Congenital Myasthenic Syndromes

Overview

Mayo Clinic is a leader in diagnosing and treating congenital myasthenic syndromes (CMS). Mayo Clinic doctors have been at the forefront in identifying the gene mutations responsible for the syndromes and in developing successful treatments.

Congenital myasthenic syndromes are not uncommon but are commonly misdiagnosed and/or incorrectly treated. Different forms of CMS vary widely in their symptoms, from mild to severely disabling. With accurate diagnosis and appropriate therapy, even potentially fatal forms can usually be treated successfully.

Children treated for CMS at Mayo Clinic benefit from collaborative care by doctors and pediatric specialists in neurology, neuromuscular disease, orthopedics, ophthalmology, anesthesiology and other areas, working together to develop an effective treatment plan for each patient.

Diagnosis

Because symptoms for congenital myasthenic syndromes vary widely and because many symptoms are shared with myasthenia gravis and other muscular diseases, CMS can be difficult to recognize and diagnose. Read more about congenial myasthenic syndrome diagnosis.

Treatment Options

Treatment depends on the form of CMS. Drugs used to treat one form of CMS may be harmful if used to treat a different form. Read more about congenital myasthenic syndrome treatment options.

• Treatment in Arizona
• Treatment in Florida
• Treatment in Minnesota
• Treatment of Children & Adolescents

About Congenital Myasthenic Syndrome

Congenital myasthenic syndromes (CMS) are inherited muscular disorders resulting from genetic flaws at the neuromuscular junction, where the nerve and muscle cells communicate.

CMS is categorized by the part of the neuromuscular junction affected:

• Presynaptic (the nerve cells)
• Postsynaptic (the muscle cells)
• Synaptic (the space between the nerve and muscle cells)

Presynaptic CMS symptoms commonly include episodic apnea (CMS-EA), where breathing stops briefly. Other symptoms include weakness of the eye, mouth and throat muscles, sometimes resulting in double vision and difficulty chewing or swallowing.

Postsynaptic CMS symptoms can range from mild to severe. Symptoms in infancy include severe muscle weakness, feeding and respiratory problems, and delays in motor milestones such as sitting, crawling and walking. Childhood or adult onset symptoms may include difficulty raising the eyelids (ptosis) and fatigue, but usually they don't interfere with daily living.

In one form of postsynaptic CMS (slow-channel CMS), severe weakness that begins in infancy or childhood can progress and lead to loss of mobility and respiratory problems in adolescence or later in life.

Synaptic CMS symptoms commonly include feeding and respiratory problems early in childhood and weakness causing delayed motor milestones, reduced mobility and curvature of the spine (scoliosis).