Amyotrophic lateral sclerosis - ALS

Amyotrophic lateral sclerosis is a progressive motor neuron disease marked by combined upper and lower motor neuron findings, bulbar dysfunction, and eventual respiratory failure. In the ED, the high-yield questions are recognizing the pattern, excluding reversible mimics, and handling respiratory decline and goals-of-care early.

ALS recognition and emergency evaluation

• Mixed motor neuron signs: Concurrent upper and lower motor neuron findings are the bedside red flag for ALS, with hyperreflexia and spasticity alongside atrophy, fasciculations, or hyporeflexia.
• Limb versus bulbar onset: Limb-onset disease accounts for about 70% of presentations, while bulbar onset more often starts with dysarthria and dysphagia before limb weakness becomes prominent.
• ALS-plus features: Sensory loss, ocular motility disturbance, autonomic dysfunction, or extrapyramidal findings should push you to think beyond classic ALS and broaden the differential.
• Cognitive and behavioral overlap: Frontotemporal involvement is common, with about 15% meeting criteria for frontotemporal dementia and many more showing executive or behavioral change, a nuance we get into in the episode.
• Initial ED workup: Start like any suspected neurologic disorder with basic labs and head CT to exclude other pathology, then prioritize urgent neurology follow-up if the patient is stable for discharge.
• Follow-up urgency: A possible new ALS diagnosis should not sit on a routine referral queue; neurology review within 1-2 weeks is the practical target, and calling from the ED can accelerate access.

Respiratory failure, prognosis, and goals of care

• Linear disease progression: ALS typically progresses without remissions, spreading from focal weakness to broader limb and bulbar involvement in a fairly predictable pattern rather than relapsing flares.
• Prognosis worth naming early: ALS is terminal: roughly 50% of patients die within 3 years of diagnosis, and only about 10% live beyond 10 years.
• Respiratory weakness pattern: Chronic respiratory failure usually reflects diaphragmatic and intercostal muscle weakness rather than primary lung disease, which changes how you frame deterioration at the bedside.
• NIV as key support: Noninvasive ventilation can reduce symptoms and prolong life, and acute pulmonary instability in ALS generally warrants admission when NIV initiation is on the table. We walk through the practical framing in the chapter.
• Search for reversible triggers: Acute respiratory decompensation in ALS still demands a hunt for pneumonia, pneumothorax, and other superimposed causes rather than assuming pure disease progression.
• Early end-of-life planning: Goals-of-care discussions belong early after diagnosis, especially around tracheostomy, gastrostomy, and communication of future preferences so unwanted emergency interventions are less likely.

Symptom management and ventilator care

• Modest disease-modifying therapy: Riluzole modestly extends survival by about 3-6 months, so day-to-day ED care remains centered on symptom control and complications rather than dramatic reversal.
• Pain treatment priorities: Pain is common from cramps, immobility, and pressure injury, with acetaminophen or NSAIDs as first-line options and gabapentin or muscle relaxants as common adjuncts.
• Opioid ventilation caution: Opioids deserve extra caution in ALS because respiratory reserve is already limited, making sedating analgesia a bigger hazard than in many other chronic neurologic illnesses.
• Nutrition and secretion burden: Dysphagia, constipation, sialorrhea, and bronchial secretions drive substantial morbidity and often explain why seemingly stable patients are struggling at home.
• Ventilator strategy in distress: If a ventilated ALS patient develops distress from a pulmonary process like pneumonia, manage the lung problem with standard lung-protective ventilation, including 6 mL/kg ideal body weight tidal volume.

References:

1. Hardiman O, Al-Chalabi A, Chio A, et al. Amyotrophic lateral sclerosis.  Nat Rev Dis Primers. 2017;3:17071. Published 2017 Oct 5. PMID: 28980624
2. Masrori P, Van Damme P. Amyotrophic lateral sclerosis: a clinical review. Eur J Neurol. 2020;27(10):1918-1929. PMID: 32526057
3. Brotman RG, Moreno-Escobar MC, Joseph J, et al. Amyotrophic Lateral Sclerosis. [Updated 2022 Aug  22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:  https://www.ncbi.nlm.nih.gov/books/NBK556151/