OVERVIEW
Cholinergic crisis, the main manifestation of myasthenia gravis crisis, is caused by an overdose of anticholinesterase drugs (e.g., pyridostigmine bromide). Clinical manifestations include vomiting, abdominal pain, diarrhea, miosis, excessive sweating, salivation, increased airway secretions, slowed heart rate, muscle tremors, spasms, and tightness. For treatment, it is advisable to discontinue cholinesterase inhibitors and relieve symptoms with intramuscular injections of cholinergic receptor blocking drugs such as atropine and 654-2 (scopolamine).
Etiology
Various physiological, pathological or pharmacological factors, such as neostigmine overdose, organophosphorus pesticide poisoning, etc., lead to excessive accumulation of acetylcholine in the neuromuscular junction, continuous action on the acetylcholine receptor, so that the postsynaptic membrane is continuously depolarized, the repolarization process is impeded, the neuromuscular junction is blocked, and signaling is impeded, so that in addition to respiratory paralysis such as respiratory distress, muscarinic-like toxicity and nicotine-like toxicity symptoms are also present. In addition to symptoms of respiratory muscle paralysis such as dyspnea, there are symptoms of muscarinic and nicotinic poisoning.
Symptoms
Cholinergic crisis is seen in patients who have been taking high doses of cholinesterase inhibitors for a long time. The crisis is often preceded by significant adverse effects of cholinesterase inhibitors, such as nausea, vomiting, abdominal pain, diarrhea, excessive sweating, tearing, clammy skin, increased oral secretions, fascicular tremor, and psychiatric symptoms such as agitation and anxiety.
Tests
A cholinesterase activity test may assist in the diagnosis.
Diagnosis
In addition to the obvious muscle weakness, there is a history of cholinesterase inhibitor overdose and corresponding clinical manifestations, such as pallor, diarrhea, vomiting, hypertension, bradycardia, pupil constriction, and increased mucosal secretions.
Differential diagnosis
Differential diagnosis between myasthenia gravis, cholinergic crisis, and refractory crisis. The three types of crisis can be differentiated in the following ways:
1. Myasthenia gravis crisis
That is, neostigmine insufficiency crisis, often caused by infection, trauma, and dose reduction. Paralysis of respiratory muscles, coughing and swallowing weakness are life-threatening. Tensilon test helps to identify.
2. Antibarbital crisis
It is difficult to distinguish the nature of the crisis and cannot improve the symptoms by stopping or increasing the dose of drugs, which mostly occurs after long-term high-dose treatment. Electromyography can help to differentiate.
Treatment principle
Once the occurrence of cholinergic crisis is detected, anticholinergic drugs should be stopped immediately, and atropine 0.4-1.0 mg should be given intravenously, and half of the previous dose should be repeated every 3-5 minutes until the muscarinic side effects are controlled. Simultaneously, 50 to 250 mg of antiphosphidine is given intravenously, followed by 50 mg every 5 minutes, for a total of up to l to 2 g. However, overdose should be prevented to avoid conversion of cholinergic crisis to myasthenia gravis. Attention should also be paid to respiratory involvement, and ventilator-assisted respiration should be used if necessary.