It is a firmly established fact that morbid processes affecting the motor cortex of the brain may produce convulsions of the muscles of the opposite side of the body. These convulsive seizures are the symptoms of motor irritation. Such localized convulsions are, therefore, referred to as "cortical epilepsy" or jacksonian convulsions. It is generally believed, however, that typical jacksonian seizures do not occur when the subcortical parts of the brain, such as the corona radiata, alone are involved, and that when jacksonian attacks have occurred as the result of cortical irritation, subsequent destruction of the motor cortex or of the subcortical motor pathways will bring about cessation of the convulsions. It was this belief that led Hughlings Jackson to suggest excision of the motor cortex for the cure of certain cases of epilepsy.
Since endotheliomas may originate in the meninges and involve the brain, not by infiltration, but by contiguity