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| Amyotrophic lateral sclerosis or ALS is a group of rare [[neurological]] diseases that mainly involve the nerve cells (neurons) responsible for controlling voluntary [[muscle]] movement. Voluntary muscles produce movements like chewing, walking, and talking. The disease is progressive, meaning the symptoms get worse over time. Currently, there is no cure for ALS and no effective treatment to halt, or reverse, the progression of the [[disease]]. | | == Amyotrophic Lateral Sclerosis (ALS) == |
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| ALS belongs to a wider group of disorders known as motor neuron diseases, which are caused by gradual deterioration (degeneration) and death of motor neurons. Motor neurons are nerve cells that extend from the brain to the spinal cord and to muscles throughout the body. These motor neurons initiate and provide vital communication links between the brain and the voluntary muscles. | | '''Amyotrophic lateral sclerosis (ALS)''' is a group of rare [[neurological]] diseases that primarily affect the nerve cells (neurons) responsible for controlling voluntary [[muscle]] movement. Voluntary muscles enable activities such as chewing, walking, and talking. ALS is a progressive disease, meaning its symptoms worsen over time. At present, there is no cure for ALS, nor any effective treatments to stop or reverse its progression. |
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| Messages from motor neurons in the brain (called upper motor neurons) are transmitted to motor neurons in the spinal cord and to motor nuclei of brain (called lower motor neurons) and from the spinal cord and motor nuclei of brain to a particular muscle or muscles.
| | ALS is classified as a type of [[motor neuron disease]] (MND), which is caused by the gradual degeneration and death of motor neurons. Motor neurons are essential for communication between the brain, spinal cord, and muscles. These cells initiate and maintain the connections necessary for voluntary muscle movement. In ALS, both the upper motor neurons (located in the brain) and the lower motor neurons (located in the spinal cord and brainstem) degenerate, disrupting this communication and leading to muscle weakness, twitching (fasciculations), and atrophy. |
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| In ALS, both the upper motor neurons and the lower motor neurons degenerate or die, and stop sending messages to the muscles. Unable to function, the muscles gradually weaken, start to twitch (called fasciculations), and waste away (atrophy). Eventually, the brain loses its ability to initiate and control voluntary movements.
| | As motor neurons die, the brain loses its ability to initiate and control voluntary movements. This can result in loss of mobility, speech, and the ability to breathe. Most people with ALS die from respiratory failure, typically within 3 to 5 years after the onset of symptoms. However, approximately 10% of people with ALS may survive for 10 years or longer. |
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| Early symptoms of ALS usually include muscle weakness or stiffness. Gradually all muscles under voluntary control are affected, and individuals lose their strength and the ability to speak, eat, move, and even breathe.
| | == Who Gets ALS? == |
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| Most people with ALS die from respiratory failure, usually within 3 to 5 years from when the symptoms first appear. However, about 10 percent of people with ALS survive for 10 or more years.
| | In 2016, the [[Centers for Disease Control and Prevention]] (CDC) estimated that between 14,000 and 15,000 people in the United States are living with ALS. It is a rare disease that affects individuals worldwide, irrespective of race or ethnic background. However, there are several factors that may influence an individual's likelihood of developing ALS. |
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| == Who gets ALS? == | | === Risk Factors === |
| | Several risk factors for ALS include: |
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| In 2016 the Centers for Disease Control and Prevention estimated that between 14,000 - 15,000 Americans have ALS. ALS is a common neuromuscular disease worldwide. It affects people of all races and ethnic backgrounds.
| | * '''Age''': The disease most commonly develops between the ages of 55 and 75, although it can occur at any age. |
| | * '''Gender''': Men are slightly more likely to develop ALS than women, but this difference diminishes with age. |
| | * '''Race and Ethnicity''': Caucasians, particularly non-Hispanic white individuals, have a higher incidence of ALS. |
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| There are several potential risk factors for ALS including:
| | Additionally, some studies suggest that military veterans are at a higher risk, being 1.5 to 2 times more likely to develop ALS. Possible explanations for this increased risk include exposure to environmental toxins such as lead and pesticides. |
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| * '''Age'''. Although the disease can strike at any age, symptoms most commonly develop between the ages of 55 and 75. | | === Types of ALS === |
| * '''Gender'''. Men are slightly more likely than women to develop ALS. However, as we age the difference between men and women disappears. | | * '''Sporadic ALS''': Over 90% of ALS cases are sporadic, meaning they occur without any clear family history. Although family members of someone with sporadic ALS are at a slightly increased risk, the overall likelihood remains low. |
| * '''Race and ethnicity.''' Most likely to develop the disease are Caucasians and non-Hispanics.
