Cholinergic crisis
Encyclopedia
A cholinergic crisis is an over-stimulation at a neuromuscular junction
due to an excess of acetylcholine
(ACh), as of a result of the inactivity (perhaps even inhibition) of the AChE
enzyme
, which normally breaks down acetylcholine. This is a consequence of some types of nerve gas, (e.g. sarin
gas). In medicine, this is seen in patients with myasthenia gravis
who take too high a dose of their cholinergic treatment medications, or seen in some surgical cases, when too high a dose of a cholinesterase inhibitor is given to reverse surgical muscle paralysis.
As a result of cholinergic crisis, the muscles stop responding to the bombardment of ACh, leading to flaccid paralysis
, respiratory failure
, and other signs and symptoms reminiscent of organophosphate
poisoning. Other symptoms include increased sweating, salivation, bronchial secretions along with miosis
. This crisis may be masked by the concomitant use of atropine
along with anticholinesterase inhibitors in order to prevent side effects. Flaccid paralysis resulting from cholinergic crisis can be distinguished from myasthenia gravis by the use of the drug edrophonium (Tensilon), which worsens the paralysis caused by cholinergic crisis, but strengthens the muscle in the case of myasthenia gravis.(Edrophonium is an anticholinesterase hence increases the concentration of acetylcholine present). Cholinergic crisis can be treated with antimuscarinic drugs like atropine.
Neuromuscular junction
A neuromuscular junction is the synapse or junction of the axon terminal of a motor neuron with the motor end plate, the highly-excitable region of muscle fiber plasma membrane responsible for initiation of action potentials across the muscle's surface, ultimately causing the muscle to contract...
due to an excess of acetylcholine
Acetylcholine
The chemical compound acetylcholine is a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans...
(ACh), as of a result of the inactivity (perhaps even inhibition) of the AChE
Ache
Ache may refer to:* Ache, a chronic, painful sensation* Ache , a You've Got Foetus on Your Breath album* "Ache" , a song by No Doubt* Ache Records, a Vancouver-based record label* The American College of Healthcare Executives...
enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
, which normally breaks down acetylcholine. This is a consequence of some types of nerve gas, (e.g. sarin
Sarin
Sarin, or GB, is an organophosphorus compound with the formula [2CHO]CH3PF. It is a colorless, odorless liquid, which is used as a chemical weapon. It has been classified as a weapon of mass destruction in UN Resolution 687...
gas). In medicine, this is seen in patients with myasthenia gravis
Myasthenia gravis
Myasthenia gravis is an autoimmune neuromuscular disease leading to fluctuating muscle weakness and fatiguability...
who take too high a dose of their cholinergic treatment medications, or seen in some surgical cases, when too high a dose of a cholinesterase inhibitor is given to reverse surgical muscle paralysis.
As a result of cholinergic crisis, the muscles stop responding to the bombardment of ACh, leading to flaccid paralysis
Flaccid paralysis
Flaccid paralysis is a clinical manifestation characterized by weakness or paralysis and reduced muscle tone without other obvious cause .-Polio:...
, respiratory failure
Respiratory failure
The term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial...
, and other signs and symptoms reminiscent of organophosphate
Organophosphate
An organophosphate is the general name for esters of phosphoric acid. Phosphates are probably the most pervasive organophosphorus compounds. Many of the most important biochemicals are organophosphates, including DNA and RNA as well as many cofactors that are essential for life...
poisoning. Other symptoms include increased sweating, salivation, bronchial secretions along with miosis
Miosis
Miosis is the constriction of the pupil of the eye to two millimeters or less...
. This crisis may be masked by the concomitant use of atropine
Atropine
Atropine is a naturally occurring tropane alkaloid extracted from deadly nightshade , Jimson weed , mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects...
along with anticholinesterase inhibitors in order to prevent side effects. Flaccid paralysis resulting from cholinergic crisis can be distinguished from myasthenia gravis by the use of the drug edrophonium (Tensilon), which worsens the paralysis caused by cholinergic crisis, but strengthens the muscle in the case of myasthenia gravis.(Edrophonium is an anticholinesterase hence increases the concentration of acetylcholine present). Cholinergic crisis can be treated with antimuscarinic drugs like atropine.