Predictors of intellectual function after a unilateral cortical lesion: study of 635 patients from infancy to adulthood.

This study investigated potential predictors of intellectual outcome in 417 children and 218 adults who had sustained a unilateral cortical lesion. Of these, 295 cases were collected from the scientific literature and 340 from medical records at seven hospitals in Canada Different sets of predictors emerged for the Wechsler Verbal and Performance IQ values, accounting for differing variances (i.e., 12.4% and 20.1%, respectively). The volume of the lesion was the factor that explained the most variance (i.e., 4.95% and 11.7%, respectively). Age at lesion onset was significantly and positively correlated with verbal intelligence scores. This variable, considered independently or in interaction with other predictors, did not account for a large portion of the variance explained in intelligence. This refutes the commonly held notion that early onset of the insults results in a better prognosis.