ALS - Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS), also known as motor neuron disease (MND), or Lou Gehrig's disease, is a specific disease which causes the death of neurons controlling voluntary muscles. ALS is characterized by stiff muscles, muscle twitching and gradually worsening weakness due to muscles decreasing in size. This results in difficulty speaking, swallowing and eventually breathing.

SIGNS AND SYMPTOMS:

• The disorder causes muscle weakness, atrophy and muscle spasms throughout the body due to the degeneration of the upper motor 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 disorder.
• Cognitive or behavioral dysfunction is present in 30-50% of individuals with ALS.
• Around half of the people with ALS will experience mild changes in cognition and behavior, and 10-15% will show signs of frontotemporal dementia.
• Repeating phrases or gestures, apathy and lose of inhibition are frequently reported behavioral features of ALS.
• Language dysfunction, executive dysfunction and troubles with social cognition and verbal memory are the most commonly reported cognitive symptoms in ALS.
• About half of the people who have ALS experience emotional lability, in which they cry or laugh for no reason.
• Sensory nerves and the autonomic nervous system are generally unaffected, meaning the majority of people with ALS maintain heavy sight, touch, smell and taste.
• Although the order and rate of symptoms vary from person to person, the disease eventually spread to unaffected regions and the affected regions become more affected.
• Most people eventually are not able to walk or use their hands and arms, lose ability to apeak and swallow food and their own saliva, and begin to lose the ability to cough and to breathe.
• The rate of progression can be measured using an outcome measure called the 'ALS Functional Rating Scale Revised (ALSFRS-R)', a 12 item instrument administered as a clinical interview or self-reported questionare that produces a score between 48 (normal function) and 0 (severe disability).
• Difficulty in chewing and swallowing makes eating very difficult and increase the risk of choking or of aspirating food into the lungs. As the diaphragm and intercoastal muscles of the ribcage that support breathing weaken, measure of lung function such as vital capacity and inspiration pressure diminish. Most people with ALS die of respiratory failure or pneumonia.

CAUSES:

Though the exact cause of ALS is unknown, genetic factors and environmental factors are thought to be roughly equal important. The genetic factors are better understood than the environmental factor; no specific environmental. factors has been definitively shown to cause ALS.

GENETICS:

• ALS can be classified as familial or sporadic, depending on whether or not there is a family history of the disease.
• The strictest definition of familial ALS is that a person with ALS must have two or more first degree relatives (children, siblings or parents) who also have ALS. or a person with ALS must have at least one second degree relative (grandparents, uncles, aunts or nephews) who also have ALS.
• Familial ALS is usually said to account for 10% of all cases of ALS.
• In sporadic ALS, there is no family history of the disease. Sporadic ALS and familial ALS appear identical clinically and pathological and are similar genetically.
• More than 20 genes have been associated with familial ALS, of which four account for the majority of cases: C9orf72 (40%), SOD1 (20%), FUS (1-5%) and TARDBP (1-5%).

ENVIRONMENTAL FACTORS:

Where no family history of the disease is present possible evidence of this disease include smoking, various proposed factors include exposure to environmental toxins, as well as alcohol and tobacco use. Chronic exposure to lead or exposure to other heavy metals, beta-carotene intake, head injury, omega-three fatty acid intake, exposure to extremely low frequency electromagnetic fields, pesticides and serum uric acid levels.

MECHANISM:

ALS attacks motor neurons in the brain and spinal cord. 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 development or movement is lost. With voluntary muscle action progressively affected, patients in the later stages of the disease may become totally paralyzed.

Other cell types in the CNS that support motor neurons called glia, including astrocytes and oligodendrocytes are also involved in disease. 

Following are the some known disease mechanisms:

Axon structure and dynamics: Transport of materials up and down the length of the motor neuron is an important cellular process that may play role into the damage seen in ALS. There are proteins within the nerve fibers that maintain the motor neurons.

Mitochondria: In ALS, evidence is building that actions on or originating in the mitochondria may be an important part of the disease. Mitochondria show damage early in the ALS disease process.

Glutamate: It can be a destructive factor in ALS. Investigators are working to find out its role and process.

Inflammation: Neuroinflammation accompanies the death of motor neurons in ALS.

TREATMENT:

Treatment depends on stage. Medications and therapies that can slow ALS and reduce discomfort, are:

Two medications are currently approved by the Food And Drug Administration for the treatment of ALS are : Riluzole (Rilutek) and Edaravone (Radicava).

Breathing core: The patient may choose mechanical ventilation to help breathe. Doctors also insert a tube surgically (tracheostomy) which is connected to respirator.

Physical therapy: Regular exercise can help patient to improve sense of well-being. Appropriate stretching can help prevent pain and help patients muscles function.

Speech therapy:  Speech therapist help the patient to explore other methods of communication.

Nutritional Support: ALS affected people should eat foods that are easier to swallow and meet their nutritional requirement.

Physiological and Social Support

PREVENTION:

• At this time, medical science can offer no means for preventing ALS because the causes are unknown. Research into molecular and biochemical factors may lead to earlier diagnosis and prevention of ALS.
• ALS can be prevented by eating plenty of vegetables and fruits.
• A higher total carotenoid intake was associated with decrease risk of ALS.
• Diets high in carotene and lutein commonly present in dark green vegetables had a decreased risk of ALS.