Endoscopic third ventriculostomy (ETV) is a surgical procedure for treatment of

hydrocephalus Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased intracranial pressure, pressure inside the skull. Older people may have headaches, double vision, poor ...

in which an opening is created in the floor of the

third ventricle The third ventricle is one of the four connected ventricles of the ventricular system within the mammalian brain. It is a slit-like cavity formed in the diencephalon between the two thalami, in the midline between the right and left lateral v ...

using an

endoscope An endoscope is an inspection instrument composed of image sensor, optical lens, light source and mechanical device, which is used to look deep into the body by way of openings such as the mouth or anus. A typical endoscope applies several modern t ...

placed within the ventricular system through a

burr hole Trepanning, also known as trepanation, trephination, trephining or making a burr hole (the verb ''trepan'' derives from Old French from Medieval Latin from Greek , literally "borer, auger"), is a surgical intervention in which a hole is drille ...

. This allows the

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...

to flow directly to the basal cisterns, bypassing the obstruction. Specifically, the opening is created in the translucent

tuber cinereum The tuber cinereum is a hollow eminence of the middle–ventral hypothalamus, specifically the arcuate nucleus, situated between the mammillary bodies and the optic chiasm. In addition to the ventral hypothalamus, the tuber cinereum includes ...

on the third ventricular floor.

Medical uses

The ETV procedure is used as an alternative to a

cerebral shunt A cerebral shunt is a device permanently implanted inside the head and body to drain excess fluid away from the brain. They are commonly used to treat hydrocephalus, the swelling of the brain due to excess buildup of cerebrospinal fluid (CSF). If ...

Hydrocephalus and Treatment: Shunts and Endoscopic Third Ventriculostomy
AboutKidsHealth.ca mainly to treat certain forms of noncommunicating obstructive hydrocephalus (such as aqueductal stenosis), but since the ETV was introduced as an accepted treatment modality the range of etiologies for which it is used has grown significantly. Whereas at first it was almost exclusively performed in patients with noncommunicating obstructive hydrocephalus (e.g. aqueductal stenosis or intracerebral tumor), in the present day patients with communicating obstructive hydrocephalus (e.g. post

intracranial hemorrhage Intracranial hemorrhage (ICH), also known as intracranial bleed, is bleeding within the skull. Subtypes are intracerebral bleeds ( intraventricular bleeds and intraparenchymal bleeds), subarachnoid bleeds, epidural bleeds, and subdural bleeds. ...

or post intracranial infection) also may be eligible for treatment by means of ETV.

Complications

A major advantage of performing an endoscopic third ventriculostomy over placement of a cerebrospinal fluid shunt is the absence of an implanted foreign body. A shunt has risk of infection and failure for which subsequent surgery is needed. Complications of ETV include hemorrhage (the most severe being due to

basilar artery The basilar artery () is one of the arteries that supplies the brain with oxygen-rich blood. The two vertebral arteries and the basilar artery are known as the vertebral basilar system, which supplies blood to the posterior part of the circle of W ...

rupture), injury to neural structures (e.g.

hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamu ...

pituitary gland In vertebrate anatomy, the pituitary gland, or hypophysis, is an endocrine gland, about the size of a chickpea and weighing, on average, in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain. The ...

fornix of the brain The fornix (from lat, fornix, lit=arch) is a C-shaped bundle of nerve fibers in the brain that acts as the major output tract of the hippocampus. The fornix also carries some afferent fibers to the hippocampus from structures in the diencephalon ...

), and late sudden deterioration. Infection, hematoma, and cerebrospinal fluid leaks may present in the direct postoperative period.

Failure of treatment

Failure of the ETV occurs. This can be due to occlusion of the ventriculostomy (e.g. closure of the ventriculostomy, formation of subarachnoid membranes in the

pontine cistern The pontine cistern, also cisterna pontis and cisterna pontocerebellaris is a notable subarachnoid cistern on the ventral aspect of the pons. It contains the basilar artery, and is continuous behind with the subarachnoid space of the spinal cord, ...

or other mechanisms). Although 60 - 90% of failures occur in the first few months after treatment, long-term failure also occurs (failures occurring after 7 years have been reported). In a very small subgroup of patients a complication of ETV can be rapid late deterioration. The mechanism is not clear.

