EEG prediction of brain metastases. A controlled study with neuropathological confirmation.

A retrospective study comparing the EEG findings of two groups of patients with primary systemic malignant disease (mainly bronchial carcinoma) was carried out. One group of 13 patients (20 EEGs) had proven supratentorial cerebral metastases at necropsy, some also subtentorial, and the other group of 10 patients (15 EEGs) had no cerebral involvement at necropsy. The latter group was studied to assess the possible confusing effects in the EEG of metabolic derangements and other factors which would interfere with accurate prediction of the presence of metastases. The EEGs were masked and assessed independently by two raters using a special proforma. They found that recordings from patients with cerebral metastases had persistent focal delta activity, intermittent focal or local delta activity, persistent or intermittent lateralized delta activity, monorhythmic frontal delta activity in the alert patient, as well as a higher frequency of post-central background rhythms. These factors predicted the presence of cerebral metastases (when they were 2 cm in diameter or larger) in 12 out of the 13 patients (four of these without localized neurological disorder), the EEGs being taken on average eight weeks before death. It is concluded that the EEG is valuable in the investigation of these patients.