Amyotrophic Lateral Sclerosis
Overview
Plain-Language Overview
Amyotrophic Lateral Sclerosis (ALS) is a serious disease that affects the nervous system, specifically the nerve cells that control muscle movement. It causes these nerve cells to gradually die, leading to muscle weakness and loss of control over voluntary movements. People with ALS may experience difficulty with walking, speaking, swallowing, and eventually breathing. The disease affects both the upper and lower motor neurons, which are essential for sending signals from the brain to the muscles. Over time, this leads to increasing disability and challenges in daily activities. ALS does not typically affect the senses or thinking abilities.
Clinical Definition
Amyotrophic Lateral Sclerosis (ALS) is a progressive neurodegenerative disorder characterized by the selective loss of both upper motor neurons in the motor cortex and lower motor neurons in the brainstem and spinal cord. The core pathology involves motor neuron degeneration leading to muscle atrophy, weakness, and spasticity. The exact cause is often unknown but can involve genetic mutations such as in the SOD1 or C9orf72 genes. ALS results in a combination of upper motor neuron signs (spasticity, hyperreflexia) and lower motor neuron signs (fasciculations, muscle atrophy). The disease is clinically significant due to its relentless progression and fatal outcome, typically from respiratory failure within 3 to 5 years of symptom onset. Diagnosis is primarily clinical, supported by electrophysiological studies.