Early symptoms of amyotrophic lateral sclerosis include:

• Muscle twitching
• Muscle spasms
• Increasing muscle weakness
• Generalized weakness

Later symptoms include:

• Arm weakness (bilateral)
• Clumsiness of the hands
• Difficulty swallowing
• Difficulty talking
• Difficulty walking
• Leg weakness (bilateral)
• Loss of balance
• Muscle wasting
• Unintentional weight loss

A person with ALS may become unable to breath and require mechanical ventilation.