ALTERNATE NAMES

Congenital Muscular Dystrophy Due to LMNA Mutation; Dropped Head Syndrome; Laminopathy L-CMD; LAMIN A/C; LAMIN Congenital Muscular Dystrophy; LAMIN-related Congenital Muscular Dystrophy; L-CMD; LMNA-MD; LMNA-related Muscular Dystrophy

DESCRIPTION

LMNA-related congenital muscular dystrophy (L-CMD) is a rare neuromuscular disorder caused by mutations in the LMNA gene. L-CMD primarily affects muscles used for movement (skeletal muscles). It is part of a group of genetic conditions called congenital muscular dystrophies, which cause weak muscle tone (hypotonia) and muscle wasting (atrophy) beginning very early in life.

DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM/ICD-10-CM CODING

Diagnostic testing: The diagnosis of L-CMD is made by:

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  Physical examination;

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  Genetic testing;

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  Monitoring elevated creatine kinase levels in the blood which indicates muscle weakness; and

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  Electromyography (EMG).

Physical findings: The physical signs and symptoms of L-CMD are:

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  Muscle hypotonia (muscle weakness);

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  Joint contractures;

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  Spinal rigidity;

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  Respiratory difficulties due to weak chest muscles;

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  Dropped head syndrome (weak neck muscles);

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  Heart arrhythmias (abnormal heart rhythms);

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  Developmental delays; and

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  Abnormal curvature of the spine.

ICD-9: 359.0

ICD-10: G71.09; G71.2

PROGRESSION

Muscle weakness becomes apparent in infancy or early childhood and can worsen quickly. The most severely affected infants develop few motor skills, and they are never able to hold up their heads, roll over, or sit. Less severely affected children may learn to sit, stand, and walk before muscle weakness becomes apparent. First, the neck muscles weaken, causing the head to fall forward (dropped-head syndrome). As other skeletal muscles become weaker, these children may ultimately lose the ability to sit, stand, and walk unassisted. Over time, most infants and children with L-CMD will develop trouble eating and breathing. The breathing problems result from restrictive respiratory insufficiency, which occurs when muscles in the chest are weakened, and the ribcage becomes increasingly rigid. This problem can be life-threatening, and many affected children require support with mechanical ventilation to help them breathe.

Respiratory insufficiency is the main cause of death. Thereafter, cardiac dysfunction and arrhythmias leading to sudden death, which are very frequent in young adults, determines the vital prognosis. Embolic complications due to conduction disorders and right heart failure may worsen the poor prognosis. Respiratory insufficiency and recurrent pulmonary infections reduce the lifespan or may lead to permanent ventilation or tracheostomy.

TREATMENT

There is no cure for L-CMD. Treatment is supportive and focuses on improving quality of life and managing symptoms. Treatments include corticosteroids, cardiac monitoring, and respiratory support. An individual with L-CMD may have multidisciplinary treatment that includes gene therapy, physical therapy, occupational therapy, and speech therapy. Supplemental feeding may help with eating and weight control to avoid obesity. Mechanical devices may be used to help with ambulation and mobility.

Suggested MER for Evaluation:

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  Clinical examination including a description of physical findings;

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  Laboratory testing reports that document creatine kinase level;

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  Sequential pulmonary function testing (PFT);

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  Echocardiography (echo) testing results; and

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  Genetic testing documenting mutations in the LMNA gene.

Suggested Listings for Evaluation:

Meets

101.00

103.14

104.05

110.08 B

111.13

112.14

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