Background: Ketamine is an arylcyclohexylamine derivative with sedative properties, which is also used in the management of perioperative and neuropathic pain. The compound produces a dissociative state apparently through electrophysiological inhibition of thalamocortical connections and stimulation of the limbic system. In this report we describe an EEG-derived spectrographic pattern observed after ketamine administration.
Case report: A 30-year-old male patient (80 kg) presenting with acute abdomen from a bullet wound was submitted to general anesthesia (sufentanil 75 μg, propofol 200 mg, succinylcholine 70 mg), orotracheal intubation and neuromuscular blockade (rocuronium 1ED95%). Anesthesia was maintained with desflurane adjusted to maintain a BIS value of 45-60 and zero burst suppression. The spectrogram evidenced hypersynchronization of alpha, delta and slow oscillations, with low amplitudes at high frequencies. After anesthesia stabilization, ketamine (80 mg) was administered, resulting in a rise in the BIS value from 46 to 68, a rise in the raw EEG frequency, and high amplitudes predominantly in the beta band, with attenuation of alpha, delta and slow oscillations.
Discussion: Ketamine administration during anesthesia with desflurane significantly increased beta oscillations and reduced alpha, delta and slow oscillations as a result of the inhibition of the glutamatergic stimulus in the inhibitory GABAergic interneurons, producing aberrant excitatory activity in the cortex, hippocampus and the limbic system.

Effects of ketamine on EEG data: a case report