Neuromuscular Conditions

Gillette Children’s Specialty Healthcare offers one of the region’s top neuromuscular programs. In fact, Gillette is the Twin Cities’ only nationally ranked Best Children’s Hospital in pediatric neurology and neurosurgery. Our Center for Pediatric Neurosciences is the only one in the region integrating research and clinical services.

We focus on congenital neuromuscular conditions that affect nerves and muscles and that typically worsen with age. They include muscular dystrophy, myotonic dystrophy, spinal muscular atrophy, peripheral neuropathies (such as Charcot-Marie-Tooth disease), and generalized muscle and nerve issues (such as mitochondrial disorders). 

The Muscular Dystrophy Association recognizes Gillette’s Neuromuscular Clinic as a leader in providing multidisciplinary care to manage these often incurable but treatable conditions.

Why Choose Gillette?


Definition

Neuromuscular conditions affect the nerves and/or muscles—typically the peripheral nerves (those outside the brain and spinal cord) and skeletal muscles (such as those in the trunk, arms and legs). The conditions can be static (unchanging) or progressive (growing worse). Most neuromuscular conditions are present at birth, have a genetic component and can affect several generations in a family.


Types

There are hundreds of neuromuscular conditions, many with subtypes related to specific genetic causes. Although some conditions look similar and have similar treatments, most require unique treatment strategies.

Muscular Dystrophy

At Gillette, we treat the complications associated with many types of muscular dystrophy.

  • Duchenne muscular dystrophy, a common form, affects males almost exclusively. (Some females show mild characteristics of the disorder.) A defective gene on the X chromosome prevents the production of a muscle protein, dystrophin. Eventually, muscle cells break down, resulting in muscle weakness and lost mobility.
  • Becker muscular dystrophy is similar to Duchenne muscular dystrophy, except that instead of making no dystrophin, the defective gene creates an inadequate amount or a defective form of dystrophin. As a result, some males with this form appear less affected than males with Duchenne muscular dystropy (although manifestations vary greatly). 
  • Facioscapulohumeral muscular dystrophy primarily affects the face, shoulders and upper arms. Muscle weakness results from a defect on chromosome 4, which is found throughout the body. Over time, other muscles and body parts can show slow but progressive weakening.
  • Congenital muscular dystrophy (CMD) describes a group of disorders that result in severe muscle weakness that is evident from birth. Types include merosin-deficient, Ullrich, Bethlem myopathy, integrin-deficient, Fukuyama, muscle-eye-brain (MEB) disease, Walker-Warburg syndrome, and CMD with rigid spine syndrome. CMD affects males and females. Because of its congenital onset, most forms affect bone development, heart and lung function, brain function and mobility.
  • Myotonic muscular dystrophy affects most if not all muscles and some organs. The term myotonic refers to an inability to relax a muscle normally.

Spinal Muscular Atrophy (SMA)

Gillette treats the complications associated with all forms of spinal muscular atrophy (SMA). The condition affects nerves as they exit the spinal cord. Because the nerves lack a gene that helps maintain their function, they ultimately stop carrying signals from the brain to the muscles. That results in muscle weakness and wasting (atrophy).

  • SMA I, also called infantile onset or Werdnig-Hoffmann disease, is the most severe form of the condition. Most infants diagnosed with SMA I show severe muscle weakness and floppiness (hypotonia). They have difficulty gaining strength and often cannot sit independently. The muscle weakness also causes difficulty with swallowing and breathing.
  • SMA II, sometimes called intermediate SMA, results in muscle weakness and hypotonia, but the problems are less severe than in SMA I. Babies and toddlers with SMA II learn to sit on their own, but they have difficulty standing or walking. As they grow, some will lose the ability to stand and move freely, and they’ll need to use mobility devices, such as wheelchairs. 
  • SMA III, known as late onset SMA or Kugelberg-Welander disease, often isn’t identified until children are 18 to 24 months. Most children with this form of SMA walk independently, but they might have trouble jumping or using stairs. The severity of this form varies widely, and some people aren’t diagnosed until well into adulthood. In such cases, the condition is sometimes called SMA IV or adult-onset SMA.  

