Case 19 Aqueductal stenosis

Figure 19: MRI axial T1.

• Q1: What is the score used to determine the ETV success rate, and what are the items it considers?
• The score (0-90) for predicting the success of an ETV depends on three factors: age, etiology, and history of VP shunt insertion. It is more likely to succeed in patients aged 2 years or older. Success is more likely when the etiology is obstruction rather than infection. A previous VP shunt decreases the chances of success.

• Q2: Why does the success rate increase with the patient’s age?
• The success rate increases with age due to the patency of the prepontine cistern.

• Q3: What methods are used to perforate the floor of the third ventricle, and which is the safest?
• The safest method to perforate the floor of the third ventricle is using a Fogarty catheter. Monopolar cautery or grasping forceps can also be used.

• Q4 What are the causes of aqueductal stenosis?
• Congenital Causes:

1. Aqueductal Gliosis: This involves the proliferation of glial cells within the aqueduct, leading to its narrowing.
2. Aqueductal Webs or Septa: Thin membranous structures can form within the aqueduct, partially or completely obstructing it.
3. Congenital Stenosis: Some individuals may be born with a naturally narrow aqueduct due to developmental anomalies.

• Acquired Causes:

1. Infections: Infections like meningitis can lead to inflammation and subsequent scarring, narrowing the aqueduct.
2. Hemorrhage: Bleeding in or around the aqueduct can cause clots and fibrotic changes, leading to stenosis.
3. Neoplasms: Tumors within or near the aqueduct can compress it and cause obstruction.
4. Trauma: Head injuries can result in swelling and scarring, affecting the aqueduct.

• Idiopathic Causes:

In some cases, the cause of aqueductal stenosis cannot be determined and is labeled idiopathic.