| | * '''Familial (Genetic) ALS''': Approximately 5-10% of ALS cases are familial, meaning they are inherited. Many cases of familial ALS are caused by mutations in the [[SOD1]] gene, while others are linked to mutations in the [[C9ORF72]] gene, which can also contribute to [[frontotemporal dementia]] (FTD). This form of ALS is referred to as [[ALS-FTD]] when both motor neuron symptoms and cognitive decline appear simultaneously. |
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| Some studies suggest that military veterans are about 1.5 to 2 times more likely to develop ALS. Although the reason for this is unclear, possible risk factors for veterans include exposure to lead, pesticides, and other environmental toxins. ALS is recognized as a service-connected disease by the U.S. Department of Veterans Affairs.
| | == Symptoms of ALS == |
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| '''Sporadic ALS'''<br />
| | The onset of ALS can be subtle, and early symptoms may be overlooked. However, as the disease progresses, the symptoms become more noticeable and can lead to a diagnosis. Early signs often include: |
| The majority of ALS cases (90 percent or more) are considered sporadic. This means the disease seems to occur at random with no clearly associated risk factors and no family history of the disease. Although family members of people with sporadic ALS are at an increased risk for the disease, the overall risk is very low and most will not develop ALS. | |
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| '''Familial (Genetic) ALS'''<br />
| | * [[Fasciculations]] (muscle twitches) in the arms, legs, or tongue |
| About 5 to 10 percent of all ALS cases are familial, which means that an individual inherits the disease from his or her parents. The familial form of ALS usually only requires one parent to carry the gene responsible for the disease. Mutations in more than a dozen genes have been found to cause familial ALS. About 25 to 40 percent of all familial cases (and a small percentage of sporadic cases) are caused by a defect in a gene known as “chromosome 9 open reading frame 72,” or ''C9ORF72''. Interestingly, the same mutation can be associated with atrophy of frontal-temporal lobes of the brain causing frontal-temporal lobe dementia. Some individuals carrying this mutation may show signs of both motor neuron and dementia symptoms (ALS-FTD). Another 12 to 20 percent of familial cases result from mutations in the gene that provides instructions for the production of the enzyme copper-zinc superoxide dismutase 1 (''SOD1'').
| | * Muscle cramps |
| | * [[Spasticity]] (muscle tightness) |
| | * Muscle weakness in the arms, legs, neck, or diaphragm |
| | * [[Dysarthria]] (slurred or nasal speech) |
| | * [[Dysphagia]] (difficulty chewing or swallowing) |
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| == What are the symptoms? ==
| | Some individuals may first notice difficulty performing simple tasks, such as buttoning a shirt, writing, or turning a key. Others may experience awkward walking or tripping when the symptoms initially affect the legs. |
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| The onset of ALS can be so subtle that the symptoms are overlooked but gradually these symptoms develop into more obvious weakness or atrophy that may cause a physician to suspect ALS. Some of the early symptoms include:
| | ALS can begin with either of the following: |
| | * '''Limb onset ALS''': When symptoms begin in the arms or legs. |
| | * '''Bulbar onset ALS''': When symptoms first affect speech or swallowing. |
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| * fasciculations (muscle twitches) in the arm, leg, shoulder, or tongue
| | As the disease progresses, muscle weakness and atrophy spread throughout the body. Affected individuals may lose the ability to walk, stand, or perform daily activities. Eventually, people with ALS may experience difficulty swallowing and eating, which increases the risk of choking and malnutrition. Weight loss is common due to rapid calorie consumption, and individuals may become malnourished. |
| * muscle cramps
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| * tight and stiff muscles (spasticity)
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| * muscle weakness affecting an arm, a leg, neck or diaphragm.
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| * slurred and nasal speech
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| * difficulty chewing or swallowing.
