General anesthesia: neurologic complications

K K Jain MD (Dr. Jain is a consultant in neurology and has no relevant financial relationships to disclose.)
Originally released November 13, 1998; last updated September 10, 2020; expires September 10, 2023


This article reviews the neurologic complications of general anesthesia, which may occur during the procedure or in the postoperative period. Contributing factors are preoperative medications and the surgical procedures. This article describes the effect of general anesthesia on cerebral circulation and metabolism as well as the pathomechanism of neurologic complications. Prevention and management of these complications are also discussed.

Key points


• Several neurologic complications may occur after general anesthesia.


• Operation under general anesthesia in some neurologic disorders requires special precautions to reduce aggravation of the condition.


• Some of the complications, such as delirium and cognitive impairment, are usually transient, but persisting neurologic deficits may occur.

Historical note and terminology

Various methods of anesthesia have been applied during the evolution of medicine. The era of modern general anesthesia started in 1945 by William Morton with the administration of ether anesthesia for a general operation at the Massachusetts General Hospital, Boston (Falconer and Keys 1965). Hepatotoxicity of chloroform was recognized early but neurologic complications of anesthesia have not been a subject of special interest until recent years. Part of the reason for this is that anesthesia is closely tied with surgery; some of the complications are difficult to attribute to anesthetics alone. However, adverse effects of anesthetics are well recognized and are more obvious with some local anesthetics. Various types of general anesthesia with the commonly used agents are as follows:


• Inhalation: nitrous oxide (most widely used), halothane, enflurane, isoflurane, sevoflurane.


• Intravenous: barbiturates, benzodiazepines, propofol, ketamine.


• Narcotics: opioids, fentanyl. It has been argued that narcotics should not be classified as anesthetics because their action is subcortical rather than cortical even though loss of consciousness occurs with large doses of fentanyl.


• Muscle relaxants: polarizing and depolarizing.

This article will focus on complications of general anesthesia. Neurologic complications of local anesthesia and epidural anesthesia are described in separate topics.

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