The incidence of epilepsy, the IQ, and laterality of cerebral palsy were investigated in 51 children with hemiparetic CP at the Department of Neurology, Charles University, Katerinska, Praha, Czechoslovakia. Epilepsy had developed in 19; two had partial jacksonian seizures and 17 generalized tonic-clonic seizures. Epileptic paroxysms in the EEG were found in 35 (80%). An IQ of 95 or above was found in 32 and an IQ of 94 or below in 19. No difference in IQ was found between patients with right-sided or left-sided hemiparesis whereas clinical seizures were more common in those with right-sided hemiparesis. Clinical epilepsy was related to impaired intellectual performance. Abnormal paroxysmal EEGs were more frequent with left-sided hemiparesis. Among those with clinical epilepsy a lower IQ was found in almost all with left-sided hemiparesis and almost half of those with right-sided hemiparesis. 
COMMENT. A lower IQ may be expected in CP patients with clinical epilepsy, especially in those with left-sided hemiparesis. EEG abnormalities alone are not associated with a lower IQ.