What Do These Readings From Left Partial Craniotomy For Tumor Indicate?

this is a mostly awake electroencephalogram on a 56 year old patient who has had a left parietal craniotomy for tumor. the patient has a posterior dominant rhythm of 9 hz which is significantly better formed on the right side. The left side os overall slower and shows more activity of 6-7 Hz. There is intermittent 9-10 Hz activity over right central region. The left hemisphere on the hand shows mostly 4-7 Hz theta. Overall the activity over the left hemisphere is slower and of higher amplitude. The patient does appear to have drowsiness, at which time there is an attenuation of the posterior rhythm and increased theta. However sustained sleep was not seen. Photic stimulation induced driving at some of the frequencies. hyperventilation was not performed . Impression this a moderately abnormal electroencephalogram due to left hemispheric structural lesion. no epilepiform activity was observed