Pathology of Hypertonia in Children

Pathophysiology

Preterm infant

• Periventricular leukomalacia: PVL is the common abnormality seen in the premature infant with CP. PVL is a white matter injury due to either ischemia/hypoxia or inflammation in the periventricular white matter. IVH is a risk factor for its development but is a separate pathological process and etiology for CP. The corticospinal pathway passes through the periventricular region and, as a consequence, is affected in the injury.
• IVH: IVH is the bleeding from the subependymal matrix into the ventricles seen in premature infants. The smooth muscles of the brain’s arterioles do not develop until late in gestation, resulting in this vulnerability.

Term infant

• Gray matter injury: As the brain’s vascularity matures, the injuries resulting from ischemia and hemorrhage begin to resemble those seen in adults. Injuries tend to be in watershed areas and in the basal ganglia. This gives rise to extrapyramidal injuries. Dyskinetic CP becomes more common than the spastic CP of prematurity.

Molecular/Genetic Pathology

Cerebral palsy

• Associated genetic conditions: Genetic anomalies relate to production of proteins involved in inflammation or coagulation in the infant or vascular endothelium formation in the placenta (18).

Familial spastic paraparesis

• 59 genes identified: To date, 59 genes have been identified as being associated with familial spastic paraparesis. Of these, 19 are autosomal dominant, 35 are autosomal recessive, and 5 are X-linked (8).