Inclusion Criteria:  age > 18 years elective carotid artery surgery general anesthesia written informed consent  Exclusion Criteria:  urgent surgery recent ( < 1 month) overt stroke Mini-mental State Examination < 20 points The presence of any mental disorder according to the International Classification of Diseases 11th Revision which is confirmed by a psychiatrist. The presence of any neuromuscular disease according to the International Classification of Diseases 11th Revision Hypersensitivity or known allergy to lithium carbonate History of seizure disorder History of leukemia Estimated glomerular filtration rate < 30 ml/min/1.73 m2 Left ventricular ejection fraction < 30% Heart failure equal 3 or 4 class according to the New York Heart Association Functional Classification Pregnant or breast-feeding women Inability to undergo a preoperative assessment for any reason Previously enrolled in this trial