Neuromuscular disorders is a term that encompasses many different medical conditions that impair the functioning of the muscles. To learn more about some of the causes, symptoms, progression and management of a specific neuromuscular disorder, select the name of the condition from the list below.

Arthrogryposis (also called arthrogryposis multiplex congenital or AMC) is a congenital non-progressive neuromuscular disorder characterized by stiffness and limited range of motion in two or more joints. Joint contractures which cause the limited range of motion develop before birth (prenatally) and are evident at birth (congenitally).

Any and all joints can be affected, but it is possible for some joints to be unaffected. No two people are affected the same way. Treatment often includes stretching, range of motion exercises, splinting, serial casting, physical therapy, occupational therapy and bracing.

Arthrogryposis has been estimated to occur once in every 3,000 live births. It is not thought to be a genetic or hereditary condition. Currently, the exact cause is unknown.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a hereditary progressive neurological disorder that mainly affects people from the Saguenay-Lac-St-Jean (SLS) and Charlevoix regions as well as people whose ancestors are from these areas. There are approximately 250 people from the Charlevoix-Saguenay region who are living with this progressive disorder.

The condition, which can affect both males and females, is characterized by degeneration of the spinal cord and progressive damage of the peripheral nerves. Children are usually diagnosed at a young age with symptoms such as poor motor coordination, spastic stiffness, muscle wasting, and slurred speech. These symptoms worsen over time, leaving most patients unable to walk by their early 40s and with a reduced life expectancy.

ARSACS is caused by a gene mutation located on chromosome 13. It is estimated that one out of every 22 people from SLSJ are carriers of the mutated gene.


ARSACS Fact Sheet
ARSACS Fact sheet (.PDF)

Becker muscular dystrophy (BMD) is an inherited degenerative muscle disorder that occurs almost exclusively in males. BMD is similar to DMD — both are caused by a mutation in the dystrophin gene on the X chromosome. This protein is an important building block that helps give muscles structure and strength.

Both DMD and BMD primarily affect skeletal muscles, which are used for movement, and heart (cardiac) muscle. However, BMD is less common — 1 in 35,000 males worldwide — and has a later onset and slower progression than DMD.
Symptoms typically appear between the ages of five and 15 and include difficulty with: walking; rising from the floor; running; hopping and/or jumping.


Becker Muscular Dystrophy Fact Sheet
Becker Muscular Dystrophy Fact sheet (.PDF)

Charcot-Marie-Tooth (CMT) disease is an inherited peripheral neuropathy. Inherited means that something can be passed on from generation to generation. Neuropathy means that there is a problem with the nerves. Peripheral refers to the peripheral nervous system, which is all of the nerves that branch from the central nervous system (brain and spinal cord) and travel to the feet and hands — the periphery of the body.

People with CMT usually have problems with their feet and hands, including feet deformity (high arches and hammertoes), foot drop, abnormal sensations and loss of fine motor skills. Not everyone with CMT is affected in the same way. Some patients have mild neuropathy, while others may have more severe problems with walking, hands, and/or sensation.

CMT occurs in both men and women and can affect children and adults. There is no known predisposition to having CMT based on race or ethnicity. CMT is a genetic condition. For a person to be affected with CMT, that person must have one (or two, depending on the type of CMT) disease causing mutation in one of the genes that causes CMT. There are at least forty different genes that cause CMT when mutated. A mutation in any one of them can cause the disease.

The diagnosis of CMT is made by combining clinical features with a nerve conduction study, which is a test where an electrical signal is sent down the nerve. CMT is an inherited peripheral neuropathy — a person must have a peripheral neuropathy based on a nerve conduction test in order to be affected with the condition. Genetic testing can also be done in order to identify a specific sub-type of CMT. Once a sub-type is identified in the family, other family members may just need the nerve conduction or the genetic testing in order to determine if that person is also affected.

Treatment of CMT is supportive. Ambulation aids, such as foot orthotics and braces (anke-foot-orthotics, AFOs) are commonly needed to help with foot deformity and foot drop. Surgery to correct foot alignment or to lengthen or transfer tendons is often performed. Physical and occupational therapies are instrumental in providing long-lasting quality of life. There is no cure for CMT nor any drug or vitamin known at this time to improve CMT symptoms.

