What Are the Stages of ALS?

After receiving a diagnosis of a progressive condition like amyotrophic lateral sclerosis (ALS), it’s natural to want to know what to expect.

ALS, also known as Lou Gehrig’s disease, is a progressive neurodegenerative condition affecting motor neurons in the spinal cord. Motor neurons are the nerve cells responsible for muscle control and movement. The more of them you lose, the more severe symptoms of ALS become.

Although ALS has a generally predictable progression, the specific rate of progression and the order of abilities affected may not follow the same pattern for each person. Here’s what to know about the stages of ALS.

Below is a framework of ALS staging that can help you know what to expect.

Early stage

Early stage ALS can be subtle — so subtle that you may not yet have a diagnosis. A 2023 study tracking ALS symptoms with artificial intelligence (AI) found that the most common prediagnosis and early symptoms were:

• muscle weakness
• labored breathing
• difficulty speaking
• trouble swallowing
• muscle twitches

Of all of these, labored breathing was the presenting symptom mostly likely to go the longest without a diagnosis.

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Not everyone has such noticeable symptoms in early stage ALS. Other common symptoms include:

• muscle cramps
• tightness or “stiff” muscles
• slurred or pitch changes in speech

Where ALS begins also matters in the early stage. Most cases cause weakness of the limbs (limb-onset ALS) before they affect the “trunk” — the center of the body where internal organs are housed. Once the trunk is affected, a person will begin to experience weakness in breathing.

Bulbar-onset ALS, however, doesn’t begin in the limbs. It starts in the head and neck and can create challenges with chewing and swallowing, for example, much sooner than limb-onset ALS.

Middle stage

Middle stage ALS occurs when early stage symptoms worsen and more areas of your body are affected.

This is the zone between muscle weakness and full paralysis. You may notice some muscles barely work while others are not as severely affected.

Other symptoms can include:

• difficulty chewing or swallowing
• trouble speaking
• weight loss
• neuropathy
• muscle cramps
• difficulty breathing
• depression
• anxiety

Both early and middle stage ALS can share symptoms. What sets them apart is the level of impairment and how much of the body is affected.

During this stage, some people may undergo their first necessary ALS procedure, like insertion of a feeding tube.

Late stage

Late stage ALS, or advanced ALS, is characterized by muscle paralysis, major loss of function, and the need for life supporting procedures, like:

• tracheostomy
• noninvasive ventilation
• feeding tube insertion (gastrostomy)

At this stage, mobility is extremely limited. You may not have the muscle control to chew or swallow. You might not be able to maintain your posture, walk, or hold up your head.

A 2018 review paper estimates that in 15% of people with ALS, cognitive impairment progresses to meet the diagnostic criteria for frontotemporal dementia. Some clinicians consider this the final stage of ALS.

Others consider the end stage as when you can no longer breathe on your own and life expectancy is fewer than 6 months.

King’s clinical staging system

Formal ALS staging models do exist. They were developed to help the diagnostic process. One of the more straightforward frameworks is King’s clinical staging system. It breaks down ALS stages by how much of the body is affected.

King’s stages are:

• Stage 1: first region of symptom onset
• Stage 2A: time of diagnosis
• Stage 2B: second area of the body is affected
• Stage 3: progression to the third area of the body
• Stage 4A: need for gastrostomy
• Stage 4B: approximately 80% to 90% through ALS course; noninvasive ventilation is needed

Other clinical staging models include the Milano-Torino system and the World Federation of Neurology (WFN) ALS staging model.