Amyotrophic lateral sclerosis (ALS), sometimes called Lou Gehrig's disease, is a nervous system disease that destroys the neurons that control voluntary muscles.
ALS damages both upper and lower motor neurons, which causes muscles to gradually weaken and eventually lose function. All voluntary movement is eventually lost, and the muscles become paralyzed.
Learn about symptoms, causes, diagnosis, and treatment.
How do symptoms of ALS begin?
The onset of symptoms is usually gradual. About 70% of people with ALS first report worsening and asymmetric limb weakness which often begins with a foot drop or trouble with precise hand motions. If the upper centers are involved, there may be difficulty eating, chewing, coughing, breathing, and talking. Leg involvement is characterized by weakness, stiffness, cramps, loss of coordination, and muscular atrophy. Affected people may have trouble walking, lifting, and climbing stairs.
Localized muscular discomfort that lasts for many weeks may indicate the start of weakening and atrophy; pain may be severe in the later stages of the disease. People with ALS are unable to breathe without ventilator assistance when the diaphragm and chest wall muscles weaken. The most prevalent cause of death in people with ALS is respiratory failure, which generally occurs within 3-5 years after symptoms start.
Lou Gehrig's disease is an incurable, progressive, and fatal condition. There is currently no cure for ALS or an effective treatment to slow or stop the disease's course.
What are symptoms of ALS?
ALS symptoms may appear gradually and worsen over time. Symptoms normally appear after the age of 50, although they can appear at younger ages as well. Initial symptoms may be mild and can begin with muscular twitching, weakness, and in some cases, slurred speech.
- Limb-onset disease
- Bulbar-onset disease (when symptoms first occur in the neck or face)
- Slurred speech
- Difficulty swallowing
- Respiratory-onset disease
- Breathing difficulties
- Shortness of breath
- Waking up repeatedly during the night because the brain is briefly deprived of oxygen when lying down
- Advanced symptoms
- Muscle weakness
- Muscle atrophy
- Movement difficulty
- Excess saliva from reduced swallowing
- Thicker saliva may sometimes be difficult to clear from the chest or throat due to the weakening of muscles
- Excess yawning
- Difficulties with concentration, planning, and use of language
- Breathing difficulties, such as shortness of breath
- End-stage symptoms
- Increasing body paralysis
- Significant shortness of breath
- Secondary symptoms
People with ALS gradually lose muscle strength and coordination, which worsens with time. Weakness may begin in the arms or legs or impair the ability to breathe or swallow. As the condition progresses, additional muscle groups are affected and may cause:
- Twitching and cramping of muscles, especially those in the hands and feet
- Loss of motor control in the hands and arms
- Tripping and falling
- Severe tiredness (fatigue)
- Difficulty walking, lifting, and climbing stairs
- Difficulty breathing
- Difficulty swallowing (choking easily, drooling, or gagging)
- Head drop due to weakness of the neck muscles
- Speech problems, such as a slow or abnormal speech pattern (slurring of words)
- Voice changes, hoarseness
- Muscle cramps
- Muscle stiffness (spasticity)
- Muscle contractions
- Weight loss
Affected people may only be able to move their eyes. Others may believe they are in a coma, although they can generally see, hear, taste, smell, and feel being touched. Bowels, bladder control, and function of the heart are usually unaffected.
What are the possible causes of ALS?
Because no clear causes of the disease have been established, most cases are believed to develop randomly. It is still unclear why motor neurons begin to die in people with ALS.
Although it is not apparent why Lou Gehrig's disease occurs, studies indicate that certain risk factors are most likely involved.
Roughly 30% of ALS cases are associated with mutations occurring in genes: FUS/TLS, TDP43, and SOD1.
- FUS/TLS and TDP43 (DNA/RNA-binding protein): Although the processes by which genetic differences cause ALS are unknown, the protein produced by FUS/TLS plays a function to control the translation of RNA to protein in motor neurons. This function is like that of the protein encoded by TDP43. Variations in both genes produce protein build-up in the cytoplasm of neurons, which is thought to lead to neuronal dysfunction.
- SOD1: Defects in SOD1, which generates the enzyme superoxide dismutase, appear to promote motor neuron death by damaging chemicals called free radicals (molecular by-products of normal cell metabolism that can accumulate in and destroy cells). SOD1 mutations reduce the SOD enzyme's ability to neutralize free radicals in neurons.
- UBQLN2: Scientists have reported that ALS-related mutations in the UBQLN2 gene offered information on the pathogenic mechanism that drives neuronal degeneration in people with ALS. UBQLN2 is a protein that recycles damaged proteins from neurons in the spinal cord, as well as neurons in the cortex and hippocampus of the brain. Mutations in UBQLN2, like those in FUS/TLS and TDP43, cause protein accumulation in neurons.
Other risk factors of ALS include:
- Hereditary factors (10% of ALS cases are inherited from a mutated gene, also called familial ALS)
- Age (average age at diagnosis of ALS is 55 years, and most people who develop the disease are between 40-70 years)
- Gender (ALS is 20% more common in men than in women, although the incidence is similar between men and women with increasing age)
- Occupation (for unknown reasons, people who served in the United States Armed Forces are more likely to develop ALS than people who did not serve in the military.
