Myopathy

What is Myopathy?

 

The myopathies are neuromuscular disorders in which the primary symptom is muscle weakness due to dysfunction of muscle fiber. Other symptoms of myopathy can include include muscle cramps, stiffness, and spasm. Myopathies can be inherited (such as the muscular dystrophies) or acquired (such as common muscle cramps). Myopathies are grouped as follows:

 
congenital myopathies: characterized by developmental delays in motor skills; skeletal and facial abnormalities are occasionally evident at birth muscular dystrophies: characterized by progressive weakness in voluntary muscles; sometimes evident at birth mitochondrial myopathies: caused by genetic abnormalities in mitochondria, cellular structures that control energy; include Kearns-Sayre syndrome, MELAS and MERRF glycogen storage diseases of muscle: caused by mutations in genes controlling enzymes that metabolize glycogen and glucose (blood sugar); include Pompe’s, Andersen’s and Cori’s diseases

myoglobinurias: caused by disorders in the metabolism of a fuel (myoglobin) necessary for muscle work; include McArdle, Tarui, and DiMauro diseases dermatomyositis: an inflammatory myopathy of skin and muscle myositis ossificans: characterized by bone growing in muscle tissue familial periodic paralysis: characterized by episodes of weakness in the arms and legs polymyositis, inclusion body myositis, and related myopathies: inflammatory myopathies of skeletal muscle neuromyotonia: characterized by alternating episodes of twitching and stiffness; and stiff-man syndrome: characterized by episodes of rigidity and reflex spasms common muscle cramps and stiffness, and tetany: characterized by prolonged spasms of the arms and legs

Is there any treatment?

Treatments for the myopathies depend on the disease or condition and specific causes. Supportive and symptomatic treatment may be the only treatment available or necessary for some disorders. Treatment for other disorders may include drug therapy, such as immunosuppressives, physical therapy, bracing to support weakened muscles, and surgery.

 

What is the prognosis?

The prognosis for individuals with a myopathy varies. Some individuals have a normal life span and little or no disability. For others, however, the disorder may be progressive, severely disabling, life-threatening, or fatal.

 

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Myoclonus

What is Myoclonus?

Myoclonus refers to a sudden, involuntary jerking of a muscle or group of muscles. In its simplest form, myoclonus consists of a muscle twitch followed by relaxation. A hiccup is an example of this type of myoclonus. Other familiar examples of myoclonus are the jerks or "sleep starts" that some people experience while drifting off to sleep.  These simple forms of myoclonus occur in normal, healthy persons and cause no difficulties. When more widespread, myoclonus may involve persistent, shock-like contractions in a group of muscles.  Myoclonic jerking may develop in people with multiple sclerosis, Parkinson's disease, Alzheimer's disease, or Creutzfeldt-Jakob disease. Myoclonic jerks commonly occur in persons with epilepsy, a disorder in which the electrical activity in the brain becomes disordered and leads to seizures.

Is there any treatment?

Treatment of myoclonus focuses on medications that may help reduce symptoms. The drug of first choice is clonazepam, a type of tranquilizer.  Many of the drugs used for myoclonus, such as barbiturates, phenytoin, and primidone, are also used to treat epilepsy.  Sodium valproate is an alternative therapy for myoclonus and can be used either alone or in combination with clonazepam. Myoclonus may require the use of multiple drugs for effective treatment.

What is the prognosis?

Simple forms of myoclonus occur in normal, healthy persons and cause no difficulties. In some cases, myoclonus begins in one region of the body and spreads to muscles in other areas. More severe cases of myoclonus can distort movement and severely limit a person's ability to eat, talk, or walk. These types of myoclonus may indicate an underlying disorder in the brain or nerves. Although clonazepam and sodium valproate are effective in the majority of people with myoclonus, some people have adverse reactions to these drugs.  The beneficial effects of clonazepam may diminish over time if the individual develops a tolerance for the drug.

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Myasthenia Gravis

What is Myasthenia Gravis?

