Educational scope notice: This is a study note for medical students, not medical advice, diagnosis, or treatment guidance. Clinical management should follow local protocols and current guidelines.
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease in which upper motor neurons in the motor cortex and lower motor neurons in the brainstem and spinal cord degenerate together. Spasticity and brisk reflexes appear alongside wasting, weakness, and fasciculations in the same body region. That combined pattern is the clinical hallmark. “Motor neuron disease” is the usual umbrella term in the United Kingdom, while “ALS” is more common in the United States.
The disease takes different patterns with different pace, so recognising the pattern matters for prognosis and planning. It is uncommon and usually appears in later adult life. Reported figures vary widely because registries and methods differ, not only because the disease does.
Choose a route through the topic
- ALS Pathophysiology explains why motor neurons are vulnerable and how genes and the link with frontotemporal dementia fit together.
- ALS Clinical Phenotypes explains the main presentation patterns and how the pattern relates to pace and planning.
- ALS Diagnosis explains how combined upper and lower motor neuron involvement is demonstrated and mimics are excluded.
- ALS Treatment explains what modestly slows progression and how symptomatic, respiratory, and nutritional care preserves daily life.
The useful sequence is mechanisms and patterns first, then diagnosis, then treatment.
Evidence anchors
- NICE. Motor neurone disease: assessment and management (NG42): https://www.nice.org.uk/guidance/ng42
- National Institute of Neurological Disorders and Stroke. Amyotrophic lateral sclerosis: https://www.ninds.nih.gov/health-information/disorders/amyotrophic-lateral-sclerosis-als