objective:To discuss the characteristics and localizing significance of presurgical scale ambulatory electroencephalo-gram(AEEG)in patients with supratentorial tumor by comparison their electrocorticography(ECOG).Methods:124 subjects were collected in our hospital.All patients were monitored by the scalp AEEG before surgeries and ECOG during oprating.The interictal epileptiform discharges of ECOG were divided into five catalogs.Ⅰ:no spikes.Ⅱ:isolated spikes.Ⅲ:repetitive spike-wave pattern.Ⅳ:intermittent spikes

polyspikes waves burst.Ⅴ:continuous hyper-spikes and sharps.A

B

C

D and E were represented on the scalp AEEG which corresponded the above ECOG classification.Then AEEG and ECOG were analyzed.Re-sults:(1)The scalp AEEG was abnormal in 83.87% of all subjects before surgery.Ⅱ type and Ⅲ type on ECOG did not appear easily on the scalp AEEG(P<0.05).(2)The most type on ECOG(62.96%)was Ⅳ type.In Ⅳ type

47 cases showed D type(61.04%)and some showed C type and there was higher coherence with D type on the scalp AEEG(P<0.01)(.3)There was higher concordance in the rate and part of abnormal discharge in the frontal lobe both on the scalp AEEG and ECOG.In the temporal and parietal lobe tumors

abnormal discharges which appeared in front of tumors were more than those of other spots

P<0.05.The abnormal discharges of 82.35% on ECOG and 80.88% on the scalp AEEG respectively appeared in frontal lobe and in the front of temporal lobe(4)The 19.35% abnormal discharges on the scalp AEEG appeared independently on contralateral hemisphere and these cases showed that their abnormal discharges were mainly located at near median side.Conclusions:(1)There were higher abnormal rate on ECOG than that on the scalp AEEG in patients with supratentorial tumor(.2)C type and D type have more value in localizing(.3)There were wider distribution of abnormal discharges on the scalp AEEG than on ECOG.But the spots of abnormal discharges on the scalp AEEG can indicate the conducting direction of abnormal dischargers on ECOG.