White matter injury correlates with hypertonia in an animal model of cerebral palsy

Alexander Drobyshevsky, Matthew Derrick, Alice Mary Wyrwicz, Xinhai Ji, Ila Englof, Lauren Marie Ullman, Mario Enrique Zelaya, Frances Josephine Northington, Sidhartha Tan

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


Hypertonia and postural deficits are observed in cerebral palsy and similar abnormalities are observed in postnatal rabbits after antenatal hypoxia-ischemia. To explain why some kits become hypertonic, we hypothesized that white matter injury was responsible for the hypertonia. We compared newborn kits at postnatal day 1 (P1) with and without hypertonia after in vivo global fetal hypoxia-ischemia in pregnant rabbits at 70% gestation. The aim was to examine white matter injury by diffusion tensor magnetic resonance imaging indices, including fractional anisotropy (FA). At P1, FA and area of white matter were significantly lower in corpus callosum, internal capsule, and corona radiata of the hypertonic kits (n=32) than that of controls (n=19) while nonhypertonic kits (n=20) were not different from controls. The decrease in FA correlated with decrease in area only in hypertonia. A threshold of FA combined with area identified only hypertonic kits. A reduction in volume and loss of phosphorylated neurofilaments in corpus callosum and internal capsule were observed on immunostaining. Concomitant hypertonia with ventriculomegaly resulted in a further decrease of FA from P1 to P5 while those without ventriculomegaly had a similar increase of FA as controls. Thus, hypertonia is associated with white matter injury, and a population of hypertonia can be identified by magnetic resonance imaging variables. The white matter injury manifests as a decrease in the number and density of fiber tracts causing the decrease in FA and volume. Furthermore, the dynamic response of FA may be a good indicator of the plasticity and repair of the postnatal developing brain.

Original languageEnglish (US)
Pages (from-to)270-281
Number of pages12
JournalJournal of Cerebral Blood Flow and Metabolism
Issue number2
StatePublished - Feb 2007


  • Cerebral palsy
  • Diffusion tensor imaging
  • Hypertonia
  • Hypoxia-ischemia
  • Rabbit
  • White matter injury

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Cardiology and Cardiovascular Medicine


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