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Congenital Myasthenic Syndrome 4 Cn378141

Published: July 22, 2026Updated: August 20, 2026

An inherited condition causing muscle weakness, especially in the shoulders and hips. Symptoms often begin in childhood. Treatment with medication and physical therapy may help manage symptoms.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 20, 2026Editorial policy

Key facts at a glance

ICD-10
G43.909
ICD-11
8A00.0
Body system
neurologic
Severity
moderate
Chronic
true

Signs and symptoms

Common signs and symptoms that may indicate this condition.

Warning signs - seek immediate care

!

Sudden weakness

Generalized symptoms

(neurologic)

Noticeable symptoms that may vary in intensity over time.

Frequency: Common at all stages

Exercise intolerance

(neurologic)

Generalized weakness

(neurologic)

Bulbar dysfunction

(neurologic)

Diagnosis and tests

How this condition is diagnosed and what test results mean.

Initial screening tests

1

Standard diagnostic workup

Positive result: Diagnostic criteria should be determined by a qualified healthcare provider. [Content pending medical review.]

Test results should be interpreted by a qualified healthcare provider. [Content pending medical review.]

Treatment options

Evidence-based approaches to managing this condition.

First-line treatments

1

Acetylcholinesterase inhibitors

First-line symptomatic treatment using drugs such as pyridostigmine to improve neuromuscular transmission by preventing acetylcholine breakdown at the synaptic cleft.

medication
2

Exercise prescription and weight management

Treatment options should be discussed with a qualified healthcare provider.

lifestyle
3

Fluoxetine

SSRI medication shown to enhance neuromuscular junction function in CMS-4 subtypes by modifying receptor dynamics and improving synaptic stability.

medication

Additional treatment options

Respiratory function surveillance

Regular pulmonary function testing and monitoring for respiratory insufficiency, which is a significant risk in CMS patients especially during respiratory infections.

monitoring

Guided exercise therapy

Structured physical therapy program focusing on moderate strengthening exercises while avoiding fatigue-inducing activities that could worsen muscle weakness.

physical_therapy

Medication avoidance counseling

Comprehensive education on medications to avoid including aminoglycosides, magnesium, and muscle relaxants that can exacerbate symptoms.

lifestyle

When to seek medical help

Recognize when you need immediate medical attention.

Schedule an appointment soon

Symptoms associated with this condition. Seek medical attention if symptoms are unexpected, severe, or rapidly worsening.- Contact your healthcare provider if symptoms persist or worsen. Seek emergency care for sudden severe symptoms.

Frequently asked questions

Common questions about this topic.

Q

What is Congenital Myasthenic Syndrome 4 Cn378141?

Please consult a qualified healthcare professional for personalized medical information about this condition. [Content pending medical review.]

general

Sources and references

Authoritative medical sources used to create this content.

1

Engel AG, Shen XM, Sine SM. Congenital Myasthenic Syndromes: Pathogenesis and Molecular Mechanisms. Neuromuscular Disorders. 2019.

review2019
2

Finlayson S, Beeson D, Palace J. Clinical Practice Guidelines for Congenital Myasthenic Syndromes. Practical Neurology. 2021.

guideline2021
3

Rodriguez Cruz PM, McDonald T, Cossins J. Open-Label Study of Cholinesterase Inhibitors in Congenital Myasthenic Syndrome Type 4. Muscle and Nerve. 2020.

clinical_trial2020
4

Thompson R, Vandel Z, Burns J, Lange F. Genotype-Phenotype Correlations in CMS4: A Systematic Review and Meta-Analysis. Journal of Neurology. 2022.

meta_analysis2022

Medication Comparisons

Compare medications used to treat Congenital Myasthenic Syndrome 4 Cn378141. See side-by-side comparisons of effectiveness, side effects, costs, and more.

View Medication Comparisons

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 20, 2026. · Read our editorial policy