Amyotrophic Lateral Sclerosis
ALS High-yield Verified · Sep 2026Amyotrophic lateral sclerosis is a progressive, paralytic, neurodegenerative disease of the upper and lower motor neurons that control voluntary muscle movement and breathing. It is the most common motor neuron disease; most cases are sporadic and about 10% are familial.
Upper plus lower motor neuron signs, the functions spared until late, why weight loss and a falling vital capacity set the timetable for a feeding tube and noninvasive ventilation, what riluzole, edaravone and tofersen can and cannot do, and why communication plans and advance directives belong at the start, not the end.
What’s going wrong in the body
The normal physiology, where it fails, and why the body’s compensation backfires.
01 Both motor neurons die — so upper and lower signs appear together
"Amyotrophic lateral sclerosis (ALS), formerly known as Lou Gehrig’s disease, is a neurological disorder that affects motor neurons. Motor neurons are the nerve cells in the brain and spinal cord that control voluntary muscle movement and breathing." "The pathological hallmarks of ALS are the degeneration of the pyramidal Betz cells in the motor cortex, anterior horn cells of the spinal cord (due to retrograde axonal loss), and lower cranial motor nuclei of the brainstem." "Gliosis replaces the lost neurons."
The signature: two kinds of weakness at once. "The hallmark feature is upper and lower motor neuron signs and symptoms coexist." "Upper motor neuron (UMN) findings are hyperreflexia, poor dexterity, incoordination, and spasticity." "Lower motor neuron (LMN) findings are muscle atrophy and fasciculations." "As motor neurons degenerate and die, they stop sending messages to the muscles. This causes the muscles to weaken, start to twitch (fasciculations), and waste away (atrophy)."
Why it happens is not settled. "The possible mechanisms described in the literature are genetic mutations, oxidative stress, excitotoxicity, mitochondrial and proteasomal dysfunctions, altered synaptic function, disturbed axonal transport, and neuroinflammation." "Relative glutamate excess has been shown to lead to upper and lower motor neuron excitotoxicity contributing to neuronal cell death" — the rationale for riluzole. "Nearly all cases of ALS are considered sporadic"; "About 10% of all ALS cases are familial," most often C9orf72 or SOD1 mutations, and C9ORF72 mutations "are also involved in the development of frontotemporal dementia (FTD)."
02 The pattern of spread — limb to limb to throat to diaphragm
Onset is usually one limb. "Most patients present with asymmetric LMN symptoms isolated to the arm or leg." "Common initial clinical findings are hand weakness, shoulder girdle weakness, and foot drop." "Bulbar onset ALS accounts for 25% of patients," and "The most common bulbar symptoms are dysarthria and dysphagia." The spread is predictable: unilateral limb onset "progresses to include the contralateral limb, then the other ipsilateral extremity" and on to the remaining limb "before ultimately affecting the bulbar muscles." "Progression of ALS is usually linear, without episodes of remissions or exacerbations."
Some things are spared — for a while. "Eye and sphincter muscles are spared until late in the disease," and on nerve studies "Sensory action potentials will be normal." Constipation still occurs. Thinking is usually preserved — people with ALS "usually remain able to reason, remember, and understand," so "they are aware of their progressive loss of function. This can cause anxiety and depression" — but "Many patients (30% to 50%) diagnosed with ALS will develop varying degrees of cognitive impairment, and 15 to 20% of cohorts develop frontotemporal dementia." "Pseudobulbar palsy (ie, inappropriate periods of crying, laughing, or yawning) is also observed due to the involvement of frontopontine motor neurons."
Swallowing and saliva. Drooling is not over-production: "Siallorhoea is caused by the inability to swallow saliva, which may be the result of tongue spasticity, weakness of the facial, mouth and pharyngeal muscles, loss of pharyngeal coordination, and function." "Severe dysphagia may lead to weight loss, choking, and aspiration," and "Weight loss (particularly within the first two years after diagnosis) is associated with a poorer prognosis."
