Aqueduct stenosis

Dr Amir Rezaee and A.Prof Frank Gaillard et al.

Aqueductal stenosis (AS) is a the most common cause of congenital obstructive hydrocephalus, but can also be seen in adults as an acquired abnormality. 

Congenital aqueductal stenosis has an estimated incidence is at ~1:5000 births although the reported range varies greatly (3.7:1,000,000 to 1:2000) 5. Rarely it may be inherited in an X-linked recessive manner (Bickers-Adams-Edwards syndrome) 5

In adults, as an acquired abnormality, AS has different aetiologies and thus different demographics related to them. 

The clinical presentation depends on the severity and age of presentation as well as whether or not it is X-linked. In the infant enlarging head size, bulging fontanelles and gaping cranial sutures are seen. Setting sun phenomenon may also be present. In X-linked form (Bickers-Adams-Edwards syndrome) which is associated with profound mental retardation, clinical assessment would reveal bilateral adducted thumbs. 

The usual symptoms and signs of raised intracranial pressure and chronic hydrocephalus may also be present, including headache, vomiting, decreased conscious state 3

Ultrasound

Antenatal exam can show features of fetal hydrocephalus with a near normal posterior fossa. There can be secondary thinning of the cortical mantle as well as secondary macrocephaly.

MRI

Better delineates the extent of obstructive hydrocephalus, with enlargement (often marked) of the lateral and third ventricles. The aqueduct may show funnelling superiorly. The 4th ventricle is not dilated. In cases of secondary obstruction the underlying abnormality may also be evident (e.g. tumour). 

An MRI CSF flow study is helpful, and the absence of a flow-void signal intensity on sagittal T2 images at the aqueductal level has been suggested as a sign of aqueductal stenosis 3

Treatment is often either with a third ventriculostomy or VP shunting. There is small recurrence risk (~4%) for congenital cases even when it is not X linked.

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Article information

rID: 928
Synonyms or Alternate Spellings:
  • Aqueductal stenosis
  • Stenosis of the aqueduct of Sylvius
  • Perinatal aqueductal stenosis
  • Perinatal aqueduct stenosis
  • Perinatal aqueductal atresia
  • Aqueduct stenoses
  • Aqueduct stenosis (AS)

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    Axial T1
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    Case 12: aqueductal web
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    Case 13: with setting sun appearence to eyes
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