Long-term follow-up data from the Shunt Design Trial

BACKGROUND

A previously reported multicenter randomized trial assessed whether 2 new shunt valve designs would reduce shunt failure rates compared to differential pressure valves. The study did not show a significant difference in the time to first shunt failure. Patients entered the trial between October 1, 1993, and October 31, 1995. The primary results were based on the patients' status as of October 31, 1996 (a minimum follow-up of 1 year). This report describes the late complications based on the patients' most recent follow-up.

METHODS

Three hundred and forty-four hydrocephalic children at 12 North American and European centers were randomized to 1 of 3 valves: a standard differential pressure valve; a Delta valve (PS Medical-Medtronic) or a Sigma valve (NMT Cordis). Patients were followed until their first shunt failure. Shunt failure was defined as shunt surgery for obstruction, overdrainage, loculation or infection. If the shunt did not fail, follow-up was continued until August 31, 1999.

RESULTS

One hundred and seventy-seven patients had shunt failure. Shunt obstruction occurred in 131, overdrainage in 13, loculated ventricles in 2 and infection in 29. The overall shunt survival was 62% at 1 year, 52% at 2 years, 46% at 3 years, 41% at 4 years. The survival curves for the 3 valves were similar to those from the original trial and did not show a survival advantage for any particular valve.

CONCLUSIONS

Prolonged follow-up to date does not alter the primary conclusions of the trial: there does not appear to be one valve that is clearly the best for the initial treatment of pediatric hydrocephalus.

Relationship of cerebral perfusion pressure and survival in pediatric brain-injured patients

BACKGROUND

Adult brain injury studies recommend maintaining cerebral perfusion pressure (CPP) above 70 mm Hg. We evaluated CPP and outcome in brain-injured children.

METHODS

We retrospectively reviewed the hospital courses of children at two Level I trauma centers who required insertion of intracranial pressure (ICP) monitors for management of traumatic brain injury. ICP, CPP, and mean arterial pressure were evaluated hourly, and means were calculated for the first 48 hours after injury.

RESULTS

Of 188 brain-injured children, 118 had ICP monitors placed within 24 hours of injury. They suffered severe brain injury, with average admitting Glasgow Coma Scale scores of 6 +/- 3. Overall mortality rate was 28%. No patient with mean CPP less than 40 mm Hg survived. Among patients with mean CPP in deciles of 40 to 49, 50 to 59, 60 to 69, or 70 mm Hg, no significant difference in Glasgow Outcome Scale distribution existed.

CONCLUSION

Low mean CPP was lethal. In children with survivable brain injury (mean CPP > 40 mm Hg), CPP did not stratify patients for risk of adverse outcome.

Randomized trial of cerebrospinal fluid shunt valve design in pediatric hydrocephalus

OBJECTIVE

Forty percent of standard cerebrospinal fluid shunts implanted for the treatment of pediatric hydrocephalus fail within the first year. Two new shunt valves designed to limit excess flow, particularly in upright positions, were studied to compare treatment failure rates with those for standard differential-pressure valves.

METHODS

Three hundred-forty-four hydrocephalic children (age, birth to 18 yr) undergoing their first cerebrospinal fluid shunt insertion were randomized at 12 North American or European pediatric neurosurgical centers. Patients received one of three valves, i.e., a standard differential-pressure valve; a Delta valve (Medtronic PS Medical, Goleta, CA), which contains a siphon-control component designed to reduce siphoning in upright positions; or an Orbis-Sigma valve (Cordis, Miami, FL), with a variable-resistance, flow-limiting component. Patients were monitored for a minimum of 1 year. Endpoints were defined as shunt failure resulting from shunt obstruction, overdrainage, loculations of the cerebral ventricles, or infection. Outcome events were assessed by blinded independent case review.

RESULTS

One hundred-fifty patients reached an endpoint; shunt obstruction occurred in 108 (31.4%), overdrainage in 12 (3.5%), loculated ventricles in 2 (0.6%), and infection in 28 (8.1%). Sixty-one percent were shunt failure-free at 1 year and 47% at 2 years, with a median shunt failure-free duration of 656 days. There was no difference in shunt failure-free duration among the three valves (P = 0.24).

CONCLUSION

Cerebrospinal fluid shunt failure, predominantly from shunt obstruction and infection, remains a persistent problem in pediatric hydrocephalus. Two new valve designs did not significantly affect shunt failure rates.

Translocation t(1;11)(q21;q23), a new subgroup within M4 acute nonlymphocytic leukemia

A case of acute myelomonocytic leukemia (M4) with a t(1;11)(q21;q23) as the sole chromosome anomaly is presented. The results, taken with those of previously published cases, point to the possibility of a subgroup within M4.

Singlet oxygen formation by a peroxidase, H2O2 and halide system

Evidence for singlet oxygen formation has been obtained for the lactoperoxidase, H2O2 and bromide system by monitoring 2,3-diphenylfuran and diphenylisobenzofuran oxidation, O2 evolution, and chemiluminescence. This could provide an explanation for the cytotoxic and microbicidal activity of peroxidases and polymorphonuclear leukocytes. Evidence for singlet oxygen formation included the following. (a) Chemiluminescence accompanying the enzymic reaction was doubled in a deuterated buffer and inhibited by singlet oxygen traps. (b) The singlet oxygen traps, diphenylfuran and diphenylisobenzofuran, were oxidized to their known singlet oxygen oxidation products in the presence of lactoperoxidase, hydrogen peroxide and bromide. (c) The rate of oxidation of diphenylfuran and diphenylisobenzofuran was inhibited when monitored in the presence of known singlet oxygen traps or quenchers. (d) Oxygen evolution from the enzymic reaction was inhibited by singlet oxygen traps but not by singlet oxygen quenchers. (e) The traps or quenchers which were effective inhibitors in the experiments above did not inhibit peroxidase activity, were not competitive peroxidase substrates and did not react with the hypobromite intermediate since they did not inhibit hydrogen peroxide consumption by the enzyme. Using these criteria, various biological molecules were tested for their reactivity with singlet oxygen. Furthermore, by studying their effect on oxygen release by the enzymic reaction, it could be ascertained whether they were acting as singlet oxygen traps or quenchers.