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| For many individuals the first sign of ALS may appear in the hand or arm as they experience difficulty with simple tasks such as buttoning a shirt, writing, or turning a key in a lock. In other cases, symptoms initially affect one of the legs, and people experience awkwardness when walking or running or they notice that they are tripping or stumbling more often.
| | Although ALS does not affect cognitive functions in most individuals, some may experience [[cognitive]] or [[behavioral changes]], with a small subset developing [[dementia]] over time. |
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| When symptoms begin in the arms or legs, it is referred to as “limb onset” ALS. Other individuals first notice speech or swallowing problems, termed “bulbar onset” ALS.
| | == Diagnosis of ALS == |
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| Regardless of where the symptoms first appear, muscle weakness and atrophy spread to other parts of the body as the disease progresses. Individuals may develop problems with moving, swallowing (dysphagia), speaking or forming words (dysarthria), and breathing (dyspnea).
| | ALS is diagnosed primarily based on the patient’s symptoms and a physical exam. There is no single test to confirm ALS, so a physician will typically perform a series of tests to rule out other conditions that may mimic ALS symptoms. The presence of both upper and lower motor neuron signs increases the likelihood of an ALS diagnosis. |
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| Although the sequence of emerging symptoms and the rate of disease progression vary from person to person, eventually individuals will not be able to stand or walk, get in or out of bed on their own, or use their hands and arms.
| | === Diagnostic Tests === |
| | Some of the diagnostic tests for ALS include: |
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| Individuals with ALS usually have difficulty swallowing and chewing food, which makes it hard to eat normally and increases the risk of choking. They also burn calories at a faster rate than most people without ALS. Due to these factors, people with ALS tend to lose weight rapidly and can become malnourished.
| | * '''Electromyography (EMG)''': This test records electrical activity in muscles and helps detect abnormal muscle activity associated with ALS. |
| | * '''Nerve Conduction Studies (NCS)''': Measures electrical activity in nerves and can reveal issues with nerve signals. |
| | * '''Magnetic Resonance Imaging (MRI)''': Although MRI scans are generally normal in ALS, they can identify other conditions like tumors or spinal cord issues that could explain symptoms. |
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| Because people with ALS usually retain their ability to perform higher mental processes such as reasoning, remembering, understanding, and problem solving, they are aware of their progressive loss of function and may become anxious and depressed.
| | Other diagnostic tools include blood and urine tests to rule out infections or other diseases that may mimic ALS. |
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| A small percentage of individuals may experience problems with language or decision-making, and there is growing evidence that some may even develop a form of dementia over time.
| | == Causes of ALS == |
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| Individuals with ALS will have difficulty breathing as the muscles of the respiratory system weaken. They eventually lose the ability to breathe on their own and must depend on a ventilator. Affected individuals also face an increased risk of pneumonia during later stages of the disease. Besides muscle cramps that may cause discomfort, some individuals with ALS may develop painful neuropathy (nerve disease or damage).
| | While the exact cause of ALS remains unknown, scientific studies suggest both genetic and environmental factors may contribute to its development. |
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| == How is ALS diagnosed? == | | === Genetic Factors === |
| | The discovery of [[SOD1]] mutations in 1993 marked a breakthrough in understanding ALS. Since then, additional genetic mutations have been identified. Notably, mutations in the [[C9ORF72]] gene are linked not only to ALS but also to [[frontotemporal dementia]] (FTD), indicating a genetic overlap between these two conditions. |
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| No one test can provide a definitive diagnosis of ALS. ALS is primarily diagnosed based on detailed history of the symptoms and signs observed by a physician during physical examination along with a series of tests to rule out other mimicking diseases. However, the presence of upper and lower motor neuron symptoms strongly suggests the presence of the disease.
| | Other mutations affect protein recycling processes, motor neuron structure, or susceptibility to environmental toxins, shedding light on the complex causes of ALS. |
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| Physicians will review an individual’s full medical history and conduct a neurologic examination at regular intervals to assess whether symptoms such as muscle weakness, atrophy of muscles, and spasticity are getting progressively worse.
| | === Environmental Factors === |
| | Environmental influences, such as exposure to toxins, infections, or physical trauma, are under investigation. Military veterans and athletes, for example, may be at increased risk due to environmental exposures. However, no single environmental factor has been consistently linked to ALS. |
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| ALS symptoms in the early stages of the disease can be similar to those of a wide variety of other, more treatable diseases or disorders. Appropriate tests can exclude the possibility of other conditions. | | == Treatment of ALS == |
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| '''Muscle and imaging tests'''<br />
| | There is no cure for ALS, but various treatments aim to alleviate symptoms, manage complications, and improve the quality of life for those affected. |
| Electromyography (EMG), a special recording technique that detects electrical activity of muscle fibers, can help diagnose ALS. Another common test is a nerve conduction study (NCS), which measures electrical activity of the nerves and muscles by assessing the nerve’s ability to send a signal along the nerve or to the muscle. Specific abnormalities in the NCS and EMG may suggest, for example, that the individual has a form of peripheral neuropathy (damage to peripheral nerves outside of the brain and spinal cord) or myopathy (muscle disease) rather than ALS.