Myasthenia gravis is a chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal (voluntary) muscles of the body. The hallmark of myasthenia gravis is muscle weakness that increases during periods of activity and improves after periods of rest. Muscles that control eye and eyelid movements, facial expression, chewing, talking, and swallowing are often, but not always, involved. The muscles that control breathing and neck and limb movements may also be affected. Myasthenia gravis is caused by a defect in the transmission of nerve impulses to muscles. Normally when impulses travel down the nerve, the nerve endings release a neurotransmitter substance called acetylcholine. In myasthenia gravis, antibodies produced by the body's own immune system block, alter, or destroy the receptors for acetylcholine. The first noticeable symptoms of myasthenia gravis may be weakness of the eye muscles, difficulty in swallowing, or slurred speech. Symptoms vary in type and severity. Myasthenia gravis is not directly inherited nor is it contagious. The first steps in diagnosing myasthenia gravis include a review of the individual's medical history and physical and neurological examinations. If the doctor suspects myasthenia gravis, several diagnostic tests are available to confirm the diagnosis, including a special blood test that can detect the presence of immune molecules or acetylcholine receptor antibodies.

Is there any treatment?

Myasthenia gravis can be controlled. Some medications improve neuromuscular transmission and increase muscle strength, and some suppress the production of abnormal antibodies. These medications must be used with careful medical follow up because they may cause major side effects. Thymectomy, the surgical removal of the thymus gland (which often is abnormal in myasthenia gravis patients), improves symptoms in certain individuals, possibly by re-balancing the immune system. Other therapies include plasmapheresis, a procedure in which abnormal antibodies are removed from the blood, and high-dose intravenous immune globulin, which temporarily modifies the immune system and provides the body with normal antibodies from donated blood.

What is the prognosis?

With treatment, the outlook for most patients with myasthenia is bright: they can expect to lead normal or nearly normal lives. Some case of myasthenia gravis may go into remission temporarily, and muscle weakness may disappear so that medications can be discontinued. In a few cases, the severe weakness of myasthenia gravis may cause respiratory failure, which requires immediate emergency medical care.

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Muscular Dystrophy

What is Muscular Dystrophy?

The muscular dystrophies (MD) are a group of more than 30 genetic diseases characterized by progressive weakness and degeneration of the skeletal muscles that control movement. Some forms of MD are seen in infancy or childhood, while others may not appear until middle age or later. The disorders differ in terms of the distribution and extent of muscle weakness (some forms of MD also affect cardiac muscle), age of onset, rate of progression, and pattern of inheritance.

Duchenne MD is the most common form of MD and primarily affects boys. It is caused by the absence of dystrophin, a protein involved in maintaining the integrity of muscle. Onset is between 3 and 5 years and the disorder progresses rapidly. Most boys are unable to walk by age 12, and later need a respirator to breathe. Girls in these families have a 50 percent chance of inheriting and passing the defective gene to their children. Boys with Becker MD (very similar to but less severe than Duchenne MD) have faulty or not enough dystrophin.

Facioscapulohumeral MD usually begins in the teenage years. It causes progressive weakness in muscles of the face, arms, legs, and around the shoulders and chest. It progresses slowly and can vary in symptoms from mild to disabling.

Myotonic MD is the disorder’s most common adult form and is typified by prolonged muscle spasms, cataracts, cardiac abnormalities, and endocrine disturbances. Individuals with myotonic MD have long, thin faces, drooping eyelids, and a swan-like neck.

Is there any treatment?

There is no specific treatment to stop or reverse any form of MD. Treatment may include physical therapy, respiratory therapy, speech therapy, orthopedic appliances used for support, and corrective orthopedic surgery. Drug therapy includes corticosteroids to slow muscle degeneration, anticonvulsants to control seizures and some muscle activity, immunosuppressants to delay some damage to dying muscle cells, and antibiotics to fight respiratory infections. Some individuals may benefit from occupational therapy and assistive technology. Some patients may need assisted ventilation to treat respiratory muscle weakness and a pacemaker for cardiac abnormalities.

What is the prognosis?

