Endoscopic third ventriculostomy (ETV) is a minimally invasive neurosurgical procedure designed to treat a specific type of fluid buildup in the brain. It creates an internal bypass for cerebrospinal fluid (CSF) that is blocked from circulating normally. By establishing a new pathway, ETV relieves the pressure that accumulates within the head due to this obstruction. This technique restores the natural flow of CSF without the permanent implantation of a medical device.
The Condition ETV Addresses
The brain and spinal cord are surrounded by cerebrospinal fluid (CSF), a clear liquid produced in the brain’s four interconnected chambers, called ventricles. CSF circulates through the ventricular system and is ultimately reabsorbed into the bloodstream from the subarachnoid space.
Hydrocephalus occurs when there is an imbalance between CSF production and absorption, causing excess fluid to collect and the ventricles to swell. This leads to increased intracranial pressure, which can damage brain tissue. ETV is specifically indicated for obstructive or non-communicating hydrocephalus, caused by a physical blockage within the ventricular pathway.
In this condition, CSF is blocked from exiting the ventricular system to reach the absorption sites. A common site for obstruction is the aqueduct of Sylvius, the narrow channel connecting the third and fourth ventricles. This blockage causes fluid to accumulate, leading to the enlargement of the lateral and third ventricles. Conditions such as aqueductal stenosis, tumors, or certain congenital malformations are frequent causes of this localized obstruction, making them excellent candidates for ETV.
Performing the Endoscopic Third Ventriculostomy
The ETV procedure is performed under general anesthesia. It begins with a small incision on the scalp and a tiny burr hole drilled into the skull. The surgeon inserts a specialized neuro-endoscope—a thin, flexible tube equipped with a light source, magnifying lens, and surgical tools—through this opening.
The surgeon navigates the ventricular system, passing from a lateral ventricle into the third ventricle. The procedure is guided by real-time images projected onto a monitor.
The core of the ETV involves creating a new opening, or fenestration, in the thin membrane forming the floor of the third ventricle. This opening allows the accumulated CSF to bypass the original obstruction and flow directly into the interpeduncular cisterns, which are normal fluid spaces at the base of the brain. From there, the fluid flows into the subarachnoid space where it is naturally reabsorbed into the bloodstream, relieving the pressure. The operation is minimally invasive and typically takes one to two hours to complete.
Distinguishing ETV from Shunt Placement
The primary alternative treatment for hydrocephalus is the placement of a ventriculoperitoneal (VP) shunt. ETV offers an intracranial solution, creating an internal detour that restores physiological CSF flow within the brain’s existing anatomy. This means no foreign material is left permanently in the body.
A VP shunt, conversely, is an extracranial diversion system involving the implantation of a long silicone tube. One end is placed into a ventricle, and the other is tunneled to the abdomen (peritoneum), where the excess fluid is absorbed. A pressure-regulating valve controls the amount of fluid drained. The shunt is a permanent device that constantly drains fluid, while ETV is a one-time structural modification providing a permanent bypass.
The cause of hydrocephalus determines the appropriate procedure. ETV is most effective for obstructive hydrocephalus as it directly addresses the anatomical blockage. Shunts are necessary for communicating hydrocephalus, where fluid flows out of the ventricles but is not properly reabsorbed. ETV is generally preferred for appropriate candidates to avoid the lifelong risk of shunt complications, such as infection, blockage, or mechanical failure, which often require repeated surgeries.
Immediate Post-Operative Expectations and Follow-up
Following the ETV procedure, patients are monitored closely, often spending a brief period in a specialized intensive care setting. The hospital stay is relatively short, frequently lasting only one to two days. Staff watch for complications such as bleeding, infection, or immediate failure to relieve pressure.
Discharge instructions focus on incision care and managing pain. Patients are advised to keep activity light, with a return to normal activities often occurring within a couple of weeks. A follow-up appointment with the neurosurgeon is scheduled soon after discharge to check the incision and assess for clinical improvement.
Long-term follow-up is necessary to monitor the function of the ventriculostomy, as the newly created opening can sometimes close over time. Success is gauged by the relief of the patient’s original symptoms, such as headaches, nausea, or changes in alertness, and is confirmed through periodic imaging studies. If symptoms return or imaging shows rising intracranial pressure, it indicates ETV failure, and the patient may require a repeat ETV or the placement of a shunt system.