Amyotrophic lateral sclerosis
DefinitionAmyotrophic lateral sclerosis (ALS) is a disease that breaks down tissues in the nervous system (a neurodegenerative disease) of unknown cause that affects the nerves responsible for movement. It is also known as motor neuron disease and Lou Gehrig's disease, after the baseball player whose career it ended.
DescriptionALS is a disease of the motor neurons, those nerve cells reaching from the brain to the spinal cord (upper motor neurons) and the spinal cord to the peripheral nerves (lower motor neurons) that control muscle movement. In ALS, for unknown reasons, these neurons die, leading to a progressive loss of the ability to move virtually any of the muscles in the body. ALS affects "voluntary" muscles, those controlled by conscious thought, such as the arm, leg, and trunk muscles. ALS, in and of itself, does not affect sensation, thought processes, the heart muscle, or the "smooth" muscle of the digestive system, bladder, and other internal organs. Most people with ALS retain function of their eye muscles as well. However, various forms of ALS may be associated with a loss of intellectual function (dementia ) or sensory symptoms.
10% of cases are inherited or genetic problem while in the rest of cases there is no known cause for ALS. Currently, experts do not know precisely what causes ALS. It can affect anyone, regardless of gender, race, ethnicity or geographical location.
As well as inheritance, researchers are investigating several different possible causes of ALS, including the following:
- Disorganized immune response: the immune system may attack some of the body's cells, potentially killing nerve cells
- Chemical imbalance: people with ALS often have higher levels of glutamate, a chemical messenger in the brain, near the motor neurons. Glutamate in high quantities is known to be toxic to nerve cells
- Mishandling of proteins: if proteins are not processed correctly by nerve cells, abnormal proteins could potentially accumulate and cause the nerve cells to die.
- Environmental factor: Those living in some part of the world may likely have the condition than some living elsewhere.
Signs And SymptomsThe symptoms of ALS develop at different rates for different people. The onset of symptoms can be so slight that they can be overlooked until they have developed into more obvious weaknesses or atrophy.
Common symptoms of ALS are:
- Difficulty in carrying out daily activities, including walking
- Increased clumsiness
- Weakness in the feet, hands, legs and ankles
- Cramping and twitching in the arms, shoulders or tongue
- Difficulty in maintaining good posture and holding the head up
- Uncontrolled outbursts of laughing or crying
- Slurring of speech and difficulty with voice projection
- Difficulties with breathing and swallowing (in advanced cases).
Other factorsWhere no family history of the disease is present – i.e., in around 90% of cases – there is no known cause for ALS. Potential causes for which there is inconclusive evidence includes head trauma, military service, frequent drug use, and participation in contact sports. More recently, some research has suggested that there may be a link between ALS and food contaminated by blue-green algae.
Test And Diagnosis.There is no single test that can be used to diagnose ALS. Instead, a health care provider will make a decision based on the symptoms that are presented, alongside using tests in order to rule out other conditions that can cause similar symptoms.
Electromyography (EMG) and nerve conduction study (NCS) can detect electrical energy in muscles and the ability of nerves to send signals respectively. EMG and NCS can be used to support ALS diagnosis and rule out peripheral neuropathy (peripheral nerve damage) and myopathy (muscle disease).
Magnetic resonance imaging (MRI) does not reveal evidence of ALS, but can be used to show other problems that could be causing the patient's symptoms. These problems include spinal cord tumors and herniated disks in the neck.
Doctors can also request that blood and urine tests are carried out, as well as tests on spinal fluid samples, extracted with a lumbar puncture. A muscle biopsy can be carried out in order to rule out myopathy.
As well as the conditions mentioned above, the following medical problems can also produce similar symptoms to ALS, and thus may need to be ruled out prior to a diagnosis being made:
- Human immunodeficiency virus (HIV)
- Lyme disease
- Multiple sclerosis
- West Nile virus.
Treatment And Prevention.There is no cure for ALS and so treatment focuses on alleviating the effects of the symptoms and preventing the development of unnecessary complications.
As the effects of ALS can cause a range of physical, mental and social changes for patients, it may be beneficial to have ALS care managed by an integrated multidisciplinary team of doctors. An integrated team could help to improve the quality of life with ALS and prolong survival.
Riluzole (Rilutek) is the only drug that has been approved for ALS treatment by the Food and Drug Administration (FDA). In some people, it slows the progression of the disease and may work by reducing the body's levels of glutamate. Doctors can also prescribe medication to treat many of the symptoms of ALS.
Support groups can provide emotional support for patients and carers alike.
Occupational therapy can help people with ALS maintain their independence for as long as possible. Occupational therapists can suggest adaptive equipment and assistive technology to enable people to continue their daily routines. Therapists can also train people to compensate for hand and arm weaknesses.
Breathing therapy may be required as the disease progresses and the respiratory muscles get weaker. Doctors can provide devices to assist breathing at night, and mechanical ventilation is also an option. In mechanical ventilation, a tube connected to a respirator is inserted in a surgically created hole in the neck (tracheostomy) into the windpipe.
Speech therapy becomes useful when the muscles used in speech become affected by ALS. Speech therapists can teach adaptive techniques when speech becomes difficult. Other methods of communication such as writing can be discussed, or more advanced forms of technology such as computer-based equipment.
Nutritional support is important when swallowing becomes difficult. Nutritionists can advise patients and caregivers on how to prepare meals that are easier to swallow while meeting all of the individual's nutritional needs. Suction devices and feeding tubes can be employed to help individuals eating food orally.
Psychological and social support is important for helping patients and caregivers with the emotional and financial challenges that are created by ALS, particularly as the disease progresses. Support groups can provide comfort through shared experiences, for both patients, family and friends alike.
For the first time, researchers have successfully constructed a strategy targeting a specific genetic mutation that causes amyotrophic lateral sclerosis and a type of dementia. And the exciting news is that their findings show it may be possible to treat a large number of patients who have these two diseases.
Copper compound could form basis for first Lou Gehrig's disease therapy
Lou Gehrig's disease - also known as amyotrophic lateral sclerosis - is an incurable, fatal disease that affects as many as 30,000 individuals in the US. But a new study published in the Journal of Neuroscience suggests a copper compound could be used in therapy for the condition.