Amyotrophic lateral sclerosis (ALS), sometimes called Lou Gehrig's disease, is a rapidly progressive, invariably fatal neurological disease that attacks the nerve cells (neurons) responsible for controlling voluntary muscles (muscle action we are able to control, such as those in the arms, legs, and face). The disease belongs to a group of disorders known as motor neuron diseases, which are characterized by the gradual degeneration and death of motor neurons.
Symptoms: The onset of ALS may be so subtle that the symptoms are overlooked. The earliest symptoms may include fasciculations, cramps, tight and stiff muscles (spasticity), muscle weakness affecting an arm or a leg, slurred and nasal speech, or difficulty chewing or swallowing.
Progression of ALS is not always a straight line in an individual either. It is not uncommon to have periods lasting weeks to months where there is very little or no loss of function. There are even very rare examples in which there is significant improvement and recovery of lost function. These ALS "arrests" and "reversals" are unfortunately usually transient. Less than 1% of patients with ALS will have significant improvement in function lasting 12 months or more.