What Are the Stages of ALS Progression? King's & MiToS

Your doctor uses specific staging systems to track how ALS is progressing and to help you plan for future care needs. Unlike cancer, where stages describe the size and spread of a tumor, ALS stages describe how the disease affects your daily life and which parts of your body are involved. To do this, doctors primarily rely on a questionnaire called the ALS Functional Rating Scale-Revised (ALSFRS-R), alongside two specific staging frameworks: the King’s Staging System and the MiToS System.

The ALSFRS-R: The Foundation of ALS Staging

The ALSFRS-R is a 12-item questionnaire that measures your physical function across four key areas: gross motor skills (like walking), fine motor skills (like using your hands), bulbar function (speech and swallowing), and breathing ^[1].

Each item is scored from 0 to 4, giving a maximum total score of 48. Higher scores indicate better physical function. While the ALSFRS-R is excellent for tracking day-to-day functional changes ^[1], a single total score doesn’t clearly define a “stage” of the disease ^[2]. To translate these scores into a clearer picture of your disease progression, doctors use the King’s and MiToS systems.

The King’s Staging System: Tracking Anatomical Spread

The King’s Staging System focuses on how ALS spreads across different regions of your body—specifically the bulbar (head and neck), upper limbs (arms), and lower limbs (legs) ^[3]. It is particularly sensitive to the early and middle stages of the disease ^[4].

This system breaks the disease into stages based on the number of body regions involved and the need for specific medical interventions ^[5]. It’s important to remember that progression is highly individual—some people may stay in one stage for a long time, and the timeline varies from person to person.

• Stage 1: Symptoms have appeared in one body region ^[3].
• Stage 2: Symptoms have spread to a second body region ^[3].
• Stage 3: Symptoms involve a third body region ^[3].
• Stage 4: This stage is reached when medical interventions are needed to support vital functions. It is divided into Stage 4A, where a feeding tube (gastrostomy) may be recommended, and Stage 4B, where non-invasive breathing support (like BiPAP or NIV) may be chosen ^[3][5].
• Stage 5: This final stage represents the end of life, where the focus shifts entirely to comfort and palliative or hospice care ^[6].

The King’s system helps your care team anticipate when you might want to consider interventions like a feeding tube or breathing support, allowing you to discuss and plan for these milestones proactively rather than in an emergency ^[7][8].

The MiToS Staging System: Tracking Loss of Independence

The Milano-Torino (MiToS) system takes a different approach. Instead of looking at which body regions are affected, it maps specific answers from your ALSFRS-R questionnaire to track the loss of functional independence ^[9].

MiToS is especially useful for providing clarity in the later stages of the disease ^[10]. It looks at four critical areas of independence: walking/self-care, swallowing, communicating, and breathing ^[11].

• Stage 0: You have symptoms, but you have not lost independence in any of the four areas ^[11].
• Stage 1: You have lost independence in one area ^[11].
• Stage 2: You have lost independence in two areas ^[11].
• Stage 3: You have lost independence in three areas ^[11].
• Stage 4: You have lost independence in all four areas ^[11].
• Stage 5: This final stage represents the end of life, emphasizing comfort and quality of life through palliative care ^[11].

How These Systems Work Together

Doctors use these tools together to get a complete picture of your health. The King’s system helps predict the timeline for physical spread and the need for supportive equipment ^[12][13]. Meanwhile, the MiToS system focuses on your daily autonomy and what kind of caregiving support you might need ^[4].

For example, you might be at King’s Stage 3 because symptoms have appeared in your legs, arms, and speech, but you might only be at MiToS Stage 1 if you have only lost full independence in walking. Together, these systems ensure that your medical management adapts to your evolving needs, giving you and your family time to plan for the future ^[7].