Cholinergic syndrome: common causes and symptoms

There are multiple neurotransmitters that have an effect on our body, regulating our psyche and our behavior. One of the main ones is acetylcholine., which is essential in the activity of the cerebral cortex and in the performance of a large number of mental and physical processes. Examples of this are attention, awareness, memory and muscle activation.

However, an excess of this substance can be dangerous or even fatal, and may cause the group of alterations known as cholinergic syndrome.

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What is cholinergic syndrome?

The group of cholinergic syndromes is called alterations or symptoms generated by the stimulation of the various acetylcholine receptors in the organism before an excess of this substance. Poisoning occurs, generally a consequence of exposure or administration of external substances that generate said excess.

Among them stands out the overdose of certain drugs with cholinergic action such as pilocarpine (a glaucoma drug also used to treat dry mouth in various disorders), bethanechol (for use in megacolon and vesicular problems) or medications that inhibit anticholinesterase such as those used to combat Alzheimer's (for example, rivastigmine), due to its excessive use and in excessive amounts in relation to the time in which they act on the organism.

It can also be caused by poisoning from pesticides and insecticides. We can also find cases derived from excesses of nicotine or the consumption of some mushrooms concrete and fungi such as the fly agaric.

Cholinergic syndrome is potentially fatal, necessarily requiring medical attention. The most common symptoms are the exaggerated secretion of fluids (saliva, tears, sweat, mucus and mucosa at the level of the digestive tract). respiratory...), muscle pain and paralysis (which may include the muscles that allow breathing) and alterations cardiorespiratory

Tachycardias tend to appear initially that can evolve into bradycardias (that is, accelerations of the heart rate that can becoming slowing down) and breathing difficulties (including bronchospasms that prevent the passage of air into the lungs) that they can end in cardiorespiratory arrest and death in case of not having assisted respiration. Vomiting, lethargy and confusion, and diarrhea are also common.

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Main symptoms depending on the activation of specific receptors

Acetylcholine has different receptors within the nervous system, among which are nicotinic and muscarinic. In this sense, a cholinergic syndrome may appear in which only one of the types of receptors is affected, or follow a process depending on the type of receptors that are activated. Generally, the following sequence occurs.

1. Nicotinic cholinergic syndrome

This type of cholinergic syndrome is characterized by the presence of muscle pain, cramps and paralysis, tachycardia and hypertension which may be followed by bradycardia, hyperglycemia, and calcium excess. The presence of mydriasis (ie, dilation of the pupil) in the first moments of acute intoxication is also very characteristic.

However, this mydriasis is only initial, since over time the sympathetic nervous system to produce miosis (abnormal contraction of the pupil). Muscles weaken and reflexes are lost.

2. Muscarinic cholinergic syndrome

At this stage of the syndrome the effect is due to excess activation of muscarinic receptors. Miosis or contraction of the pupil, blurred vision, decreased heart rate appear or bradycardia, tearing, drooling (excess salivation), incontinence, nausea and vomiting, and respiratory problems that could lead to respiratory arrest. Hypothermia and problems such as hypotension also appear.

3. Central or neurological cholinergic syndrome

It is common for neurological syndrome to appear in addition to those mentioned above, consisting of the appearance of headache, irritability, hypothermia, alteration of consciousness that can go as far as coma, seizures, cardiorespiratory depression and even death.

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Treatment

As we have indicated previously, cholinergic syndrome requires immediate medical treatment due to its potential to cause the death of the sufferer.

The first step to follow is the stabilization of the patient in terms of keeping his rhythm under control. cardiac and respiratory and, if necessary, use life support measures and even breathing assisted. Oxygen administration is essential. In severe cases, intubation of the patient may be required, and the elimination of excess secretions by this or other routes.

Subsequently at the pharmacological level the administration of atropine is usually seen as a solution for muscarinic symptoms together with substances that reactivate or enhance cholinesterases (the natural enzymes that break down acetylcholine in our body) to relieve nicotinic symptoms. The use of diazepam or other tranquilizers may be required in cases where seizures appear in order to decrease the level of activation.

Bibliographic references:

• Bargull-Díaz, I.C.; Lozano, N.; Pinto, J.K. & Aristizabal, J.J. (2012).Intermediate syndrome in acute organophosphate poisoning: case report. Medicine U.P.B. 31(1): 53-58.
• Gervilla, J.; Otal, J.; Torres, m. and Duran, J. (2007). Organophosphate poisoning. SEMERGEN.; 33: 21-3.
• Moreno, a. (2014). Main toxic syndromes and antidotes. Hospital October 12.