Charcot-Marie-Tooth (CMT) Disease

Charcot-Marie-Tooth (CMT) disease affects the nerves that stimulate and receive messages from muscles. CMT also affects vital cells that support and protect nerves. As a result, muscle tissue begins to waste and weaken. CMT has many types, each linked to one or more genetic mutations. The type of CMT determines the severity of the condition and the most appropriate treatment.

Friedreich’s Ataxia

Friedreich’s ataxia (FA) mainly affects the spinal cord and the nerves that extend from the spinal cord to the muscles. It results from a defective gene passed down through a family. FA also affects the cerebellum (the part of the brain that helps coordinate movement) and can affect heart muscle and function. FA can cause generalized muscle weakness and loss of balance and coordination.

Mitochondrial Myopathies

Mitochondrial myopathies are characterized by malfunctioning mitochondria (the parts of muscle cells that generate the energy required for a muscle to contract). The causes and results of mitochondrial myopathy vary, and new forms are discovered frequently. Most lead to some form of muscle weakness, but some affect specific parts of the body. The nine most common forms are:

  • Kearns-Sayre syndrome
  • Leigh syndrome and maternally-inherited Leigh syndrome
  • Mitochondrial DNA depletion syndrome
  • Mitochondrial encephalomyopathy, lactic acidosis and strokelike episodes
  • Mitochondrial neurogastrointestinal encephalomyopathy
  • Myoclonus epilepsy with ragged red fibers
  • Neuropathy, ataxia and retinitis pigmentosa
  • Pearson syndrome
  • Progressive external ophthalmoplegia

Metabolic Myopathies

Metabolic myopathies disrupt the ability of muscles to convert nutrients (usually glucose or another carbohydrate) into energy. That conversion process takes place thousands of times every second and involves many intermediate steps, each one associated with a nutrient, protein or other substance. Understanding the exact type of metabolic myopathy is vital, because treatments exist for some specific deficiencies. The most common forms of metabolic myopathy are:

  • Acid maltase deficiency (AMD, Pompe disease, glycogenosis type 2, lysosomal storage disease)
  • Carnitine deficiency
  • Carnitine palmityl transferase deficiency
  • Debrancher enzyme deficiency (Cori or Forbes disease, glycogenosis type 3)
  • Lactate dehydrogenase deficiency (glycogenosis type 11)
  • Myoadenylate deaminase deficiency
  • Phosphofructokinase deficiency (Tarui disease, glycogenosis type 7)
  • Phosphogylcerate kinase deficiency (glycogenosis type 9)
  • Phosphogylcerate mutase deficiency (glycogenosis type 10)
  • Phosphorylase deficiency (McArdle disease, myophosphorylase deficiency, glycogenosis type 5)

Juvenile Dermatomyositis

Juvenile dermatomyositis (DM) is a common form of inflammatory myopathy. It can involve the muscles or their blood supply. DM is distinct among neuromuscular diseases because a red or purplish rash can develop on the face, neck, shoulders, or upper arms and legs. The inflammatory process can lead to muscle deterioration, muscle weakness and joint problems. Gillette has rheumatologists (physicians familiar with inflammatory diseases) and neuromuscular specialists to treat the condition.


Causes and Risk Factors

People who develop neuromuscular conditions typically have a genetic disorder. (That means a defective, duplicated or missing gene causes the problem.) Most neuromuscular conditions are congenital (their effects are present at birth). Many go undiagnosed for several years, however, either because symptoms are slow to appear or because the conditions are so rare providers might not be familiar with them.

People who pass defective genes to their children are called carriers. Because carriers often aren’t affected by the defective gene, most are unaware of the issue until a child is diagnosed. With some conditions, both parents must be carriers before a child can be affected. In many instances, some children born to carriers are affected; others born to the same parents aren’t. Often the genetic abnormality is spontaneous (that child is the first in the family to develop the condition).

It’s not clear whether environmental factors are associated with genetic abnormalities. In most cases, there are no identifiable causes. Neuromuscular conditions generally aren’t caused by accidents or injuries.


