Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig's disease, is a progressive neurological disorder that affects motor neurons—the nerve cells in the brain and spinal cord responsible for controlling voluntary muscle movement. As these neurons degenerate and die, the brain loses its ability to initiate and control muscle movement, leading to muscle weakness, paralysis, and eventually respiratory failure.

The most common initial symptom is a gradual onset of progressive muscle weakness, which is generally painless. Other early signs may include muscle twitching (fasciculations), cramping, stiffness, slurred speech, difficulty swallowing, or trouble walking. Symptoms typically start in the limbs but can begin in the muscles that control speech and swallowing. As the disease progresses, it affects more muscle groups, leading to severe disability.

Currently, there is no cure for ALS. Treatments focus on slowing disease progression, managing symptoms, and improving quality of life. Multidisciplinary care involving neurologists, physical therapists, speech therapists, and nutritionists is essential for symptom management.

Symptom management includes physical therapy to maintain mobility, occupational therapy for daily activities, speech therapy for communication, and nutritional support. Assistive devices like wheelchairs, voice amplifiers, or eye-gaze technology help maintain independence. Palliative care focuses on comfort and quality of life.

Calcium ions (Ca²⁺) are essential messengers in neurons, involved in synaptic transmission, plasticity, gene expression, and cell survival. They enter cells through channels like voltage-gated or receptor-operated channels, triggering neurotransmitter release and muscle contraction. Mitochondria and endoplasmic reticulum help regulate calcium levels to prevent overload.