- Mitochondrial dysfunction
- Heavy metal toxicity
- Head and neck trauma
- Genetic predisposition
- Low levels of magnesium and calcium
- Antioxidant deficiency, including SOD and glutathione
- Depletion of essential fatty acids
- Trouble digesting protein properly
- Low levels of vitamins E and B12
- Exposure to toxins, including pesticides (environmental exposures to lead, mercury, and cyanobacteria have been studied for their potential role to raise the risk of ALS)
- Problems with the immune system
How is ALS diagnosed?
In order to be diagnosed with Lou Gehrig's disease, a person must exhibit symptoms of both upper and lower motor neuron impairment that cannot be ascribed to other causes. No one test may offer a conclusive diagnosis of ALS. Diagnosis is primarily dependent on the symptoms observed in the person and a set of tests to rule out other diseases.
Physicians will ask for a complete medical history and generally perform a neurologic examination at regular intervals to see whether symptoms such as muscular weakness, atrophy of muscles, hyperreflexia, and spasticity are growing worse.
Because ALS symptoms in the early stages can be similar to those of a wide range of other, more curable diseases or disorders, proper tests must be performed to rule out the likelihood of other problems.
Tests used to confirm Lou Gehrig's disease include:
- Electromyography (EMG): This is a diagnostic test used to determine the health of muscles and the nerve cells that control them (motor neurons). The results of an EMG can reveal nerve and muscle dysfunction or issues with nerve-to-muscle signal transmission. Certain EMG results can help confirm an ALS diagnosis.
- Nerve conduction study (NCS): This test assesses electrical energy by examining the nerve's capacity to deliver a signal. Specific anomalies in the NCS and EMG may indicate ALS or rule it out.
- MRI: This is a noninvasive test that uses a magnetic field and radio waves to create detailed pictures of the brain and spinal cord. In people with ALS, standard MRI scans are normal. They can, however, provide evidence of other issues that may be causing the symptoms.
- Other tests:
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What are treatment options for ALS?
ALS treatment often necessitates a multidisciplinary team approach, which has been linked to better survival and treatment satisfaction. However, there is currently no cure for ALS.
ALS treatment consists of two major components:
- Rilutek (riluzole): In clinical studies, riluzole was demonstrated to extend life by 3-5 months on average, but it did not significantly delay muscle degeneration.
- Radicava (edaravone): This delays the rate of functional loss in certain people with ALS. The advantages appear to be more obvious in people with early ALS.
- Medications: Some people with ALS may experience pain for different reasons, which can be managed with several medications depending on the type of pain.
- Baclofen, tizanidine, or diazepam: Muscle relaxants can be used to treat muscle stiffness and fasciculations. Baclofen can be injected directly into the spinal canal in certain individuals with severe and debilitating spasticity. Some people with spasticity may benefit from cannabinoid therapy as well.
- Quinine sulfate, levetiracetam, or mexiletine: These may help treat muscle cramps in people with ALS
- Atropine, scopolamine, amitriptyline, glycopyrrolate, or botulinum toxin injections: Some people with ALS may develop hypersalivation (sialorrhea) and cannot regulate secretory pooling. Oral suction devices, in addition to medication, may be beneficial.
- Antidepressants, such as selective serotonin reuptake inhibitors: Can be used to treat mood disorders, such as depression or behavioral symptoms, associated with frontotemporal dementia.
- Physical and occupational therapy: These include some range of motion exercises that can help keep the afflicted joints flexible and prevent contractures (muscle fixation). Individuals with dysarthria may benefit from speech therapy and augmentative communication technologies.
- Proper nutrition: It is necessary for people with ALS to eat properly. Weight loss is an independent indicator of poor prognosis. People with dysphagia should eat soft meals with caution. A gastric feeding tube might be considered when enough nutrition and fluids cannot be maintained due to dysphagia.
- Addressing respiratory issues: When people develop ventilator muscle weakness, noninvasive positive pressure ventilation can help them breathe. Cough-assist devices can be used to help remove secretions. Ventilator weakness eventually worsens to the point that people are unable to breathe by themselves, and some will choose tracheostomy and permanent artificial ventilation.
- Hospice: Hospice can provide supportive care and assistance with comfort measures for those who choose not to use mechanical ventilation.
- Clinical trials: Patients can participate in clinical studies before, during, or after starting treatment.
Rehabilitation, braces, a wheelchair, or other treatments may be required to improve muscular function and overall health.
The burden of ALS is not only physical; it is emotional and economical, especially for caretakers. Emotional support is an important component in coping with this disease.
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What is the life expectancy for people with Lou Gehrig's disease?
According to studies, the average life expectancy for ALS is 3 years. Most individuals with ALS live for 3-5 years after their symptoms first manifest. A few people with ALS will live for 5-10 years after being diagnosed, with some even living for up to 20 years.
Some people with ALS have a mutation in a gene called KIFAP3 that appears to decrease the development of the disease. In people with ALS who inherit this genetic variation, survival could be increased by 40%-50%.
Understanding ALS. https://www.als.org/understanding-als/what-is-als
ALS/Lou Gehrig’s Disease. https://www.uofmhealth.org/conditions-treatments/brain-neurological-conditions/als-lou-gehrigs-disease
Amyotrophic Lateral Sclerosis (ALS) Fact Sheet. https://www.ninds.nih.gov/amyotrophic-lateral-sclerosis-als-fact-sheet
Amyotrophic Lateral Sclerosis (ALS). https://www.cdc.gov/dotw/als/index.html
Amyotrophic Lateral Sclerosis: Lou Gehrig's Disease. https://www.aafp.org/pubs/afp/issues/1999/0315/p1489.html
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