Amyotrophic Lateral Sclerosis (ALS)
Lou Gehrig's Disease
What is amyotrophic lateral sclerosis?
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
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.
Motor neurons are nerve cells located in the brain,
brain stem, and spinal cord that serve as controlling units and vital
communication links between the nervous system and the voluntary muscles
of the body. Messages from motor neurons in the brain (called upper
motor neurons) are transmitted to motor neurons in the spinal cord
(called lower motor neurons) and from them to particular muscles. In
ALS, both the upper motor neurons and the lower motor neurons degenerate
or die, ceasing to send messages to muscles. Unable to function, the
muscles gradually weaken, waste away (atrophy), and twitch
(fasciculations). Eventually, the ability of the brain to start and
control voluntary movement is lost.
ALS causes weakness with a wide range of disabilities. Eventually,
all muscles under voluntary control are affected, and patients lose
their strength and the ability to move their arms, legs, and body. When
muscles in the diaphragm and chest wall fail, patients lose the ability
to breathe without ventilatory support. Most people with ALS die from
respiratory failure, usually within 3 to 5 years from the onset of
symptoms. However, about 10 percent of ALS patients survive for 10 or
Although the disease usually does not impair a person's mind or
intelligence, several recent studies suggest that some ALS patients may
have alterations in cognitive functions such as depression and problems
with decision-making and memory.
ALS does not affect a person's ability to see, smell, taste, hear, or
recognize touch. Patients usually maintain control of eye muscles and
bladder and bowel functions, although in the late stages of the disease
most patients will need help getting to and from the bathroom.
Who gets ALS?
As many as 20,000 Americans have ALS, and an estimated 5,000 people
in the United States are diagnosed with the disease each year. ALS is
one of the most common neuromuscular diseases worldwide, and people of
all races and ethnic backgrounds are affected. ALS most commonly strikes
people between 40 and 60 years of age, 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. Patients do not have a
family history of the disease, and their family members are not
considered to be at increased risk for developing ALS.
About 5 to 10 percent of all ALS cases are inherited. The familial
form of ALS usually results from a pattern of inheritance that requires
only one parent to carry the gene responsible for the disease.
What are the symptoms of ALS?
The onset of ALS may be so subtle that the symptoms are frequently
overlooked. The earliest symptoms may include twitching, cramping, or
stiffness of muscles; muscle weakness affecting an arm or a leg; slurred
and nasal speech; or difficulty chewing or swallowing. These general
complaints then develop into more obvious weakness or atrophy that may
cause a physician to suspect ALS.
The parts of the body affected by early symptoms of ALS depend on
which muscles in the body are damaged first. In some cases, symptoms
initially affect one of the legs, and patients experience awkwardness
when walking or running or they notice that they are tripping or
stumbling more often. Some patients first see the effects of the disease
on 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. Other patients notice speech problems.
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. Patients have increasing problems with moving,
swallowing (dysphagia), and speaking or forming words (dysarthria).
Symptoms of upper motor neuron involvement include tight and stiff
muscles (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 fleeting twitches of muscles that can be seen under
the skin (fasciculations).
To be diagnosed with ALS, patients must have signs and symptoms of
both upper and lower motor neuron damage that cannot be attributed to
Although the sequence of emerging symptoms and the rate of disease
progression vary from person to person, eventually patients 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 patient's ability to eat
normally and increase the risk of choking. Maintaining weight will then
become a problem. Because the disease usually does not affect cognitive
abilities, patients are aware of their progressive loss of function and
may become anxious and depressed.
In later stages of the disease, patients have difficulty breathing as
the muscles of the respiratory system weaken. Patients eventually lose
the ability to breathe on their own and must depend on ventilatory
support for survival. Patients also face an increased risk of pneumonia
during later stages of ALS.
How is ALS diagnosed?
No one test can provide a definitive diagnosis of ALS, although the
presence of upper and lower motor neuron signs in a single limb is
strongly suggestive. Instead, the diagnosis of ALS is primarily based on
the symptoms and signs the physician observes in the patient and a
series of tests to rule out other diseases. Physicians obtain the
patient's full medical history and usually conduct a neurologic
examination at regular intervals to assess whether symptoms such as
muscle weakness, atrophy of muscles, hyperreflexia, and spasticity are
getting progressively worse.
Because symptoms of ALS can be similar to those of a wide variety of
other, more treatable diseases or disorders, appropriate tests must be
conducted to exclude the possibility of other conditions.
One of these tests is electromyography
(EMG), a special recording technique that detects electrical activity
in muscles. Certain EMG findings can support the diagnosis of ALS.
Another common test measures nerve conduction velocity (NCV).
How is ALS treated?
