Hydrocephalus in Adults: Causes, Symptoms, Diagnosis & Treatment

Medically Reviewed and Edited by Dr. Asif Baliyan, MD - October 27, 2026

Introduction

Hydrocephalus ("hydro", meaning water, and "cephalus", referring to the head) is an abnormal buildup of fluid in the brain's cavities. It can occur in people of any age.

In young and middle-aged adults, hydrocephalus is a distinct and frequently confusing condition. This differs significantly from hydrocephalus identified in infancy, early childhood, or adult-onset normal pressure hydrocephalus (NPH) found in older adults (usually 60 and older).

Hydrocephalus in adults presents various challenges for patients and healthcare professionals. These extend beyond routine or specialized medical care to include behavioral, emotional, and occupational concerns.

What Is Hydrocephalus?

Hydrocephalus occurs when excess cerebrospinal fluid (CSF) accumulates in the ventricles (cavities) of the brain, which may increase the pressure inside the head. Although "water on the brain" is a common description of hydrocephalus, the "water" is actually CSF, the clear fluid that flows in and around the brain and spinal cord, cushioning them against injuries.

CSF performs three vital tasks:

• Protecting the brain and spinal cord against mechanical shocks
• Transporting nutrients and wastes away from the brain
• Moving between the skull and spine to control pressure variations inside the brain

How Much CSF Do We Make per Hour?

The average rate of CSF production is approximately 20 mL per hour. One or more of the ventricles swell as CSF builds up when an injury or disease disrupts the CSF circulation. As a result, the pressure inside the brain may significantly rise because the adult skull is stiff and cannot expand.

What Causes Fluid on the Brain in Adults? Types & Etiology

There are four types of hydrocephalus in adults.

Newly Diagnosed Congenital Hydrocephalus (Unrecognized Congenital)

The term congenital hydrocephalus describes hydrocephalus present at birth. However, symptoms may not always appear until adolescence or maturity.

Congenital hydrocephalus is caused by a complex combination of environmental and genetic variables during fetal development. The following are the most common causes of congenital hydrocephalus:

• Spina bifida
• Brain malformations
• Aqueductal stenosis

It is unclear how hydrocephalus can remain undiagnosed for an extended time before developing symptoms. It may become apparent when the fluid gradually builds up to the point that it causes brain malfunction, or when chronic, static expansion of the fluid spaces causes subtle, ongoing injury that eventually reduces the brain's capacity to compensate. These situations can be categorized as decompensated congenital hydrocephalus.

Sometimes individuals with dizziness or headaches undergo brain imaging (a head computed tomography (CT) or magnetic resonance imaging (MRI)) to investigate unrelated conditions such as migraines, inner ear abnormalities, or minor head injuries. Such imaging may incidentally detect asymptomatic hydrocephalus before symptoms attributable to the condition develop. The trauma in these cases had nothing to do with the hydrocephalus, which was present all along.

Acquired Hydrocephalus in Adults

Hydrocephalus that appears after birth is known as acquired hydrocephalus. It can be diagnosed in both adults and children. The most frequent causes of acquired hydrocephalus include the following:

• Brain tumors
• Head injuries
• Meningitis or other infection of the brain or spinal cord
• Brain bleed (Intraventricular hemorrhage)

Hydrocephalus Diagnosed and Treated in Childhood (Transition)

Before shunts became widely available for treating hydrocephalus, treatment options were limited, and long-term outcomes were often poor. Today, as more children with hydrocephalus reach adulthood, they transition into adult neurological care, where they may need ongoing medical care to address their evolving healthcare needs and monitor shunt function throughout life.

Even years after shunt placement, complications may arise that require further surgery. Adults treated for hydrocephalus during childhood may also experience long-term complications such as epilepsy or difficulties with memory, thinking, and everyday activities. These challenges highlight the importance of lifelong medical follow-up and attention to cognitive health.

Normal Pressure Hydrocephalus (NPH)

NPH occurs when fluid accumulation in or around the brain impairs brain function. It may affect memory, thinking and concentration, movement, and other cognitive functions. NPH can sometimes be reversed, even though its symptoms closely resemble those of dementia.

Sometimes, the reason for the obstruction in the CSF absorptive pathways is not known. This type of NPH is known as Idiopathic NPH (iNPH). The term "secondary NPH" refers to situations where a cause is obvious (e.g., trauma, stroke, tumor, or meningitis).

