what are the causes and symptoms of als?
['Difficulty walking or doing normal daily activities.', 'Tripping and falling.', 'Weakness in your leg, feet or ankles.', 'Hand weakness or clumsiness.', 'Slurred speech or trouble swallowing.', 'Muscle cramps and twitching in your arms, shoulders and tongue.', 'Inappropriate crying, laughing or yawning.']