Cholinergic crisis
A cholinergic crisis is an over-stimulation at a neuromuscular junction due to an excess of acetylcholine, as a result of the inactivity of the acetylcholinesterase enzyme, which normally breaks down acetylcholine.
Signs and symptoms
As a result of cholinergic crisis, the muscles stop responding to the high synaptic levels of acetylcholine, leading to flaccid paralysis, respiratory failure, and other signs and symptoms reminiscent of organophosphate poisoning. Cholinergic crisis is sometimes known by the mnemonic "SLUDGE syndrome".Some of the symptoms of increased cholinergic stimulation include:
- Salivation: stimulation of the salivary glands
- Lacrimation: stimulation of the lacrimal glands
- Urination: relaxation of the internal sphincter muscle of urethra, and contraction of the detrusor muscles
- Defecation
- Gastrointestinal distress: smooth muscle tone changes causing gastrointestinal problems, including cramping
- Emesis: vomiting
- Miosis: constriction of the pupils of the eye via stimulation of the pupillary constrictor muscles
- Muscle spasm: stimulation of skeletal muscle
- Diaphoresis: increased sweating
- Bronchial secretions
Causes
- Contamination with – or excessive exposure to – certain chemicals including:
- *nerve agents,.
- *organophosphorus insecticides
- Ingestion of certain poisonous fungi.
- Taking too high a dose of medications such as cholinesterase inhibitors, in patients with myasthenia gravis
- Providing too high a dose of a cholinesterase inhibitor drug in order to reverse surgical muscle paralysis following general anaesthesia.
Treatment
Some elements of the cholinergic crisis can be reversed with antimuscarinic drugs like atropine or diphenhydramine, but the most dangerous effect — respiratory depression - cannot.The neuromuscular junction, where the brain communicates with muscles, works by acetylcholine activating nicotinic acetylcholine receptors and leading to muscle contraction. Atropine only blocks muscarinic acetylcholine receptors, so it will not improve the muscle strength and ability to breathe in someone with cholinergic crisis. Such a patient will require neuromuscular-blocking drugs and mechanical ventilation until the crisis resolves on its own.