The prevalence of NPH increases with age and is most common among people over 65. This condition typically manifests itself at the age of 70. Advancing age is the primary factor associated with an increased likelihood of this condition. Risk appears to be similar across different races, genders, and ethnicities.

Hydrocephalus Symptoms in Adults

Adult-Onset Hydrocephalus

The signs of hydrocephalus in young adults can resemble those of NPH in the elderly in some ways, but they are frequently far more subtle. Nevertheless, these challenges can significantly affect daily life and, in more severe cases, they may limit an adult’s ability to work or maintain independence.

Sometimes, symptoms are misattributed to a midlife crisis or other psychological or emotional concerns. However, if left undetected, progressive symptoms may disrupt daily functioning and affect personal relationships besides work.

Symptoms include, but are not limited to:

• Nausea
• Chronic headaches
• Balance and coordination issues
• Unsteady walk or gait
• Difficulty focusing the eyes and vision problems
• Leg weakness
• Irritability
• Change in personality and behavior
• Short-term memory issues
• Seizures
• Drowsiness
• Fainting (syncope)

Normal Pressure Hydrocephalus

Typically, normal pressure hydrocephalus symptoms develop and worsen gradually over several months to years. Hakim's triad refers to three main symptoms of NPH. Between 50% and 75% of adults with NPH simultaneously exhibit all three symptoms. It includes the following three types of symptoms:

1. Gait issues
2. Cognitive difficulties
3. Urinary incontinence

Gait issues

Gait issues occur when you struggle with walking-related movements. These symptoms are the most frequent, present in about 80% to 95% of NPH patients. A significant distinction between NPH symptoms and the movement-related symptoms of Parkinson's is that the former predominantly affect the legs and feet.

NPH commonly results in the following gait-related symptoms:

Difficulty lifting the feet: The feet may feel as though they are stuck to the ground while walking. This is often described as a “magnetic” sensation, similar to the resistance felt when pulling magnets apart.

Short, unsteady steps: Walking may involve short, shuffling steps and reduced stability, increasing the likelihood of tripping, stumbling, or falling.

Difficulty starting or continuing to walk: A person may struggle to take the first step or continue walking. There may also be pauses while walking or difficulty making wide turns.

Outward turning of the toes: The toes may turn outward while walking, causing the feet to spread farther apart. This can result in a side-to-side, penguin-like walking pattern.

Cognitive difficulties

Cognitive difficulties are the second most prominent NPH symptom type. These may manifest as, or even be the cause of, any of the following:

Reduced physical and mental speed: This is when someone exhibits signs of thinking more slowly than usual or moving more slowly than expected.

Poor executive performance: This makes it difficult for people to control their emotions, thoughts, and actions. This may manifest as issues with concentration and focus, as well as sluggish and erratic decision-making.

Memory issues: Individuals with memory issues may appear absent-minded or forgetful.

Emotional changes: Sometimes, people with NPH can appear lethargic or uninterested in activities they once found enjoyable.

Urinary incontinence

Urinary incontinence involves the unintentional leakage of urine due to loss of bladder control. In the early stages, a person may experience frequent urges to urinate, sudden and unusually strong urges, or both.

Loss of bladder control can cause embarrassment or distress for some individuals, while others may not appear particularly concerned by it. In some cases, this lack of concern or embarrassment may be associated with cognitive difficulties.

Diagnosing Hydrocephalus

Doctors use brain imaging methods, including CT, MRI, and a thorough clinical neurological evaluation during a medical visit to make a diagnosis.

During a physical and neurological exam, a medical professional looks for visible signs and symptoms. They assess reflexes, arm and leg muscle strength, and other senses such as vision, hearing, and touch.

The doctor may ask questions about symptoms and medical history. These, along with medical records, can help diagnose NPH.

Adults frequently undergo more tests to diagnose the condition. These tests could consist of the following:

• Lumbar puncture
• Continuous lumbar CSF drainage
• Measurement of cerebrospinal fluid outflow resistance
• Intracranial pressure (ICP) monitoring
• Isotope cisternography

The doctor may also recommend a neuropsychological evaluation. The specific clinical scenario, the medical team's preferences, and their collective experience can influence which tests they order.

Listed below are the tests involved in the diagnosis. Not all the tests mentioned are essential for a diagnosis.

