Ventricular shunts that require multiple revisions are familiar to ped
iatric neurosurgeons. We conducted a retrospective study to determine
whether patients who require repeated shunt revisions represent a part
icular cohort within shunted hydrocephalic children. The clinical reco
rds of 244 children who had undergone shunt procedures between January
1990 and January 1996 were examined. They were divided into group 1:
children with no shunt failure (n=136), group 2: children with one shu
nt revision (n=52), group 3: children with 2 or 3 shunt revisions (n=3
4), and group 4: patients who had 4 or more shunt revisions (n=22). Pa
tients in groups 3 and 4 accounted for 54.8% of the total of 531 shunt
procedures. Etiology of hydrocephalus, nature of the dysfunction, CSF
characteristics, and variables related to the surgical procedure were
analyzed for each group. We observed a progressive shortening of the
intervals between revisions as the numbers of surgeries increased, ind
icating that shunts that tended to fail repeatedly did so sooner than
those that did not. A Kaplan-Meier shunt survival curve showed that gr
oup 2 had a slower rate of failure than either group 3 (chi(2)=7.13, P
<0.01) or group 4 (chi(2)=4.76, P<0.05). The etiologies of the hydroce
phalus were not randomly distributed among the four groups (chi(2)=81.
4, P < 0.001); there was a predominance of congenital conditions in gr
oup 1. Repeated shunt revisions were associated with a progressive inc
rease in the concentration of monocytes in the CSF (Kruskal-Wallis, P
< 0.05). Our data suggest that multiple shunt revisions constitute a p
henomenon that may be caused by specific, still unidentified, biologic
al factors.