Amyotrophic lateral sclerosis (ALS) is a progressive, degenerative
disease of the nervous system. It is one of a group of diseases, called motor neuron diseases (MND), in which specialized
nerve cells that control movement of the voluntary muscles gradually cease functioning and die. These nerve cells, called
motor neurons, carry impulses from the brain to the brainstem and the spinal cord. The impulses are then carried to the muscles.
The muscles respond to these messages by coordinated relaxation or contraction corresponding to willed movement. In ALS and
other motor neuron diseases, motor neurons gradually deteriorate. Because the nerve cells that stimulate them have died, the
muscle tissues waste away. This results in progressive muscle weakness, atrophy, and often spasticity, or excess muscle tone.
Only the motor neurons are affected. Other nerve cells, such as sensory neurons that bring information from sense organs to
the brain, remain healthy.
Are there other names for ALS?
ALS, also known as motor neuron disease
(MND), is commonly called Lou Gehrig's disease for the famous New York Yankee's baseball player who died of ALS in 1941. ALS
is sometimes referred to as Charcot's disease for the French neurologist Jean-Martin Charcot who identified the disease in
Who gets ALS?
Most who develop ALS are between
40 and 70 years of age, although the disease can strike at any age. Men are affected slightly more frequently than women.
ALS occurs throughout the world regardless of racial, ethnic or socioeconomic status.
Some studies have identified areas
that at certain times have appeared to have greater than expected numbers of cases. This has occurred in the past in the western
Pacific islands and in parts of Japan and Australia.
Other areas in the continental United States
have been reported but have not stood up to careful epidemiological investigations.
How common is ALS?
More than 5,600 Americans are diagnosed
with ALS each year or two new ALS cases per 100,000 people (incidence). Approximately 35,000 people at any given time are
living with ALS in the United States or
six to eight people per 100,000 population (prevalence). The incidence of ALS is close to that of multiple sclerosis and four
times that of muscular dystrophy.
What are the symptoms of ALS?
ALS strikes people in different ways
and progression of the disease is often irregular. Some of the early symptoms of ALS are:
or difficulty in coordination in one limb
in speaking or swallowing
muscle twitches, spasms, or cramps
weight loss or loss of muscle bulk
The symptoms and clinical features
of the disease depend on the location of the affected motor neurons. Speech and swallowing impairments are called bulbar symptoms.
They indicate that neurons in the brainstem are affected. Weakness of the respiratory muscles, muscle weakness, and loss of
mobility in the arms and legs are called somatic symptoms. They indicate spinal cord involvement. In classical ALS, a mixture
of upper and lower motor neurons are involved, with both bulbar and somatic symptoms.
- Lower motor neuron symptoms
Weakness and muscle wasting are common
when lower motor neuron involvement predominates. The patient or physician usually notices fasciculation, or muscle twitching.
Fasciculation is a sign of muscle irritability, as the normal action of the lower motor neuron on the muscle is impaired.
The sole involvement of lower motor neurons can be seen in a form of ALS called progressive muscular atrophy. Fasciculation
is described as "benign" if there is no muscle weakness, atrophy, or impairment of motor function. Fasciculation is described
as "pathologic" when it occurs in ALS with other symptoms.
motor neuron symptoms
Spasticity, or stiffness, in the lower limbs, face, or jaw indicates upper motor neuron involvement. Spasticity in
the legs often produces severe walking difficulties. The patient may complain of heaviness, fatigue, stiffness, or lack of
coordination of any affected limb. Reflexes are very brisk, or exaggerated. Outbursts of laughter or crying with minimal provocation
can occur. This is called emotional lability and is referred to as a pseudo-bulbar affect. Both brisk reflexes and emotional
lability involve the inability to inhibit reflexes.
How is ALS diagnosed?
The diagnosis of ALS is a "clinical
diagnosis," meaning there is no specific test that gives a definitive answer. Before a diagnosis of ALS is confirmed, many
tests must be administered to rule out illnesses with symptoms that may mimic ALS. These may include an MRI of the brain or
spinal cord, an electromyography (EMG) study of nerve and muscle function and a variety of blood and urine tests. By evaluating
these tests, the patient's medical history and performing a complete neurological exam, the neurologist can usually reach
a definitive diagnosis.
It is always recommended that patients
seek a second opinion by a neurologist experienced with ALS in order to decrease the possibility of an incorrect diagnosis.
In some cases a definitive diagnosis can be made only after several months of observation and retesting.
