What is Hydrocephalus? How is it Treated?

Hydrocephalus is a condition that occurs as a result of the abnormal accumulation of cerebrospinal fluid (CSF) in the cavities (ventricles) inside the brain. This excess fluid expands the ventricles and exerts pressure on the surrounding brain tissue. Cerebrospinal fluid normally floats the brain, making it lighter within the skull, acts as a cushion against impacts, and helps remove metabolic waste from the brain. Disruption of the balance between fluid production, circulation, and absorption leads to the accumulation of excess fluid and increased intracranial pressure.

Hydrocephalus can occur at any age, but it appears more frequently in infants and adults over the age of 60. Left untreated, it can lead to progressive brain damage, developmental delay, and even fatal outcomes. Conversely, thanks to modern surgical methods applied today, the vast majority of patients can lead a normal or near-normal life.

Why does hydrocephalus occur?

Hydrocephalus can develop due to an obstruction in CSF circulation, excessive fluid production, or inadequate fluid absorption. It is examined in two main groups based on its causes:

Congenital hydrocephalus: Occurs due to structural malformations arising during fetal brain development, aqueductal stenosis (blockage of a narrow channel in the brain), or congenital anomalies such as Chiari malformation or Dandy-Walker malformation associated with spina bifida.

Acquired hydrocephalus: Can develop at any age after birth. It may arise following brain hemorrhages (especially intraventricular hemorrhage in premature infants), infections like meningitis or encephalitis, brain tumors, head trauma, or subarachnoid hemorrhage.

Additionally, hydrocephalus is classified according to the CSF flow mechanism:

• Obstructive (non-communicating) hydrocephalus: There is a physical blockage within the ventricular system; fluid cannot circulate freely between the ventricles.
• Communicating hydrocephalus: Flow between the ventricles is free, but fluid absorption in the subarachnoid space is impaired.
• Normal pressure hydrocephalus (NPH): A specialized form usually seen in individuals over 60, where despite ventricular enlargement, intracranial pressure remains within normal limits in most measurements. It is recognized by the classic triad of symptoms comprising gait disturbance, cognitive decline, and urinary incontinence.

What are the symptoms?

Symptoms of hydrocephalus vary greatly depending on the patient’s age, the rate of disease progression, and the underlying cause.

In infants: Abnormal growth in head circumference, a tense and bulging soft spot (fontanelle) at the front of the skull, downward fixation of the eyes (“sunsetting” appearance), irritability, excessive sleepiness, vomiting, and feeding difficulties may be observed.

In older children and adults: Headache (especially worsening in the mornings), nausea and vomiting, blurred or double vision, loss of balance and coordination, difficulty walking, impairment in urinary control, memory problems, sleepiness, and a slowing of general mental functions are common findings.

In the elderly (normal pressure hydrocephalus): Progressing with small steps as if “feet are glued to the floor,” forgetfulness and cognitive decline, and urinary incontinence are typical symptoms in this group that are frequently confused with dementia or Parkinson’s disease.

How is it diagnosed?

The diagnosis of hydrocephalus relies on imaging methods along with a detailed neurological examination:

• Computed tomography (CT): Shows ventricular enlargement quickly and clearly; it is preferred in emergency evaluations.
• Magnetic resonance imaging (MRI): Reveals the location and cause of obstruction and changes in brain tissue in greater detail.
• Lumbar puncture and “tap test”: Especially when normal pressure hydrocephalus is suspected, a specific amount of CSF is drained to observe temporary improvements in gait and cognitive functions; this test is used to predict the likelihood of benefiting from surgical treatment.
• Intracranial pressure monitoring: In certain cases, especially when the decision for surgery cannot be clarified, continuous pressure measurement can be performed.

What are the treatment approaches?

There is no medical drug treatment that corrects the underlying fluid imbalance of hydrocephalus. Although medications such as acetazolamide are used in certain specific situations (for example, temporarily in premature infants) to reduce CSF production, this approach does not provide a permanent solution and generally serves as a bridge to surgery. The primary goal of treatment is to relieve intracranial pressure and prevent further damage to brain tissue by draining excess accumulated fluid. Therefore, in current medical practice, the standard treatment for hydrocephalus is surgery.