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| A physician may also order a magnetic resonance imaging (MRI) test, a noninvasive procedure that uses a magnetic field and radio waves to produce detailed images of the brain and spinal cord. Standard MRI scans are generally normal in people with ALS. However, they can reveal other problems that may be causing the symptoms, such as a spinal cord tumor, a herniated disk in the neck that compresses the spinal cord, syringomyelia (a cyst in the spinal cord), or cervical spondylosis (abnormal wear affecting the spine in the neck).
| | === Medications === |
| | Two FDA-approved drugs for ALS are: |
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| '''Laboratory tests'''<br />
| | * [[Riluzole]] (Rilutek): This drug may prolong survival by a few months by reducing the toxicity of glutamate, a neurotransmitter involved in motor neuron damage. |
| Based on the person’s symptoms, test results, and findings from the examination, a physician may order tests on blood and urine samples to eliminate the possibility of other diseases.
| | * [[Edaravone]] (Radicava): Edaravone has shown the potential to slow the decline in motor function. |
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| '''Tests for other diseases and disorders'''<br />
| | Physicians may also prescribe medications to address symptoms such as muscle cramps, saliva management, and mood disorders. |
| Infectious diseases such as human immunodeficiency virus (HIV), human T-cell leukemia virus (HTLV), polio, and West Nile virus can, in some cases, cause ALS-like symptoms. Neurological disorders such as multiple sclerosis, post-polio syndrome, multifocal motor neuropathy, and spinal and bulbar muscular atrophy (Kennedy’s disease) also can mimic certain features of the disease and should be considered by physicians attempting to make a diagnosis. Fasciculations and muscle cramps also occur in benign conditions.
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| Because of the prognosis carried by this diagnosis and the variety of diseases or disorders that can resemble ALS in the early stages of the disease, individuals may wish to obtain a second neurological opinion.
| | === Supportive Care === |
| | Supportive care is an essential part of managing ALS and is provided by a multidisciplinary team of healthcare professionals, including: |
| | * Physicians |
| | * [[Physical therapists]] |
| | * [[Occupational therapists]] |
| | * [[Speech therapists]] |
| | * Nutritionists |
| | * Respiratory therapists |
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| == What causes ALS? ==
| | Therapies can help manage symptoms such as muscle stiffness, mobility issues, and swallowing difficulties. In some cases, individuals may require [[feeding tubes]] or [[noninvasive ventilation]] to aid with breathing. |
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| The cause of ALS is not known, and scientists do not yet know why ALS strikes some people and not others. However, evidence from scientific studies suggests that both genetics and environment play a role in the development of ALS.
| | === Physical and Speech Therapy === |
| | Physical therapy can help strengthen unaffected muscles and improve mobility, while speech therapy assists individuals in maintaining communication as the disease progresses. |
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| '''Genetics'''<br />
| | === Nutritional Support === |
| An important step toward determining ALS risk factors was made in 1993 when scientists supported by the National Institute of Neurological Disorders and Stroke (NINDS) discovered that mutations in the ''SOD1'' gene were associated with some cases of familial ALS. Although it is still not clear how mutations in the'' SOD1'' gene lead to motor neuron degeneration, there is increasing evidence that the gene playing a role in producing mutant SOD1 protein can become toxic.
| | As ALS can impair the ability to eat and swallow, nutritionists play a key role in ensuring patients receive adequate nourishment, often recommending a feeding tube to prevent malnutrition. |
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| Since then, more than a dozen additional genetic mutations have been identified, many through NINDS-supported research, and each of these gene discoveries is providing new insights into possible mechanisms of ALS.
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| The discovery of certain genetic mutations involved in ALS suggests that changes in the processing of RNA molecules may lead to ALS-related motor neuron degeneration. RNA molecules are one of the major macromolecules in the cell involved in directing the synthesis of specific proteins as well as gene regulation and activity.
