Pseudocholinesterase Deficiency: Symptoms, Causes, Treatment

What are the symptoms of pseudocholinesterase deficiency?

Pseudocholinesterase deficiency is a rare genetic condition that affects the body’s ability to break down certain muscle relaxants and other drugs. The symptoms of pseudocholinesterase deficiency are typically noticed after exposure to specific medications, particularly those used during anesthesia, such as succinylcholine.

The symptoms include prolonged muscle paralysis after surgery or anesthesia, which can result in a longer-than-expected recovery time and extended need for mechanical ventilation. This condition may also cause increased sensitivity to certain drugs, leading to excessive sedation or other drug-related effects.

In some cases, individuals with pseudocholinesterase deficiency may not exhibit any symptoms until they are exposed to triggering medications. The condition is usually discovered after an unexpected reaction to anesthesia.

What are the causes of pseudocholinesterase deficiency?

Pseudocholinesterase deficiency is primarily caused by mutations in the BCHE gene, which provides instructions for making the enzyme pseudocholinesterase (also known as butyrylcholinesterase). This enzyme is responsible for breaking down certain types of drugs, including muscle relaxants like succinylcholine and mivacurium, as well as other substances such as cocaine and certain anesthetics.

Mutations in the BCHE gene can lead to reduced levels of pseudocholinesterase or alter the enzyme’s structure, making it less effective at breaking down these substances. As a result, people with pseudocholinesterase deficiency experience prolonged effects of drugs that are normally quickly metabolized by this enzyme.

The condition is inherited in an autosomal recessive manner, meaning that a person must inherit two copies of the mutated gene (one from each parent) to have the deficiency. People who inherit only one copy of the mutated gene are typically carriers and usually do not show symptoms but can pass the mutation to their offspring.

How is the diagnosis of pseudocholinesterase deficiency made?

The diagnosis of pseudocholinesterase deficiency is made through a combination of clinical history, laboratory testing, and genetic analysis.

1. Clinical History: The diagnosis often begins with a suspicion based on the patient’s history of prolonged muscle paralysis or delayed recovery from anesthesia following surgery, particularly when certain muscle relaxants like succinylcholine are used.
2. Laboratory Testing: Blood tests are used to measure the levels and activity of pseudocholinesterase enzyme in the blood. Low levels or reduced activity of the enzyme can indicate a deficiency.
3. Genetic Testing: If a pseudocholinesterase deficiency is suspected, genetic testing can be performed to identify mutations in the BCHE gene, which confirms the diagnosis. This can be particularly useful in determining whether the deficiency is inherited and assessing the risk for family members.
4. Dibucaine Number: In some cases, a specific test called the “dibucaine number” is used. This test measures the inhibition of pseudocholinesterase activity by dibucaine, a local anesthetic. A lower dibucaine number indicates a variant enzyme that is less effective at breaking down certain drugs, supporting the diagnosis of pseudocholinesterase deficiency.

What is the treatment for pseudocholinesterase deficiency?

There is no specific treatment to cure pseudocholinesterase deficiency. Management focuses on preventing complications and optimizing care when dealing with the condition. Here are key strategies:

1. Avoidance of Triggering Medications: The primary approach is to avoid drugs that are metabolized by pseudocholinesterase, such as succinylcholine and mivacurium, during anesthesia. Healthcare providers should be informed of the deficiency to use alternative medications.
2. Careful Monitoring: If exposure to triggering medications is unavoidable, close monitoring in a medical setting is essential. This includes monitoring for prolonged muscle relaxation and ensuring adequate ventilation support until the effects of the drugs wear off.
3. Emergency Preparedness: In cases where the condition is known, having an emergency plan and alerting medical professionals can help manage and mitigate complications promptly.
4. Genetic Counseling: For individuals with a family history of the condition, genetic counseling may be recommended to understand the inheritance pattern and implications for family members.

The focus is on preventive measures and careful management of anesthesia to minimize the risk of prolonged neuromuscular effects.