ALS - Amyotrophic Lateral Sclerosis

What is ALS?

Amyotrophic lateral sclerosis (ALS), often referred to as "Lou Gehrig's Disease," is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. Motor neurons reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. The progressive degeneration of the motor neurons in ALS eventually leads to their death. When the motor neurons die, the ability of the brain to initiate and control muscle movement is lost. With voluntary muscle action progressively affected, patients in the later stages of the disease may become totally paralyzed.

A-myo-trophic comes from the Greek language. "A" means no or negative. "Myo" refers to muscle, and "Trophic" means nourishment–"No muscle nourishment." When a muscle has no nourishment, it "atrophies" or wastes away. "Lateral" identifies the areas in a person's spinal cord where portions of the nerve cells that signal and control the muscles are located. As this area degenerates it leads to scarring or hardening ("sclerosis") in the region.

Who gets ALS?

ALS is one of the most common neuromuscular diseases worldwide, and people of all races and ethnic backgrounds are affected. ALS is more common among white males, non-Hispanics, and persons aged 60–69 years, but younger and older people also can develop the disease. Men are affected more often than women.

In 90 to 95 percent of all ALS cases, the disease occurs apparently at random with no clearly associated risk factors. Individuals with this sporadic form of the disease do not have a family history of ALS, and their family members are not considered to be at increased risk for developing it.

About 5 to 10 percent of all ALS cases are inherited. The familiar form of ALS usually results from a pattern of inheritance that requires only one parent to carry the gene responsible for the disease. Mutations in more than a dozen genes have been found to cause familial ALS.

Signs and symptoms

The disorder causes muscle weakness and atrophy throughout the body due to the degeneration of the upper and lower motor neurons. Individuals affected by the disorder may ultimately lose the ability to initiate and control all voluntary movement, although bladder and bowel function and the muscles responsible for eye movement are usually spared until the final stages of the disease. Cognitive function is generally spared for most patients, although some (about 5%) also develop frontotemporal dementia. A higher proportion of patients (30–50%) also have more subtle cognitive changes which may go unnoticed, but are revealed by detailed neuropsychological testing. Infrequently ALS coexists in individuals who also experience dementia, degenerative muscle disease, and degenerative bone disease as part of a syndrome called multisystem proteinopathy. Sensory nerves and the autonomic nervous system are generally unaffected, meaning the majority of people with ALS will maintain hearing, sight, touch, smell, and taste.

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. In most cases, people with ALS do not experience difficulties in bowel, bladder or sexual function.

The parts of the body showing early symptoms of ALS depend on which muscles in the body are affected. Many individuals first see the effects of the disease in a hand or arm as they experience difficulty with simple tasks requiring manual dexterity such as buttoning a shirt, writing, or turning a key in a lock. In other cases, symptoms initially affect one of the legs, and people experience awkwardness when walking or running or they notice that they are tripping or stumbling more often. When symptoms begin in the arms or legs, it is referred to as “limb onset” ALS.

Other individuals first notice speech problems, termed “bulbar onset” ALS. Regardless of the part of the body first affected by the disease, muscle weakness and atrophy spread to other parts of the body as the disease progresses. Individuals may develop problems with moving, swallowing (dysphagia), and speaking or forming words (dysarthria). Symptoms of upper motor neuron involvement include spasticity and exaggerated reflexes (hyperreflexia) including an overactive gag reflex. An abnormal reflex commonly called Babinski’s sign (the large toe extends upward as the sole of the foot is stimulated in a certain way) also indicates upper motor neuron damage. Symptoms of lower motor neuron degeneration include muscle weakness and atrophy, muscle cramps, and fasciculation’s.

Although the sequence of emerging symptoms and the rate of disease progression vary from person to person, eventually individuals will not be able to stand or walk, get in or out of bed on their own, or use their hands and arms. Difficulty swallowing and chewing impair the person’s ability to eat normally and increase the risk of choking. Maintaining weight will then become a problem. Because cognitive abilities are relatively intact, people are aware of their progressive loss of function and may become anxious and depressed. A small percentage of individuals may experience problems with memory or decision-making, and there is growing evidence that some may even develop a form of dementia over time. In later stages of the disease, individuals have difficulty breathing as the muscles of the respiratory system weaken. They eventually lose the ability to breathe on their own and must depend on ventilatory support for survival. Affected individuals also face an increased risk of pneumonia during later stages of ALS.

Monitoring ALS

After receiving a diagnosis, people with ALS typically attend regular clinic visits about every 3-4 months. During these visits, each patient is monitored for changes in their functional abilities.

Commonly used tests include:

ALS Functional Rating Scale-Revised (ALSFRS-R): A rating scale that measure changes including breathing, speaking, sleeping, swallowing, and walking. The score is based on answers to 12 questions using a 48-point scale.

Spirometry: A test that measures lung function. Breathing abilities are typically estimated based on the maximum amount of air that can be blown out either slowly (slow vital capacity - SVC) or quickly (slow vital capacity - SVC).

What causes ALS?

The cause of ALS is not known, and scientists do not yet know why ALS strikes some people and not others. Genetic mutations are believed to be involved in ALS. Researchers also propose that ALS is a disorder with genetic, clinical, and pathological overlap.

In searching for the cause of ALS, researchers are also studying the role of environmental factors such as exposure to toxic or infectious agents, as well as physical trauma or behavioral and occupational factors.

How is ALS treated?

No cure has yet been found for ALS. Treatment for ALS is generally designed to relieve symptoms and improve the quality of life for individuals with the disorder. This supportive care is best provided by multidisciplinary teams of health care professionals such as physicians; pharmacists; physical, occupational, and speech therapists; nutritionists; and social workers and home care and hospice nurses. Working with patients and caregivers, these teams can design an individualized plan of medical and physical therapy and provide special equipment aimed at keeping patients as mobile and comfortable as possible.