What Is ALS? Symptoms, Diagnosis and Treatment of Amyotrophic Lateral Sclerosis

Created: 26.06.2024 · Last Updated: 17.08.2026 · Category: Neurology · Prepared by the Academic Hospital Web and Editorial Board.

What Is ALS?

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease in which motor neurons in the brain and spinal cord gradually deteriorate.

Motor neurons transmit signals that allow voluntary muscles to move. As these cells lose function, progressive muscle weakness, muscle wasting and loss of movement can develop.

ALS can involve both upper motor neurons, which carry signals from the brain towards the spinal cord, and lower motor neurons, which connect the brainstem and spinal cord to muscles.

What Are the Symptoms of ALS?

  • Progressive weakness in an arm or leg
  • Loss of hand dexterity
  • Foot drop, tripping or falls
  • Muscle wasting
  • Muscle twitching or fasciculations
  • Muscle cramps
  • Muscle stiffness or spasticity
  • Speech impairment
  • Difficulty swallowing
  • Respiratory muscle weakness as disease progresses

What Are the Early Symptoms of ALS?

ALS often begins with weakness affecting one region of the body before spreading over time.

Early features can include reduced grip strength, difficulty with fine hand movements, weakness in one arm, foot drop, repeated tripping or muscle fasciculations.

Some people have bulbar-onset ALS, in which the earliest symptoms affect speech or swallowing.

Muscle twitching alone does not mean that a person has ALS. Fasciculations can occur in healthy people and in many other neurological conditions.

How Are Speech and Swallowing Affected?

When motor neurons controlling bulbar muscles are affected, speech, chewing and swallowing can become progressively impaired.

Patients may develop slurred or slower speech, changes in voice quality, difficulty swallowing food or liquids, coughing during meals, problems managing saliva and weight loss.

Are Sensation and Cognition Affected?

ALS primarily affects the motor system, and sensations such as touch, pain and temperature are generally preserved.

However, it is too absolute to state that sensory symptoms can never occur. Atypical sensory findings should also prompt consideration of conditions that can mimic ALS.

ALS is also not exclusively a muscle disorder. Some patients develop changes in executive function, language or behaviour, and ALS can occur within a clinical spectrum that overlaps with frontotemporal dementia.

What Causes ALS?

In most patients, a single cause cannot be identified.

ALS appears to involve multiple biological mechanisms, including genetic susceptibility, abnormal protein processing, disturbances in RNA metabolism, oxidative stress, cellular energy pathways and neuroinflammation.

ALS is not contagious.

Is ALS Genetic?

Most ALS occurs without a previously known family history, although disease-associated genetic variants can be found in a proportion of patients.

Genes associated with ALS include C9orf72, SOD1, FUS and TARDBP.

The need for genetic testing can be assessed according to family history, age, clinical features and whether a genetic result could affect treatment or counselling.

Identifying an ALS-associated SOD1 mutation is particularly relevant because a targeted therapy is now available for appropriate patients with SOD1-associated ALS.

How Is ALS Diagnosed?

There is no single blood test or scan that confirms ALS in every patient.

Diagnosis is based on neurological history and examination, evidence of upper and lower motor-neuron dysfunction, progression over time and exclusion of other conditions that can mimic ALS.

Investigations may include:

  • Electromyography and nerve-conduction studies
  • Blood tests
  • MRI of the brain or spine
  • Genetic testing when appropriate
  • Respiratory-function testing
Diagnosis also requires consideration of potentially treatable ALS mimics, including spinal disorders, peripheral neuropathies, muscle diseases and selected metabolic or immune-mediated conditions.

What Is the Role of EMG in ALS?

Electromyography (EMG) evaluates electrical activity in muscles and the motor nerves supplying them.

In suspected ALS, EMG can demonstrate active and chronic denervation across different anatomical regions.

Nerve-conduction studies can also help identify alternative diagnoses such as peripheral neuropathy.

EMG findings must be interpreted together with the neurological examination and clinical course.

Is There a Treatment for ALS?

There is currently no treatment that completely cures ALS or restores all lost motor neurons.

However, it is also inaccurate to say that nothing can be done.

Modern ALS management aims to:

  • Use disease-modifying treatment when appropriate
  • Support breathing
  • Maintain nutrition and safe swallowing
  • Preserve mobility and independence
  • Support speech and communication
  • Manage cramps, spasticity, saliva and other symptoms
  • Support quality of life for patients and families

Which Medicines Are Used for ALS?

Riluzole

Riluzole is an established disease-modifying treatment for ALS and can provide a modest but clinically meaningful benefit in appropriate patients.

Edaravone

Edaravone is authorised for ALS in some countries. Suitability and access vary according to clinical characteristics and local regulatory and reimbursement conditions.

Tofersen

Tofersen is an antisense oligonucleotide therapy designed for adults with ALS associated with a disease-causing mutation in the SOD1 gene.