The prognosis for people with MD varies according to the type and progression of the disorder. Some cases may be mild and progress very slowly over a normal lifespan, while others produce severe muscle weakness, functional disability, and loss of the ability to walk. Some children with MD die in infancy while others live into adulthood with only moderate disability.

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Multiple System Atrophy with Orthostatic Hypotension

Synonym(s): Shy-Drager Syndrome

What is Multiple System Atrophy with Orthostatic Hypotension?

Multiple system atrophy with orthostatic hypotension is the current classification for a neurological disorder that was once called Shy-Drager syndrome. A progressive disorder of the central and autonomic nervous systems, it is characterized by orthostatic hypotension (an excessive drop in blood pressure when standing up) which causes dizziness or fainting. Multiple system atrophy can occur without orthostatic hypotension, but it is rare. Doctors classify the disorder into 3 types: the Parkinsonian-type includes symptoms of Parkinson's disease such as slow movement, stiff muscles, and tremor; the cerebellar-type, which causes problems with coordination and speech; and the combined-type, which includes symptoms of both parkinsonism and cerebellar failure. Problems with urinary incontinence, constipation, and sexual impotence in men happen early in the course of the disease. Other symptoms include generalized weakness, double vision or other vision disturbances, difficulty breathing and swallowing, sleep disturbances, and decreased sweating. Because the disease resembles others, a correct diagnosis may take years.

Is there any treatment?

There is no cure for multiple system atrophy with orthostatic hypotension. Treatment is aimed at controlling symptoms. Anti-Parkinson medication such as Sinemet may improve the general sense of well-being. Medications to elevate blood pressure while standing are often used, but may cause high blood pressure when lying down. Individuals should sleep with the head of the bed elevated. An artificial feeding tube or breathing tube may be required for problems with swallowing and breathing.

What is the prognosis?

Most individuals with multiple system atrophy with orthostatic hypotension die within 7 to 10 years after the onset of symptoms. A problem with the respiratory system is the most common cause of death.

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Multiple System Atrophy

What is Multiple System Atrophy?

Multiple system atrophy (MSA) is a progressive neurodegenerative disorder characterized by symptoms of autonomic nervous system failure such as fainting spells and bladder control problems, combined with motor control symptoms such as tremor, rigidity, and loss of muscle coordination. MSA affects both men and women primarily in their 50s.

Is there any treatment?

There is no cure for MSA. Currently, there are no treatments to delay the progress of neurodegeneration in the brain. But there are treatments available to help people cope with some of the more disabling symptoms of MSA.

What is the prognosis?

The disease tends to advance rapidly over the course of 9 to 10 years, with progressive loss of motor skills, eventual confinement to bed, and death. There is no remission from the disease. There is currently no cure.

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Multiple Sclerosis

What is Multiple Sclerosis?

An unpredictable disease of the central nervous system, multiple sclerosis (MS) can range from relatively benign to somewhat disabling to devastating, as communication between the brain and other parts of the body is disrupted.  Many investigators believe MS to be an autoimmune disease — one in which the body, through its immune system, launches a defensive attack against its own tissues. In the case of MS, it is the nerve-insulating myelin that comes under assault. Such assaults may be linked to an unknown environmental trigger, perhaps a virus.

Most people experience their first symptoms of MS between the ages of 20 and 40; the initial symptom of MS is often blurred or double vision, red-green color distortion, or even blindness in one eye.  Most MS patients experience muscle weakness in their extremities and difficulty with coordination and balance.  These symptoms may be severe enough to impair walking or even standing. In the worst cases, MS can produce partial or complete paralysis.  Most people with MS also exhibit paresthesias, transitory abnormal sensory feelings such as numbness, prickling, or "pins and needles" sensations.  Some may also experience pain.  Speech impediments, tremors, and dizziness are other frequent complaints. Occasionally, people with MS have hearing loss. Approximately half of all people with MS experience cognitive impairments such as difficulties with concentration, attention, memory, and poor judgment, but such symptoms are usually mild and are frequently overlooked.  Depression is another common feature of MS.

Is there any treatment?