What is the prognosis of ALS?
ALS progresses at different rates
in each individual. The average survival for someone affected by ALS is three to five years. A small percentage of people
have a very slow progression and live 10-20 years with the illness at various levels of disability. Weakness of the bulbar
and somatic muscles produces a decline in speech, swallowing, and limb strength and function. The ALS patient usually remains
alert throughout the course of the illness and retains normal sensation, vision, and bowel function. Bladder function is impaired
in 1% of patients. Generally, ALS is not a physically painful condition. Discomfort can result from immobility and joint contractures,
a shortening of muscles resulting in deformity. While most patients do not have loss of intellectual function, some may have
subtle changes in mood, behavior, or personality. In a small minority of patients, more significant changes in behavior and
judgment suggest a form of dementia.
Each ALS patient is unique in regard
to the rate and characteristics of the progression of the disease. The Lois
Insolia ALS Center
provides a multidisciplinary approach to patient care, including an individualized treatment plan guided by the patient's
personal preferences and wishes. Although the clinical progression can vary greatly, 50 percent of those diagnosed will succumb
to the illness within five years of the onset of symptoms
What causes ALS?
It is likely that there are several
different causes of ALS. Two genes have been identified that cause familial ALS. The causes of sporadic forms of ALS are still
One hypothesis is that a group of
gene mutations inherited together predispose one to ALS such that a threshold is formed. Environmental factors may "push"
someone over the threshold so that ALS symptoms occur. Both the predisposing genes and environmental factors are unknown at
Is there any treatment for ALS?
Many of the symptoms of ALS are treatable,
but there are no drugs available to cure the disease. Rilutekę, the first FDA-approved medication for the treatment of ALS,
has been shown to modestly increase lifespan. Since it became available in 1996, two retrospective studies presented at the
12th International Symposium on ALS/MND in 2001 indicated that Rilutekę appears to have a greater impact on life expectancy
than was reported in initial drug trials.
The quality of life of patients with ALS can often be improved by various
treatments and interventions. Proper positioning, exercise, physiotherapy, and medications can help keep patients comfortable.
Patients with significant bulbar involvement may require help to improve communication or ensure safe and adequate nutrition.
A gastrostomy (feeding) tube may be suggested if there is recurrent pneumonia, high risk of aspiration (inhaling food or liquids
into the lungs), inadequate nutrition, rapid weight loss, or extended feeding time. A wide range of devices and techniques
can address problems with communication. Ultimately, ALS may result in respiratory decline, requiring consideration of respiratory
support, including non-invasive ventilation such as a BiPAP (bilevel positive airway pressure), or a tracheostomy and a ventilator.
Is ALS inherited?
Familial (genetic) ALS accounts for
10% of all ALS cases. ALS is considered familial if there are two or more cases within the same bloodline. If no family history
exists, the disease is termed sporadic and other family members are not thought to be at increased risk for developing the
Are there diseases similar to
Although it is the most serious,
ALS is one of a number of diseases affecting the nerve cell, or motor neuron. Some involve only upper motor neurons, which
run from the motor cortex of the brain to the brain stem and/or spinal cord. Others involve lower motor neurons, which run
from the brain stem and spinal cord to muscles.
Spinal bulbar muscular atrophy (Kennedy's Disease)
- Spinal muscular atrophy (SMA)
SMA variations include childhood forms
and a less frequent adult form, which involves only the lower motor neurons. Inheritance of adult SMA is autosomal recessive.
Symptoms are generalized weakness and muscle wasting with muscle twitching. Onset is over 18 years into adulthood with variable
progression and normal life expectancy.
- Primary lateral sclerosis (PLS)
PLS, a degenerative disease of the upper
motor neurons only, has symptoms of progressive spasticity, difficulty in walking, and pseudobulbar affect. PLS affects the
trunk, extremities and bulbar muscles. PLS is not considered to shorten life expectancy as it has a slow progression over
the course of approximately 20 years. Because ALS may initially present with signs of only upper motor neuron involvement,
a diagnosis of PLS has the potential to be reclassified as ALS if sufficient signs of upper and lower motor neuron involvement
Symptoms are weakness and muscle wasting
of the bulbar muscles (throat and mouth) and skeletal muscles. Facial and muscle jumping is common; breast development, infertility
and testicular wasting can occur. It usually affects only men. Females are carriers who are usually asymptomatic or have a
mild form. Onset is adulthood with progression being slow and variable with normal lifespan. Inheritance is X-linked recessive.