ALS stages and progression timeline

Amyotrophic lateral sclerosis (ALS) is a progressive disease that usually begins with mild symptoms in one region of the body and eventually spreads to other parts of the body, interfering with a range of bodily functions.

This progression is not linear, and progression rates can vary considerably from person to person based on factors such as age at symptom onset, where symptoms begin, certain genetic changes, and some prior environmental and occupational exposures.

Some people experience a relatively rapid decline over a few years, while others have a much slower form of the disease and live for many years after being diagnosed. However, virtually all patients will go through several stages of ALS as their disease progresses.

How many stages of ALS are there?

There is no single universally accepted way to divide ALS into stages. Instead, clinicians generally describe the disease as progressing through four broad phases:

• early stage
• middle stage
• late stage
• final stage

The timing of each stage may vary substantially from patient to patient. Available ALS treatments may slow disease progression and help people maintain function longer. However, for many people, these stages unfold over about two to five years after symptoms first appear.

Early-stage ALS

Early-stage ALS begins when symptoms first appear. These symptoms are often subtle and start in one region of the body, so some people may reach the next stage before receiving a diagnosis.

Common early signs of ALS include:

• muscle weakness
• muscle twitching (fasciculations)
• muscle cramps
• stiffness or spasticity
• fatigue

A person’s first symptoms depend on where ALS begins. In about two-thirds of patients, the disease initially starts in the limbs, usually affecting muscles in the hands, arms, feet, or legs. This form of the disease, called limb-onset ALS, may cause:

• difficulty gripping objects or buttoning clothes
• poor balance and frequent tripping

About one-third of patients have bulbar-onset ALS, in which the first symptoms are caused by weakness in the bulbar muscles, a group of muscles located in the head and neck. Early bulbar-onset ALS symptoms often include:

• speech difficulties, such as slurred speech, trouble articulating words, or a hoarse voice
• difficulty chewing and swallowing

During the early stage of ALS, many people retain a fair amount of functionality and independence, but they may need help with some physical tasks and might benefit from a walking aid.

Middle-stage ALS

As ALS progresses into the middle stages, muscle weakness becomes more widespread and begins affecting additional parts of the body. Symptoms often become more noticeable and may interfere with everyday activities, increasing the need for assistive devices and caregiver support.

During this stage:

• Some muscles may become very weak or completely paralyzed, while others remain less affected.
• Muscles that are no longer used regularly may become shortened over time, leading to contractures that can cause joint stiffness and pain.
• Weakness in the mouth and throat muscles can make speaking, chewing, and swallowing more difficult. Problems managing saliva may increase the risk of choking.
• Weakness in the muscles used for breathing may cause ALS breathing difficulties, especially when lying down.
• Some people develop pseudobulbar affect, which causes episodes of uncontrollable laughing or crying that do not reflect how they actually feel.

During this stage, many people begin to lose independence in certain daily activities. Driving may no longer be safe as weakness increases. Falls may occur, and some people may no longer be able to stand up on their own afterward.

During this stage, adaptive equipment such as wheelchairs, communication devices, and home adaptations becomes more important to help people retain some independence.

Medical interventions such as feeding tubes and noninvasive ventilation may also be needed to help patients get enough nutrition and maintain breathing function. Emotional support can also be important in helping patients navigate feelings of frustration, sadness, and a sense of loss.

Late-stage ALS

During late-stage ALS, weakness has spread to most of the body, and many voluntary muscles are paralyzed. Most people require assistance with nearly all daily activities, including moving, dressing, bathing, and eating.

At this stage:

• Swallowing becomes difficult or unsafe, and a feeding tube may be needed to provide nutrition.
• Speaking may be impossible, making communication devices important.
• Difficulty breathing can increase the risk of respiratory infections, such as pneumonia, and lead to symptoms such as fatigue, headaches, and difficulty concentrating.
• Assisted ventilation may be needed to support breathing.

Final stages of ALS

In the final stages of ALS, patients typically require around-the-clock care, and many people and their families choose to focus on comfort and quality of life.

Hospice care for ALS can usually be considered for people with a prognosis of six months or less. It can be provided at home or in a specialized care facility and can offer physical, emotional, and spiritual support for patients and their families and friends.

Patients and families should plan ahead for the final stages of ALS to ensure their end-of-life care is consistent with their wishes. Families may want to contact a hospice provider early to learn what services are available.

ALS is a fatal disease, and most people with the disorder die within about two to five years after symptom onset. Respiratory failure in ALS is the most common cause of death and occurs when the breathing muscles become too weak to support normal breathing.

Other causes of death in ALS may include:

• cardiovascular disease
• pneumonia
• inflammation of lung tissue
• terminal cachexia (severe muscle wasting accompanied by weight loss)

The timing of ALS disease progression varies widely. While many people reach the final stages of ALS within a few years of symptom onset, others experience a slower course and may live with the disease for much longer.

ALS progression timeline

Framing ALS progression in four simple phases can help patients and caregivers understand where they are in the disease course. Researchers and healthcare professionals also use formal ALS staging scales to monitor changes and more accurately establish ALS stages.

The two most commonly used scales are the King’s College staging system and the Milano-Torino (MiToS) system.

King’s College staging system

The King’s College staging system assesses how ALS symptoms spread across four body regions — the upper limbs, the lower limbs, the bulbar muscles, and the diaphragm — as well as whether a feeding tube or noninvasive ventilation is needed.

The system includes stages 1 through 4, with stage 5 representing death.

• Stage 1: Symptoms are limited to one body region, roughly corresponding to early-stage ALS. Studies suggest this stage may last about 9-18 months.
• Stages 2 and 3: Symptoms spread to additional body regions, generally corresponding to the middle stage of ALS. Together, these stages usually last about 9-12 months.
• Stage 4: This stage is marked by the need for a feeding tube or ventilatory support, which broadly aligns with late-stage ALS. It typically lasts about 4-7 months.
• Stage 5: Death, which generally occurs about three months after reaching stage 4, although this varies considerably among individuals.

MiToS staging system

The MiToS system measures disease progression differently. Instead of tracking how ALS spreads through the body, it focuses on when people lose independence in four key areas: walking and self-care, swallowing, speaking, and breathing.

Because it stages patients by loss of independence, this system provides more detail during the later stages of ALS. Its stages include:

• Stage 0: Symptoms are present, but the person remains independent in all four functions. This stage typically lasts about nine months.
• Stages 1-4: Independence is gradually lost in one, two, three, and eventually all four functional areas. Together, these stages usually span about 1.5 years.
• Stage 5: Death, which typically occurs within a month after independence has been lost in all four functions.

Factors influencing ALS progression

While some studies have estimated when people with ALS typically reach each formal stage, there is no one-size-fits-all timeline.

ALS progression timelines vary considerably from person to person. Some people may progress through these stages rather quickly, but others may progress more slowly or remain in a particular stage for several years.

Some factors associated with slower ALS progression include:

• younger age at symptom onset
• limb-onset ALS
• better respiratory function and nutritional status
• early access to ALS therapies
• access to multidisciplinary ALS care

Advances in diagnosis and treatment have improved outcomes for many people with ALS. Researchers are also studying newer therapies that may further slow disease progression and extend life expectancy.