Computed tomography in evaluation of hydrocephalus.

OBJECTIVE: A prospective computed tomography(CT) study to detect , determine the cause, type and severity of hydrocephalus in a study group. To evaluate shunt related complications in hydrocephalus and compare results with other studies. RESULTS : 80 consecutive patients diagnosed with hydrocephalus on CT were studied over a 2 year period . TB meningitis(32%)followed by tumors(25%) intracranial hemorrhage(20%) and congenital causes(12%) were found to be the most common causes. Hydrocephalus was communicating (60%) and moderate to severe(80%) in majority cases. Displaced shunt and shunt malfunction were found to be the most common shunt related complications. CONCLUSION: Computed Tomography is a non invasive, readily available, easy to perform, non operator dependent modality with superb spatial resolution, ability to detect calcium and density discrimination. Therefore CT is a valuable tool with a very high diagnostic sensitivity and helps in early detection of hydrocephalus and its management INTRODUCTION Hydrocephalus is a pathological state of diverse causes in which there is increased accumulation of CSF within the cranial cavity. It will develop under the following three circumstances8:1. Overproduction of CSF as seen in tumors of the choroid plexus. 2. Defective absorption of CSF by the arachnoid granulations. 3. Most common cause however is the obstruction in CSF pathways which result in dilatation of channels proximal to the site of obstruction. Hydrocephalus may be with or without raised pressure8. In hypotensive hydrocephalus(hydrocephalus ex vacuo) there is increased intracranial accumulation of CSF secondary to diminished brain volume . In this not only ventricular enlargement but also dilatation of cerebral sulci and basilar cisterns occurs. Obstructive hydrocephalus is further subdivided into noncommunicating hydrocephalus if the block lies within the ventricular pathway or communicating if the obstruction is distal to the outlet foramina of the fourth ventricle. CT clearly demonstrates the size and position of the ventricles, level of obstruction and the obstructing lesion, if present, the width of the subarachnoid spaces at the base of the brain and over the cerebral convexities. Pathophysiological changes in brain substances, periventricular exudation, diminished density of white matter, all these changes are clearly and early perceived with CT. Several measurement or indices have been ultilised in assessing hydrocephalus. The most commonly used indices are Ventricular size index 7 : This is the ratio of transverse diameter of forntal horns : Transverse diameter of skull at inner table.