Congenital muscular dystrophy (CMD) is the name for a group of muscular dystrophies that are united by the fact that muscle weakness begins in infancy or in early childhood (typically before age 2). Sometimes, the condition is not detected until a child is found to have trouble with certain developmental milestones — such as learning to walk. Both boys and girls can develop CMD. There are several different types of CMD, which have different symptoms, degrees of severity, and rates of progression.


Congenital Muscular Dystrophy Fact Sheet
Congenital Muscular DystrophyFact sheet (.PDF)

Duchenne Muscular dystrophy (DMD) is an inherited disorder, which usually affects boys (it is very rare in girls). The muscles become weaker as boys get older. This is because the body cannot make the muscle protein called dystrophin. This makes the muscle cells weak and they gradually break down. Signs of weakness start when the boys are between 3 and 5 years of age (sometimes earlier). At first, the weakness is seen mostly in the legs and hips. The children may:

  • Fall frequently
  • Have trouble running as fast as their peers
  • Have trouble climbing stairs
  • Have trouble getting up from a chair
  • Develop big calves
  • Frequently walk on their toes and lean backwards to keep their balance

Eventually this weakness also makes walking more difficult and a wheelchair is needed. Gradually, all the muscles become very weak, including the muscles used for breathing and the heart.

Anaesthesia or Sedation Risks

The American College of Chest Physicians issued a consensus statement (published in Chest, 2007) on the management of patients with DMD undergoing anaesthesia or sedation.

Thanks to better cardiac and respiratory care, patients with Duchenne muscular dystrophy (DMD) are living longer than in the past. Increased lifespan means it is more likely that DMD patients will undergo surgical procedures. Therefore, it is important to be aware of the risks and guidelines for patient care during and after surgery.

Summary of the recommendations:

  • Consider using intravenous, rather than gas, anaesthetics.
  • Do not use depolarizing muscle relaxants, such as succinylcholine; fatal reactions can occur.
  • Have an intensive care unit available for postoperative care.
  • Provide respiratory support during anaesthesia or sedation, using any of a variety of techniques.
  • Monitor blood oxygen saturation using pulse oximeter throughout the procedure.
  • When possible, monitor blood or lung carbon dioxide levels.
  • Consider moving the patient from intubation (tube in the trachea) during surgery to noninvasive positive pressure ventilation right after surgery.
  • Use extreme caution when administering supplemental oxygen.
  • Use manually assisted cough and insufflation-exsufflation assisted cough postoperatively to clear secretions.
  • Obtain a cardiology consultation, and closely monitor cardiac and fluid status postoperatively.
  • Initiate bowel regimens to avoid and treat constipation.
  • Consider gastric (stomach) decompression with a nasogastric tube.
  • Start intravenous feeding or enteral (through the stomach and intestines) tube feeding if oral intake is delayed for more than 24 to 48 hours postoperatively.

Respiratory Care

American Thoracic Society, in 2004, published guidelines about respiratory care in Duchenne muscular dystrophy (DMD).

In summary, the statement recommends that physicians caring for patients with DMD should provide:

  • Baseline respiratory status evaluation early in the disease course (between ages 4 and 6).
  • Regular consultations with a physician specializing in pediatric respiratory care twice a year after starting wheelchair use, reaching a vital capacity (maximal amount of air that can be exhaled after a maximal inhalation) that’s below 80 percent of predicted (normal), or reaching age 12.
  • Consultations every three to six months after starting mechanically assisted ventilation or airway clearance device.
  • Tests to evaluate pulmonary function at each clinic visit.
  • Education about assisted ventilation options well before an emergency occurs.
  • Nutritional guidance and support, including the placement of a feeding (gastrostomy) tube when indicated.
  • Regular evaluations of sleep quality and sleep-disordered breathing.
  • Regular cardiac evaluations, including annual electrocardiograms and echocardiograms, starting at least by school age.
  • Regular evaluations of the ability to clear secretions (cough).
  • Manually assisted cough techniques or mechanical cough assistance with an insufflator-exsufflator (positive and negative pressure) device when secretion clearance becomes less than adequate.
  • Education in the use of pulse oximetry (measurement of the amount of oxygen in the blood through the skin, via a painless sensor) at home to monitor the effectiveness of airway clearance.
  • Non-invasive ventilatory support via nasal intermittent positive pressure ventilation, either with a bilevel (using different pressures for inhalation and exhalation) airway pressure device, or with a mechanical ventilator, when disrupted or inadequate breathing during sleep or low blood oxygen levels during sleep are detected.
  • Avoidance of supplemental oxygen to treat sleep-related hypoventilation (inadequate breathing) unless ventilatory assistance is also being used.
  • Non-invasive daytime ventilation when breathing becomes inadequate during the day, using intermittent positive pressure ventilation through a mouthpiece, or an inflatable bladder that provides intermittent abdominal pressure simulating breathing.
  • Education in glossopharyngeal breathing (a “gulping” type of breathing) to use during short periods when off mechanical ventilation.
  • The option of ventilation via tracheostomy (surgical opening into the trachea in the neck) if noninvasive ventilation isn’t feasible or isn’t desired, with appropriate education for the patient and family.
  • Avoidance of preventive (before required) mechanically assisted ventilation, unless and until it is proven useful, since it may lead to a false sense of security and inadequate respiratory function monitoring.
  • Evaluation of pulmonary and cardiac function and of breathing during sleep before scoliosis surgery, and airway clearance and respiratory support in the postoperative period.
  • The option of oral steroid therapy with prednisone or deflazacort as a possible means to preserve lung function.
  • Education about respiratory function and treatment, including end-of-life care options, for the patient and family.
  • End-of-life care that includes treatment of pain or difficulty breathing, while attending to the psychosocial and spiritual needs of the patient and family and respecting their choices concerning tests and treatments.

