The electroencephalogram in acute fatal head injuries

A comparison between electroencephalography and somatosensory evoked potentials for outcome prediction following severe head injury

The value of somatosensory evoked potentials (SEPs) for the prediction of outcome following severe head injury (HI) is established. The role of the electroencephalogram (EEG) in this setting is uncertain. In this comparative study, SEPs and EEGs were recorded within 3 days of severe HI in 90 patients, and the results related to outcome at 6 months. Patients with an isoelectric EEG or an EEG with repeated isoelectric intervals died. Reactivity of the EEG to external stimulation tended to be associated with favorable outcome. Grading of the EEGs on the basis of frequency composition otherwise provided no prognostic information. The presence of SEP scalp potentials bilaterally predicted favorable outcome, particularly if the central conduction times were normal. Conversely, the absence of one of both scalp potentials was associated with unfavorable outcome. EEGs thus provided useful prognostic information in only a minority of patients. By comparison, SEPs allowed prediction of both favorable and unfavorable outcomes in a much larger number of patients, and were therefore prognostically superior.

[The EEG after frontal and frontobasal skull and brain injury (author's transl)]

Eighty-eight patients with confirmed frontal and frontobasal lesions were examined. The EEG changes were investigated according to type and frequency both after recent trauma and in the later stages (Fig. 1). The general changes showed mainly slight (Fig. 2B) and only rarely severe, dysrhythmias (Fig. 3A) which, however, were frequently associated with paroxysmal outbursts. Focal findings were largely temporal and frontal in the second place (Fig. 2A). All pathological EEG changes showed a tendency to improvement, so that in the late phase they occurred rarely and less severe (Fig. 4). They showed no essential difference from the EEG of uncomplicated craniocerebral traumata. The relations between the EEG and the clinical form of craniocerebral trauma were examined. In contusions of the head the normal EEG was predominant. The pathological EEG was prominent with cerebral concussion and even more so with cerebral contusion. On the other hand, there was no relationship between the EEG and the type of fracture. A significant predominance of pathological EEG was found only in frontobasal fractures with rhinorrhoea. The EEG changes, classified as focal and dysrhythmic, show no statistically significant relationship either to the form of craniocerebral trauma or to the type of fracture. The effect of force coming form in front has apparently been used up chiefly in producing the frontal or frontobasal fractures, and leads to relatively slight cerebral damage. The clinical significance of the EEG does not actually lie in the diagnosis of these injuries, but, as always, in the establishment of the severity and extent of the cerebral lesion and the detection of complications.

Some aspects of electroencephalographic disturbances following head injury

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