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| Other gene mutations indicate defects in the natural process in which malfunctioning proteins are broken down and used to build new ones, known as protein recycling. Still others point to possible defects in the structure and shape of motor neurons, as well as increased susceptibility to environmental toxins. Overall, it is becoming increasingly clear that a number of cellular defects can lead to motor neuron degeneration in ALS.
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| In 2011 another important discovery was made when scientists found that a defect in the ''C9ORF72'' gene is not only present in a significant subset of individuals with ALS but also in some people with a type of frontotemporal dementia (FTD). This observation provides evidence for genetic ties between these two neurodegenerative disorders. Most researchers now believe ALS and some forms of FTD are related disorders.
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| '''Environmental factors'''<br />
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| In searching for the cause of ALS, researchers are also studying the impact of environmental factors. Researchers are investigating a number of possible causes such as exposure to toxic or infectious agents, viruses, physical trauma, diet, and behavioral and occupational factors.
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| For example, researchers have suggested that exposure to toxins during warfare, or strenuous physical activity, are possible reasons for why some veterans and athletes may be at increased risk of developing ALS.
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| Although there has been no consistent association between any environmental factor and the risk of developing ALS, future research may show that some factors are involved in the development or progression of the disease.
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| == How is ALS treated? == | |
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| No cure has yet been found for ALS. However, there are treatments available that can help control symptoms, prevent unnecessary complications, and make living with the disease easier.
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| Supportive care is best provided by multidisciplinary teams of health care professionals such as physicians; pharmacists; physical, occupational, and speech therapists; nutritionists; social workers; respiratory therapists and clinical psychologists; and home care and hospice nurses. These teams can design an individualized treatment plan and provide special equipment aimed at keeping people as mobile, comfortable, and independent as possible.
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| '''Medication'''<br />
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| The U.S. Food and Drug Administration (FDA) has approved the drugs riluzole (Rilutek) and edaravone (Radicava) to treat ALS. Riluzole is believed to reduce damage to motor neurons by decreasing levels of glutamate, which transports messages between nerve cells and motor neurons. Clinical trials in people with ALS showed that riluzole prolongs survival by a few months, particularly in the bulbar form of the disease, but does not reverse the damage already done to motor neurons. Edaravone has been shown to slow the decline in clinical assessment of daily functioning in persons with ALS.
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| Physicians can also prescribe medications to help manage symptoms of ALS, including muscle cramps, stiffness, excess saliva and phlegm, and the pseudobulbar affect (involuntary or uncontrollable episodes of crying and/or laughing, or other emotional displays). Drugs also are available to help individuals with pain, depression, sleep disturbances, and constipation. Pharmacists can give advice on the proper use of medications and monitor a person’s prescriptions to avoid risks of drug interactions.
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| '''Physical therapy'''<br />
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| Physical therapy and special equipment can enhance an individual’s independence and safety throughout the course of ALS. Gentle, low-impact aerobic exercise such as walking, swimming, and stationary bicycling can strengthen unaffected muscles, improve cardiovascular health, and help people fight fatigue and depression. Range of motion and stretching exercises can help prevent painful spasticity and shortening (contracture) of muscles.
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| Physical therapists can recommend exercises that provide these benefits without overworking muscles. Occupational therapists can suggest devices such as ramps, braces, walkers, and wheelchairs that help individuals conserve energy and remain mobile.
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| '''Speech therapy'''<br />
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| People with ALS who have difficulty speaking may benefit from working with a speech therapist, who can teach adaptive strategies to speak louder and more clearly. As ALS progresses, speech therapists can help people maintain the ability to communicate. They can recommend aids such as computer-based speech synthesizers that use eye-tracking technology and can help people develop ways for responding to yes-or-no questions with their eyes or by other nonverbal means.
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| Some people with ALS may choose to use voice banking while they are still able to speak as a process of storing their own voice for future use in computer-based speech synthesizers. These methods and devices help people communicate when they can no longer speak or produce vocal sounds.
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| '''Nutritional support'''<br />
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| Nutritional support is an important part of the care of people with ALS. It has been shown that individuals with ALS will get weaker if they lose weight. Nutritionists can teach individuals and caregivers how to plan and prepare small meals throughout the day that provide enough calories, fiber, and fluid and how to avoid foods that are difficult to swallow. People may begin using suction devices to remove excess fluids or saliva and prevent choking. When individuals 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.
