What ALS is
NINDS explains that ALS affects motor neurons, the nerve cells in the brain and spinal cord that control voluntary muscle movement and breathing. As they degenerate and die, they stop sending messages to the muscles, which weaken, twitch (fasciculations) and waste away (atrophy). Mayo Clinic notes that ALS affects both upper motor neurons, from the brain to the spinal cord, and lower motor neurons, from the spinal cord to the muscles.
ALS is progressive. Mayo Clinic explains that the cause is not known in most people; about 10% have a genetic form inherited from a parent. Risk rises with age, and NINDS notes that symptoms most commonly develop between 55 and 75, although ALS can occur at any age. There is currently no cure, but treatment and support can improve quality of life.
Early signs: hands, legs, speech
Mayo Clinic explains that ALS often begins with mild symptoms that may be hard to notice at first. Early signs may include:
- trouble walking or doing usual daily activities, tripping and falling
- weakness in the legs, feet or ankles
- hand weakness or clumsiness
- slurred or nasal speech, or trouble chewing or swallowing
- muscle cramps, stiffness and twitching, together with weakness in the arms, shoulders, neck or tongue
- crying, laughing or yawning at inappropriate times, and changes in thinking or behavior
Mayo Clinic notes that there is generally no pain in the early stages, and that ALS does not usually affect bladder function or the senses such as taste, smell, touch and hearing.
Why early signs vary from person to person
Mayo Clinic explains that symptoms vary and depend on which nerve cells are affected first. ALS often starts in the hands, feet, arms or legs and then spreads to other parts of the body; in other people, the first changes affect speech or swallowing. As more nerve cells die, muscles get weaker, eventually affecting chewing, swallowing, speaking and breathing.
NINDS adds that, eventually, people with ALS become unable to stand or walk, use their hands and arms or breathe on their own. Because the course and speed vary widely, no single early sign predicts how the condition will evolve in a particular person.
Cramps and twitching: what they do and do not mean
Twitching and cramps are part of ALS, but in ALS they come together with weakness and muscle wasting that progress over time. NINDS lists muscle twitches in the arm, leg, shoulder or tongue, cramps and stiff muscles (spasticity) alongside weakness among early symptoms.
Muscle twitches on their own are common and usually harmless. Twitching without weakness does not mean ALS, and neither the feel of a twitch nor repeated self-testing of strength can confirm or exclude it. If you notice weakness that is progressing, see a doctor.
Speech and swallowing changes
Mayo Clinic explains that most people with ALS develop weakness of the muscles used for speech. It usually starts with slower speech and occasional slurring and then becomes harder to speak clearly; over time, others may have trouble understanding. Many people then use other forms of communication and technology. NINDS lists difficulty forming words (dysarthria), chewing and swallowing problems (dysphagia) and drooling among the problems that may develop.
Weakness of the swallowing muscles can lead to malnutrition and dehydration and raises the risk of food, liquids or saliva entering the lungs, which can cause pneumonia. Our guide to dysphasia vs dysphagia explains the difference between language and swallowing problems.
Breathing and when to seek urgent care
Over time, ALS weakens the muscles used to breathe. NINDS explains that people may notice shortness of breath during activity and difficulty breathing at night or when lying down, and that a weak cough makes it harder to clear the throat. Noninvasive ventilation through a mask, at first at night, can help; some people later need mechanical ventilation, and Mayo Clinic notes that some choose a tracheostomy.
Both sources state that breathing failure is the most common cause of death, usually three to five years after symptoms begin, although about 1 in 10 people live 10 years or more. These are averages, not predictions for an individual. Breathing difficulty, choking or inability to swallow need prompt medical attention.
How ALS is diagnosed (including EMG)
NINDS explains that there is no single test that can definitely diagnose ALS. A doctor reviews the full medical history and performs a neurological examination of reflexes, muscle strength and other responses, repeated at regular intervals to see whether symptoms are progressing. A neurologist familiar with ALS can help achieve an earlier diagnosis.
