Mutism as a complication of total intravenous anesthesia by propofol.

Abstract

To the Editor: We read with interest the recent case report by Kati et al. (1). The authors describe a 56-year-old woman who developed somnolence and mutism for 11 days postoperatively, after total intravenous anesthesia with fentanyl, propofol, and vecuronium for a femur fracture fixation. The authors concluded that this neurologic complication may be attributed to an unknown effect of propofol. We think another possible explanation for the symptoms described in the case may have been a presentation of central anticholinergic syndrome (CAS). The signs and symptoms of CAS are similar to those described with atropine overdose and consist of somnolence, confusion, amnesia, agitation, hallucinations, ataxia, delirium, stupor, or coma in addition to tachycardia, dry mouth, dry skin, visual disturbances, and dysarthria (2). CAS occurs when drugs occupy central cholinergic sites leading to insufficient release of acetylcholine (2). CAS has been linked to many drugs including atropine sulfate, hyoscine, promethazine, benzodiazepines, opioids, halothane, and ketamine (3). CAS has also been described after propofol anesthesia (4) and even after nitrous oxide withdrawal (5). In animal studies, it has been shown that fentanyl has strong affinity for muscarinic receptors, whereas morphine and alfentanil do not exhibit any affinity for muscarinic receptors (6). Since the patient in the presented case received propofol, fentanyl, and atropine during anesthesia, we feel that CAS is a distinct possibility. CAS symptoms may last from hours to days (7). The diagnosis of CAS is made by exclusion, after ruling out other causes of delayed recovery from anesthesia and by a positive therapeutic response to physostigmine, a centrally active anticholinesterase agent. The incidence of CAS during the postoperative period has been reported to be up to 9.4% after general anesthesia and 3.3% after regional anesthesia with sedation (2). In a prospective study of 962 patients by Link et al. (8), 18 patients developed the syndrome, all of whom responded promptly to physostigmine administration. Katsanoulas et al. (9), reported two cases in which a delay in diagnosis of CAS resulted in unanticipated intensive care admission and acute lung injury. We suggest that the diagnosis of CAS should be considered in all patients, including the one in the case report by Kati et al. (1), who demonstrate abnormal postanesthetic awakening. Additionally, physostigmine should be readily available (10) and administered perioperatively in situations where the possibility of this diagnosis is considered. Venkatesh Srinivasa, MD Peter Gerner, MD Sunil Eappen, MD