PITFALLS IN THE DIAGNOSIS OF VENTRICULAR SHUNT DYSFUNCTION - RADIOLOGY REPORTS AND VENTRICULAR SIZE

Introduction. The diagnosis of shunt malfunction can be difficult even for the experienced clinician and may lead to disastrous circumstance s when misinterpreted. Less experienced physicians may rely more on ra diographic reports as a primary diagnostic modality. In this study, we evaluated the reliability of using these reports without accurate cli nical assessment. Methods. All shunt revisions seen at Children's Hosp ital (Birmingham, AL) between January 1996 and August 1996 were review ed, excluding patients with brain tumors, supratentorial extraaxial fl uid collections, and infections. Sixty-eight patients underwent 100 op erations for shunt malfunction. All patients had evidence of shunt blo ckage, disconnection, catheter malposition, or valve pressure incompat ibility. The prospective radiographic interpretation of preoperative c omputed tomography and magnetic resonance imaging scans was reviewed i n each case. Results. Twenty-four percent of the reports made no menti on of shunt malfunction. In this group, the ventricular system was des cribed as ''unchanged,'' ''stable,'' ''normal,'' ''unremarkable,'' ''s mall,'' ''smaller,'' ''slit,'' ''negative,'' and ''no hydrocephalus,'' with no other comment to support a diagnosis of shunt malfunction. An additional 9% of reports contained the same terms, while also hinting at some other clinical or radiographic data that suggest the possibil ity of shunt failure leg, a shunt disconnection seen on plain radiogra phs), despite the scan findings. In all patients in this group, sympto ms improved after surgery. Conclusion. We conclude that as many as one third of patients presenting with shunt malfunction will not have the diagnosis of shunt malfunction supported by a prospective radiologic interpretation of brain imaging. Although the neurosurgical community can assess the clinical situation to determine the need for surgery, o ther clinicians can be easily reassured by a radiographic report that does not mention or diagnose shunt malfunction. Today, more than ever, nonneurosurgeons are being called on to evaluate complex clinical sit uations and may rely on radiographic reports.