ALS, also known as Lou Gehrig's disease, Charcot's disease, and motor neuron disease (MND), attacks certain cells in the brain and spinal cord needed to keep our muscles moving. Early signs and symptoms of ALS include:
- muscle cramps and muscle twitching
- weakness in hands, legs, feet or ankles
- difficulty speaking or swallowing
The senses, including hearing, sight, smell, taste, and touch, are not affected by ALS.
There is no single diagnostic test for ALS. However, experts in the disease, usually neurologists specializing in neuromuscular diseases, are very capable of diagnosing ALS. In some cases, they might order additional tests if the diagnosis is not clear. These include:
- electromyography and nerve conduction
- magnetic resonance imaging (MRI)
- genetic tests
- muscle biopsy
- spinal tap
- blood and urine tests
Most people with ALS live 2-5 years after their first signs of disease. About 10% of people with ALS survive at least 10 years. This variable rate of disease progression makes prognosis difficult to predict and therapies challenging to develop.
Currently, there is only a single medicine for specifically treating ALS - riluzole. The drug, marketed by Sanofi-Aventis under the name Rilutek, extends survival by only about 2 to 3 months.
This urgent unmet medical need for effective treatments for this devastating and fatal disease is the basis for the research and drug development effort at the nonprofit biotech organization, ALS Therapy Development Institute.
In people with ALS, the motor neurons deteriorate leading to muscle weakness and paralysis. Why these cells are particularly vulnerable remains an open question, but scientists are beginning to unravel how these cells are destroyed, leading to new ways to attack the disease.
Many cells in the nervous system contribute to ALS.
Courtesy of Stanford University School of Medicine
When neurologist Jean-Martin Charcot, MD, first peered into the tissues of his patients lost to ALS in 1865, he noticed clear signs of progressive neuronal damage that stretched from the brain to the brain stem (upper motor neurons) to the spinal cord (lower motor neurons) and atrophy of neighboring muscles.
Scientists now understand that this neurodegeneration is extremely complicated and occurs through several mechanisms.
Misfolded proteins accumulate. Sodium channels act up (hyperexcitability).Epigenetic and genetic switches are thrown. Energy-producing mitochondriamalfunction, leading to a power drop. Free radicals build up, increasing oxidative stress. Toxic substances accumulate (excitotoxicity).
All of these mechanisms appear to contribute to motor neuron destruction in ALS. Many more are suspected to play a key role in the onset and progression of the disease.
Since the 1980s, scientists have recognized that ALS is much more than a motor neuron disease. Astrocytes andmicroglia entrusted to keep motor neurons healthy and free from infection turn traitor, producing toxic substances that damage them, fuel the progression of ALS. Macrophages and certain T-cells infiltrate the nervous system potentially unleashing a storm of cytokines of their own that further contributes to the disease.
Oligodendrocytes appear to lose their ability to power motor neurons up in people with ALS, contributing to the energy drain and their destruction.