Alternative treatment

When it is not possible to perform an ETV for different reasons, an alternative treatment is opening the

lamina terminalis The median portion of the wall of the forebrain consists of a thin lamina, the lamina terminalis, which stretches from the interventricular foramen (Foramen of Monro) to the recess at the base of the optic stalk (optic nerve) and contains the va ...

anterior to the third ventricle. The effectiveness of this approach is not certain. The surgical treatment options for hydrocephalus are, as previously mentioned, implantation of a

and ETV. Especially in the youngest age group (younger than two years of age) it remains uncertain what is the superior treatment modality. Currently, a large international, multicenter study is conducted to address this issue. Patients under the age of two, diagnosed with

aqueductal stenosis Aqueductal stenosis is a narrowing of the aqueduct of Sylvius which blocks the flow of cerebrospinal fluid (CSF) in the ventricular system. Blockage of the aqueduct can lead to hydrocephalus, specifically as a common cause of congenital and/or ob ...

without a history of

preterm birth Preterm birth, also known as premature birth, is the Childbirth, birth of a baby at fewer than 37 weeks Gestational age (obstetrics), gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 we ...

or other associated

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...

anomalies are being included (International Infant Hydrocephalus Study).

Combined with choroid plexus cauterization

There is a discussion regarding the additional benefit of combining endoscopic third ventriculostomy with

choroid plexus The choroid plexus, or plica choroidea, is a plexus of cells that arises from the tela choroidea in each of the ventricles of the brain. Regions of the choroid plexus produce and secrete most of the cerebrospinal fluid (CSF) of the central nerv ...

cauterization Cauterization (or cauterisation, or cautery) is a medical practice or technique of burning a part of a body to remove or close off a part of it. It destroys some tissue in an attempt to mitigate bleeding and damage, remove an undesired growth, or ...

. This combined procedure is referred by the abbreviation "ETV/CPC" and has also been called the "Warf Procedure" after Dr.

Benjamin Warf Benjamin Warf is an American pediatric neurosurgeon. Warf was awarded a MacArthur Fellowship in 2012. Work and career Warf is Professor of Neurosurgery at Harvard Medical School and holds the Hydrocephalus and Spina Bifida Chair at Boston Childre ...

. There have been research studies published about the experience of authors with this procedure. The lion's share of the data that show favorable results is reported on patients in

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

. More recent studies from research groups in Western countries also show that the combination of ETV with choroid plexus cauterization seems to be effective, safe, and durable, and that predictions for success are similar to those of ETV alone. The degree of choroid plexus cauterization in infants might be dependent on the experience of the neurosurgeon (

learning curve A learning curve is a graphical representation of the relationship between how Skill, proficient people are at a task and the amount of experience they have. Proficiency (measured on the vertical axis) usually increases with increased experience ...

) and thus surgeons training might improve results. The ETV/CPC procedure is now being performed in a number of hospitals in US and Canadian cities, including Seattle, Washington; Houston, Texas; Calgary, Alberta; Toronto, Ontario; Salt Lake City, Utah; and Boston, Massachusetts.

Prediction of ETV success

The chances of success of treatment of a pediatric patient can be calculated using the ETV success score (ETVSS). The ETVSS is derived from patient age, etiology of hydrocephalus and history of previous cerebrospinal fluid shunt (e.g. ventriculo-peritoneal shunt). The percentage probability of ETV success = Age score + Etiology score + Previous shunt score. A two years old patient with hydrocephalus due to aqueductal stenosis, without previous shunt would have an 80% chance of success (40 for age + 30 for etiology + 10 for no previous shunt = 80). ETVSS table The ETVSS was derived and validated without the use of adult data and it has inadequate discriminative ability in mixed adult and pediatric populations.

Second ETV

After a patient gets readmitted with recurrent clinical and radiological symptomatology of hydrocephalus, it is unclear what the next step in treatment should be. Implantation of a cerebrospinal fluid shunt or repeat ETV. Data suggest that a second ETV might be worthwhile if implantation of cerebrospinal fluid shunt can be avoided.

Training ETV

In most countries and neurosurgical centres, the ETV procedure is part of the basic

neurosurgery Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the medical specialty concerned with the surgical treatment of disorders which affect any portion of the nervous system including the brain, spinal cord and peri ...

training program. For the sake of teaching and practicing, various

simulation A simulation is the imitation of the operation of a real-world process or system over time. Simulations require the use of Conceptual model, models; the model represents the key characteristics or behaviors of the selected system or proc ...

models have been developed.

Virtual reality Virtual reality (VR) is a simulated experience that employs pose tracking and 3D near-eye displays to give the user an immersive feel of a virtual world. Applications of virtual reality include entertainment (particularly video games), educ ...

simulators, and synthetic simulators. This allows neurosurgical trainees to practice skills in a low-risk environment. Educators can select either a virtual reality simulator or a physical model for the training of residents, the selection should be based on educational objectives. Where training focused on anatomy and using anatomical landmarks for decision making may better be aided with virtual reality model, the focus on familiarizing the resident with endoscopic equipment and developing manual dexterity may be better learned on a physical model. The technical skill and competency of a trainee can be evaluated using the Neuro-Endoscopic Ventriculostomy Assessment Tool (NEVAT).

References

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External links

Video and more about the ETV procedure from an article on Medscape
Endoscopy Neurosurgical procedures Ventricular system