There is as yet no cure for MS. Many patients do well with no therapy at all, especially since many medications have serious side effects and some carry significant risks.  However, three forms of beta interferon (Avonex, Betaseron, and Rebif) have now been approved by the Food and Drug Administration for treatment of relapsing-remitting MS. Beta interferon has been shown to reduce the number of exacerbations and may slow the progression of physical disability. When attacks do occur, they tend to be shorter and less severe.  The FDA also has approved a synthetic form of myelin basic protein, called copolymer I (Copaxone), for the treatment of relapsing-remitting MS. Copolymer I has few side effects, and studies indicate that the agent can reduce the relapse rate by almost one third. An immunosuppressant treatment, Novantrone (mitoxantrone), is approved by the FDA for the treatment of advanced or chronic MS.

One monoclonal antibody, natalizumab (Tysabri), was shown in clinical trials to significantly reduce the frequency of attacks in people with relapsing forms of MS and was approved for marketing by the U.S. Food and Drug Administration (FDA) in 2004.  However, in 2005 the drug’s manufacturer voluntarily suspended marketing of the drug after several reports of significant adverse events.  In 2006, the FDA again approved sale of the drug for MS but under strict treatment guidelines involving infusion centers where patients can be monitored by specially trained physicians.

While steroids do not affect the course of MS over time, they can reduce the duration and severity of attacks in some patients.  Spasticity, which can occur either as a sustained stiffness caused by increased muscle tone or as spasms that come and go, is usually treated with muscle relaxants and tranquilizers such as baclofen, tizanidine, diazepam, clonazepam, and dantrolene. Physical therapy and exercise can help preserve remaining function, and patients may find that various aids — such as foot braces, canes, and walkers — can help them remain independent and mobile.  Avoiding excessive activity and avoiding heat are probably the most important measures patients can take to counter physiological fatigue.  If psychological symptoms of fatigue such as depression or apathy are evident, antidepressant medications may help.  Other drugs that may reduce fatigue in some, but not all, patients include amantadine (Symmetrel), pemoline (Cylert), and the still-experimental drug aminopyridine. Although improvement of optic symptoms usually occurs even without treatment, a short course of treatment with intravenous methylprednisolone (Solu-Medrol) followed by treatment with oral steroids is sometimes used.

What is the prognosis?

A physician may diagnose MS in some patients soon after the onset of the illness. In others, however, doctors may not be able to readily identify the cause of the symptoms, leading to years of uncertainty and multiple diagnoses punctuated by baffling symptoms that mysteriously wax and wane.  The vast majority of patients are mildly affected, but in the worst cases, MS can render a person unable to write, speak, or walk.  MS is a disease with a natural tendency to remit spontaneously, for which there is no universally effective treatment.

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Multifocal Motor Neuropathy

What is Multifocal Motor Neuropathy?

Multifocal motor neuropathy is a progressive muscle disorder characterized by muscle weakness in the hands, with differences from one side of the body to the other in the specific muscles involved. It affects men much more than women. Symptoms also include muscle wasting, cramping, and involuntary contractions or twitching of the leg muscles. The disorder is sometimes mistaken for amyotrophic laterial sclerosis (ALS, or Lou Gehrig's disease) but unlike ALS, it is treatable. An early and accurate diagnosis allows patients to recover quickly.

Is there any treatment?

Treatment for multifocal motor neuropathy varies. Some individuals experience only mild, modest symptoms and require no treatment. For others, treatment generally consists of intravenous immunoglobulin (IVIg) or immunosuppressive therapy with cyclophosphamide.

What is the prognosis?

Improvement in muscle strength usually begins within 3 to 6 weeks after treatment is started. Most patients who receive treatment early experience little, if any, disability. However, there is evidence of slow progression over many years.

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Mucopolysaccharidoses

What are Mucopolysaccharidoses?

