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Amyotrophic lateral sclerosis

ALS, Lou Gehrig disease, Amyotrophic lateral sclerosis type 1, ALS1

Overview

Amyotrophic lateral sclerosis (ALS), is a progressive motor neuron disease which leads to problems with muscle control and movement. There are various types of ALS, which are distinguished by their signs and symptoms and their cause. Early symptoms may include muscle twitching, cramping, stiffness, or weakness, eventually followed by slurred speech and difficulty chewing or swallowing (dysphagia). As the disease progresses, individuals become weaker are are eventually wheelchair-dependent. Death often results from respiratory failure within 2 to 10 years after the onset of symptoms. Most affected individuals have a sporadic (not inherited) form of ALS; about 5-10% have a familial (inherited) form of the condition. Familial ALS may caused by mutations in any one of several genes and the pattern of inheritance varies depending on the gene involved. Treatment is generally supportive.

Symptoms - Amyotrophic lateral sclerosis

Early signs and symptoms of ALS include:

  • Difficulty walking or doing your normal daily activities
  • Tripping and falling
  • Weakness in your leg, feet or ankles
  • Hand weakness or clumsiness
  • Slurred speech or trouble swallowing
  • Muscle cramps and twitching in your arms, shoulders and tongue
  • Difficulty holding your head up or keeping good posture
ALS often starts in the hands, feet or limbs, and then spreads to other parts of your body. As the disease advances and nerve cells are destroyed, your muscles progressively weaken. This eventually affects chewing, swallowing, speaking and breathing.

ALS doesn't usually affect your bowel or bladder control, your senses or your thinking ability. It's possible to remain actively involved with your family and friends.

Causes - Amyotrophic lateral sclerosis

ALS is inherited in 5 to 10 percent of cases, while the rest have no known cause. Researchers are studying several possible causes of ALS, including:

  • Gene mutation. Various genetic mutations can lead to inherited ALS, which causes nearly the same symptoms as the noninherited form.
  • Chemical imbalance. People with ALS generally have higher than normal levels of glutamate, a chemical messenger in the brain, around the nerve cells in their spinal fluid. Too much glutamate is known to be toxic to some nerve cells.
  • Disorganized immune response. Sometimes a person's immune system begins attacking some of his or her body's own normal cells, which may lead to the death of nerve cells.
  • Protein mishandling. Mishandled proteins within the nerve cells may lead to a gradual accumulation of abnormal forms of these proteins in the cells, destroying the nerve cells.

Established risk factors for ALS include:

  • Heredity. Five to 10 percent of the people with ALS inherited it (familial ALS). In most people with familial ALS, their children have a 50-50 chance of developing the disease.
  • Age. ALS risk increases with age, and is most common between the ages of 40 and 60.
  • Sex. Before the age of 65, slightly more men than women develop ALS. This sex difference disappears after age 70.
  • Genetics. Some studies examining the entire human genome (genomewide association studies) found many similarities in the genetic variations of people with familial ALS and some people with noninherited ALS. These genetic variations might make people more susceptible to ALS.

Environmental factors may trigger ALS. Some that may affect ALS risk include:

  • Smoking. Smoking is the only likely environmental risk factor for ALS. The risk seems to be greatest for women, particularly after menopause.
  • Environmental toxin exposure. Some evidence suggests that exposure to lead or other substances in the workplace or at home may be linked to ALS. Much study has been done, but no single agent or chemical has been consistently associated with ALS.
  • Military service. Recent studies indicate that people who have served in the military are at higher risk of ALS. It's unclear exactly what about military service may trigger the development of ALS. It may include exposure to certain metals or chemicals, traumatic injuries, viral infections, and intense exertion.

Prevention - Amyotrophic lateral sclerosis

You may want to see a genetic counselor, if you have a family history of ALS.

Diagnosis - Amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is difficult to diagnose early because it may mimic several other neurological diseases. Tests to rule out other conditions may include:

  • Electromyogram (EMG). During an EMG, your doctor inserts a needle electrode through your skin into various muscles. The test evaluates the electrical activity of your muscles when they contract and when they're at rest.

