Electroencephalography in posterior fossa lesions

Abstract

The authors have analysed 22 cases of verified infratentorial surgical lesions and found: 1. In 9 cases the EEG was normal and in 13 abnormal. The predominant EEG modifications were: outbursts of bilateral synchronous waves, 4 to 7 c/s. (θ rhythm) and δ waves, diffuse or localized, with temporal dispersion in relation to predominant projection areas. 2. The EEG changes did not differentiate the inflammatory lesions from the tumors. 3. The outbursts of 4 to 7 c/s. bilateral synchronous waves did not differentiate the midline lesions from the lateral lesions. 4. The normal EEG was dominant in the cases of extraencephalic lesions in relation to the intraparenchymatous lesions. 5. In the cases of definite localized δ waves the lesions were contralateral in the posterior fossa. 6. The outburst of diffuse δ waves were more frequent in the midline lesions.