The mucopolysaccharidoses are a group of inherited diseases in which a defective or missing enzyme causes large amounts of complex sugar molecules to accumulate in harmful amounts in the body’s cells and tissues. This accumulation causes permanent, progressive cellular damage that affects appearance, physical abilities, organ and system functioning, and, in most cases, mental development.  Depending on the type of mucopolysaccharidosis, affected individuals may have normal intellect or may be profoundly retarded, may experience developmental delay, or have severe behavioral problems. Physical symptoms generally include coarse or rough facial features, thick lips, an enlarged mouth and tongue, short stature with a disproportionately short trunk (dwarfism), abnormal bone size or shape (and other skeletal irregularities), thickened skin, enlarged organs such as the liver or spleen, hernias, and excessive body hair growth.

Is there any treatment?

Currently there is no cure for these disease syndromes.  Medical care is directed at treating systemic conditions and improving the person’s quality of life. Physical therapy and daily exercise may delay joint problems and improve the ability to move. Surgery to remove tonsils and adenoids may improve breathing among affected individuals with obstructive airway disorders and sleep apnea.  Surgery can also correct hernias, help drain excessive cerebrospinal fluid from the brain, and free nerves and nerve roots compressed by skeletal and other abnormalities. Corneal transplants may improve vision among patients with significant corneal clouding. Enzyme replacement therapy has proven useful in reducing non-neurological symptoms and pain. In 2006, the FDA approved the drug idursulfase (Elaprase) for the treatment of MPS II (Hunter syndrome).  This is the first drug shown to have any benefit for one of the mucopolysaccharidoses.

What is the prognosis?

The mucopolysaccharidoses syndromes share many clinical features but have varying degrees of severity. Most individuals with a mucopolysaccharidosis syndrome generally experience a period of normal development followed by a decline in physical and mental function. Longevity is dependent upon the particular syndrome. For example, children with a form of mucopolysaccharidosis called Hurler syndrome often die before age 10 from obstructive airway disease, respiratory infections, or cardiac complications.  A child with the type known as Scheie syndrome can live into adulthood, while one with a mild case of the type known as Hunter syndrome may live into his or her 50s or beyond.

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Mucolipidoses

What are Mucolipidoses?

The mucolipidoses (ML) are a group of inherited metabolic diseases that affect the body’s ability to carry out the normal turnover of various materials within cells. In ML, abnormal amounts of carbohydrates or fatty materials (lipids) accumulate in cells. Because our cells are not able to handle such large amounts of these substances, damage to the cells occurs, causing symptoms that range from mild learning disabilities to severe mental retardation and skeletal deformities.

The group includes four diseases:

• Mucolipidosis I (sialidosis)
• Mucolipidosis II (inclusion-cell, or I-cell, disease)
• Mucolipidosis III (pseudo-Hurler polydystrophy)
• Mucolipidosis IV

The MLs are classified as lysosomal storage diseases because they involve increased storage of substances in the lysosomes, which are specialized sac-like components within most cells. Patients with ML are born with a genetic defect in which their bodies either do not produce enough enzymes or, in some instances, produce ineffective forms of enzymes. Without functioning enzymes, lysosomes cannot break down carbohydrates and lipids and transport them to their normal destination. The molecules then accumulate in the cells of various tissues in the body, leading to swelling and damage of organs.

The mucolipidoses occur only when a child inherits two copies of the defective gene, one from each parent. When both parents carry a defective gene, each of their children faces a one in four chance of developing one of the MLs.

Is there any treatment?

No cure for ML currently exists.  Therapies are generally geared toward treating symptoms and providing supportive care to the child.  For individuals with corneal clouding, surgery to remove the thin layer over the eye has been shown to reduce the cloudiness in the eye.  However, this improvement is only temporary.   Physical and occupational therapy may help children with motor delays.  Children with language delays may benefit from speech therapy.    Children at risk for failure to thrive (growth failure) may need nutritional supplements, especially iron and vitamin B12 for patients with ML IV.  Respiratory infections should be treated immediately and fully with antibiotics.

What is the prognosis?

Symptoms of ML can be congenital (present at birth) or begin in early childhood or adolescence. Early symptoms can include vision problems and developmental delays. Over time, many children with ML develop poor mental capacities, have difficulty reaching normal developmental milestones, and, in many cases, eventually die of the disease.

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