it.

Diagnosis and Treatment Options

Understanding how to diagnose and treat hydrocephalus is key. Doctors use a mix of clinical checks and advanced imaging to find the problem.

Imaging Techniques

Imaging is vital for spotting hydrocephalus. We use different methods to see the brain’s ventricles and check how cerebrospinal fluid (CSF) moves.

• MRI (Magnetic Resonance Imaging): Gives clear pictures of the brain and CSF flow.
• CT (Computed Tomography) Scan: Quickly shows ventricular size and spots hemorrhages.
• Ultrasound: Helps in babies with open fontanelles to check ventricular size.

Shunt Procedures

Shunt placement is a common surgery for hydrocephalus. It moves extra CSF away from the brain to ease pressure.

“Shunt systems have evolved to include adjustable valves, reducing the need for additional surgeries.”

— A Neurosurgeon

Shunt Type	Description	Advantages
Ventriculoperitoneal (VP) Shunt	CSF is diverted to the peritoneal cavity.	Commonly used, effective.
Ventriculoatrial (VA) Shunt	CSF is diverted to the atrium.	Alternative when VP shunt is not feasible.

Endoscopic Third Ventriculostomy

Endoscopic third ventriculostomy (ETV) is a surgery that makes a new path for CSF flow. It goes around blockages.

• Procedure: Creates a hole in the third ventricle’s floor.
• Benefits: May cut down on shunt use, leading to fewer problems.

Medication Management

While surgery is often needed, meds can help manage symptoms. They can lower CSF production or ease headaches.

• Acetazolamide: Reduces CSF production.
• Furosemide: Used with acetazolamide.

Knowing about these diagnosis and treatment options helps us manage hydrocephalus better. This leads to better results for patients.

Conclusion

It’s important to know why hydrocephalus happens in adults. This knowledge helps in getting the right treatment early. We’ve looked at how things like head injuries, tumors, and infections can cause fluid buildup in the brain.

Spotting the signs and getting help is key. Hydrocephalus can really affect how you live. Luckily, there are treatments like shunts and surgeries to help manage it.

Knowing what can cause fluid on the brain helps us stay healthy. If you’re worried or notice symptoms, see a doctor. They can give you the best advice and care.

FAQ

References:

1. Author(s). (Year). Normal pressure hydrocephalus. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK560875