Surgical Treatment Methods

Two main approaches are used in hydrocephalus surgery: shunt placement (drainage system) and endoscopic third ventriculostomy (ETV). Which method is chosen depends on the patient’s age, the cause of hydrocephalus, the location of the obstruction, and overall health status.

Shunt Surgery (Drainage System Placement)

A shunt is a permanent medical device that diverts excess CSF away from the brain to another region of the body where it can be absorbed. The system consists of three main components:

• Proximal catheter: A thin, flexible tube whose tip is placed into one of the ventricles of the brain.
• Valve mechanism: A pressure-sensitive valve that ensures fluid flows only in the correct direction and at an appropriate rate, attempting to prevent over- or under-drainage. Fixed-pressure, adjustable (programmable), and flow-sensitive (anti-siphon) valve technologies are used today; programmable valves allow pressure settings to be modified non-invasively over the skin with a magnetic device after surgery.
• Distal catheter: A tube tunneled beneath the skin that extends to a body cavity where excess fluid can be absorbed.

Shunt types are classified according to the region where the distal catheter is placed:

• Ventriculoperitoneal (VP) shunt: The most commonly applied method; the tube is directed into the abdominal cavity (peritoneum), where excess fluid is absorbed.
• Ventriculoatrial (VA) shunt: The tube is advanced into the right atrium of the heart; it is generally preferred in special cases where the abdominal cavity cannot be used.
• Lumboperitoneal (LP) shunt: Fluid is taken from the spinal canal in the lumbar region instead of the ventricle and transferred to the abdominal cavity; it is used particularly in certain cases of normal pressure hydrocephalus and pseudotumor cerebri.

How does the surgical process work?

Shunt surgery is performed under general anesthesia. The neurosurgical team opens a small hole in the skull to place the proximal catheter into the ventricle, then tunnels the catheter beneath the skin behind the ear, down the neck and chest line to reach the abdominal or cardiac cavity. The procedure usually takes one to two hours, and patients can often be discharged within a few days. The vast majority of patients with a shunt continue their lives knowing that the device requires lifelong regular follow-up.

What are the long-term outcomes of shunt surgery?

A shunt is a life-saving and effective system that generally allows patients to lead a normal life; however, like any medical device implanted long-term, it may malfunction over time. According to published data, approximately 40% of VP shunts require revision within the first year, and up to a cumulative 50% by the end of the second year. Therefore, patients with shunts and their families must learn to recognize signs of failure (recurrence of headache, vomiting, increased sleepiness, redness along the shunt tract).

Shunt Complications and Revision Surgery

Although shunt systems are reliable, they carry certain risks of complications; early recognition of these complications and timely revision surgery are vital:

• Mechanical obstruction: The most common cause of shunt failure; occurs as a result of catheter blockage or displacement due to tissue or cellular debris.
• Infection: Usually appears within the first few weeks to two months after surgery; it can manifest with fever, abdominal pain, and redness or swelling along the shunt tract. Infection rates in adults range between approximately 1.6% and 16.7%. When an infection develops, the standard approach involves surgical removal of all shunt components, temporary management of hydrocephalus with an external ventricular drain (EVD), administration of antibiotic therapy for 10–14 days, and placement of a new shunt after the infection is cleared.
• Over-drainage: Excessive fluid evacuation resulting in severe ventricular collapse, which can lead to conditions like subdural hematomas or “slit ventricle syndrome.”
• Under-drainage: Persistence of hydrocephalus symptoms due to failure of the valve to open sufficiently.
• Abdominal (peritoneal) region complications: Distal catheter displacement, intra-peritoneal pseudocyst formation, bowel perforation, or herniation have been reported as rare but serious complications; in some case reports, catheter migration into the bowel protruding from the anus and causing meningitis has even been observed.
• Risks specific to VA shunts: Infections in catheters placed in the heart chamber can spread into the bloodstream, leading to severe conditions (renal damage, chronic damage to the heart and lungs); for this reason, VA shunts are generally reserved for special cases where the peritoneal cavity cannot be utilized. Nevertheless, some studies report that the blockage and revision rate of VA shunts may be lower compared to VP shunts, especially in elderly normal pressure hydrocephalus patients.

