Correlation of evoked potentials (SEP and VEP), EEG and CT in the diagnosis of brain tumors and cerebrovascular diseases.

In studying evoked potentials, EEG and CT in 29 patients with cerebral lesions (25 brain tumors and 4 with cerebrovascular diseases), a pathological EEG was found in 24 cases, pathological CT in 26 cases, pathological VEP in 10 of the 25 cases, pathological SEP in 10 cases out of 19. - Patients with pituitary tumors (chiasmatic tumors) showed pathological VEP and normal SEP due to compression of the visual pathway, and this correlated with the clinical site of the lesion, EEG and CT. - One patient with thalamic tumor showed pathological SEP and VEP due to affection of the somatic relay nucleus and the lateral geniculate body, this correlated with EEG and CT. - Patients with supratentorial tumors showed pathological SEP (absent cortical response), when there was cortical sensory loss and delayed conduction between N14-N20 when the posteior columns was affected. - Cases with infratentorial tumors showed pathological SEP only when there was affection of the ascending sensory pathway or the visual pathway. These cases showed pathological EEG and CT. - Cases with cerebrovascular disease showed pathological SEP when the lesion is at the thalamic level or affecting the thalamo-cortical pathway, evidenced clinically by cortical sensory loss or posterior column affection.