Using pneumoencephalography and computerized axial tomography (EMI scanning) Polaroid pictures, the relationship between ventricular size and cerebral size was investigated in 35 patients. Evans' index was used for pneumoencephalograms, and planimetric measurement of the ventricular and cerebral cross-sectional areas was used for EMI scanning. The percentage ratio for the latter technique is termed VBR. The correlation coefficient between the two methods was 0.9510 (p less than 0.001).

The prognostic validity for survival of a recently devised EEG grading scale was tested in anoxic and post-traumatic coma. This scale divides EEG in coma into five major grades and ten subdivisions with emphasis on the presence of dominant activities, their amplitude, persistence, distribution and reactivity. In this scale, patterns previously not allocated, such as "spindle pattern coma," "alpha pattern coma," and "theta pattern coma" are also included. The prognostic power of the revised scale was tested retrospectively without knowledge of clinical data in a group of patients with cerebral anoxia after cardiac arrest lasting more than seven minutes and in a group of diffuse head injuries. The validity of the scale was found to be higher than those used in previously published studies, reaching 98.4% prognostic accuracy in anoxic encephalopathies and was very high in head injuries.

A correlation has been shown between the cross-sectional area of the cerebral ventricular system and the cross-sectional area of the brain in 62 patients, using the EMI Scanner. The percentage ratio has been abbreviated to VBR. The patients were divided into normal, equivocal, cerebral atrophy and hydrocephalus, according to their PEG's. The measurements were obtained by the use of a plaimeter and by outlining the ventricular and cerebral perimeters from the EMI Polaroid pictures. The VBR was found to be approximately five in those patients without detectable pathology, about seven in equivocal cases, and above ten in abnormal cases (atrophy, hydrocephalus). The hydrocephalic readings were generally higher than those for cerebral atrophy.

The EEG has long been established as an important laboratory test when assessing cerebral function in comatose states. During the last three decades, several grading scales regarding severity of the EEG abnormality in coma have been suggested to increase the prognostic power of the EEG for survival. Their main limitation was, that the majority of EEG abnormalities in coma fell in the middle of the five point scaling systems, i.e. Grade 3 abnormality on the five grade abnormality scales. In addition, it was considered that non-reactivity of EEG pattern in coma is confined only to the most advanced grades. The purpose of the present article is to define precisely the main five abnormality grades and their subdivisions, and to allocate them in five principal categories regarding their significance for survival. The five categories are: 1 = optimal, 2 = benign if persistent, 3 = uncertain, 4 = malignant if persistent, and 5 = fatal unless caused by drug effect or hypothermia. After the inclusion of more recently described coma patterns, it was possible to outline prognostic significance for survival in eleven types of abnormalities with assurance. Only four remain of uncertain prognostic significance. The EEG abnormalities as discussed in this article are generally applicable only to coma after diffuse brain trauma and cerebral hypoxia. However, they may also be found in some other diffuse encephalopathies associated with coma.

Electroencephalograms with a dominant rhythmic areactive 5Hz theta activity are reported in two comatose patients with fatal outcome. This pattern was followed by isoelectric EEG and death in the first patient, who suffered multiple injuries including severe cerebral concussion and later tentorial herniation. The second patient died eight hours after the second EEG recording, both EEGs having shown a very rhythmic 5-6 Hz activity which was maximal anteriorly. He died two days after a severe cerebral hypoxic episode due to acute respiratory failure. Both patients were in their late sixties. It is suggested that the dominant areactive theta activity is a variant of malignant "alpha pattern coma".