Every revision surgery carries the same general anesthesia and infection risks as the initial shunt placement; furthermore, treating an infected shunt can cost three to five times more than the initial placement. Therefore, neurosurgical teams recommend monitoring patients with long-term, regular imaging and clinical follow-ups.

Endoscopic Third Ventriculostomy (ETV)

ETV is a minimally invasive method applied as an alternative to shunts, especially in obstructive (blocking) hydrocephalus, which does not require foreign body implantation.

The surgeon reaches the floor of the third ventricle by inserting a thin endoscope through a small hole opened in the skull. Under direct visualization with the assistance of a video camera, a small opening (fenestration) is created in the floor of the third ventricle. This opening allows CSF to flow directly from the ventricular system into the subaraknoid space, bypassing the obstructed natural pathway. Because the procedure implants no foreign devices (shunts, tubes, valves), it significantly reduces the risks of infection and mechanical failure.

Advantages and Limitations of ETV Compared to Shunts

When ETV is successful, the patient does not remain dependent on a permanent device, which eliminates the risk of infection and mechanical failure. However, the procedure can only be performed in selected patients with suitable anatomy; the success rate may be lower in communicating hydrocephalus, certain Chiari malformation cases, and very young infants. When ETV fails, most patients are directed to shunt surgery; in some centers, a second ETV attempt can yield successful results with a patency rate of up to 90%. Therefore, expert opinion leans toward evaluating ETV as a primary treatment option before VP shunting in carefully selected patients diagnosed with obstructive hydrocephalus.

Temporary Surgical Measures: External Ventricular Drainage (EVD)

In emergency situations, especially during acute intracranial pressure spikes or while treating a shunt infection, an external ventricular drain (EVD) is applied as a temporary solution before placing a permanent shunt. In this system, the catheter tip is placed into the ventricle, while the other end is brought outside the skin and connected to an external collection bag. EVD provides fluid drainage and pressure measurement until the patient’s clinical status stabilizes or the infection is treated; it is not a permanent solution, and either a permanent shunt is placed afterward or ETV is applied in suitable cases.

Surgical Approach in Normal Pressure Hydrocephalus

In normal pressure hydrocephalus seen in elderly patients, the standard treatment is again shunt surgery; major clinical studies show that shunt surgery in carefully selected patients can provide significant improvement in the triad of gait disturbance, cognitive decline, and urinary incontinence. The surgical decision in this patient group is usually supported by the lumbar puncture “tap test”: patients who demonstrate temporary improvement during the test have a higher probability of benefiting from a shunt. The choice between VA and VP shunts remains controversial in this population; although some retrospective studies report lower revision rates for VA shunts, VP shunts generally remain the first choice due to cardiopulmonary and renal complication risks.

Post-Operative Process and Lifelong Follow-up

Most patients with a shunt live with the device for life and require regular neurological examinations along with periodic imaging. Warning signs to watch for in the post-operative period include worsening headaches, recurrent vomiting, changes in consciousness, fever, or redness/swelling along the shunt tract; development of any of these symptoms warrants emergency evaluation. In patients undergoing ETV, follow-up relies on monitoring changes in ventricular size and clinical recovery via imaging; because late-stage ETV failure can rarely occur years later, long-term monitoring is recommended.

Non-Surgical Supportive Treatments and Rehabilitation

Although surgery corrects the root cause of hydrocephalus, additional supportive therapies may be required to address developmental or functional losses caused by the disease. Physical therapy, occupational therapy, speech therapy, and special education programs contribute to managing developmental delays, especially in childhood hydrocephalus cases. In adults, post-surgical walking and balance exercises support the recovery process.

Post-Surgical Quality of Life

With appropriate and timely surgical treatment, the majority of hydrocephalus patients can achieve a quality of life close to normal. The prognosis depends on the cause of hydrocephalus, age at diagnosis, degree of accompanying brain damage, and speed of access to treatment. While untreated hydrocephalus can be progressive and potentially fatal, timely shunt or ETV surgery normalizes intracranial pressure to prevent further damage and can achieve significant regression of symptoms in many patients.