Rapid changes in the volume of the lateral ventricles at encephalography

A triad of airencephalographic findings in patients with mental impairment: a controlled prospective study

A controlled prospective study of 82 patients examined consecutively during one year by airencephalography was made. Care was taken to excude bias and to assess observer error. A close correlation was found between mental impairment (as a sign of "organic brain syndrome", resulting from various cerebral diseases), and three airencephalographic findings, namely 1) lack of air filling over the parietal convexities (parietal air block), 2) widening of the lateral and third ventricles and 3) widening of the Sylvian and interhemispheric fissures. Of these, parietal air block was found to be the most sensitive sign. In addition to the patients with normal-pressure hydrocephalus, the majority of patients with presenile dementia and alcoholic encephalopathy had parietal air block. The results are in agreement with those reported in an earlier retrospective study. Leptomeningeal changes may account for the finding of parietal air block in certain patients, but in the majority of cases there is no complete obstruction of the subarachnoid space, as judged from the results of isotope cisternography. Organic changes in the brain and leptomeninges may create special physical conditions for the appearance of convexity air block at airencephalography. Recognition of convexity air blocks seems to have considerable diagnostic and therapeutic implications, since it contributes appreciably to the judgment whether a patient's condition is basically determined by an organic brain syndrome or constitutes a functional mental disorder. The possible pathophysiological association between mental impairment and parietal air block warrants attention.

The twenty-four hour pneumoencephalogram: with particular reference to ventricular size a series of 150 patients and a review of the literature

A series of 150 pneumoencephalograms which included 24 h films was reviewed to evaluate previous contradictory reports concerning changes in ventricular size at 24 h and to establish whether it is useful to obtain these follow-up films. In normal patients the changes in the ventricular index one day following the pneumoencephalogram ranged between -4-1 to +6-4% of the initial index. Statistically significant dilatation of the frontal horns of the lateral ventricles was observed in both patients who had dementia and central atrophy, and in those with normal pressure hydrocephalus. This ventricular enlargement was associated with deterioration in neurological status in some cases. Since ventricular enlargement at 24 h occurs in patients both with normal pressure hydrocephalus and with cerebral atrophy with hydrocephalus, it cannot be used to differentiate between these conditions although the most marked changes have been seen in the former. Significant dilatation did not occur in patients without intracranial disease, with cortical atrophy without hydrocephalus, or in a miscellaneous group. In patients with a history of trauma, enlargement at 24 h occurred only when there was some other encephalographic abnormality. The changes in size of the ventricles were not related to the age of the patient, the volume of the injected air, or to the presnece of subdural air. There were other findings on the follow=up radiographs. Cortical atrophy was more clearly demonstrated than on the filling films. Dilatation of the temporal horns, of questionable diagnostic significance, was not infrequently observed 24 h after air injection. The mechanisms of these changes are discussed; no single theory provides a complete explanation.