Hydrocephalus is a neurological condition characterized by the excessive buildup of cerebrospinal fluid (CSF) within the brain’s ventricles. This accumulation occurs when there is an imbalance between the production and absorption of CSF, often due to a blockage in circulation pathways. The resulting increase in fluid volume causes the ventricles to enlarge, placing pressure on surrounding brain tissues. Because this elevated pressure can lead to physical and cognitive impairments, and be life-threatening, immediate treatment is necessary to relieve the pressure and restore normal brain function.
Ventricular Shunting Procedures
The most common surgical approach for managing hydrocephalus involves the permanent implantation of a ventricular shunt system. This flexible medical device diverts excess cerebrospinal fluid (CSF) from the brain to another area of the body where it can be safely absorbed, typically the abdominal cavity (ventriculoperitoneal or VP shunt).
The shunt has three main components: a ventricular catheter, a valve, and a distal catheter. The ventricular catheter collects CSF from a ventricle and connects to a one-way valve, usually placed behind the ear or in the neck. The valve regulates the pressure and amount of drainage.
Valves are either fixed-pressure or adjustable (programmable). Adjustable valves allow the clinician to non-invasively change the pressure setting after implantation using magnetic tools. The distal catheter is tunneled under the skin and terminates in the peritoneal cavity, where the body naturally absorbs the CSF. The goal is to maintain controlled intracranial pressure, relieving symptoms and preventing further brain damage.
Endoscopic Third Ventriculostomy
An alternative to shunt placement is the Endoscopic Third Ventriculostomy (ETV) procedure, often used for obstructive hydrocephalus. ETV is a minimally invasive technique that creates a new, internal pathway for CSF flow, bypassing implanted hardware.
The procedure uses a neuroendoscope, inserted through a small incision and burr hole in the skull. The surgeon navigates to the floor of the third ventricle, where a small perforation is created.
This opening allows the CSF to flow out of the blocked ventricular system into the basal cisterns, a normal CSF space surrounding the brain. From there, the CSF is reabsorbed by the body. The primary advantage of ETV is that it restores a more physiological flow and avoids shunt complications.
Managing Complications and Revisions
Long-term management of hydrocephalus involves addressing treatment failure and the need for revision surgery. For shunts, the most common reasons for failure are obstruction, infection, and mechanical malfunction.
Obstruction occurs when the catheters or valve clog with tissue or protein deposits, necessitating surgical revision. Infections are serious, often requiring temporary shunt removal, external CSF drainage, and antibiotics before a new shunt is placed.
Shunt systems have a high lifetime failure rate; pediatric patients face up to an 80% risk of revision surgery. Patients often require multiple revisions throughout their lives to maintain proper device function.
Even ETV can fail over time, often because the surgically created opening closes. Most ETV failures occur within the first six months. When ETV fails, patients may require a repeat ETV or, more commonly, the placement of a shunt system. Treating hydrocephalus is a process of continuous management rather than a one-time cure.