03 Care is timed to the decline — breathing, feeding, and decisions made early
Breathing. "Most people with ALS die from being unable to breathe on their own (known as respiratory failure), usually within three to five years of symptoms first appearing." "Pulmonary function tests are done every three months," and "Supine Forced vital capacity (FVC) may be used as a marker of diaphragmatic weakness." StatPearls: "NIV will be helpful when the vital capacity (VC) is less than 50%, sniff nasal inspiratory pressure (SNIP) < 40 cm H2O, pCO2 > 45mmHg, significant desaturations are noted on overnight oximetry, or when evidence of respiratory weakness is present." "The use of NIV prolongs survival." "At first, NIV may only be necessary at night, but people may eventually need it full time."
Feeding. Dysphagia is "Initially managed with diet modifications," with "calorically dense foods and supplemental nutritional beverages." StatPearls: "Enteral tube feeding is indicated when weight loss exceeds 10%, BMI is less than 18.5 kg/m2, swallowing impairments are observed during instrumental tests, or the VC is <50%," and timing matters: "Decreased FVC of 50% or less almost precludes PEG placement because of the intolerance to the required sedation at this stage" (Iranian ALS guideline 2023). (The Motor Neuron Disease chapter advises PEG for weight loss "in excess of five percent.")
Decisions. "As this weakness is progressive, an early, careful discussion regarding respiratory management and future options such as tracheostomy, chronic ventilatory support, and noninvasive ventilation (NIV) is warranted." "The issue of end-of-life care and advanced directives should be broached soon after diagnosis." "Patients should understand that they can discontinue therapy at any time during the treatment process." Care in a multidisciplinary clinic helps: interprofessional care "has been shown to improve one-year mortality by almost 30% and overall lifespan by almost 8 months."
Causes & risk factors
Modifiable factors are teaching targets — the patient can act on them.
Signs & symptoms
Each finding tied to the mechanism that produces it — and the triage it calls for.
Diagnostics
Complications
Medications for this condition
Why each class is prescribed here — every card links to its full pharmacology page.
Spasticity and cramps. "Gabapentin, baclofen, tizanidine, benzodiazepines, and levetiracetam have been advised for the management of spasticity." "The practice of these drugs is limited by the occurrence of fatigue and weakness."
Mexiletine for cramps — "a sodium channel-blocking antiarrhythmic drug"; it "can cause gastrointestinal upset and arrhythmias." Quinine: "Caution is advised with the use of quinine sulfate as it has been associated with QT prolongation, arrhythmias, and bradycardia."
Sialorrhea. "Anticholinergic drugs such as atropine, hyoscine, glycopyrrolate, and amitryptiline have been found to be beneficial in the management of sialorrhea. Salivary gland irradiation and botulinum toxin injections have also been proposed as treatment modalities." "Anticholinergic drugs have been associated with urinary retention and constipation." "They are contraindicated in patients with heart block and benign prostatic hypertrophy."
Depression, insomnia, sialorrhea and pseudobulbar affect. "Amitriptyline is commonly used as it can also treat other symptoms such as insomnia, sialorrhea, and pseudobulbar affect."
"Selective serotonin reuptake inhibitors are another alternative if the TCAs are not tolerated."
Dyspnea, pain and end-of-life breathlessness. "In addition to NIV, relaxation techniques, psychosocial support, morphine, and benzodiazepines are helpful" for dyspnea and anxiety; "when these fail, opioids become the mainstay of pain treatment."
Anxiety and breathlessness near the end of life. "The use of opioids and benzodiazepines for breathlessness, glycopyrrolate for increased secretions, antipsychotics for delirium, and other non-pharmacological treatment options may be indicated in patients approaching their end of life."
"Immunization with the annual influenza and pneumococcal vaccines is important."
Thrombosis prophylaxis in immobility. "The annual incidence of coagulation abnormalities has been in the range of 3 and 11 percent"; prophylaxis "as per existing guidelines" has been advised.
