Cholinergic crisis is caused by an accumulation of acetylcholine due to acetylcholinesterase inactivity or insufficiency. It can be caused by medication overdose, exposure to nerve agents, or post-surgical overdose. Diagnosis can be difficult, but a test using the drug edrophonium can help. Treatment involves the use of atropine. In cases of organophosphate poisoning, decontamination and administration of atropine and oximes are necessary.
The biochemical phenomenon known as a cholinergic crisis is an episode of overstimulation at one of the body’s neuromuscular junction points. This event results from an accumulation of acetylcholine (ACh) resulting from acetylcholinesterase inactivity or insufficiency. A common cause of cholinergic crisis episodes is inadvertent overdose of medications for treatment in patients with myasthenia gravis. Additional causes include exposure to nerve agents and post-surgical overdose of cholinesterase inhibitors intended to reverse residual muscle paralysis. When a cholinergic crisis occurs, the muscles can no longer react to the influx of ACh, and respiratory failure, flaccid paralysis, excessive salivation, and sweating are likely to result.
Patients diagnosed with myasthenia gravis who are experiencing attacks of flaccid paralysis can pose diagnostic difficulties, because it is impossible to immediately determine whether the problem is caused by aggravation of the underlying disease or by a cholinergic crisis resulting from a drug overdose. To ascertain the true cause of the paralysis, a doctor is likely to conduct a test using the drug edrophonium. People with myasthenia gravis who are given this drug will have the severity of their paralysis increase after the drug is introduced if they are experiencing a true cholinergic crisis. Conversely, if the patient sees an increase in muscle strength after receiving the drug, it is likely that he is experiencing a worsening of his underlying condition. It is important that this type of diagnostic procedure is performed only by a trained physician who is trained to use intubation, ventilation, and resuscitation techniques as needed.
Once diagnostic tests confirm that a patient is indeed suffering from a cholinergic crisis rather than a myasthenic crisis, they will follow a standard course of treatment. Atropine is the accepted antidote when a patient has overdosed on anticholinesterases. It is imperative that patients with myasthenia gravis who present with this particular diagnostic puzzle and who routinely undergo anticholinesterase drug therapy have immediate access to intervention with atropine. If atropine is not given soon after the onset of cholinergic crisis, serious side effects can follow, including severe muscle weakness and possibly respiratory failure leading to death.
A cholinergic crisis caused by organophosphate poisoning following exposure to nerve agents causes the same types of symptoms as those seen in myasthenia gravis patients after a treatment overdose. The harmful effects of nerve agents develop when their composite chemicals bind to and render acetylcholinesterase ineffective in the body. The result is aggregation of excess ACh at the neuromuscular junctions, consistent with a cholinergic event. Muscle weakness, respiratory failure, and excessive salivation are likely to follow. Treatment protocols for a nerve agent crisis include decontamination of the body, clothing, and associated surfaces, as well as administration of atropine and oximes that break the bond between the nerve agent and the ACh enzyme.
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