Related Experiment Video
Updated: Aug 14, 2026
08:23
A Multimodal Imaging- and Stimulation-based Method of Evaluating Connectivity-related Brain Excitability in Patients with Epilepsy
Published on: November 13, 2016
[Studies using S-(+)-ketamine on probands. Computerized EEG-analysis and transcranial Doppler ultrasonography]
Der Anaesthesist
|October 1, 1992
Summary
S(+)-ketamine and racemic ketamine show similar effects on electroencephalogram (EEG) and cerebral blood flow. S(+)-ketamine may offer better cortical function recovery, suggesting potential clinical advantages.
Area of Science:
- Neuroscience
- Anesthesiology
- Pharmacology
Background:
- S(+)-ketamine, an isomer of ketamine, demonstrates twice the anesthetic potency compared to the racemic mixture.
- Clinical practice currently utilizes the racemic mixture of ketamine for anesthesia.
- Understanding the differential effects of S(+)-ketamine and racemic ketamine on brain activity and cerebral hemodynamics is crucial.
Purpose of the Study:
- To compare the effects of S(+)-ketamine and racemic ketamine on electroencephalogram (EEG) and middle cerebral artery blood flow velocities.
- To assess potential differences in cortical function recovery between the two ketamine forms.
- To investigate the impact on cerebral blood flow dynamics in healthy volunteers.
Main Methods:
- A randomized, double-blind, cross-over study involving ten healthy volunteers.
- Administration of a bolus injection: 2 mg/kg racemic ketamine or 1 mg/kg S(+)-ketamine.
- Assessment of EEG parameters (spectral edge frequency, total activity, band activities) and transcranial Doppler sonography (TCD) variables (flow velocities, pulsatility index) at multiple time points post-injection.
Main Results:
- Both ketamine forms induced comparable EEG changes, with transient increases in theta and beta activities.
- Absolute delta and theta activities were higher with racemic ketamine at 120 minutes, but without statistical significance.
- Transcranial Doppler sonography revealed significant increases in middle cerebral artery blood flow velocities and decreases in pulsatility index for both groups, with no intergroup differences.
Conclusions:
- Racemic ketamine and S(+)-ketamine produce similar acute EEG alterations.
- S(+)-ketamine might be associated with a faster recovery of cortical function, indicated by lower slow EEG activity.
- Both ketamine forms significantly increase cerebral blood flow velocity, likely due to increased partial pressure of carbon dioxide.