CT Scan

A CT scan is a reliable procedure for identifying hydrocephalus and helping the treatment process. It is a sophisticated technology in which X-ray beams are sent through the patient's body, and the computer creates images of the internal structures.

The initial sign of hydrocephalus in an adult is frequently an unexpected enlargement of the ventricles, but this discovery is typically insufficient to move forward with surgical treatment. Hydrocephalus can either be compensated (non-progressing) or uncompensated (progressing), and additional testing is frequently required.

It is potentially harmful to place a shunt in a person with compensated hydrocephalus, just as it is potentially harmful not to do so in a person with decompensated hydrocephalus.

MRI

Like a CT scan, an MRI is a diagnostic tool that creates brain images. However, MRI does not use radiation or X-rays. Instead, MRI scans the patient's body using radio signals and a strong magnet.

A computer then converts the signals into images. MRI scans are painless and generally very safe.

MRI scans can use different imaging sequences. The Single Shot Fast Spin Echo (also known as a "quick brain MRI"), which takes around three minutes and hardly ever needs sedation, is used to measure ventricular size. A complete MRI takes 30 to 60 minutes, and sedation may be necessary for those prone to claustrophobia or anxiety. This is beneficial as it reveals more minute details.

After analyzing the images, the radiologist will report interpretations to the physician. Sometimes, it is necessary to perform both a contrast-enhanced and a non-enhanced MRI. For example, adding a chemical agent enhances the clarity of the MRI image, enabling the physician to identify subtle indicators of a tumor or persistent infection that might cause adult-onset hydrocephalus. This helps them discern the need for extra therapy in addition to shunt surgery.

Prior to the procedure, the dye agent is administered intravenously (IV), usually through a vein in your arm. The MRI will then proceed normally.

Lumbar Puncture (Spinal Tap)

A lumbar puncture allows the analysis of the fluid and estimation of CSF pressure. Under local anesthesia, a tiny needle is inserted into the spinal fluid space at the lower back. A 30-50 mL sample of CSF is removed to check for any potential short-term symptom relief of symptoms. Surgery is likely to be successful if removing CSF significantly reduces symptoms, even temporarily.

Nonetheless, the prospect of improvement with shunt surgery is not ruled out if there is no improvement after a lumbar puncture. Many patients who show little to no improvement after the test benefit from shunts.

This test is crucial when the cause of hydrocephalus is unknown. Occult infections or malignancies with CSF spread may be detected through culture and testing the CSF for fungal organisms or tuberculosis.

Lumbar Catheter

External lumbar drainage, often known as continuous lumbar drainage or lumbar catheter insertion, is a variation of lumbar puncture. In this method, a spinal needle reaches the spinal fluid space in the lower back and extracts fluid via a catheter (a thin, flexible tube).

The lumbar catheter enables the continuous removal of spinal fluid over several days and the more accurate observation of spinal fluid pressure over time. In addition, external lumbar drainage can mimic the physiological effects of a shunt procedure.

Individuals who improve significantly after spinal fluid drainage can probably benefit from shunt surgery. A tiny percentage of patients who do not improve with lumbar drainage may still benefit from a shunt procedure. Hospitalization is necessary for lumbar catheter insertion.

Intracranial Pressure (ICP) Monitoring

ICP monitoring is a diagnostic technique that enables doctors to evaluate whether the symptoms are caused by high or low CSF pressure. This requires hospital admission.

To measure ICP, the surgeon creates a small hole in the skull called a burr hole and inserts a tiny, pressure-sensitive probe into the brain or ventricles that directly detects the pressure.

Isotopic Cisternography

This involves inserting a radioactive isotope via a spinal tap into the lumbar subarachnoid region (lower back), which allows periodic scanning to measure CSF absorption over time (up to 96 hours). The procedure helps determine whether the isotope is absorbed over the brain's surface or is trapped inside the ventricles. Compared to CT or MRI, isotopic cisternography requires lumbar puncture and is much more complicated.

Even when it returns a "positive" result, a cisternogram test does not decisively predict whether a patient would respond to shunt surgery. For this reason, the procedure is now used less often.

Neuropsychological Testing

Neuropsychology is the study of the brain-behavior connection. When a patient's main issues are linked to cognition, emotion, and behavior, a neuropsychological assessment can be a crucial addition to clinical work in making a diagnosis. This assessment can also help doctors and family members understand how hydrocephalus affects a patient's day-to-day functioning.

