Ketamine and Its Emergence in the Field of Neurology

Summary & key facts

Ketamine was found in the mid-1900s as an anesthetic that can make people feel detached from their senses. After being used in war and later as a recreational drug, doctors learned more about how it works and began using it again. Ketamine blocks a brain receptor tied to overexcitation, which seems to protect brain cells in some injuries. It also keeps blood flow to the brain steady, does not raise pressure inside the skull, can stop damaging slow waves after injury, and usually does not suppress the heart or breathing. Because of these properties, researchers are exploring ketamine for problems like migraine, ongoing seizures, stroke, and serious head injury, but the review describes growing interest rather than giving a final proof that it works for every condition.

Key facts:

• Ketamine was discovered in the mid-1900s as an anesthetic and is called a “dissociative anesthetic” because it can make people feel cut off from their senses.
• After early use in war, ketamine became less common in human anesthesia because of its psychedelic effects and was often used recreationally or in veterinary medicine, but medical interest returned as researchers learned more about how it acts in the brain.
• Ketamine works mainly by blocking the NMDA receptor — a site on brain cells where signals pass — which lowers calcium entry into cells and reduces overactive excitatory signaling; this action has been shown to be protective in some neurological conditions.
• Studies and reports say ketamine does not increase pressure inside the skull and can help keep blood flow to the brain steady, which supports brain perfusion pressure (the pressure that keeps blood moving through the brain).
• Ketamine can inhibit cortical spreading depolarizations, which are slow waves of electrical disturbance that often occur after acute brain injury and can make damage worse.
• Unlike many other anesthetic drugs, ketamine does not cause cardiac or breathing suppression, which is one reason clinicians are interested in using it for very sick neurological patients.
• Because of these properties, clinicians and researchers are increasingly studying ketamine for migraine, ongoing seizures (status epilepticus), stroke, and traumatic brain injury, but this review summarizes those developments rather than proving effectiveness for every patient.

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