Complete statement: Respiratory Care of the Patient with Duchenne Muscular Dystrophy


Duchenne Muscular Dystrophy Fact Sheet
Duchenne Muscular Dystrophy Fact sheet (.PDF)

Facioscapulohumeral muscular dystrophy (FSH or FSHD) is an inherited muscle disorder that causes progressive breakdown of muscle fibres, resulting in muscle atrophy and weakness. FSHD is the third most common muscular dystrophy worldwide, after Duchenne muscular dystrophy and myotonic dystrophy, affecting approximately 1 in 20,000 individuals.

Symptoms typically begin in teenage years, predominantly affecting the face (facio), shoulder blades (scapular), upper arm (humeral), and legs. There are currently no treatments to slow down, stop, or reverse the symptoms of FSHD.

Friedreich’s ataxia (FA) is a genetic neuromuscular disorder characterized by spinocerebellar degeneration. People with FA have gene mutations that limit the production of frataxin, which is an important protein that functions in the mitochondria (energy producing factories) of the cell. Additionally, in FA, specific nerve cells (neurons) degenerate, which is directly manifested in FA symptoms.

FA affects approximately 1 in 40,000 people. Childhood onset of FA is usually between the ages of 5 and 15, and is often associated with rapid progression. Late onset FA can occur anytime during adulthood.

FA symptoms may include:

  • loss of arm and leg coordination
  • fatigue
  • muscle loss
  • vision impairment
  • hearing loss
  • slurred speech
  • aggressive scoliosis (curvature of the spine)
  • diabetes mellitus
  • and a serious heart condition

The mental capabilities of people with FA are unaffected.

Guillain-Barré syndrome (GBS) is an inflammatory disorder of the (located outside the brain and spinal cord) which are attacked by the body’s immune system. These damaged nerves are unable, to varying degrees, to perform their functions correctly. The reason for the immune system’s attack on the body is currently unknown. However, the focus of the attack is the myelin sheath that surrounds the axons of nerve cells and sometimes, the axons themselves.

GBS is considered a rare disorder, affecting approximately 2 to 3 per 100,000 people a year. The incidence tends to increase with age, so GBS is most common in people between the ages of 50 and 80.

Most often, GBS follows a viral or bacterial infection, but pregnancy, surgery, or vaccinations may trigger the disorder in rare instances. GBS symptoms may include: lower limb numbness and tingling, symmetrical leg and arm weakness, severe back pain, muscle aching and cramping, shortness of breath and bieralfacial drooping (palsy). Severity of symptoms can vary greatly from person to person.

Note: Symmetrical leg and arm weakness helps differentiate GBS from other disorders.

GBS treatment may include plasmapheresis (plasma exchange), immunoglobulin therapy, assisted ventilation and occupational therapy.

Hereditary Motor and Sensory Neuropathy with Agenesis of the Corpus Callosum (HMSN/ACC) is a progressive hereditary neuromuscular disorder that mainly affects people from the Saguenay-Lac-St-Jean (SLSJ) and Charlevoix regions of Quebec as well as people whose ancestors originated from these regions. Some cases of HMSN/ACC have also been identified in other countries.