    Abnormalities in muscles seen in an electromyogram can help doctors diagnose ALS, or determine if you have a different muscle or nerve condition that may be causing your symptoms. It can also help guide your exercise therapy.

  • Nerve conduction study. This study measures your nerves' ability to send impulses to muscles in different areas of your body. This test can determine if you have nerve damage or certain muscle diseases.
  • Magnetic resonance imaging (MRI). Using radio waves and a powerful magnetic field, an MRI produces detailed images of your brain and spinal cord. An MRI can spot spinal cord tumors, herniated disks in your neck or other conditions that may be causing your symptoms.
  • Blood and urine tests. Analyzing samples of your blood and urine in the laboratory may help your doctor eliminate other possible causes of your signs and symptoms.
  • Spinal tap (lumbar puncture). Sometimes a specialist may remove a sample of your spinal fluid for analysis. A specialist inserts a small needle between two vertebrae in your lower back and removes a small amount of cerebrospinal fluid for testing in the laboratory.
  • Muscle biopsy. If your doctor believes you may have a muscle disease rather than ALS, you may undergo a muscle biopsy. While you're under local anesthesia, a small portion of your muscle is removed and sent to a lab for analysis.

Prognosis - Amyotrophic lateral sclerosis

Regardless of the part of the body first affected with the disease, muscle weakness and atrophy spread to other parts of the body and eventually of the respiratory. Although ventilation support can ease problems with breathing and prolong survival, it does not affect the progression of ALS. Most people with ALS die from respiratory failure within 3 to 5 years from the onset of symptoms. About 25 percent of patients live more than 5 years after diagnosis.

Treatment - Amyotrophic lateral sclerosis

Management of ALS attempts to relieve symptoms and extend life expectancy. This supportive care is best provided by multidisciplinary teams of health care professionals working with the person and their caregivers to keep them as mobile and comfortable as possible.

Medications:

Riluzole (Rilutek) has been found to modestly improve survival. It lengthens survival by several months, and may have a greater survival benefit for those with a bulbar onset. It also extends the time before a person needs ventilation support. People taking it must be monitored for liver damage (occurring in about 10% of people taking the drug). It is approved by Food and Drug Administration (US) and recommended by the National Institute for Clinical Excellence (UK). Riluzole does not reverse damage already done to motor neurons.

Other medications may be used to help reduce fatigue, ease muscle cramps, control spasticity, and reduce excess saliva and phlegm. Drugs also are available to help patients with pain, depression, sleep disturbances, dysphagia, and constipation. Baclofen and diazepam are often prescribed to control the spasticity caused by ALS, and trihexyphenidyl or amitriptyline may be prescribed when people with ALS begin having trouble swallowing their saliva.

Breathing support:

When the muscles that assist in breathing weaken, use of ventilatory assistance (intermittent positive pressure ventilation, bilevel positive airway pressure (BiPAP), or biphasic cuirass ventilation (BCV) may be used to aid breathing. Such devices artificially inflate the person's lungs from various external sources that are applied directly to the face or body. When muscles are no longer able to maintain oxygen and carbon dioxide levels, these devices may be used full-time. BCV has the added advantage of being able to assist in clearing secretions by using high-frequency oscillations followed by several positive expiratory breaths. People may eventually consider forms of mechanical ventilation (respirators) in which a machine inflates and deflates the lungs. To be effective, this may require a tube that passes from the nose or mouth to the windpipe (trachea) and for long-term use, an operation such as a tracheotomy, in which a plastic breathing tube is inserted directly in the person's windpipe through an opening in the neck.