No cure has yet been found for ALS. However, the Food and Drug
Administration (FDA) has approved the first drug treatment for the
disease—riluzole (Rilutek). Riluzole is believed to reduce damage to motor neurons by decreasing the release of glutamate.
Clinical trials with ALS patients showed that riluzole prolongs
survival by several months, mainly in those with difficulty swallowing.
The drug also extends the time before a patient needs ventilation
support. Riluzole does not reverse the damage already done to motor
neurons, and patients taking the drug must be monitored for liver damage
and other possible side effects. However, this first disease-specific
therapy offers hope that the progression of ALS may one day be slowed by
new medications or combinations of drugs.
Other treatments for ALS are designed to relieve symptoms and improve the quality of life for patients.
Physicians can prescribe medications to help reduce fatigue, ease
muscle cramps, control spasticity, and reduce excess saliva and phlegm.
Drugs also are available to help patients with pain, depression, sleep disturbances, and constipation.
Physical therapy and special equipment can enhance patients'
independence and safety throughout the course of ALS. Gentle, low-impact
aerobic exercise such as walking, swimming, and stationary bicycling
can strengthen unaffected muscles, improve cardiovascular health, and
help patients fight fatigue and depression. Range of motion and
stretching exercises can help prevent painful spasticity and shortening
(contracture) of muscles.
ALS patients who have difficulty speaking may benefit from working
with a speech therapist. These health professionals can teach patients
adaptive strategies such as techniques to help them speak louder and
more clearly. As ALS progresses, speech therapists can help patients
develop ways for responding to yes-or-no questions with their eyes or by
other nonverbal means and can recommend aids such as speech
synthesizers and computer-based communication systems. These methods and
devices help patients communicate when they can no longer speak or
produce vocal sounds.
Patients and caregivers can learn from speech therapists and
nutritionists how to plan and prepare numerous small meals throughout
the day that provide enough calories, fiber, and fluid and how to avoid
foods that are difficult to swallow. Patients may begin using suction
devices to remove excess fluids or saliva and prevent choking. When
patients can no longer get enough nourishment from eating, doctors may
advise inserting a feeding tube into the stomach. The use of a feeding
tube also reduces the risk of choking and pneumonia that can result from
inhaling liquids into the lungs. The tube is not painful and does not
prevent patients from eating food orally if they wish.
When the muscles that assist in breathing weaken, use of nocturnal
ventilatory assistance (intermittent positive pressure ventilation
[IPPV] or bilevel positive airway pressure [BIPAP]) may be used to aid
breathing during sleep. Such devices artificially inflate the patient's
lungs from various external sources that are applied directly to the
face or body. When muscles are no longer able to maintain oxygen and
carbon dioxide levels, these devices may be used full-time.
Patients may eventually consider forms of mechanical ventilation
(respirators) in which a machine inflates and deflates the lungs. To be
effective, this may require a tube that passes from the nose or mouth to
the windpipe (trachea) and for long-term use, an operation such as a
tracheostomy, in which a plastic breathing tube is inserted directly in
the patient's windpipe through an opening in the neck. Patients and
their families should consider several factors when deciding whether and
when to use one of these options.
Ventilation devices differ in their effect on the patient's quality
of life and in cost. Although ventilation support can ease problems with
breathing and prolong survival, it does not affect the progression of
ALS. Patients need to be fully informed about these considerations and
the long-term effects of life without movement before they make
decisions about ventilation support.
What causes ALS?
The cause of ALS is not known, and scientists do not yet know why ALS strikes some people and not others.
Studies also have focused on the role of glutamate in motor neuron
degeneration. Glutamate is one of the chemical messengers or
neurotransmitters in the brain. Scientists have found that, compared to
healthy people, ALS patients have higher levels of glutamate in the
serum and spinal fluid. Laboratory studies have demonstrated that
neurons begin to die off when they are exposed over long periods to
excessive amounts of glutamate. Now, scientists are trying to understand
what mechanisms lead to a buildup of unneeded glutamate in the spinal
fluid and how this imbalance could contribute to the development of ALS.
Autoimmune responses—-which occur when the body's immune system
attacks normal cells-—have been suggested as one possible cause for
motor neuron degeneration in ALS. Some scientists theorize that
antibodies may directly or indirectly impair the function of motor
neurons, interfering with the transmission of signals between the brain
In searching for the cause of ALS, researchers have also studied
environmental factors such as exposure to toxic or infectious agents.
Other research has examined the possible role of dietary deficiency or
trauma. However, as of yet, there is insufficient evidence to implicate
these factors as causes of ALS.
© 2010 Vivacare. Last updated April 4, 2011.
Vivacare public information from The National Institute of Neurological Disorders and Stroke
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