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| '''Breathing support'''<br />
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| As the muscles responsible for breathing start to weaken, people may experience shortness of breath during physical activity and difficulty breathing at night or when lying down. Doctors may test an individual’s breathing to determine when to recommend a treatment called noninvasive ventilation (NIV). NIV refers to breathing support that is usually delivered through a mask over the nose and/or mouth. Initially, NIV may only be necessary at night. When muscles are no longer able to maintain normal oxygen and carbon dioxide levels, NIV may be used full-time. NIV improves the quality of life and prolongs survival for many people with ALS.
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| Because the muscles that control breathing become weak, individuals with ALS may also have trouble generating a strong cough. There are several techniques to help people increase forceful coughing, including mechanical cough assist devices and breath stacking. In breath stacking, a person takes a series of small breaths without exhaling until the lungs are full, briefly holds the breath, and then expels the air with a cough.
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| As the disease progresses and muscles weaken further, individuals may consider forms of mechanical ventilation (respirators) in which a machine inflates and deflates the lungs. Doctors may place a breathing tube through the mouth or may surgically create a hole at the front of the neck and insert a tube leading to the windpipe (tracheostomy). The tube is connected to a respirator.
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| Individuals with ALS and their families often consider several factors when deciding whether and when to use ventilation support. These devices differ in their effect on a 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. People may choose to be fully informed about these considerations and the long-term effects of life without movement before they make decisions about ventilation support.
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| | === Breathing Support === |
| | Noninvasive ventilation (NIV) may be used to help individuals breathe more easily as respiratory muscles weaken. In advanced stages, invasive mechanical ventilation may be considered. |
| {{neuroscience}} | | {{neuroscience}} |
| | | [[Category:Motor neuron diseases]] |
| | | [[Category:Neurological disorders]] |
| {{stb}}
| | [[Category:Rare diseases]] |
| [[Category:Uncategorized]] | | [[Category:Neurodegenerative diseases]] |
Amyotrophic Lateral Sclerosis (ALS)
Amyotrophic lateral sclerosis (ALS) is a group of rare neurological diseases that primarily affect the nerve cells (neurons) responsible for controlling voluntary muscle movement. Voluntary muscles enable activities such as chewing, walking, and talking. ALS is a progressive disease, meaning its symptoms worsen over time. At present, there is no cure for ALS, nor any effective treatments to stop or reverse its progression.
ALS is classified as a type of motor neuron disease (MND), which is caused by the gradual degeneration and death of motor neurons. Motor neurons are essential for communication between the brain, spinal cord, and muscles. These cells initiate and maintain the connections necessary for voluntary muscle movement. In ALS, both the upper motor neurons (located in the brain) and the lower motor neurons (located in the spinal cord and brainstem) degenerate, disrupting this communication and leading to muscle weakness, twitching (fasciculations), and atrophy.
As motor neurons die, the brain loses its ability to initiate and control voluntary movements. This can result in loss of mobility, speech, and the ability to breathe. Most people with ALS die from respiratory failure, typically within 3 to 5 years after the onset of symptoms. However, approximately 10% of people with ALS may survive for 10 years or longer.
Who Gets ALS?
In 2016, the Centers for Disease Control and Prevention (CDC) estimated that between 14,000 and 15,000 people in the United States are living with ALS. It is a rare disease that affects individuals worldwide, irrespective of race or ethnic background. However, there are several factors that may influence an individual's likelihood of developing ALS.
Risk Factors
Several risk factors for ALS include:
- Age: The disease most commonly develops between the ages of 55 and 75, although it can occur at any age.
- Gender: Men are slightly more likely to develop ALS than women, but this difference diminishes with age.
- Race and Ethnicity: Caucasians, particularly non-Hispanic white individuals, have a higher incidence of ALS.
Additionally, some studies suggest that military veterans are at a higher risk, being 1.5 to 2 times more likely to develop ALS. Possible explanations for this increased risk include exposure to environmental toxins such as lead and pesticides.
Types of ALS
- Sporadic ALS: Over 90% of ALS cases are sporadic, meaning they occur without any clear family history. Although family members of someone with sporadic ALS are at a slightly increased risk, the overall likelihood remains low.
- Familial (Genetic) ALS: Approximately 5-10% of ALS cases are familial, meaning they are inherited. Many cases of familial ALS are caused by mutations in the SOD1 gene, while others are linked to mutations in the C9ORF72 gene, which can also contribute to frontotemporal dementia (FTD). This form of ALS is referred to as ALS-FTD when both motor neuron symptoms and cognitive decline appear simultaneously.
