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المستخلص
Hydrocephalus is commonly defined as a pathologic increase in the cerebral ventricular volume. It’s due to imbalance between the formation of CSF and its absorption. With the possible exception of choroid plexus papilloma hydrocephalus results from blockage of CSF pathways or impaired absorption. An impairment to the normal flow or to the return of CSF into the blood leads to an increase in ventricular pressure. Currently, the term (noncommunicating hydrocephalus) refers to lesions that obstruct the ventricular system. The term (communicating hydrocephalus) refers to lesions that obstruct at the level of the subarachnoid space and arachnoid villi.
Transcranial Doppler Ultrasonography was the most common modality used in practical in infants who have a patent fontanelle. Its usefulness lies in its relative low cost as well as its ease of application at the bedside or in restless infants. It is excellent at establishing ventricular size, symmetry, and even the cause of hydrocephalus. Yet, its show many limitations; as it’s not available after fontanelle closure, limited resolution.
The CT diagnosis of hydrocephalus relied on certain observations: enlargement of the lateral and third ventricles,enlargement of the temporal horns,prominent basilar cisterns, enlarged suprasellar cistern, nonvisualization of the high cerebral convexity sulci, and possible enlargement of the fourth ventricle. CT also allows assessment of the degree of associated white matter changes in the periventricular regions.
Early in the use of MR imaging a signal void was often seen in the cerebral aqueduct. Furthermore, the signal void observed in patients with hydrocephalus was often more pronounced than that seen in patients with normal ventricles. This finding was later used in attempts to select patients to CSF shunting based on the appearance and extent of the flow void.
MR Ventriculography is superior to conventional x-ray ventriculography, metrizamide CT ventriculography or cisternography, and isotope cisternography as its shows good spatial resolution and multiplanar imaging capability. The addition of velocity measurements in the phase-contrast technique has improved the accuracy. The usefulness of MR imaging with intraventricular or cisternal injections of a gadolinium based contrast agent to study CSF flow has been reported as This study can determining the functional status of third ventriculostomies,in
assessing communication between cysts and the ventricles, and in determining the site of CSF block in noncommunicating hydrocephalus