Persons and their families should consider several factors when deciding whether and when to use one of these options. Ventilation devices differ in their effect on the person's quality of life and in cost. Although ventilation support can ease problems with breathing and prolong survival, it does not affect the progression of ALS. Patients need to be fully informed about these considerations and the long-term effects of life without movement before they make decisions about ventilation support and have deep discussions on quality of life. Some persons under long-term tracheotomy intermittent positive pressure ventilation with deflated cuffs or cuffless tracheotomy tubes (leak ventilation) are able to speak, provided their bulbar muscles are strong enough, though in all cases speech will be lost as the disease progresses. This technique preserves speech in some persons with long-term mechanical ventilation. Other persons may be able to use a speaking valve such as a Passey-Muir speaking valve with the assistance and guidance of a speech-language pathologist.

External ventilation machines that use the ventilation mode of BiPAP are frequently used to support breathing, initially at night, and later during the daytime, as well. The use of BPAP (more often referred to as noninvasive ventilation, NIV) is only a temporary remedy, however, and long before BPAP stops being effective, persons should decide whether to have a tracheotomy and long-term mechanical ventilation. At this point, some persons choose palliative hospice care.

Therapy:

Physical therapy plays a large role in rehabilitation for individuals with ALS. Specifically, physical and occupational therapists can set goals and promote benefits for individuals with ALS by delaying loss of strength, maintaining endurance, limiting pain, preventing complications, and promoting functional independence.

Occupational therapy and special equipment such as assistive technology can also enhance patients' independence and safety throughout the course of ALS. Gentle, low-impact aerobic exercise such as performing activities of daily living, walking, swimming, and stationary bicycling can strengthen unaffected muscles, improve cardiovascular health, and help patients fight fatigue and depression. Range of motion and stretching exercises can help prevent painful spasticity and shortening (contracture) of muscles. Physical and occupational therapists can recommend exercises that provide these benefits without overworking muscles. They can suggest devices such as ramps, braces, walkers, bathroom equipment (shower chairs, toilet risers, etc.), and wheelchairs that help patients remain mobile. Occupational therapists can provide or recommend equipment and adaptations to enable people to retain as much safety and independence in activities of daily living as possible.

ALS patients who have difficulty speaking may benefit from working with a speech-language pathologist. These health professionals can teach patients adaptive strategies such as techniques to help them speak louder and more clearly. As ALS progresses, speech-language pathologists can recommend the use of augmentative and alternative communication such as voice amplifiers, speech-generating devices (or voice output communication devices) and/or low tech communication techniques such as alphabet boards or yes/no signals.

Nutrttion:

Patients and caregivers can learn from dieticians how to plan and prepare numerous small meals throughout the day that provide enough calories, fiber, and fluid and how to avoid foods that are difficult to swallow. Patients may begin using suction devices to remove excess fluids or saliva and prevent choking. Occupational therapists can assist with recommendations for adaptive equipment to ease the physical task of self-feeding. Speech-language pathologists make food choice recommendations that are more conducive to their unique deficits and abilities. When patients can no longer get enough nourishment from eating, doctors may advise inserting a feeding tube into the stomach. The use of a feeding tube also reduces the risk of choking and pneumonia that can result from inhaling liquids into the lungs. The tube is not painful and does not prevent patients from eating food orally if they wish.

Researchers have stated, "ALS patients have a chronically deficient intake of energy and recommended augmentation of energy intake" and have a severe loss of appetite. Both animal and human research suggest that ALS patients should be encouraged to consume as many calories as possible and not to restrict their caloric intake. As of 2012, "a lack of robust evidence for interventions" remained for the management of weight loss.

Palliative care:

Social workers and home care and hospice nurses help people with ALS, their families, and caregivers with the medical, emotional, and financial challenges of coping, particularly during the final stages of the disease. Social workers provide support such as assistance in obtaining financial aid, arranging durable power of attorney, preparing a living will, and finding support groups for patients and caregivers. Home nurses are available not only to provide medical care, but also to teach caregivers about tasks such as maintaining respirators, giving feedings, and moving patients to avoid painful skin problems and contractures. Home hospice nurses work in consultation with physicians to ensure proper medication, pain control, and other care affecting the quality of life of patients who wish to remain at home. The home hospice team can also counsel patients and caregivers about end-of-life issues.

Resources - Amyotrophic lateral sclerosis

  • Research Publications
  • NIH
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