HMSN/ACC is responsible for the degeneration of the peripheral nerves involved in both body movement and the perception of sensations. Irregularities are observed in the brain of people affected with HMSN/ACC, mainly in the anatomical structure connecting the two cerebral hemispheres known as the corpus callosum. The corpus callosum is completely absent in 57.8% of patients and partially absent in 9.4% of patients. The presence or absence of corpus callosum in the brain of people affected does not seem to influence the severity or nature of symptoms. Men and women are equally affected.

HMSN/ACC is an autosomal recessive genetic disorder. It is caused by a gene mutation located on chromosome 15, one of the 22 autosomal pairs of chromosomes. The gene is expressed (resulting in the manifestation of HMSN/ACC) only when it is inherited from both parents. This means that both parents must be carriers of the gene. Often, carriers of the HMSN/ACC gene do not have symptoms and do not know that they are carriers.

When both parents are carriers of the HMSN/ACC gene, at each pregnancy:

  • There is a 1 in 4 (25%) chance that the child will have the disorder.
  • There is a 2 in 4 (50%) chance that the child will be a carrier of the gene.
  • There is a 1 in 4 (25%) chance that the child will neither have the disorder nor be a carrier of the gene.

The carrier status of the HMSN/ACC gene can be confirmed through genetic testing. If you have a family history of HMSN/ACC, you may wish to consult a genetic counselor to understand your chances of having a child affected with HMSN/ACC and discuss family planning alternatives.

A paediatrician and/or neurologist will conduct a clinical examination, as well as genetic testing to confirm diagnosis of HMSN/ACC. Additional testing may be recommended, such as a brain scan performed with highly precise radiography technology (cerebral tomography) or an analysis of the electrical activity in the arm and leg muscles (electromyogram).

Symptoms appear shortly after birth or during the first year of life and are characterized by a lack of muscle strength and a delay in the development of motor skills. HMSN/ACC results in a loss of mobility and developmental abnormalities in the spine, hands, and feet. In addition to the physical symptoms, HMSN/ACC also causes mild to moderate cognitive impairment.

Babies with HMSN/ACC have difficulty sitting and crawling. An intensive physiotherapy and occupational therapy treatment can stimulate motor development. With the use of assistive devices, such as feet and ankle orthoses, walkers, quadripods or support canes, toddlers usually begin to walk around the age of two or three. Typically, a child affected with HMSN/ACC has a slow gait and poor balance. In most cases, tremors are experienced throughout all parts of the body.

Children with HMSN/ACC experience delays in gross and fine motor development. Young children will be less prone to use their arms. Handgrip strength is weak, and keeping a grip on an object often requires extra exertion. Sometimes, this weakness in the upper limbs will cause muscle tremors when under strain. Often, children with HMSN/ACC are hypersensitive to touch. They are rarely toilet trained before the age of three.

Language development is delayed and learning capacity is affected. Students with HMSN/ACC usually require the support of a teaching assistant, or may be placed in a specialized class. Most children with HMSN/ACC learn to read, write, and count and are able to acquire general knowledge. However, skills typically remain at a second grade level.

Children with HMSN/ACC are usually very sociable, affectionate, and cheerful, and are able to integrate well in school and group activities. Additionally, they are able to follow codes of conduct and demonstrate social and moral judgment.

Around the age of twelve, the orthopedic surgeon may recommend scoliosis surgery to correct the curvature or bending of the spine. This surgery allows for a better expansion of the lungs and other organs as well as a better body alignment. Prior to the surgery, some children wear a corset for a few years to minimize the curvature of the spine or delay of the surgery. However, the corset is not a substitute for the surgery.

With the help of a walker, some people with HMSN/ACC will be able to walk until their early twenties. Many teenagers, however, will use a manual wheelchair or an electric scooter for mobility.

By the end of the teenage years or at the beginning of adulthood, some people may experience episodes of anxiety, agitation, visual or auditory hallucinations or depression. These problems are caused by dysfunctions in the brain and may require treatment.

Due to the progressive nature of the disorder, the person affected typically requires a power wheelchair and assistance with their personal needs by early twenties. Respiratory muscle weakness results in a high risk of respiratory failure and bronchopneumonia, which can be fatal. The average life span is 29 years, although many have lived up to their forties.

Currently, there is no known cure for HMSN/ACC or treatments to prevent the onset of symptoms. However, therapeutic interventions offered by various health care providers may help maintain physical abilities, avoid further complications and enhance comfort.

