Diagnostic problems of shunt malfunctions without ventriculomegaly

Abstract

Shunt malfunction is the most common complication of a shunting procedure for hydrocephalus and is often encountered in emergency case of a sudden increase in intracranial pressure. Most cases of shunt malfunction are easily diagnosed by ventriculomegaly observed on CT scan. However, a few cases have normal ventricular size and are consequently sometimes misdiagnosed. Thirteen cases of shunt malfunction without ventriculomegaly on CT scan are presented, and the methods of their diagnosis are discussed. Four cases were diagnosed based slight enlargement of the ventricle on CT scan as compared with that of previous CT scan during follow-up, although these ventricular sizes were within the normal range. Six cases were diagnosed by tapping the flushing device. In 3 of these cases, intracranial pressure was measured by manometer and increased intracranial pressure following distal catheter occlusion was suspected. In the other 3 cases, it was assumed that the ventricular catheter was obstructed because no cerebrospinal fluid flow was obtained during device taps. One case was diagnosed as having a disconnected shunt catheter on skull X-ray, a second case as having a fractured catheter on chest X-ray, and the remaining case as having a shortening of the peritoneal catheter due to growth on abdominal X-ray. Plain X-ray along the shunt catheter and taps of the flushing device aided the diagnosis of shunt malfunction with normal ventricular size on CT scan. It is most important, however, to suspect shunt malfunction in patients with shunt a who present with headache, vomiting, or impaired consciousness.