ALS is the abbreviation for "Amyotrophic Lateral Sclerosis."
"A-myo-trophic" comes from the Greek language. "A" means no or negative.
"Myo" refers to muscle, and "Trophic" means nutrition or stimulation. When a
muscle has no stimulation, it "atrophies" or wastes away. "Lateral"
identifies the area of the spinal cord where the pathways for motor nerves, those that innervate
the muscles, are located. As this area degenerates it leads to scarring or hardening,
"sclerosis," in the region.
ALS is a progressive neuromuscular disease. It attacks motor neurons in the brain and spinal
cord which transmit signals to the voluntary muscles throughout the body. When motor neurons die
as a result of ALS, the ability of the brain to control muscle movement is lost. Weakness
spreads to all the voluntary muscles and progresses to paralysis. ALS does not affect sensory
nerves so there is no loss of feeling in the paralyzed areas. ALS only affect motor pathways in
the brain so awareness, thought and intelligence are not generally affected even after paralysis
makes it impossible for the patient to communicate.
In the United States, ALS is also known as Lou Gehrig's Disease after the baseball
player who died from ALS. In other countries it is often called "Motor Neuron
Disease." This leads to some confusion because there are several other forms of motor
neuron diseases such as SMA (Spinal Muscular Atrophy) and Kennedy's Disease. ALS is actually
just one of the motor neuron diseases. Currently ALS is categorized in two forms, Familial and
Sporadic. About 10% of ALS patients have Familial ALS which is an inherited disease. The
majority have Sporadic ALS in which no family history can be found. There is no difference in
the symptoms and progression of the familial and the sporadic forms of the illness.
Even though changes in the levels of a substance called glutamate have been identified as
being at least a part of the process that kills the motor neurons, the cause of the increased
glutamate is not fully understood. Research continues to look for links between ALS, genetics,
toxins, antioxidants, viruses, and autoimmunity. Although some scientists believe it is possible
that ALS is caused by a slow-acting or latent virus, no such virus has ever been identified, and
there is no increased incidence among family members, care givers or medical personnel because
they are in close contact with ALS patients. Many researchers believe that in the end it will be
found that there are many ways in which the process of motor neuron degeneration can be
triggered and therefore several possible causes of ALS.
Who Gets ALS?
ALS occurs throughout the world with no racial, ethnic or socioeconomic boundaries. Most
people who develop ALS are between the ages of 40 and 70. It is not uncommon among people in
their twenties and thirties however. Men are affected slightly more frequently than women.
ALS is not an extremely rare disease. The incidence is about 2 new cases per 100,000 every
year. Because life expectancy is so short, the number of ALS patients alive at any time is low,
but about 5,000 people in the U.S. are newly diagnosed with ALS each year.
Signs and Symptoms of ALS
Even before weakness is noted, muscle twitches, (fasciculations) are common. Other patients
notice a stiffness in their arms and legs. Many have increased muscle cramping. Some people
first experience weakness in their arms or legs. This is referred to as limb-onset ALS. Arm
weakness is somewhat more common and begins with a weakening of the grip and fumbling fingers.
Leg weakness causes fatigue when walking, difficulty climbing stairs, stumbling. For others, the
first symptoms may involve problems with speaking or swallowing: Slurred speech, a nasal tone,
or choking easily. This is bulbar-onset ALS.
As the disease progresses, the weakness becomes more severe and spreads to other areas of
the body. Although one side of the body may be a little ahead of the other in deteriorating, ALS
is usually quite symmetrical. Eventually arms and legs, swallowing and speech and breathing are
all affected. As the muscle weaken, affected areas become thin and wasted. Muscle cramping and
twitching eases as the weakness turns into paralysis, but the twitching and cramping moves on to
newly affected muscles. In some patients, the stiffness noted earlier increases to severe
spasticity and hyperactive reflexes.
Although the areas of the body first affected and the rate of progression varies, the
progression of the disease is generally steady. Plateaus have been documented but are often more
a matter of function than actual delay in the spreading of the weakness. For example, a patient
may seem to plateau after beginning to use a wheelchair. Because he is no longer attempting to
walk, further weakness of his legs is less notable. Involuntary muscles are not affected, so the
heart, bladder and bowel are not directly affected.
The senses, including vision, hearing and touch, are not affected. Although intelligence and
thought are not generally affected, some ALS patients do experience a problem with their
emotional responses sometimes referred to as "pseudobulbar emotionality." They find
themselves bursting into tears or into helpless laughter even though they are not thinking or
feeling overly sad or amused. The mechanism for this misdirected response is unclear and can be
very distressing and embarrassing for the patient. It is often assumed that weeping spells are
due to depression since depression is certainly common in ALS patients. However, if
inappropriate laughter is also seen, this emotional lability is probably not an indication of
emotional problems but rather a physical "short circuit" in the pathways between
emotional thought and the motor responses.
A small percentage of ALS patients do experience a concurrent progressive dementia. The
dementia is not considered part of the usual ALS disease process but rather an added
complication in which other areas of the brain are atypically susceptible to the process that is
destroying the motor neurons. In these patients, personality changes, mood swings, irritability,
unreasonableness occur. Early on it can be very difficult to differentiate between a possible
dementia and an inability to cope with the stresses of the disease. If dementia occurs, it is
usually obvious before the patient loses the ability to communicate so it should never be
assumed that a late stage, non-communicating patient has become demented or vegetative.
At present there is no definitive means of diagnosis of ALS. Most diagnoses are made by
eliminating all other possibilities -- ailments whose symptoms resemble those of ALS.
Neurologists use a number of clinical tests to establish a profile, including blood
testing, EMG, MRI, etc.
Average life expectancy for ALS patients is 2-5 years with the cause of death being
respiratory failure, most often hastened by pneumonia. Weakening of the inspiratory and
expiratory muscles compromises the ability to cough and clear pulmonary secretions. Respiratory
failure usually results from an upper-respiratory infection that develops into pneumonia. When
swallowing problems occur, aspiration greatly increases the incidence of repeated pneumonia and
respiratory failure can occur long before the patient actually reaches the point where his
respiratory muscles are too weak to sustain breathing.
Just as the onset and progression of extremity weakness and swallowing/speech problems
varies, so does the onset of ventilatory muscle weakness. It may occur early on before arms
and/or legs are paralyzed, or later. It may precede, coincide with, or follow the onset of
swallowing and speech problems.
While the average life expectancy for ALS patients is 2-5, twenty percent of patients will
live more than five years. Up to 10% will survive more than ten years. A very small percentage
progress very slowly and may survive as long as 15 or 20 years or more.
It is important to note that these figures are based on patients who do not go on BiPAP
or a full ventilator. Patients who opt for tube feedings and a ventilator when swallowing
and respiratory muscles fail can generally be maintained for many more years. Life expectancy
among these patients has not been reported, but the patient's age, other health problems and
the quality of nursing care available will affect life expectancy.
A decision to go on a ventilator does not halt the disease process however. Paralysis will
continue to progress and all movement including facial expression, eye movement, blinking may
eventually be lost. The patient can become "Locked In", meaning that a fully alert and
aware mind is trapped in a body that won't allow communication with care givers.