Limb-girdle muscular dystrophy (LGMD) is an inherited group of disorders that cause arm and leg muscle weakness and atrophy. The muscles most affected are those closest to the body (proximal muscles), specifically the shoulder, upper arm, pelvic and thigh muscles. Occasionally, the heart (cardiac) and breathing (respiratory) muscles may be affected. There are many subtypes of LGMD, including some that don’t have LGMD in their name, such as Bethlem myopathy, desmin myopathy, dysferlinopathy, myofibrillar myopathy, sarcoglycanopathies and ZASP-related myopathy. As of late 2012, there are more than 20 different LGMD subtypes, which is a complex and continuously evolving area of research.

LGMD incidence ranges from 1 in 14,500 to 1 in 123,000 individuals. The various LGMD forms are caused by mutations in many different genes. These genes provide instructions for making proteins that are involved in muscle maintenance and repair.

The severity, age of onset, and features of LGMD vary among the many subtypes. Early symptoms may include: difficulty walking, running, and rising from the floor. LGMD treatment may include: physical and occupational therapy, assistive devices, physiotherapy, orthoses and surgery.

Also known as Glycogen Storage Disease Type V (GSD V), Phosphorylase Deficiency, and Myophosphorylase Deficiency.

McArdle’s disease is an inherited condition that affects the skeletal muscles, causing severe muscle pain and cramping. It is caused by the lack of an enzyme called phosphorylase or myophosphorylase, which is needed to break down glycogen (stored form of sugar). Without the enzyme, glycogen can’t be used to produce energy during exercise.

McArdle’s disease is rare, and its prevalence is unknown. The condition is present from birth, but may not be diagnosed until young adulthood. People with McArdle’s disease often report they had symptoms, such as painful muscle spasms, during childhood. Treatment may include physiotherapy and regular moderate exercise (i.e. walking).

Important: Some anaesthetics used during surgery can cause acute muscle damage or other complications. You should notify the surgeon and/or the anesthesiologist that you have been diagnosed with McArdle’s disease prior to receiving any anaesthetics.


McArdle's Disease Fact Sheet
McArdle’s Disease Fact sheet (.PDF)

Mitochondrial myopathy affects the mitochondria — the tiny energy-producing structures that serve as “power plants of the cell.”

The term refers to a group of muscle disorders, including:

Kearns-Sayre syndrome (KSS)

  • Leigh’s syndrome
  • Mitochondrial Depletion syndrome (MDS)
  • Mitochondrial Encephalomyopathy
  • Lactic Acidosis and Stroke-like episodes (MELAS)
  • Myoclonic epilepsy with Ragged Red Fibers (MERRG)
  • Mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE)
  • Neuropathy, Ataxia, and Retinitis Pigmentosa (NARP)
  • Pearson syndrome
  • Chronic Progressive External Opthalmoplegia (CPEO)

Some types of mitochondrial myopathy are inherited, while some are sporadic (the mutation only occurs in the affected person; it was not inherited and will not be passed onto children). These disorders are caused by a defect in either a mitochondrial gene or a gene in the cell nucleus that affects the functioning of the mitochondria.

Symptoms may include:

  • nervous system impairment
  • eye problems
  • hearing issues
  • cardiac irregularities
  • skeletal muscle abnormalities
  • gastrointestinal tract disorders
  • muscle weakness and pain
  • fatigue
  • lack of endurance
  • poor balance
  • difficulty swallowing

Treatment may include:

  • hearing aids
  • medication
  • surgery
  • specialized glasses
  • assistive devices
  • speech therapy
  • diet modification
  • respiratory support

Some patients report minor improvement in symptoms when taking a supplement “cocktail” of Creatine, L-carnitine, and coenzyme Q10.


Mitochondrial Myopathy Fact Sheet
Mitochondrial Myopathy Fact sheet (.PDF)

Multicore myopathy (MM) or Multi Minicore myopathy causes muscle fibre degeneration. Most cases of MM are inherited, but some are sporadic (the mutation only occurs in the affected person; it was not inherited and will not be passed onto children).

There are four types of MM:

  • Classic form
  • Progressive form with hand involvement
  • Antenatal form with arthrogryposis multiplex congenita
  • Ophthalmoplegic form

MM affects both males and females. Close to half of MM cases are caused by a defective gene in one of two proteins: Selenprotein N1 (SEPN1) and Ryanodine receptor 1 (RYR1).

