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Amyotrophic lateral sclerosis (ALS)
ALS is a degenerative disease of upper and lower motor neurons, so it combines upper motor neuron signs (spasticity, brisk reflexes) and lower motor neuron signs (wasting and fasciculations) — without involvement of sensation, eye movements or sphincters.
Why it matters in the exam
Questions present a patient with weakness and wasting of the hand muscles, fasciculations, and alongside them brisk reflexes or an extensor plantar, or a patient with slurred speech, swallowing difficulty and a wasted, quivering tongue. They test the combination of upper and lower neuron signs in one patient, the absence of sensory loss, the differential diagnosis (cervical myelopathy, multifocal motor neuropathy), the link to frontotemporal dementia, and treatment: riluzole, non-invasive ventilation and gastrostomy. Common distractors include unnecessary neck surgery or delaying ventilation until full respiratory failure. The C9orf72 gene and a specific treatment for SOD1 carriers are also asked. Median survival from symptom onset is a few years, and death is usually from respiratory failure. An early conversation about the patient's wishes on ventilation, feeding and end of life is therefore part of care, as are palliative referral and family support.
Key points
- ALS combines upper and lower motor neuron signs in the same patient.
- Sensation, eye movements and sphincters are spared, so their involvement should prompt a search for another diagnosis rather than be blamed on ALS.
- Cervical myelopathy and MMN must be excluded in the differential.
- Riluzole 50 mg twice daily, and tofersen for SOD1 carriers.
- Non-invasive ventilation, gastrostomy and a multidisciplinary team improve survival and quality of life.
Summary table
| Aspect | Findings | Meaning |
|---|---|---|
| Upper motor neuron | Spasticity, brisk reflexes, Babinski sign, uncontrolled laughing and crying | Combination with lower motor neuron signs is the key to diagnosis |
| Lower motor neuron | Weakness, wasting, fasciculations (including the tongue), "split hand" | EMG shows denervation in several regions |
| What is spared | Sensation, eye movements, sphincters, and the heart muscle is not affected either | Sensory or sphincter involvement suggests another diagnosis |
| Differential diagnosis | Cervical myelopathy (no bulbar signs), MMN with conduction block, Kennedy disease, inclusion body myositis | Neck MRI and an electrical study for every patient |
| Treatment | Riluzole 50 mg twice daily; tofersen for SOD1 carriers; non-invasive ventilation and vital-capacity monitoring; gastrostomy with weight loss | Multidisciplinary care improves survival; non-invasive ventilation prolongs life and improves its quality |
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Sources
- EFNS Guidelines on the Clinical Management of Amyotrophic Lateral Sclerosis, 2012 — Diagnosis, ventilation and nutrition
- Gold Coast Criteria for the Diagnosis of ALS (Shefner et al., Clinical Neurophysiology), 2020 — Diagnostic criteria
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.