Article
The obstructive nature of pediatric hydrocephalus – results of a high-resolution MRI study
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Published: | September 16, 2010 |
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Objective: Modern theories and approaches to hydrocephalus suggest that there is no malresorptive or communicating hydrocephalus. Traditionally all cases of hydrocephalus were termed mal- or aresorptive, if imaging did not reveal an obvious cause of intraventricular obstruction. Even standard MRI sequences, designed to detect tissue pathology, are blind to subtle pathology of the CSF spaces. We used high-resolution MRI sequences to prospectively investigate new cases of hydrocephalus and cases of shunt malfunction with regard to obstruction as underlying cause of hydrocephalus.
Methods: To image CSF spaces we performed – in addition to standard T2 spin echo sequences – either an incubator coil operated high resolution T2 sequence (newborns and premature babies, SL 1–2 mm, TR 5711, TE 120), a 3D-CISS sequence (constructive Interference in Steady State SL 0.7 mm, TR 12.06, TE 6.03) or a 3D-trueFISP sequence (True Fast Imaging with Steady Precession, SL 1 mm, TR 4.97, TE 2.49). Standard 1.5 T MR scanners (Philips and Siemens) were used.
Results: 42 children were recruited.In addition to standard T1 and T2 SE and TSE sequences we performed 11 HR-T2, 7 CISS and 28 trueFISP studies. All 21 children with post-hemorrhagic hydrocephalus had obstruction at the following sites alone or in combination: cerebral aqueduct, fourth ventricular outlet, craniocerebral junction, basal cisterns. In 13 children an aquaeductal stenosis or occlusion and in 3 a Blake‘s Pouch was found. In one child a suprasellar arachnoid cyst caused obstruction. MRI could not establish the site of obstruction in two children, despite the fact that both showed a lowering of the third ventricular floor.
Conclusions: Almost all cases of non-spina bifida related pediatric hydrocephalus had an obstructive component. Fourth ventricular dilatation is most likely caused by fourth ventricular outflow obstruction and not a sign of „communicating hydrocephalus“. The visualization of multiple suprasellar and retroclival membranes is important regarding indication for third ventriculostomy. Pediatric hydrocephalus is predominantely obstructive.