The main symptoms of MM are generalized weakness and muscle atrophy. Other symptoms depend on the type of MM. In some people, the disorder may remain stable for a long period of time, while some may experience progressive muscle weakness.


Multicore Myopathy Fact Sheet
Multicore Myopathy Fact sheet (.PDF)

Myasthenia gravis (MG) is an autoimmune disorder that produces weakness and irregularly rapid fatigue of voluntary muscles. In MG, the immune system attacks the body; the acetylcholine (ACH) receptor sites at the neuromuscular junction (point where the nerve endings join the muscle surface) are the targets.

MG affects approximately 20 per 100,000 people worldwide. Currently, the cause of MG is unknown. The disorder is seldom fatal, though it can be life-threatening in situations where muscle weakness interferes with respiration (breathing).

The first noticeable symptom is often eye muscle weakness, resulting in droopy eyelids (ptosis) or double vision (diplopia).

Other symptoms may include:

  • weakness in muscles used for chewing, swallowing and talking
  • severe fatigue
  • an unstable or waddling gait
  • arm weakness resulting in an inability to raise the arms over the head
  • hand and finger weakness
  • breathing difficulty

Myasthenia Gravis Fact Sheet
Myasthenia Gravis Fact sheet (.PDF)

Myositis disorders are autoimmune conditions characterized by voluntary (skeletal) muscle inflammation. The primary symptom of these disorders is muscle weakness, which is usually progressive and may be severely impairing.

There are three main types:

  • Polymyositis — inflammation is found in many muscles
  • Inclusion body myositis — muscle is characterized by irregular inclusions—accumulations of misfolded protein
  • Dermatomyositis — muscle inflammation is accompanied by a skin rash

All three conditions are considered rare. The cause of each of these disorders is currently unknown. Each of these disorders greatly differs in response to treatment.


Myositis Disorders Fact Sheet
Myositis Disorders Fact sheet (.PDF)

Myotonia congenita is an inherited condition that affects muscle relaxation. It is congenital, meaning that it is present from birth.

The two major types of myotonia congenita are known as Thomsen disease and Becker disease. These conditions are distinguished by the severity of their symptoms and their patterns of inheritance.

Abnormal repeated electrical signals occur in the muscles, causing a stiffness called myotonia.

Although myotonia can affect any skeletal muscles, including muscles of the face and tongue, it occurs most often in the legs. Myotonia causes muscle stiffness that can interfere with movement. In some people the stiffness is very mild, while in other cases it may be severe enough to interfere with walking, running, and other activities of daily life. These muscle problems are particularly noticeable during movement following a period of rest. Many affected individuals find that repeated movements can temporarily alleviate their muscle stiffness, a phenomenon known as the warm-up effect.

Myotonia congenita has been estimated to occur once in every 100,000 people worldwide.


Myotonic Disorders Fact Sheet
Myotonic Disorders Fact sheet (.PDF)

Myotonic dystrophy is the most common form of adult-onset muscular dystrophy, with a worldwide prevalence of 14 per 100,000 population and 189 per 100,000 population in Saguenay-Lac-Saint-Jean region of Quebec. Myotonic dystrophy is an autosomal dominant disorder caused by an error in genes located on chromosome 19 or chromosome 3.

There are two types of myotonic dystrophy:

  • Type 1, also known as Steinert’s disease
  • Type 2, also known as proximal myotonic myopathy (PROMM) – is caused by a mutation in the CNBP gene. This type is only found in adults, with an age of onset generally between 30 and 60 years.

Symptoms include:

  • myotonia that results in a delay in the ability to relax the muscles after a prolonged contraction
  • voluntary muscle weakness
  • muscle stiffness
  • drooping eyelids
  • unclear word pronunciation
  • difficulty raising the head when lying down
  • difficulty holding an object firmly
  • a shuffling gait
  • difficulty climbing stairs or rising from a seated position

Dystrophy Disorders Fact Sheet
Myotonic Dystrophy Fact sheet (.PDF)

Nemaline myopathy (NM) is a group of inherited disorders that affects muscle tone and strength. At various stages in life, the shoulder, upper arm, pelvic and thigh muscles may be affected. Symptoms usually begin between birth and early childhood. There are two main forms of NM:

  • Typical – is the most common form, usually presenting in infants with muscle weakness and floppiness. It may be slowly progressive or non-progressive, and most adults are able to walk.
  • Severe – is characterized by absence of spontaneous movement or respiration at birth, and is often fatal in the first few months of life. Occasionally, late-childhood or adult-onset can occur.

