Mar 01, 2005
Hemiplegic cerebral palsy usually results from occlusion of a cerebral artery during the perinatal period producing a stroke in the infants brain. There are many risk factors for these strokes. Most children who suffer perinatal stroke will have several risk factors. When only one risk factor is present, the child usually develops normally.
Unfortunately, the medical and common term “stroke” includes two rather different types of disorder: hemorrhage and infarction1. The former term is self explanatory. Infarction, however, is a more technical term used to denote a process of tissue injury most often caused by the interruption of arterial blood flow to some part of an organ, in this case the brain. Such arterial occlusion is the most common cause of “stroke” in the elderly as well as hemiparetic cerebral palsy. These children are weak and spastic on one side of the body. Characteristically the arm is more affected than the leg.
Lee and her colleagues studied the incidence and causes of perinatal cerebral infarction confirmed by either MRI or CT scan among nearly 200,000 infants born in the Kaiser Permanente Medical Care Program of northern California between the years of 1997 and 2000, an incidence of 20/100,000 live births. They compared these children to a well selected control panel of 120 children without perinatal stroke.
Among the strengths of this study is their careful selection of patients including their insistence of imaging criteria characteristic of major artery occlusion. On the other hand, this might have excluded children with less severe brain injury. The study did not address the outcome of these children although is seems clear that all would have some degree of impairment.
Several risk factors were seen in the infants who suffered strokes. Strokes were more common among first born children and children of mothers with a history of infertility or preeclampsia. Risk factors during labor and delivery included emergency cesarean section, prolonged rupture of membranes, prolonged second stage labor, and vacuum extraction. Factors specific to the infant include heart anomalies, chorioamnionitis (inflammation of the placenta), and umbilical cord abnormalities. Many infants had more than one of these risk factors. 86% of infants with perinatal stroke had at least one compared to 59% of the controls; 25% had two or more compared to 25% of controls; 60% had 3 or more compared to 6% of the controls; and 31% had 4 or more risk factors compared with 2% of controls.
This study emphasizes the multifactoral causes of this form of cerebral palsy. It is impressive that more than half of the controls had at least one risk factor for perinatal stroke but did not suffer one. This speaks well of the hardiness of the infant. It is similar to data being published on premature infants where the majority do not display cerebral palsy.
1 Lee J, Croen LA, Yoshida CK et al. Maternal and infant characteristics associated with perinatal arterial stroke in the infant. JAMA. 2005; 293(6):723-729
© UCP Research & Educational Foundation, March 2005