Symptoms and Diagnosis

Most neuromuscular conditions cause obvious muscle weakness that worsens as a child grows. In some disorders, the weakness is evident at birth; in others, a thorough physical exam is needed.

Developmental Delays

Many children with neuromuscular conditions learn to roll, crawl, stand and walk, although they might exhibit developmental delays (learning new skills more slowly than typically developing children do). For example, most babies hold their heads up at 2 to 3 months and sit independently at 6 months. Babies who have neuromuscular conditions might develop those skills later or not at all. 

In some instances, babies and young children might lose skills or have more difficulty with certain skills as they grow older and larger. Trouble getting up from the floor, and labored or unusual walking patterns, are typical. Younger children might have trouble swallowing, eating, drinking and learning to talk. Infants with severe neuromuscular conditions move very little and cry weakly.

Muscle Weakness

Muscle weakness refers to strength, which is the force muscles produce to move a joint (such as an elbow or shoulder). Muscle strength also helps people perform tasks, such as picking up toys. 

In most cases, neuromuscular disorders prevent muscles from strengthening. Sometimes, attempting to strengthen a muscle weakened by a neuromuscular disease can make the disease worse.

Muscle Tone

Muscle tone isn’t the same as muscle strength. Muscle tone refers to the degree of tension in a resting muscle. It varies widely among people, and it’s usually a problem only when extremely low (hypotonia) or high (hypertonia).

One sign of a neuromuscular condition is hypotonia. Babies or young children with hypotonia are often described as floppy. One floppy muscle doesn’t necessarily mean a child has a neuromuscular disease. In cases of extreme hypotonia and muscle weakness, however, a qualified professional should evaluate the child as soon as possible. Those issues can affect breathing and feeding, increasing the risk of death.

Secondary Conditions

As neuromuscular conditions progress—especially if they aren’t well-managed by a team of specialists—secondary conditions can appear. Muscle or joint contractures (stiffness) are common. Bones (especially the spine) can become deformed. Children can struggle to breathe and eat. Because most neuromuscular conditions can’t be cured, the goal of treatment is to avoid or lessen the severity of secondary issues.

Diagnosis

Many neuromuscular conditions have a genetic cause.  Our physicians and genetic counselors work together to identify conditions and help families understand the causes of the condition and the likelihood of other family members developing the disorder.

We can diagnose many neuromuscular disorders with only a blood test. Some conditions require a muscle or nerve biopsy. A biopsy involves making a small incision, removing a piece of tissue, and examining it in a laboratory. Clinical examinations also can result in diagnoses.

Because some conditions respond best to early interventions, it’s important to obtain an accurate diagnosis as soon as a neuromuscular condition is suspected. Early treatment can also help patients avoid some secondary effects of the conditions.


Care and Treatment

Although most neuromuscular conditions have no cures, proper treatment can reduce the intensity and slow the progression of symptoms associated with the conditions. (Those symptoms might include muscle contractures, joint deformities and loss of function.) Treatments are designed to maximize function, increase independence, and improve the quality of a patient’s life.

Sometimes medications can improve muscle function. Rarely, proper management of a muscle or nerve disorder will help patients avoid its effects. An early and accurate diagnosis is the key to achieving such an outcome.

Common interventions include:


Our Services

Accurate testing helps ensure that each patient receives the best possible care. Test results help our team diagnose conditions, establish a patient’s baseline status and monitor the progression of a patient’s condition.

Once we establish a diagnosis, our team works with families to create customized treatment plans that address each patient’s needs. Because most neuromuscular conditions aren’t curable, regular checkups are important to slowing the progression of symptoms and avoiding secondary complications.

Medical and Specialties

Testing and Diagnostic Services

  • Blood and urine analysis
  • Echocardiogram and electrocardiogram tests
  • Electromyography tests
  • Functional ability tests
  • Genetic and DNA tests
  • Manual muscle tests
  • Muscle biopsies
  • Pulmonary function tests
  • Seating evaluations
  • Swallowing studies

Rehabilitation Therapies

Family Support

Why Gillette?

Because all children deserve a lifetime of amazing health care.

Why Gillette »