Symptoms of ALS
The onset of ALS can be subtle, and early symptoms may be overlooked. However, as the disease progresses, the symptoms become more noticeable and can lead to a diagnosis. Early signs often include:
- Fasciculations (muscle twitches) in the arms, legs, or tongue
- Muscle cramps
- Spasticity (muscle tightness)
- Muscle weakness in the arms, legs, neck, or diaphragm
- Dysarthria (slurred or nasal speech)
- Dysphagia (difficulty chewing or swallowing)
Some individuals may first notice difficulty performing simple tasks, such as buttoning a shirt, writing, or turning a key. Others may experience awkward walking or tripping when the symptoms initially affect the legs.
ALS can begin with either of the following:
- Limb onset ALS: When symptoms begin in the arms or legs.
- Bulbar onset ALS: When symptoms first affect speech or swallowing.
As the disease progresses, muscle weakness and atrophy spread throughout the body. Affected individuals may lose the ability to walk, stand, or perform daily activities. Eventually, people with ALS may experience difficulty swallowing and eating, which increases the risk of choking and malnutrition. Weight loss is common due to rapid calorie consumption, and individuals may become malnourished.
Although ALS does not affect cognitive functions in most individuals, some may experience cognitive or behavioral changes, with a small subset developing dementia over time.
Diagnosis of ALS
ALS is diagnosed primarily based on the patient’s symptoms and a physical exam. There is no single test to confirm ALS, so a physician will typically perform a series of tests to rule out other conditions that may mimic ALS symptoms. The presence of both upper and lower motor neuron signs increases the likelihood of an ALS diagnosis.
Diagnostic Tests
Some of the diagnostic tests for ALS include:
- Electromyography (EMG): This test records electrical activity in muscles and helps detect abnormal muscle activity associated with ALS.
- Nerve Conduction Studies (NCS): Measures electrical activity in nerves and can reveal issues with nerve signals.
- Magnetic Resonance Imaging (MRI): Although MRI scans are generally normal in ALS, they can identify other conditions like tumors or spinal cord issues that could explain symptoms.
Other diagnostic tools include blood and urine tests to rule out infections or other diseases that may mimic ALS.
Causes of ALS
While the exact cause of ALS remains unknown, scientific studies suggest both genetic and environmental factors may contribute to its development.
Genetic Factors
The discovery of SOD1 mutations in 1993 marked a breakthrough in understanding ALS. Since then, additional genetic mutations have been identified. Notably, mutations in the C9ORF72 gene are linked not only to ALS but also to frontotemporal dementia (FTD), indicating a genetic overlap between these two conditions.
Other mutations affect protein recycling processes, motor neuron structure, or susceptibility to environmental toxins, shedding light on the complex causes of ALS.
Environmental Factors
Environmental influences, such as exposure to toxins, infections, or physical trauma, are under investigation. Military veterans and athletes, for example, may be at increased risk due to environmental exposures. However, no single environmental factor has been consistently linked to ALS.
Treatment of ALS
There is no cure for ALS, but various treatments aim to alleviate symptoms, manage complications, and improve the quality of life for those affected.
Medications
Two FDA-approved drugs for ALS are:
- Riluzole (Rilutek): This drug may prolong survival by a few months by reducing the toxicity of glutamate, a neurotransmitter involved in motor neuron damage.
- Edaravone (Radicava): Edaravone has shown the potential to slow the decline in motor function.
Physicians may also prescribe medications to address symptoms such as muscle cramps, saliva management, and mood disorders.
Supportive Care
Supportive care is an essential part of managing ALS and is provided by a multidisciplinary team of healthcare professionals, including:
Therapies can help manage symptoms such as muscle stiffness, mobility issues, and swallowing difficulties. In some cases, individuals may require feeding tubes or noninvasive ventilation to aid with breathing.
Physical and Speech Therapy
Physical therapy can help strengthen unaffected muscles and improve mobility, while speech therapy assists individuals in maintaining communication as the disease progresses.
Nutritional Support
As ALS can impair the ability to eat and swallow, nutritionists play a key role in ensuring patients receive adequate nourishment, often recommending a feeding tube to prevent malnutrition.
Breathing Support
Noninvasive ventilation (NIV) may be used to help individuals breathe more easily as respiratory muscles weaken. In advanced stages, invasive mechanical ventilation may be considered.
