Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by the degeneration of motor neurons in the brain and spinal cord. These nerve cells control voluntary muscle movements, and as they deteriorate, they cease sending signals to the muscles, leading to a loss of muscle control. The condition is also widely known as Lou Gehrig’s disease, named after the famous baseball player who was diagnosed with it.
Symptoms and Disease Progression
The initial manifestations of ALS often vary from person to person. Some individuals experience “limb-onset” ALS, where the first signs appear in the arms or legs, such as muscle twitches or weakness. In other cases, the disease begins with “bulbar-onset,” affecting the muscles used for speaking and swallowing, leading to slurred speech or difficulty with meals.
As the disease advances, muscle weakness and atrophy spread throughout the body. This loss of muscle function leads to difficulty with mobility, impacting the ability to walk, stand, or use the hands and arms. The muscles responsible for breathing also weaken, causing shortness of breath. This respiratory weakness eventually becomes a significant challenge.
A notable aspect of ALS is that it does not affect all bodily functions. The senses, including sight, hearing, touch, taste, and smell, remain intact. For most individuals, the disease does not directly impair bladder and bowel control, and the involuntary muscles of the heart and digestive system continue to function.
While ALS is a motor neuron disease, some individuals also experience changes in cognitive function and behavior. There is a link between ALS and frontotemporal dementia (FTD), and up to half of those with ALS may face mild to moderate difficulties. These can include problems with decision-making, organization, or shifts in personality.
Causes and Risk Factors
The precise cause for most ALS cases remains unknown. Approximately 90% of diagnoses are for “sporadic” ALS, which occurs randomly without clear risk factors or a family history of the condition. Researchers are investigating potential environmental triggers, but no definitive links have been established.
The remaining cases are classified as “familial” ALS, which is the inherited form of the disease. This type is caused by mutations in specific genes that are passed down through families. A family history of ALS is the most significant indicator for this form of the condition.
Certain demographic factors are associated with a higher likelihood of developing ALS. The disease most commonly appears in individuals between the ages of 40 and 70. Men are also slightly more likely to develop ALS than women, particularly before the ages of 65 or 70.
The Diagnostic Process
There is no single test to diagnose amyotrophic lateral sclerosis. The diagnosis is a process of elimination, using clinical assessments and tests to rule out other conditions that present with similar symptoms, as many neurological disorders can mimic the early signs of ALS.
A thorough neurological examination is the first step, where a physician assesses motor skills, muscle strength, reflexes, and coordination. This clinical evaluation helps to identify patterns of weakness and other signs consistent with motor neuron damage. The doctor will look for evidence of both upper and lower motor neuron involvement.
Electromyography (EMG) and nerve conduction studies (NCS) are commonly performed to gather more evidence. An EMG measures electrical activity within muscles, while an NCS assesses the ability of nerves to send signals. These tests can confirm that muscle weakness is due to nerve cell destruction and not a problem within the muscles.
Imaging and laboratory tests are used to exclude other medical problems. A magnetic resonance imaging (MRI) scan of the brain and spinal cord cannot show ALS but can reveal other causes for the symptoms, such as a spinal tumor or multiple sclerosis. Blood and urine tests also check for other diseases that might cause muscle weakness.
Managing ALS
While there is no cure for ALS, a management strategy can help maintain quality of life and may slow the rate of decline. Treatment focuses on alleviating symptoms and providing supportive care through medical and therapeutic interventions. This approach is tailored to the individual’s needs as the disease progresses.
Several medications have been approved by the U.S. Food and Drug Administration (FDA) to treat ALS. Drugs such as Riluzole and Edaravone have been shown in clinical trials to have a modest effect on slowing disease progression. Other medications are prescribed to manage specific symptoms, including muscle cramps, stiffness, and excess saliva.
Therapeutic support is a central component of ALS care. Physical therapy helps patients maintain mobility, while occupational therapy provides strategies and adaptive equipment to assist with daily tasks. Speech therapists work with individuals to preserve communication skills and address swallowing difficulties.
As the disease affects respiratory muscles, breathing support becomes necessary. Initially, non-invasive ventilation (NIV) can assist with breathing, especially at night, while mechanical ventilation may be required in later stages. If swallowing becomes too difficult, a feeding tube can be placed to ensure adequate nutrition and hydration. This care is delivered by a multidisciplinary team of specialists.