Amyotrophic Lateral Sclerosis
(Lou Gehrig's Disease · ALS)
In this condition factsheet:
The Facts on Amyotrophic Lateral Sclerosis
Amyotrophic lateral sclerosis (ALS) – commonly known as Lou Gehrig's disease or motor neuron disease – is a neuromuscular disorder. It's caused when the motor neurons that send electric "messages" from the brain to the spinal cord (upper motor neurons) or from the spinal cord (lower motor neurons) to the muscles are slowly being destroyed. These neurons are responsible for muscle movement.
When the messages don't get through from the spinal cord, the muscles eventually lose strength and waste away. This process is called atrophy or amyotrophy. When signals from the brain to the spinal cord are blocked, the muscles become stiff and slow. This is called spasticity.
It is the most common form of neuron disease, and approximately 2 out of 100,000 people each year are newly diagnosed with ALS. It's more common in men than women, with symptoms usually appearing between the ages of 50 and 75. About 10% of people with ALS have a family history of the disease. The average life expectancy is 2 to 5 years after diagnosis.
Causes of Amyotrophic Lateral Sclerosis
The causes of ALS are starting to be understood. Multiple factors are at play, both genetic and environmental. At least 16 different genes are involved in ALS. No single environmental factor has been proven to cause it. ALS does not appear to result from exposure to heavy metal or viral infection alone. Even blocking the neurotransmitter glutamate does not stop the disease.
Genetic counselling and then possible genetic testing should be offered to all people diagnosed with ALS.
Symptoms and Complications of Amyotrophic Lateral Sclerosis
The symptoms of ALS are caused by the destruction of motor neurons resulting in gradual deterioration of the muscles. Muscle atrophy often starts in the hands or feet and moves its way up the arms to the shoulders or up the legs to the hips.
The early symptoms of ALS include muscle weakness, clumsy hand movements, muscle stiffness, and difficulty performing tasks that require delicate movements of the fingers or hands. Muscular weakness in the legs may cause tripping and falling. As the muscles lose strength, some people experience muscle cramps, twitches, or spasms. When ALS progresses, more muscle groups become affected, leading to:
- impaired speech
- difficulty swallowing
- breathing problems caused by a weakened diaphragm
In most patients, only motor neurons – and therefore only muscles – are affected with ALS. Eye muscles, as well as bladder and bowel muscles, aren't usually involved, and the disease doesn't affect a person's mind or any of the 5 senses. People remain alert, but often lose the ability to take care of themselves. It can even become impossible to breathe without the help of a respirator. In about 30% to 50% of patients, other parts of the brain are affected, which can lead to progressive cognitive decline, emotional instability, and even dementia.
There are several variants of ALS. Each has different symptoms and a different outcome.
Primary bulbar palsy: The initial or predominant symptoms are impaired speech or swallowing along with wasting of the tongue. The outcome is generally worse in this condition since swallowing and breathing are affected early in the course of the disease.
Progressive muscle atrophy: Muscle weakness and wasting are the principal features. Speech and swallowing are not affected and there is no spasticity. These individuals tend to have a slower course.
Primary lateral sclerosis: The main feature is spasticity with no muscle atrophy. The outcome is usually somewhat better.
