Value of MRI CSF Flowmetry in Assessment of Grey Zone Hydrocephalic Patients

Hydrocephalus

To evaluate accuracy of (MRI) cerebrospinal fluid flowmetry after shunt operation in patients with borderline (grey zone) hydrocephalus.

Hydrocephalus could be defined as disturbance of formation, flow or absorption of CSF. We encounter some challenging cases with intermittent non specific symptoms as delayed milestones and headache with concomitant imaging showing dilated ventricular system, so we find ourselves hesitating to take the decision of surgical intervention to put shunt or not, therefore MRI CSF flowmetry gives us a chance to overcome this problem. Phase contrast MR imaging is a rapid, simple and non-invasive technique which is sensitive to even small CSF flows, and can be used to evaluate CSF flow both qualitatively and quantitatively. CSF flow measurement at the suspected level of obstruction gives reliable and reproducible results for more accurate diagnosis and can be used to guide therapeutic decisions in a more reliable manner, and follow up post treatment outcome. With the CT and magnetic resonance imaging (MRI) techniques, it is possible to localize with accuracy the exact site of blockage of flow to CSF. Hence classification is as follows: The hydrocephalus may be due to 1) overproduction of CSF 2) obstructive 3) absorption defect. Depending on the exact aetiology, a secondary classification could be added under the following headings: 1) congenital, 2) acquired, eg; traumatic inflammatory, neoplastic, and degenerative . Bypassing the site of obstruction to CSF flow by diverting the CSF from ventricular cavity to a site where it is readily absorbed is the basic principle underlying the treatment of hydrocephalus. Extensive range of complications has been reported for shunting for hydrocephalus. They could be classified as mechanical or flow-related complications as CSF over drainage leading to subdural hematoma, subdural collections, low-pressure headaches cranial deformity, and asymmetrical drainage can lead to trapping or isolation of a part of a ventricular system. The slit ventricular syndrome is a complication related to absorption. Besides, ascites, loculations, hydrocele, perforation of the stomach, large and small bowel are also described. The success rates of shunt operation for hydrocephalus depend on the age of the patient and the reason why the shunt is needed. Generally, there is around a 50% failure rate for ventriculoperitoneal shunts.

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