NM is considered rare, affecting approximately 1 in 50,000 people. NM can be caused by a mutation in one of several different genes responsible for making muscle protein.

Symptoms vary depending on the age of onset and the type of NM. They may include:

  • poor muscle tone and weakness (especially in the face, neck, upper arms and legs)
  • delay or inability to walk
  • breathing problems
  • difficulty feeding and swallowing
  • speech difficulties

Nemaline Myopathy Fact Sheet
Nemaline Myopathy Fact sheet (.PDF)

Oculopharyngeal muscular dystrophy (OPMD) is an inherited, adult-onset form of muscular dystrophy that, while found worldwide, affects French Canadian and Jewish populations more frequently. The estimated prevalence in the French-Canadian population of Quebec is 1 in 1,000 people.

OPMD is caused by a mutation in the PABPN1 gene.

Symptoms may include:

  • difficulty swallowing (dysphagia)
  • tongue weakness and atrophy
  • weakness in the proximal muscles
  • drooping eyelids (ptosis)
  • difficulty gazing upwards and double vision (diplopia)

Treatment may include:

  • surgery
  • speech and occupational therapy

Oculopharyngeal Muscular Dystrophy Fact Sheet
Oculopharyngeal Muscular Dystrophy Fact sheet (.PDF)

Pompe disease is a rare, inherited neuromuscular disorder that causes progressive muscle weakness and loss of muscle tissue.

Pompe disease goes by many different names:

  • Acid alpha-glucosidase deficiency
  • Acid Maltase Deficiency (AGM)
  • Glycogen Storage Disease Type 2
  • Lysosomal alpha-glucosidase deficiency

Pompe disease can occur between infancy and adulthood, and affects both men and women equally. Approximately one-third of people with Pompe disease are infants (infantile-onset) while the other two thirds are children or adults (late-onset).

Pompe disease is caused by mutations in a gene that makes an enzyme called acid alpha-glucosidase (GAA). The job of this enzyme is to break down glycogen, a form of sugar stored in muscle cells throughout the body. In people with Pompe disease, this enzyme is either missing or in short supply.

The symptoms and severity of Pompe disease can vary widely from person to person. Symptoms associated with the infantile-onset form may include:

  • feeding and breathing difficulties
  • an enlarged heart, tongue, and liver
  • inability to gain weight
  • a “frog-like” leg position
  • breathing problems and frequent respiratory infections

Symptoms associated with the late-onset form may include:

  • chewing and swallowing difficulties
  • lower back pain
  • scoliosis
  • frequent falls

Enzyme replacement therapy (ERT) has the ability to treat the underlying cause of the disease. Though ERT is not a cure, providing the missing enzyme may slow the progression of muscle weakness and improve muscle function. Treatment options also include supportive care, such as:

  • Respiratory therapies and ventilator assistance
  • Physical therapy
  • Occupational therapy

Speak with your health care provider about treatment options that are right for you.

Spinal muscular atrophy (SMA) is a group of inherited genetic muscle-wasting disorders. SMA affects the nerve cells that control voluntary muscle. These nerve cells are called motor neurons, and SMA causes them to die off. People with SMA are generally grouped into one of four types (I, II, III, IV) based on their highest level of motor function or ability.

  • Type I (severe) – also known as infantile-onset or Werdnig-Hoffman disease
  • Type II (intermediate)
  • Type III (mild) – also known as Kugelberg-Welander disease
  • Type IV – also known as adult SMA

SMA is rare condition, occurring in approximately 1 out of every 6,000 live births. It is a autosomal recessive genetic disease. About 1 out of 40 people are genetic carriers of the disease (meaning that they carry the mutated gene but do not have SMA).

SMA is caused by a missing or abnormal (mutated) gene known as survival motor neuron gene 1 (SMN1). In a healthy person, this gene produces a protein in the body called survival motor neuron (SMN) protein. In a person with mutated genes, this protein is absent or significantly decreased, and causes severe problems for motor neurons. Motor neurons are nerve cells in the spinal cord which send out nerve fibers to muscles throughout the body. Since SMN protein is critical to the survival and health of motor neurons, nerve cells may shrink and eventually die without this protein, resulting in muscle weakness.


Spinal Muscular Atrophy Fact Sheet
Spinal Muscular Atrophy Fact sheet (.PDF)