Although it is touted as new technology, the Third Ventriculostomy has actually been in use since 1922. It has recently found renewed favor due to use of neuro-endoscopy which allows the passage of a small endoscope into the third ventricle affording the surgeon a clear view of the ventricular system during the surgical procedure (Hydrocephalus Association, 2013). My purpose in writing this article is to help the general public better understand what the Third Ventriculostomy is, how it is done and potential problems.
What is an Endoscopic Third Ventriculostomy?
Endoscopic Third Ventriculostomy (ETV) involves a small perforation (hole) in the thinned floor of the third ventricle allowing the movement of Cerebrospinal Fluid (CSF) out of the blocked ventricular system and into the interpenducular cistern which is a normal CSF space. The result is a decrease in intracranial pressure and a reduction of its associated symptoms. Known in medical language as an “Intracranial CSF diversion”, it is not a cure for hydrocephalus but, rather, a method to normalize pressure on the brain without the use of a shunt.
As I mentioned earlier, the first open ventriculostomy was first performed in the early 1900s when Dr. Walter E. Dandy utilized a primitive endoscope to perform a choroid plexectomy (a surgical procedure for the reduction of cerebrospinal fluid production in the ventricles of the brain) on a patient suffering from communicating hydrocephalus (Yadav, Panhar, Pande, Namdev & Agarwal, 2012). The first true ETV took place in 1923 when Dr. William Mixter, an urologist, utilized a urethroscope to perform the procedure on a child with obstructive hydrocephalus. With the advent of valve-regulated shunt systems (1952) and the relative simplicity of shunting techniques, ETVs fell out of favor. In the early 1970’s, the Leukotome was introduced which allowed surgeons to enlarge the perforation in the floor of the third ventricle without injury to the surrounding vascular structure. This percutaneous procedure – meaning it is done via needle puncture than via an incision – was further advanced with the advent of stereotactic frames (pictured above right). This resulted in a renewed interest in the use of ETV particularly in the treatment of obstructive hydrocephalus.
Who is a good candidate for Endoscopic Third Ventriculostomy?
Even though ETV has become a relatively routine procedure in the management of both communicating and obstructive hydrocephalus, the selection of patient’s who will receive the most benefit remains unclear. Current research seems to indicate that it is most effective with patients who develop an obstructive form of hydrocephalus later in life. This is presumed to be due to the fact that these patients have normal CSF pathways and, removing the obstruction, allows CSF to flow freely through them. The exception to this is obstructive hydrocephalus occurring secondary to aqueduct stenosis[1]. Additionally, there is still some debate as to whether children are best treated with an ETV during infancy or to be shunted first and considered for ETV at a later time. Various reports have indicated that there are three (3) factors affecting the outcome of an ETV procedure: 1) Age; 2) Independent of age; 3) A function of etiology (that is, its cause or origin); 4) A function of both age and etiology (Drake, Kulkarni & Kestle, 2009). Most recent evidence points to age as the determining factor in the success of an ETV procedure with young children – particularly neonates – fairing worse.
Conclusion
Endoscopic Third Ventriculostomy is increasingly being utilized for treatment of hydrocephalus. Additionally, it is now considered the treatment of choice surpassing implantation of a shunt. It is now indicated for patients showing the signs and symptoms of hydrocephalus and who exhibit anatomical features amenable to a successful procedure. There should be ample space between the basilar artery and the clivus under the floor of the third ventricle to allow for a safe procedure.
Reference
Aqueductal stenosis. (2008, January). Retrieved from http://www.nervous-system-diseases.com/aqueductal-stenosis.html Retrieved: October 11, 2013
Drake, J. M., Kulkarni, A. V., & Kestle, J. (2009, January 13). Endoscopic third ventriculostomy versus ventriculoperitoneal shunt in pediatric patients: a decision analysis.
Hydrocephalus association. (2013, January). Retrieved from http://www.hydroassoc.org/ Retrieved: October 5, 2013
Yadav, Y., Panhar, V., Pande, S., Namdev, H. & Agarwal, M. (2012, May 01). Endoscopic third ventriculostomy. Journal of Neuroscience, 163-173. DOI: www.jneurosci.org Retrieved: October 5, 2013
[1] Aqueductal stenosis is a common cause of obstructive (non-communicating hydrocephalus. The cerebral aqueduct (of Sylvius) is a narrow channel that connects two of the ventricles (fluid-filled chambers within the brain) and passes through the mid-brain. If the aqueduct is blocked, this condition is known as stenosis and causes the symptoms associated with hydrocephalus (Aqueductal stenosis, 2008)
