23 lines
5.5 KiB
Markdown
23 lines
5.5 KiB
Markdown
---
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title: "ALS"
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chunk: 3/11
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source: "https://en.wikipedia.org/wiki/ALS"
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category: "reference"
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tags: "science, encyclopedia"
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date_saved: "2026-05-05T11:04:10.701513+00:00"
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instance: "kb-cron"
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---
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=== Progression ===
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Although the initial site of symptoms and subsequent rate of disability progression vary from person to person, the initially affected body region is usually the most affected over time, and symptoms usually spread to a neighbouring body region. For example, symptoms starting in one arm usually spread to either the opposite arm or to the leg on the same side. Bulbar-onset patients most typically experience their next symptoms in their arms rather than legs, arm-onset patients typically spread to the legs before the bulbar region, and leg-onset patients typically spread to the arms rather than the bulbar region. Over time, regardless of where symptoms began, most people eventually lose the ability to walk or use their hands and arms independently. They may also lose the ability to speak and to swallow food. It is the eventual development of weakness of the respiratory muscles, with the loss of ability to cough and to breathe without mechanical support, that is ultimately life-shortening in ALS.
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The rate of progression can be measured using the ALS Functional Rating Scale - Revised (ALSFRS-R), a 12-item instrument survey administered as a clinical interview or self-reported questionnaire that produces a score between 48 (normal function) and 0 (severe disability). The ALSFRS-R is the most frequently used outcome measure in clinical trials and is used by doctors to track disease progression. On average, people with ALS lose about 1 ALSFRS-R point per month. Brief periods of stabilization ("plateaus") and even small reversals in ALSFRS-R score are not uncommon, owing to the subjective nature of scoring, effects of symptomatic medication, and patients' own compensations for changes in function. However, it is rare (<1%) for these improvements to be large (i.e. greater than 4 ALSFRS-R points) or sustained (i.e. greater than 12 months). A survey-based study among clinicians showed that they rated a 20% change in the slope of the ALSFRS-R as being clinically meaningful, hence its common usage as a threshold to determine efficacy of new treatments in clinical trials.
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=== Late-stage disease management ===
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Difficulties with chewing and swallowing make eating very difficult (dysphagia) and increase the risk of choking or of aspirating food into the lungs. In later stages of the disorder, aspiration pneumonia can develop, and maintaining a healthy weight can become a significant problem that may require the insertion of a feeding tube. As the diaphragm and intercostal muscles of the rib cage that support breathing weaken, measures of lung function such as vital capacity and inspiratory pressure diminish. In respiratory-onset ALS, this may occur before significant limb weakness is apparent. Individuals affected by the disorder may ultimately lose the ability to initiate and control all voluntary movement, known as locked-in syndrome. Bladder and bowel function are usually spared, meaning urinary and fecal incontinence are uncommon, although trouble getting to a toilet can lead to difficulties. The extraocular muscles responsible for eye movement are usually spared, meaning the use of eye tracking technology to support augmentative communication is often feasible. Despite these challenges, many people in an advanced state of disease report satisfactory well-being and quality of life with these supportive measures.
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=== Prognosis, staging, and survival ===
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Although respiratory support using non-invasive ventilation can ease problems with breathing and prolong survival, it does not affect the progression rate of ALS. Most people with ALS die between two and four years after the diagnosis. About 50% of people with ALS die within 30 months of their symptoms beginning, about 20% live between five and ten years, and about 10% survive for 10 years or longer.
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The most common cause of death among people with ALS is respiratory failure, often accelerated by pneumonia. Most ALS patients die at home after a period of worsening difficulty breathing, a decline in their nutritional status, or a rapid worsening of symptoms. Sudden death or acute respiratory distress are uncommon. Access to palliative care is recommended from an early stage to explore options, ensure psychosocial support for the patient and caregivers, and to discuss advance healthcare directives.
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As with cancer staging, ALS has staging systems numbered between 1 and 4 that are used for research purposes in clinical trials. Two very similar staging systems emerged around a similar time: the King's staging system and Milano-Torino (MiToS) functional staging.
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Providing individual patients with a precise prognosis is not currently possible, though research is underway to provide statistical models on the basis of prognostic factors, including age at onset, progression rate, site of onset, and presence of frontotemporal dementia. Bulbar-onset ALS typically has a worse prognosis than limb-onset ALS; a population-based study found that bulbar-onset ALS patients had a median survival of 2.0 years and a 10-year survival rate of 3%, while limb-onset ALS patients had a median survival of 2.6 years and a 10-year survival rate of 13%. Those with respiratory-onset ALS had a shorter median survival of 1.4 years and 0% survival at 10 years. Though notable astrophysicist Stephen Hawking lived for 55 more years following his diagnosis, his case was an unusual one. |