Ketamine and Its Emergence in the Field of Neurology

Summary & key facts

This review tells the story of ketamine from its mid-1900s discovery to its growing use in brain medicine today. It explains that ketamine works mainly by blocking a brain receptor called NMDA, which reduces a type of overactive brain signalling. That action can protect the brain in problems like migraine, very long seizures, stroke, and head injury. The paper notes useful features of ketamine: it does not raise pressure inside the skull, it keeps blood flowing in the brain, it can stop damaging waves of brain activity, and it does not usually suppress the heart or breathing the way some other anesthetics do. Because of these effects, doctors and researchers are paying more attention to ketamine for neurological care, but the article is a review of existing knowledge rather than a single test proving it works for every patient.

Key facts:

• Ketamine was first discovered in the mid-20th century as a drug called CI-581 and was called a "dissociative anesthetic" because it can make people feel cut off from their senses.
• After early use during the Vietnam War, ketamine became less common in routine human anesthesia and more often used in veterinary medicine and recreationally because of its psychedelic effects.
• Researchers now describe ketamine as an anesthetic and an analgesic, meaning it can both put people under and reduce pain.
• Ketamine's main brain action is to block NMDA receptors, which lowers certain calcium channel activity and reduces glutamate signalling; this change is thought to be one reason it can protect brain tissue in some conditions.
• In studies and clinical reports, ketamine did not raise pressure inside the skull and tended to keep brain blood flow and perfusion pressure stable, which is important after brain injury.
• Ketamine has been shown to reduce large slow waves of brain activity called cortical spreading depolarizations; these waves often happen after acute brain injury and can make damage worse.
• Unlike many other anesthetic drugs, ketamine usually does not cause major suppression of heart or lung function, which can make it useful in some acute neurological situations.
• The paper is a review of existing research and clinical use, so it summarizes growing interest and possible benefits but does not claim ketamine is proven effective for every neurological condition mentioned.

Abstract

The quest for a safe and effective anesthetic medication in the mid-20th century led to the discovery of CI-581, which was later named ketamine. Ketamine was labeled a “dissociative anesthetic” due to the state of sensory deprivation that it induces in the subjects receiving it. Although it enjoyed widespread use at the beginning of the Vietnam war, its use rapidly waned due to its psychedelic effect and it became more popular as a recreational drug, and in the field of veterinary medicine. However, as we gained more knowledge about its multiple sites of action, it has reemerged as a useful anesthetic/analgesic agent. In the last decade, the field of neurology has witnessed the growing use of ketamine for the treatment of several neurological conditions including migraine, status epilepticus, stroke, and traumatic brain injury (TBI). Ketamine acts primarily as a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist. The binding of ketamine to NMDA receptors leads to decreased frequency and duration of Ca+2 channel opening and thus inhibits glutaminergic transmission. This mechanism has proven to be neuroprotective in several neurological conditions. Ketamine does not increase intracranial pressure (ICP), and it maintains cerebral perfusion pressure (CPP) by increasing cerebral blood flow. Ketamine has also been shown to inhibit massive slow waves of neurological depolarizations called cortical spreading depolarizations (CSD), usually seen during acute neurological injury and are responsible for further neurological deterioration. Unlike other anesthetic agents, ketamine does not cause cardiac or respiratory suppression. All these favorable mechanisms and cerebral/hemodynamic actions have led to increased interest among clinicians and researchers regarding the novel uses of ketamine. This review will focus on the use of ketamine for various neurological indications.

Topics

Alcoholism and Thiamine Deficiency Neuroscience and Neuropharmacology Research Treatment of Major Depression

Categories

Health Sciences Medicine Pharmacology

Tags

Anesthesia Ketamine Medicine Neurology Psychiatry

Substances

Ketamine

Conditions & symptoms

Chronic Pain Depression PTSD Chronic pain Feeling disconnected from others Sadness or low mood