Neonate referred by paediatrician with complains of large head size.

Referred for Neurosonogram:

Findings and discussion:

On B mode ultrasound:

Both the lateral ventricles and third ventricle is dilated.

Diameter of lateral ventricle is measured at parieto-occipital fissure with maximum diameter reaching up-to 20 mm s/o ventriculomegaly.

Also, there is increase in the V/H ratio measuring 0.40 (normal range: 0.20 to 0.25)

Fourth ventricle is normal in size.

Mega cisterna magna is noted.

Thinned out corpus callosum is seen.

On Color Doppler: Pericallosal artery is well visualized.

So, in view of dilatation of bilateral lateral & third ventricle with normal fourth ventricle and thinned out corpus callosum diagnosis of Aqueduct stenosis is given.

Aqueductal Stenosis in Neonates: Ultrasound Findings and Diagnosis

Aqueductal stenosis is a condition where the cerebral aqueduct (Sylvian aqueduct) is narrowed or blocked, leading to obstructive (non-communicating) hydrocephalus in neonates. Ultrasound (USG), particularly cranial ultrasound through the anterior fontanelle, is a key imaging modality for early detection.

Ultrasound Findings in Neonatal Aqueductal Stenosis

1. Ventriculomegaly (Hydrocephalus):

1. • Dilated lateral ventricles (frontal and occipital horns).
   • Dilated third ventricle (key finding).
   • Normal or collapsed fourth ventricle (since the blockage is above it).

2. Thinning of Brain Parenchyma (due to chronic hydrocephalus in severe cases).
3. Dangling Choroid Plexus:

1. • Floating in the enlarged ventricles due to CSF accumulation.

4. Increased Resistive Index (RI) in Doppler Studies:

1. • Elevated RI (>0.8) in the pericallosal or anterior cerebral arteries suggests increased intracranial pressure.

Diagnosis and Further Imaging

• Cranial USG is the first-line imaging for neonates.
• MRI Brain (preferred for confirmation) to evaluate aqueductal narrowing, possible causes (congenital vs. acquired), and periventricular changes.

Causes of Aqueductal Stenosis

• Congenital: X-linked hydrocephalus (L1CAM mutation), Chiari II malformation, Dandy-Walker malformation.
• Acquired: Post-hemorrhagic or post-inflammatory causes.

Management

• Neurosurgical Consultation for:
  • Ventriculoperitoneal (VP) shunt (common treatment).
  • Endoscopic third ventriculostomy (ETV) (preferred in some cases).