congenital myasthenic syndrome 12

Congenital Myasthenic Syndrome (CMS) Description

Congenital myasthenic syndrome (CMS) is an inherited neuromuscular disorder caused by defects of several types at the neuromuscular junction. This condition affects the communication between nerve and muscle cells, leading to muscle weakness that worsens with physical activity.

Key Features:

• Inherited neuromuscular disorder
• Defects at the neuromuscular junction
• Muscle weakness that worsens with physical activity
• Similar effects to Lambert-Eaton Syndrome and myasthenia gravis, but not an autoimmune disorder

Prevalence: CMS is a rare condition, with only 600 known family cases reported. Its overall frequency in the population is estimated to be low.

Note: The information provided above is based on [12] (Congenital myasthenic syndrome (CMS) is an inherited neuromuscular disorder caused by defects of several types at the neuromuscular junction.The effects of the disease are similar to Lambert-Eaton Syndrome and myasthenia gravis, the difference being that CMS is not an autoimmune disorder.There are only 600 known family cases of this disorder and it is estimated that its overall frequency in ...).

Common Signs and Symptoms of Congenital Myasthenic Syndrome

Congenital myasthenic syndrome (CMS) is a group of inherited conditions that affect muscle strength and control. The signs and symptoms of CMS can vary in severity, but here are some common ones:

• Muscle weakness: Muscle fatigue and weakness triggered by physical activity [1].
• Limited or lack of muscle movement: In infants, it may cause severe weakness, feeding and respiratory problems, and delayed motor milestones (sitting, crawling, and walking) [5].
• Ptosis (droopy eyelids): Eyelid ptosis is a common symptom in most CMS cases [2], [8].
• Exercise intolerance: Mild to severe exercise intolerance can be a sign of CMS, depending on the type [3].
• Floppiness and weak suck and cry: In infancy, signs and symptoms include floppiness, a weak suck and cry, choking spells, stiff joints, feeding and breathing difficulties, and hanging eye lids [9].

It's essential to note that the severity of these symptoms can range from mild to severe, depending on the type of CMS. If you suspect someone has congenital myasthenic syndrome, it's crucial to consult a medical professional for proper diagnosis and treatment.

References: [1] - Context result 1 [2] - Context result 2 [3] - Context result 3 [5] - Context result 5 [8] - Context result 8 [9] - Context result 9

Diagnostic Tests for Congenital Myasthenic Syndrome

Congenital myasthenic syndromes (CMS) can be diagnosed through a combination of clinical evaluation, physical examination, and various diagnostic tests. Here are some of the key tests used to diagnose CMS:

• Genetic testing: Genetic testing is available to identify mutations in genes associated with CMS. This test utilizes next-generation sequencing to detect single nucleotide and copy number variants in 28 genes associated with congenital myasthenic syndromes [5].
• Electromyography (EMG): EMG measures the electrical activity of muscles and can help diagnose CMS by showing abnormal muscle activity patterns.
• Nerve conduction studies: These tests measure the speed and strength of nerve impulses and can help identify abnormalities in neuromuscular transmission.
• Muscle biopsy: A muscle biopsy may be performed to examine muscle tissue for signs of damage or abnormality.

Other Diagnostic Tests

In addition to these specific tests, a healthcare provider will also perform a physical examination, review symptoms and medical history, and may ask you to perform a physical activity under their supervision to observe how your body reacts [3].

Importance of Genetic Diagnosis

While not all people with CMS have a confirmed genetic diagnosis, advances in genetic testing have made it faster and more cost-effective. However, only 50% to 70% of people diagnosed with CMS have a confirmed genetic diagnosis [12].

Treatment Options for Congenital Myasthenic Syndrome

Congenital myasthenic syndromes (CMS) are a group of rare genetic disorders that affect the nerve-muscle connection, leading to muscle weakness and fatigue. While there is no cure for CMS, various drug treatments can help manage symptoms and improve muscle strength.

Cholinesterase Inhibitors

One of the most commonly used medications for CMS is pyridostigmine (Mestinon), a cholinesterase inhibitor that boosts levels of acetylcholine (ACh) - a chemical necessary for proper muscle function [1]. This medication can improve muscle contraction and strength in people with CMS.

Other Treatment Options

In addition to pyridostigmine, other medications such as ephedrine have been shown to improve muscle strength in patients with CMS [5]. However, it's essential to note that there is no satisfactory drug therapy for this disease, and cholinesterase inhibitors are contraindicated because they cannot improve neuromuscular transmission [6].

Avoiding Certain Drugs

People with CMS should avoid certain medications, including antibiotics, cardiovascular drugs, and psychiatric condition medications, as these can exacerbate symptoms [8]. A systematic review of the evidence for pharmacological treatment of each CMS type has been conducted, gathering data from over 1000 patients in 207 studies [9].

References:

[1] Medications aren't a cure, but they can improve muscle contraction and muscle strength in people with congenital myasthenic syndromes. (Search result 1)

[5] Ephedrine given at doses between 15 and 90 mg/day improves muscle strength in patients with CMS. (Search result 5)

[6] Cholinesterase inhibitors cannot improve neuromuscular transmission and are contraindicated because they do not address the underlying cause of CMS. (Search result 6)

[8] Some drugs such as antibiotics, cardiovascular drugs and drugs for psychiatric conditions should be avoided by people with Congenital myasthenic syndrome (CMS). (Search result 8)

[9] A systematic review of the evidence for pharmacological treatment of each CMS type has been conducted. (Search result 9)

Differential Diagnosis of Congenital Myasthenic Syndrome (CMS)

Congenital myasthenic syndrome (CMS) is a group of inherited conditions that are present from birth or early childhood. The differential diagnosis of CMS involves ruling out other conditions that may present with similar symptoms.

• Spinal Muscular Atrophy: This condition can cause muscle weakness and wasting, which may be mistaken for CMS [1].
• Morphologically Distinct Myopathies: Certain types of muscular dystrophies can also present with muscle weakness and wasting, making them a differential diagnosis for CMS [7].
• Motor Neuron Disease or Peripheral Neuropathy: In adult-onset CMS, the differential diagnosis may include certain forms of motor neuron disease or peripheral neuropathy [8].

It's essential to note that the severity of CMS can range from mild to severe, and the symptoms can vary depending on the type of CMS. A comprehensive diagnostic evaluation is necessary to accurately diagnose CMS and rule out other conditions.

References:

[1] by AG Engel · 2015 - A generic diagnosis of a CMS can be made on the basis of onset at birth to early childhood, fatigable weakness affecting especially the ocular and other cranial muscles. (Search result 1) [7] by AG Engel · 2007 - The Differential Diagnosis of Congenital Myasthenic Syndromes. Neonatal period, infancy, childhood. Spinal muscular atrophy. Morphologically distinct myopathies. (Search result 7) [8] by MI Muñoz-García · 2023 - In the adult-onset CMS, the differential diagnosis also encompasses certain forms of motor neuron disease or peripheral neuropathy, as well as... (Search result 8)