Aqueductal Stenosis

“Aqueductal stenosis (AS) accounts for the majority of cases of nonsyndromic congenital hydrocephalus (Adle-Biassette et al., 2013). While it most often presents during infancy, it may manifest at any point in life from birth to adulthood. Males are affected nearly twice as often as females. AS has been associated with both Chiari I and II malformations. It is estimated that congenital AS has a genetic etiology in 40% of patients, of whom 5–15% have an X-linked form that occurs in males and is associated with mutations in the L1CAM gene (Zhang et al., 2006). Ten percent of patients experience endocrine dysfunction, which is probably secondary to compression of the hypothalamic–pituitary axis by an enlarged third ventricle (Cinalli et al., 2011).

While the aqueduct may be congenitally narrowed due to septa, webs, membranes, or forking (splitting into multiple channels that may terminate abruptly), postinflammatory gliosis and neoplasia (particularly tectal glioma) should be considered as etiologies for AS.

Magnetic resonance imaging (MRI) utilizing isotropic steady-state free precession-based sequences such as constructive interference in steady state or its analog fast imaging employing steady-state acquisition is the imaging modality of choice in the assessment of AS (Dincer and Ozek, 2011). Phase contrast sequences are included to evaluate cerebrospinal fluid (CSF) flow through the aqueduct and patency of interventions such as endoscopic third ventriculostomies (Battal et al., 2011).

Imaging demonstrates enlargement of the lateral and third ventricles with a normal-size fourth ventricle (Fig. 58.1). In cases of uncompensated stenosis, irregular MR signal or computed tomography (CT) hypodensity in the periventricular white matter is consistent with transependymal flow of CSF (interstitial edema). The treatment of choice is often CSF shunt diversion, while endoscopic third ventriculostomy and cerebral aqueductoplasty are alternative surgical therapies in selected patients (Cinalli et al., 2011).” Read More


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