It is therefore not a general treatment for every person with ALS.

Why Is Respiratory Support Important?

ALS can weaken the diaphragm and other respiratory muscles.

Symptoms can include breathlessness when lying flat, disrupted sleep, morning headaches, daytime sleepiness, a weak cough and difficulty clearing respiratory secretions.

Respiratory function should therefore be monitored throughout the disease course.

In appropriate patients, non-invasive ventilation (NIV) can improve symptoms and quality of life and can prolong survival without stopping progression of the underlying disease.

Cough-assist techniques and devices may also be useful when cough strength declines.

How Are Nutrition and Swallowing Managed?

Progressive weakness and dysphagia can make it difficult to maintain adequate nutrition and hydration.

Weight, dietary intake, hydration and swallowing safety should therefore be monitored.

Modified food consistency, calorie supplementation and speech-and-swallowing therapy can be useful.

When safe and adequate oral intake can no longer be maintained, gastrostomy feeding may be considered according to the patient's condition, goals and preferences.

What Does Multidisciplinary ALS Care Include?

ALS management extends far beyond medication.

Depending on individual needs, multidisciplinary care can involve neurology, respiratory medicine, rehabilitation, physiotherapy, nutrition, speech and swallowing therapy, occupational therapy, psychological support and palliative care.

When speech becomes difficult, augmentative and alternative communication technology such as tablets, computers or eye-tracking systems can support communication.

What Is the Life Expectancy in ALS?

The course of ALS varies substantially between individuals, so it is not appropriate to give one fixed survival time for every patient.

Population data indicate that many patients experience progression over several years after symptom onset, while some people live considerably longer.

Factors associated with prognosis include age at onset, site of onset, rate of progression, respiratory function, nutritional status, genetic factors and access to multidisciplinary care.

Population survival statistics cannot predict an individual patient's exact course.

When Is Urgent Medical Assessment Needed?

Seek prompt medical assessment for:

  • New or rapidly worsening breathlessness
  • Difficulty breathing while lying flat
  • Severe respiratory distress or cyanosis
  • Inability to clear respiratory secretions
  • Choking or suspected aspiration
  • Inability to maintain hydration
  • Sudden neurological symptoms that are not consistent with the person's usual ALS progression

Have Progressive Muscle Weakness Assessed

Progressive asymmetric weakness, muscle wasting, fasciculations or changes in speech and swallowing may require neurological evaluation and electromyography.

Frequently Asked Questions

What is ALS?
ALS is a progressive neurodegenerative disease in which motor neurons controlling voluntary muscle movement gradually deteriorate. Loss of motor neurons can cause muscle weakness, muscle wasting and progressive loss of movement.
What are the early symptoms of ALS?
ALS can begin with progressive weakness in one hand, arm or leg, loss of fine motor skills, foot drop, falls or muscle fasciculations. Some patients initially develop difficulty speaking or swallowing.
Does muscle twitching mean that I have ALS?
No. Muscle twitching can occur in healthy people and in many other conditions. ALS assessment considers progressive weakness, muscle wasting, neurological examination and tests such as EMG rather than fasciculations alone.
Is ALS diagnosed by EMG alone?
No. EMG is an important investigation but is not used in isolation. Diagnosis combines neurological history and examination, EMG findings, progression of disease and exclusion of conditions that can mimic ALS.
Is there a treatment for ALS?
There is currently no treatment that completely cures ALS. However, disease-modifying medicines for appropriate patients, respiratory support, nutrition and swallowing management, rehabilitation and symptom treatment can improve quality of life and in some cases prolong survival.
Is tofersen used for every patient with ALS?
No. Tofersen is a gene-targeted treatment for appropriate adults with ALS associated with a disease-causing mutation in the SOD1 gene. It is not a general treatment for all forms of ALS.
Why is respiratory support important in ALS?
ALS can progressively weaken respiratory muscles. In appropriate patients, non-invasive ventilation can improve respiratory symptoms and quality of life and can prolong survival.
What is the life expectancy in ALS?
The course of ALS varies considerably between individuals. Many patients experience progression over several years after symptom onset, while some people live much longer. Population statistics cannot predict an individual's exact survival.
Academic Hospital note: ALS is not diagnosed from muscle twitching or a single EMG finding alone. Progressive muscle weakness requires neurological assessment, neurophysiological testing and evaluation for other disorders that can mimic ALS. After diagnosis, respiratory, nutritional, communication and rehabilitation support are important alongside medical treatment. You can book an appointment.

References

  1. Academic Hospital. Amyotrophic Lateral Sclerosis (ALS)
  2. National Institute of Neurological Disorders and Stroke. Focus on Amyotrophic Lateral Sclerosis
  3. National Institute for Health and Care Excellence. Motor Neurone Disease: Assessment and Management
  4. U.S. Food and Drug Administration. Qalsody (tofersen)
  5. European Medicines Agency. Qalsody