Tests help rule out other disorders and support the diagnosis. They include MRI of the brain and spinal cord and electromyography (EMG), which assesses how well nerves and muscles work through a nerve conduction study and a needle exam. EMG is requested by the neurologist as part of this process; our clinical neurophysiology service describes how these tests are done.
Conditions that can look like ALS
Because early symptoms such as weakness, cramps, twitching, slurred speech or swallowing problems can have many causes, NINDS explains that doctors use additional tests to rule out other disorders. Depending on the case, these may include blood and urine tests, a lumbar puncture to examine cerebrospinal fluid and, occasionally, a muscle biopsy.
Reaching a diagnosis can take time, because the neurologist may need to see how symptoms change between examinations. Distinguishing ALS from other conditions is a professional task, which is why online symptom lists cannot confirm or exclude it.
Where the sources differ
Mayo Clinic (May 2026) and NINDS (March 2026) agree on early symptoms, progression and average survival. Mayo Clinic gives risk ranges by age up to the mid-80s; NINDS gives 55 to 75 as the most common age of onset. On thinking, NINDS notes that most people remain able to reason, remember and understand, while both explain that some develop problems with language or decision-making, and some a form of dementia called frontotemporal dementia.
On treatment, NINDS explains that several US-approved medicines may modestly slow progression or extend survival, and that one was withdrawn from the market in 2024 after a larger trial failed to confirm its benefit. Approval and availability differ between countries, so current options should be discussed with the neurology team. No treatment currently stops or reverses ALS.
In summary
ALS often starts with weakness or clumsiness in a hand, arm or leg, tripping, slurred speech or swallowing difficulty, with cramps and twitching alongside weakness. It spreads over time and eventually affects speech, swallowing and breathing. There is no single test; diagnosis relies on repeated neurological examination, EMG, MRI and other tests. Twitching on its own is common and does not mean ALS.
After diagnosis, NINDS describes multidisciplinary teams, including physical, occupational, speech and respiratory therapists, nutritionists and psychologists, who help people stay mobile, communicate and eat safely. Speech therapists can teach strategies to speak more clearly and support communication technology and voice banking. For adults with a diagnosis, our speech therapy practice in Bilbao can support speech and swallowing as part of that care (consultations are in Spanish). Noting which daily tasks have become harder, and since when, helps each review.
Frequently asked questions about ALS symptoms
These answers are general information and do not replace an examination or individual medical advice.
What are usually the first signs of ALS?
Weakness or clumsiness in a hand, arm or leg, tripping, slurred speech or trouble swallowing, often with cramps or twitching alongside the weakness. The first signs vary from person to person.
Does muscle twitching mean ALS?
Not on its own. Twitching is very common and usually harmless. In ALS it occurs together with progressive weakness and muscle wasting, which a doctor assesses.
What is ALS commonly mistaken for?
Early symptoms can resemble other nerve, muscle or neurological conditions, which is why doctors use MRI, EMG, blood tests and sometimes other tests to rule them out.
How is ALS diagnosed?
There is no single test. Diagnosis relies on history, neurological examinations repeated over time, EMG with nerve conduction studies, MRI and tests to exclude other conditions.
How does ALS affect speech and swallowing?
Speech often becomes slower and slurred, then harder to understand. Swallowing weakness can cause choking, weight loss, dehydration and a risk of pneumonia, so specialist assessment is important.
What support is available after diagnosis?
Multidisciplinary care with neurologists, therapists, nutritionists, respiratory specialists, psychologists and social workers, plus communication technology, breathing support and help for carers.
Sources
- Mayo Clinic · Amyotrophic lateral sclerosis (ALS): symptoms and causes
- National Institute of Neurological Disorders and Stroke (NIH) · Amyotrophic lateral sclerosis (ALS)
This guide is for general information and does not replace medical advice. How a problem is diagnosed and treated depends on your examination and medical history. If you think you have an emergency, contact your local emergency services.