NEONATAL WHOLE-BLOOD HYPERVISCOSITY - THE IMPORTANT FACTOR INFLUENCING LATER NEUROLOGIC FUNCTION IS THE VISCOSITY AND NOT THE POLYCYTHEMIA

The neurologic outcome of 23 seven-year old children who had cord bloo d hyperviscosity was compared with that of children with normal cord b lood viscosity in a randomised, controlled and blinded study. Viscosit y was measured using a coaxial narrow-gap couette viscometer. Sixteen (69.6%) of the children with hyperviscous cord blood had a disability; this incidence being three times greater (22.7%) than in children who se cord blood was not hyperviscous (P < 0.01). In three children with cord-blood hyperviscosity, the disability was severe. No child had a s evere disability with normal cord blood viscosity. Of the eight childr en whose cord blood was hyperviscous, but not polycythemic, six (75.0% ) had a disability and in one child the disability was severe. These r esults demonstrate an association between cord blood hyperviscosity an d later neurologic development. Cord studies are non-invasive and resu lt in the rapid diagnosis of the neonatal hyperviscosity syndrome, so allowing earlier treatment. This may be crucial in altering the effect s of hyperviscosity on the developing brain in the early neonatal peri od. Because the neurologic outcome of children was similar whether pol ycythemia was present or not, the prime factor was the viscosity and n ot the hematocrit level. We suggest it may be necessary to perform cor d blood viscosity studies routinely.