Any anesthetic compound will have an influence on the EEG recordings. Vapourised anesthetics, but also propofol and etomidate  will result in a slowing of EEG patterns, and if dosage is high enough result in a burst-suppression or even iso-electric EEG. Ketamine, is a NMDA receptor agonist and will give a dissociative anesthesia. Blood pressure and ICP will rise. Salivation increases and it also results in intense analgesia. With regards to the EEG, it will also influence patterns, but probably in a different way, since ketamine is a psychomimeticum, resulting in an increase in brain activity and brain metabolism. Basically, the choice of anesthetic depends on what you would like to monitor with your EEG recordings. 

Thank you very much, John. Your reply is very helpful.

if its related to nociception, analgesics should be avoided, or avoid those agents which depress the cerebral cortex and affect EEG. Sedative analgesics for example will depress the EEG.  for Nociceptive studies, propofol seems better, and halothane is believed to have no analgesic effect. Again it depends on what you want to record . 

Thanks Ubedullah.

My  choice would be remifentanyl aivoc it would disturb les EEG