Beyond medications
- Disease-modifying drugs (no class page). Riluzole "is an oral medicine believed to reduce damage to motor neurons by decreasing levels of glutamate"; "riluzole may extend survival by a few months" (StatPearls: "a survival benefit averaging 3 months"). Liquid (Tiglutik) and dissolving (Exservan) forms "may be better than the pill form for people that have problems with swallowing." About half of patients in the pivotal trials "had at least one elevated ALT level above ULN," and the label warns that "Cases of drug-induced liver injury, some of which were fatal, have been reported"; monitor "every month for the first 3 months of treatment, and periodically thereafter"; "Pancreatitis and fulminant hepatic failure have also been reported as rare adverse effects," and it "is contraindicated in hepatic and renal impairments and in those who are breastfeeding and lactating." Edaravone (Radicava) "is an antioxidant given either orally or intravenously" that "has been shown to slow functional decline in some people with ALS"; it "should be used with caution in patients with asthma" because it "contains sodium bisulfite." Tofersen (Qalsody), for confirmed SOD1 mutations only, "is administered intrathecally (through a spinal injection) by healthcare professionals who are experienced in performing lumbar punctures"; "the benefits of this drug are still under study." Relyvrio was withdrawn: "the manufacturer of Relyvrio removed the drug from the market in 2024." Overall, "the impact of these disorder-modifying therapies is modest."
- Breathing support. Noninvasive ventilation when criteria are met; "mechanical cough assistive devices" and "mechanical insufflator – exsufflator devices"; tracheostomy ventilation when NIV fails, if the patient chooses it.
- Nutrition. "the change in consistency of the diet, high calories, and high protein diets, fluid thickeners along with exercises to facilitate swallowing"; "Nutritionists and registered dieticians can help plan small, nutritious meals throughout the day—and identify foods to avoid." A gastrostomy before the VC falls below 50%.
- Exercise and mobility. "Low-impact exercises such as walking, swimming, or using a stationary exercise bike—along with range of motion exercises—can help maintain muscle strength and function." "Fall prevention strategies (including assistive devices and environmental modifications) and energy conservation techniques are required to combat weakness and fatigue."
- Communication. "Speech therapy provides limited benefit, and appropriate alternative communication methods (writing, alphabet boards, and electronic assistive communication devices) are needed." "People with ALS sometimes use voice banking, a process that stores their own voice for future use in computer-based speech synthesizers," and speech synthesizers can use eye-tracking.
- Saliva and secretions. "Optimum advice on diet, swallowing, positioning, posture, hydration, and oral care should be provided." "Nebulizers, humidifiers, and mucolytics should be considered."
- Palliative care. "Hospice and palliative care providers can provide many resources that are not available or as readily available in the home and can increase the likelihood of a peaceful death." NHS: a care-team appointment "every 2 or 3 months."
Nursing considerations
The RN-specific layer — each action paired with the reason it matters.
How a real nurse thinks
The clinical-judgment loop, worked for a typical presentation — reasoning, not reference.
- 1 Recognize cues
Orthopnea, daytime fatigue, a weak cough and a falling vital capacity (68% to 52%) signal respiratory muscle weakness. Coughing when drinking, long mealtimes and 8% weight loss signal unsafe swallowing and malnutrition. He is aware and anxious about his decline.
- 2 Analyze cues
Breathing difficulty "at night or when lying down" is how respiratory weakness shows in ALS, and dyspnea, orthopnea and daytime fatigue are listed indications for NIV. His VC is close to 50% — the StatPearls threshold for NIV, and the point at which "Decreased FVC of 50% or less almost precludes PEG placement." Severe dysphagia "may lead to weight loss, choking, and aspiration."
- 3 Prioritize
Two time-sensitive problems: respiratory assessment for NIV and the feeding-tube decision before his VC drops below 50%. Both are his choices, so the goals-of-care conversation comes with them.
- 4 Generate solutions
Report the findings to the neurologist for respiratory evaluation (NIV) and a gastrostomy discussion; refer to the dietitian and speech and language therapist; teach upright, neck-flexed eating without talking; revisit his advance directive and communication plan while his speech is still understandable.
