A critical analysis of 'normal' radionucleotide shuntograms in patients subsequently requiring surgery.
BACKGROUND
Shuntograms are performed when patients present with symptoms suggestive of, but inconclusive for, shunt malfunction, without confirmatory radiological evidence.


METHODS
Shuntograms over the past 3.5 years were reviewed. Patient records were reviewed for revision in proximity to a negative (normal) study.


RESULTS
One hundred and fifteen out of 149 tests were negative. Thirty-four surgeries (in 31 patients) occurred subsequent to a negative shuntogram. In 18 out of 34 revisions the shunt was functional: 13 surgeries were for overdrainage, 4 were for unrelated reasons with shunt function confirmed incidentally and 1 was an exploration for cognitive deterioration. In 16 cases (13 patients) the shunt was not functional: 12 had proximal catheter occlusion in which, on subsequent review, there was no ventricular reflux present and the remaining had distal malfunctions.


CONCLUSIONS
The false negative rate for shuntograms was 16 out of 115 (14%) with proximal occlusion most common. This estimate of the predictive value of a normal flow study may influence the decision to revise a shunt.
Department of Pediatric Neurosurgery, St. Louis Children's Hospital, One Children's Place, St Louis, MO 63110, USA.
D F
DF
O'Brien
M
M
Taylor
T S
TS
Park
J G
JG
Ojemann
D002557:Cerebrospinal Fluid Shunts / Q000145:classification / Q000295:instrumentation*; D002648:Child; D004868:Equipment Failure; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006849:Hydrocephalus / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D014055:Tomography, Emission-Computed