ELECTROENCEPHALOGRAPHY IN CHILD NEUROLOGY AND PSYCHIATRY

The principal applications of electroencephalography to child neurology, neurosurgery and psychiatry are as follows: Abnormalities in the EEG of parents or siblings of patients with nervous or mental disease assists in evaluating possible hereditary factors. Nervous and mental disorders caused by abnormalities of intrauterine development, injuries or anoxia at birth, encephalopathies of toxic, metabolic or infectious origin, and severe head injuries, may be reflected in abnormal brain waves in many but not all cases. In some, the location and type of cerebral pathology may allow marked changes in behavior, such as spastic paraplegia, with no significant alteration in the EEG. The EEG gives little reliable information with regard to intelligence and the finer structure of personality. Cerebral damage due to tumor, abscess, trauma or local vascular lesion may be localized by the EEG but pathologic diagnosis must be made from a careful history and other methods of clinical examination in most cases.proved methods, deepseated lesions involving subcortical structures, as well as superficial lesions, may frequently be accurately localized by the EEG. Subdural hematomata are not accurately diagnosed by the EEG in most cases. The EEG is most useful in the epilepsies and convulsive disorders. Differential diagnosis between idiopathic epilepsy and symptomatic convulsive disorders can usually be made by the EEG except for certain postencephalitic conditions which may simulate the electroencephalographic patterns of the idiopathic or "genetic" epilepsies. The form of clinical seizure depends upon the brain area of onset of the epileptic discharge, and its path of spread. The form of electrical disturbance has no specific significance except as pointing to a certain localization of onset. A wide variety of seizures are caused by focal epileptic discharge arising primarily in various areas of the cortex. These may be localized by the EEG when on the convexity of the hemispheres, but may be missed when buried in fissures or on the ventral or mesial surfaces of the brain. They are frequently discovered only when electrodes are placed directly on the brain surface exposed at operation. Bifrontal rhythmic disturbances may be caused by foci on the mesial or orbital surface of one frontal lobe. Bitemporal rhythmic disturbances may be caused by a focal epileptogenic lesion deep in one temporal region. The wave and spike pattern of petit mal epilepsy can be reproduced by local stimulation in certain parts of the thalamus. The EEG may be of assistance in assessing the initial severity and progress of recovery from cerebral trauma due to head injury. Profound alterations in the EEG occur during the acute stage of any form of encephalitis. Residual changes are of value in prognosis, especially with regard to epileptiform disorders. In child psychiatry, the EEG may point to an unsuspected organic basis for particularly intractable behavior. However, it is of little value for specific diagnostic purposes except as related to epileptic equivalent states and disorders due to focal lesions or diffuse encephalopathy.