- 5 Take action
The nurse reports: 61-year-old man, limb-onset ALS 18 months, on riluzole. New orthopnea, daytime fatigue, weak cough, VC 52% from 68%, weight down 8%, coughing with fluids. Requesting respiratory review for NIV and a gastrostomy discussion today, plus dietitian and speech therapy referrals. The nurse then teaches safe-swallow positioning and arranges a goals-of-care conversation.
- 6 Evaluate
He starts NIV at night and elects a gastrostomy, which is scheduled before his VC falls further. He begins voice banking and completes his advance directive, including his wishes about tracheostomy. His wife is linked with caregiver support.
Scenario — you’re the nurse
Work each question before revealing the answer. Rationales explain the wrong options too.
A 61-year-old man was diagnosed with limb-onset ALS 18 months ago. He takes riluzole and has an advance directive in progress. His wife says he now sleeps propped up in a recliner because he ‘can’t get his breath’ lying flat, he is ‘exhausted all day’, and meals take an hour because he coughs when he drinks.
Q1 Select all that apply Which findings are expected in ALS? Select all that apply. - A. Hyperreflexia and spasticity
- B. Muscle atrophy and fasciculations
- C. Loss of sensation in a stocking distribution early in the disease
- D. Eye movements preserved until late
- E. Relapses followed by full remissions
Reveal answer & rationale
Q2 Select all that apply Which findings in this patient suggest he needs assessment for noninvasive ventilation? Select all that apply. - A. Orthopnea
- B. Daytime fatigue
- C. Vital capacity falling toward 50%
- D. Slurred speech
- E. A weak cough
Reveal answer & rationale
Q3 Multiple choice When should a gastrostomy be placed in a patient with ALS who chooses one? - A. Only after the patient can no longer swallow at all
- B. Before the vital capacity falls below 50% of predicted
- C. After tracheostomy ventilation is started
- D. At diagnosis for every patient
Reveal answer & rationale
Q4 Multiple choice Which statement about riluzole is accurate? - A. It cures ALS if started early
- B. It may extend survival by a few months and needs liver enzyme monitoring
- C. It is given by spinal injection
- D. It reverses muscle wasting
Reveal answer & rationale
Q5 Multiple choice When should the nurse begin conversations about advance directives with a person newly diagnosed with ALS? - A. Soon after diagnosis, revisiting them as the disease progresses
- B. Only when the patient needs a ventilator
- C. Only if the patient develops cognitive impairment
- D. After the patient enters hospice
Reveal answer & rationale
Common questions
What causes amyotrophic lateral sclerosis?
What are the early signs of amyotrophic lateral sclerosis?
Which medications are used to treat amyotrophic lateral sclerosis?
Is thinking affected in ALS?
What medicines are approved for ALS?
How is ALS different from multiple sclerosis?
Sources
- Amyotrophic Lateral Sclerosis — StatPearls — StatPearls (NCBI Bookshelf)
- Motor Neuron Disease — StatPearls — StatPearls (NCBI Bookshelf)
- Amyotrophic Lateral Sclerosis (ALS) — NINDS — National Institute of Neurological Disorders and Stroke (NIH)
- Motor neurone disease (MND) — NHS. Contains public sector information licensed under the Open Government Licence v3.0 (https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/) — NHS (Open Government Licence v3.0)
- FDA approves treatment of amyotrophic lateral sclerosis associated with a mutation in the SOD1 gene (April 25, 2023) — U.S. Food and Drug Administration
- Dysphagia — StatPearls — StatPearls (NCBI Bookshelf)
- Iranian clinical practice guideline for amyotrophic lateral sclerosis (Boostani et al., Front Neurol 2023) — Frontiers in Neurology via PMC (CC BY 4.0)
- Riluzole Tablets — Prescribing Information (DailyMed) — U.S. National Library of Medicine (DailyMed)
Reviewed by Hae Suk Lee, RN
Educational summary for nursing students. Scenarios are fictional teaching cases. Always verify against current guidelines and your institution's protocols before acting in practice. Not medical advice.