The occurrence of sharp waves, spikes and fast activity in supratentorial tumours

Abstract

An investigation has been made on the occurrence of sharp waves, spikes and fast activity (18–28 c/sec.) in 100 supratentorial brain tumours. 1. 1. Random localized sharp waves were observed in 23 cases, most frequently with astrocytomas (47 per cent), and less often with meningeomas (22 per cent) and glioblastomas (17 per cent). In 20 of the cases sharp waves were recorded from the same region as the tumour and in 3 from an adjacent region. There was no correlation between the incidence of clinical epilepsy and sharp waves. Of the 57 patients with epilepsy, sharp waves were demonstrated in 13 cases, while in 10 other cases these potentials were seen without the patients having any evidence of epilepsy. Focal sharp waves are of definite localizing value in brain tumours. 2. 2. Random or rhythmic spikes occurred in 4 patients. They were recorded from the region of the tumour in only one case. 3. 3. Fast activity was found in 26 patients. It was most prominent in the frontal and parietal regions. In 6 cases it was recorded from the side of the tumour, in 8 from the opposite side and in 12 it was equally prominent on both sides. There was no difference in the occurrence of fast activity in meningeomas, astrocytomas and glioblastomas. No correlation was found between the occurrence of fast activity and epilepsy. Fast activity from the side opposite to that of the tumour might in some cases have been due to barbiturate medication; in other cases no explanation could be given for its appearance on the opposite hemisphere. Fast activity arising from the side of the tumour may be of the same nature as focal sharp waves and focal spikes. Fast activity has no localizing value in supratentorial tumours. 4. 4. “Sharp activity”, most probably due to fast activity superimposed upon slower waves, was noted in 20 patients: in 6 cases only on the side of the lesion, in 6 on the opposite side and in 8 from both hemispheres. This kind of activity has not any more localizing value than the slow component alone.