How Is the ETV Success Score Calculated for Hydrocephalus?

The ETV Success Score (ETVSS) is a practical calculation originally developed for pediatric patients to estimate the likelihood that an Endoscopic Third Ventriculostomy (ETV) will successfully treat hydrocephalus ^[1]. In this medical context, “success” is specifically defined as not needing a follow-up surgery (such as placing a shunt or repeating the ETV) within six months of the procedure ^[1][2].

The final score ranges from 0 to 90, representing an estimated, population-level probability of success. For example, a score of 80 estimates roughly an 80% chance of success at six months ^[3]. However, because the score was developed and validated primarily in children, its accuracy can be different for adults (anyone 10 or older receives the same maximum age points), and it is not a perfect personal guarantee ^[4].

The Three Factors in the Score

The ETVSS calculation adds up points from three key factors ^[1].

1. Age
Generally, older patients have higher estimated ETV success rates ^[1].

• Under 1 month: 0 points
• 1 month to less than 6 months: 10 points
• 6 months to less than 1 year: 30 points
• 1 year to less than 10 years: 40 points
• 10 years or older (including adults): 50 points

2. Etiology (Cause of Hydrocephalus)
The underlying reason for your hydrocephalus strongly impacts your score. Aqueductal stenosis (a narrowing of the fluid pathway in the brain) is considered highly favorable for an ETV ^[1].

• Post-infectious hydrocephalus: 0 points
• Myelomeningocele (a severe form of spina bifida), intraventricular hemorrhage (bleeding inside the brain’s fluid spaces), or non-tectal brain tumor: 20 points
• Aqueductal stenosis, tectal brain tumors (tumors in the midbrain), or other causes: 30 points

3. Previous Shunt History
ETVs are more likely to succeed if they are the first surgical treatment for hydrocephalus ^[1].

• Previously had a cerebrospinal fluid (CSF) shunt: 0 points
• No previous shunt: 10 points

Calculating the Percentage

To calculate the final ETVSS, your neurosurgeon adds the points from these three categories together ^[3].

Example for a 2-year-old with aqueductal stenosis and no prior shunt:

• Age 2 years = 40 points
• Aqueductal stenosis = 30 points
• No previous shunt = 10 points
• Total = 80 points (an estimated 80% chance of success at 6 months).

What the Score Tells You (and What It Doesn’t)

While a higher score generally indicates a better chance of avoiding another surgery within six months ^[5], the ETVSS is only one piece of the puzzle. It does not automatically mean an ETV is a better choice than a traditional CSF shunt.

When discussing your score, keep these limitations in mind:

• It does not account for your specific anatomy: The ETVSS relies only on age, cause, and shunt history. It does not factor in important MRI details, such as the bowing of the third ventricle floor or the position of surrounding blood vessels, which your surgeon evaluates separately to determine if the surgery is safe and likely to work for you ^[6].
• It only looks at 6 months: A high score predicts early success, but it does not guarantee that the ETV will work forever. Late failures can happen even years after a successful procedure ^[7][8].
• It is not a personal guarantee: As a statistical estimate based on large groups, real-world outcomes for individuals can sometimes vary from what the score predicts ^[9].

Safety Warning: Because ETVs can fail at any time, it is vital to know the signs of returning hydrocephalus. Seek immediate emergency medical care if you or your child experience worsening headaches, repeated vomiting, unusual sleepiness, confusion, visual changes, or seizures—even if your initial ETVSS score was very high.