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To obtain continuous information about the cerebral electrical activity in the early course of coma, an apparatus was designed which included a small fast computer capable of calculating the Fourier transform. The practical application of this system of CSA to 123 comatose patients in a neurosurgical intensive care unit overcame the technical difficulties connected both with the patient's and environmental conditions. The advantages of such a technique are mainly due to its capacity of synthetising EEG signals and to its clarity of presentation, which is easily grasped even by people not specifically trained in electroencephalography. Hours of EEG activity are compressed into a pictorial and synoptic representation that shows in real time the distribution and temporal behaviour of frequencies as well as the intensity of total electrical activity. The immediate detection of these parameters permits evaluation of any worsening or improvement of cerebral electrogenesis, as well as of the inter-hemispheric asymmetries at their onset. EEG monitoring thus provides useful elements for assessing the comatose state in individual cases and for adjusting treatment. Finally, the spectrographic aspect of the first 48 h, as a whole, carries a great prognostic significance. The most striking finding from this study was the confirmation that the comatose states that, in their early course, show only a fixed slow-wave EEG activity are far more rare than those that display an electrical activity changing in time.

Patients in the early stage of severe head injuries occasionally present with a clinical picture analogous to that in vascular or neoplastic pontine lesions and they can be identified by careful clinical examination and by repeated electroencephalography (E.E.G.). The commonest features in these cases were preservation of consciousness, constriction of the pupils, disturbances of reflex ocular motility, severe pyramidal deficits, decerebrate rigidity, myoclonic manifestations, irregular breathing, and cranial nerve palsies. An E.E.G. tracing similar to the normal pattern was a common finding. These observations suggest that pontine syndromes may be directly produceg a non-reacting, but conscious, patient for one who is deeply comatose.

Spontaneous electrical activity (EEG) and event-related computer averaged brain electrical potentials (EPs) are becoming an integral part of CNS function monitoring in neurological intensive care patients. EEG monitoring using the compressed spectral array (CSA) computer analysis offers continuous information about cerebral electrical activity, permitting an accurate definition of the severity of brain injury, forecasting patient's course, and early detection of secondary intracranial changes. It offers more precise indications for treatment and prognosis. Combining EEG with multimodality EPs permits a finer diagnosis of the location and extent of CNS damage and contributes information, not otherwise obtainable, on the integrity of CNS pathways. Changes is electrophysiological patterns are often related to changes in other physiological parameters or events affecting the patient. Consequently, it appears advantageous to monitor simultaneously other CNS and body functions and record, process and display the data obtained in the patient care area. To make this comprehensive monitoring system reliable and useful, a wise application of advanced computer technology and a high degree of understanding of intracranial dynamics are required.