A detailed interview with the patient and one or more family members is usually part of a neuropsychological examination, which also closely examines studies and medical records. In addition, multiple tests evaluate different facets of cognitive function, such as executive function (the ability to plan, reason, and modulate behavior), attention, memory, language, and visual-spatial aptitude. The ultimate objective is to comprehend how structural and functional changes in the brain impact the patient's behavior.

Neuropsychological testing can help assess whether an adult patient with hydrocephalus would benefit from surgical intervention or conservative management. Also, the pattern of neuropsychological impairment can be used to identify whether a patient's cognitive symptoms are likely caused by another coexisting neurological illness or hydrocephalus.

At this stage of the diagnostic process, the medical team may include a primary care physician, neurologist, and neurosurgeon. Their involvement can help with interpreting test results, identifying individuals who may benefit from shunt surgery, coordinating the surgical procedure and postoperative care, and setting appropriate expectations for treatment. 

Hydrocephalus Treatment in Adults

There are several approaches to treating hydrocephalus. Treatment may address the condition indirectly by diverting excess cerebrospinal fluid to another part of the body, or directly by addressing the cause of the CSF obstruction.

Indirect treatment typically involves implanting a shunt that drains excess CSF away from the brain. The fluid is usually diverted to the peritoneal cavity, the space surrounding the abdominal organs.

When Is Surgery Necessary?

In some instances, two surgeries are carried out: one to reroute the CSF and one to eliminate the obstruction later on (e.g., a brain tumor). The shunt system is typically implanted once and stays in place throughout the patient's life, though subsequent surgeries to modify the shunt may be required. It continuously diverts CSF from the brain, maintaining the intracranial pressure within normal ranges.

Endoscopic Third Ventriculostomy (ETV)

An alternate procedure that may be recommended is an endoscopic third ventriculostomy (ETV). This involves gently inserting an endoscope into one of the lateral ventricles through a small incision in the skull. The neurosurgeon will then puncture the membrane of the third ventricle using the endoscope, which is equipped with a camera, as it descends into the ventricle. As a result, CSF now has a different route to go through the brain. No shunt is required in this case.

What to Expect After Hydrocephalus Surgery

If any neurological issues persist after surgery, rehabilitation may be necessary for further improvement. However, the magnitude of the hydrocephalus-related damage to the brain and its capacity for healing can restrict your potential to recover.

As hydrocephalus is a chronic disorder, constant medical monitoring is necessary. Follow-up diagnostic exams like MRIs, CT scans, and X-rays can help determine whether the shunt is functioning appropriately. Any of the following postoperative symptoms should be reported immediately to the doctor:

• Redness, pain, tenderness, or swelling of the skin along the length of the tube or incision
• Feeling irritable or sleepy
• Headache, nausea, vomiting, or double vision
• Abdominal pain
• Fever
• Returning neurological symptoms from before surgery

What Is the Prognosis for Hydrocephalus in Adults?

Adults with hydrocephalus who receive appropriate treatment can often reverse many symptoms, returning much of their cognitive and physical performance. With proper treatment, many adults with hydrocephalus can have fulfilling lives.

The long-term prognosis of hydrocephalus might differ significantly between individuals because it is a complex disorder. The cause, specific symptoms, promptness of the diagnosis, and the patient's receptivity to treatment all affect the prognosis.

Other neurological conditions can also affect the prognosis. For instance, it is widely known that Alzheimer's disease (AD), which is more relevant to cognitive dysfunction, can coexist with NPH in older adults.

Other types of neuropathology that impair gait, such as stroke and neurodegenerative illnesses, can also be essential considerations. Even though shunts are proven to be functional, some of these diagnoses have the potential to "swamp" the effects of hydrocephalus over time, causing symptoms to worsen.

Headaches, chronic pain, as well as behavioral, emotional, and employment-related concerns, are some typical medical issues. However, it is important to note that untreated progressive symptoms can become quite incapacitating and result in serious physical and cognitive loss. In addition, hydrocephalus-related complications can occasionally become fatal.

Early detection may influence how well treatment works. Another important factor is the extent to which hydrocephalus has caused reversible or permanent brain impairment, although this can be difficult to measure. Treatment is generally most effective when permanent damage has not occurred.

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